10-17-01CraniofacialAnomaliesPart1

INTRODUCTION

The field of craniofacial surgery has grown dra-matically over the past 30+ years. Since the adventof combined intra- and extracranial movements ofthe face and skull, many abnormalities previouslyconsidered uncorrectable are now amenable to sur-gery. Together with advances in craniofacial surgery,there has been a need for more accurate preopera-tive diagnostics and more sophisticated methods topredict surgical outcome.

A basic understanding of the systematic approachto analysis of facial deformities, knowledge of themore popular techniques for osteotomy and tissuemovement, and awareness of the long-term prog-noses of such surgical manipulations will enable thecraniofacial surgeon to make an appropriate treat-ment plan to deal with a patient’s deformity.

For the surgery of craniofacial malformations tobe considered successful and the results sociallyacceptable, the final dimensions and proportionsobtained through surgical movements must closelyapproximate known normal values corrected for cul-tural differences. Representative articles from thedental and surgical literature have been selected todemonstrate the normal skeletal and soft-tissue rela-tionships of the face and skull. The results of bonymovements and their intimately related soft-tissueresponses are discussed, along with a review ofosteotomies of the midface and mandible.

FACIAL PROPORTIONS

General Esthetic Relationships

Farkas1 compared the profile inclinations of ran-domly selected young adult Caucasians withoutocclusal problems to artworks of the past and present.Modern art representations are characterized by ahead which is narrower and shorter than in ancienttimes. The modern face is elongated and has a

longer chin than the classical face. In addition,Farkas’s study subjects exhibited a receding lowerface, less tilt to the forehead, and a less prominentupper lip and chin than was depicted in older artworks (Fig 1).

Fig 1. Proportions of the modern Western face. (Reprinted withpermission from Farkas LG et al: Vertical and horizontal propor-tions of the face in young adult North American Caucasians:Revision of neoclassical canons. Plast Reconstr Surg 75:328,1985.)

In a companion study, Farkas and associates2 ana-lyzed the vertical and horizontal proportions of theCaucasian face. Analysis of their data led the authorsto the following conclusions, confirmed and illus-trated by Lehocky3 (Figs 2.1–2.7).

The width of the nose is either smaller or greaterthan one-fourth the width of the face 63% of thetime.

The nasal bridge inclination exceeds the tilt of themedial axis of the ear in 91% of subjects.

Farkas and Kolar4 analyzed ethnic variations inaesthetic facial parameters among North AmericanCaucasian women, and concluded that these varia-tions are not of major concern when planning aes-thetic correction. While an awareness of the idealfacial proportions undoubtedly sharpens our aestheticsense, strict adherence to predetermined values does

CRANIOFACIAL ANOMALIES I:CEPHALOMETRICS AND ORTHOGNATHIC SURGERY

Raj S Ambay MD, DDS and Delora L Mount MD, FACS

SRPS Volume 10, Number 17, Part 1

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Fig 2.2. Classical: The combined forehead–face height isdivided into three equal parts. Modern: The nasion-subnasaledistance is always less than the subnasale-gnathion distance. Thetrichion-nasion distance is greater than the nasion-subnasaledistance in 95% of subjects. The relationship between trichion-nasion and subnasale-gnathion varies.

Fig 2.3. Classical: The combined head-face height is dividedinto four equal parts. Modern: The glabella-subnasale distanceis greater than the vertex-trichion distance in 87% and the vertex-trichion distance is greater than the trichion-glabella distance in52% of subjects. The subnasale-gnathion distance is greater thanthe glabella-subnasale 68% of the time, greater than the trichion-glabella 100% of the time, and greater than the vertex-trichion100% of the time.

Fig 2.5. The interocular distance is less than the nasal width in38% of subjects, greater in 21.4%.

Fig 2.6. The interocular distance is greater than or equal to thefissure distance 85% of the time.

Fig 2.4. The width of the mouth is greater than 1.5× the widthof the nose 60% of the time.

Fig 2.1. Classical: The combined head–face height is dividedinto two equal parts. Modern: The vertex-endocanthiondistance is greater than the endocanthion-gnathion distance in80% of subjects.

Figs 2.1 to 2.6 reprinted with permission from Lehocky B:Anthropometry and Cephalometric Facial Analysis. In: MathesSJ (ed), Plastic Surgery, 2nd ed. Philadelphia, Elsevier, 2006. Vol2, Part 1, Ch 41, pp 1-30.)


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not necessarily make for an attractive face in everycase.

In an effort to reduce the esthetics of the face tothe language of mathematics, Ricketts5 proposed arelationship between facial form and the GoldenMean. The ancient Greeks deemed mathematicalprogression in nature as both pleasing and reproduc-ible while recognizing that absolute symmetry ismonotonous and uninteresting. The Golden Mean,also called the Golden Section, Golden Ratio, orDivine Proportion, refers to the point on a given lineat which the ratio of the smaller to the larger portionis exactly the same as that of the larger section to theoriginal line. Ricketts5 claims the same proportionsapply in the human face: A ratio of 1.0:1.618 isconsistent with facial balance (Fig 3).

FACIAL SUBUNITS

A general impression of the configuration of theface can be obtained by observing the head. Headsare categorized as brachycephalic (short and wide),dolichocephalic (long and narrow), or mesocephalic(of medium length and width). The size, location,and angulation of the specific parts contribute to theoverall impression and are important in facial har-mony. Ethnic variations do not detract from theinherent balance between the facial subunits.3-5

Ears. The ear canal is located along a horizontalline halfway between the outer canthus of the eyeand the alar-facial junction and between the back ofthe skull and the frontofacial plane. The superiorpoint of attachment of the ear to the head is justabove the upper lid; the inferior point is in line withthe alar-facial junction.

The longitudinal axis of the ear is usually morevertical than the nasal dorsum by approximately 15°.

There is a great deal of variability in the exact inclina-tion of the ear among subjects (9° to 29°), but 20° offthe vertical seems to be a pleasing angle. The earprotrudes from the skull posteriorly at an angle of20°.2,6

Forehead. Ousterhout7 discusses the occurrenceand surgical correction of excessive glabellar promi-nence and supraorbital ridge projection, which hesees as characteristic of overly masculine features.The normal male skull has extensive supraorbital boss-ing above which there is a flat area comprising thevertical component of the forehead, which then givesway to a convex curvature in the upper forehead. Inwomen the supraorbital bossing is considerably lesspronounced and frequently nonexistent; above itthere is usually less flatness and more of a continu-ous mild curvature to the upper forehead. The degreeof contour deformity and the thickness of bone dic-tate treatment, as follows:

Fig 2.7. Nose length is less than ear length in 95% of subjects.

Fig 3. Golden sections in vertical and horizontal analysis of theface. (Reprinted with permission from Ricketts RM: Divineproportion in facial esthetics. Clin Plast Surg 9:401, 1982.)


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Group I includes patients with normal or slightlyanterior projection of the supraorbital rims, minimalto moderate bossing, thick skull bone over the fron-tal sinus, or absence of the frontal sinus. Thesedeformities are corrected by bone reduction aloneusing a power burr.

Group II includes individuals with relatively nor-mal or slightly anterior placement of the supraorbitalrims in whom the frontal bossing is combined withrelatively thin bone over the frontal sinuses, whichare of normal size. Correction requires completingas much contouring of the bone as possible withoutentering the sinus, and then augmenting the concav-ity above the frontal bossing with methyl methacry-late until the desired shape is achieved. Edgerton8

believes sinus cranialization and secondary correc-tion with methyl methacrylate is a reasonable alter-native in these patients.

Group III consists of patients whose supraorbitalrims are so pronounced that adequate bone reduc-tion is impossible without entering the frontal sinus.In this case the sinus is opened by an osteotomy andthe entire anterior wall and associated supraorbitalrim are set back and wired in position.

Eyes. The eyes are located at the junction of theupper and middle thirds of the face. They are typi-cally separated by one eye-breadth, which equalsthe width of the root of the nose. The eyes arebounded by the bony orbital rims, which relate spe-cifically to the cornea. In the Caucasian adult, theaverage vertical orbital height measured from thesuperior rim to the inferior rim is about 19mm. Thesuperior orbital rim protrudes beyond the inferiororbital rim some 11–14mm. The anterior edge ofthe cornea lies approximately 2–3mm anterior tothe inferior orbital rim, 12–16mm anterior to thelateral orbital rim, and 8–10mm posterior to thesuperior orbital rim.9

The canthi distinguish the eyelids medially andlaterally. The medial canthus is normally in line withor medial to a vertical plane taken from the lateralala. The lateral canthus is 3mm above the medialcanthus,10 contributing to a fissure opening ofapproximately 30mm. The intercanthal distance isapproximately equal to the alar base width or one-half the interpupillary distance.3,4,11

The upper lid is larger, more curved, and muchmore active and mobile than the lower lid. If theeye is divided into vertical thirds, the highest point of

the upper lid is at the junction of the medial andcentral thirds while the lowest point of the lower lidcorresponds with the border of the central and lat-eral thirds.

Farkas and others12 compared anthropometric andcephalometric orbital measurements in white adultNorth Americans with hypertelorism. Both sexes and13 craniofacial syndromes were represented. Theabnormally wide intercanthal distance had a 90%correlation with an abnormally wide bony interor-bital distance. The surface intercanthal width waslarger than the bony interorbital width in all patients.The differences were smaller in mild cases and largerin severe cases. The article offers useful tables ofage-adjusted orbital measurements in the various syn-dromes compared with the normal population.

Mouth and Lips. The distance from the base ofthe nose to the inferior border of the upper lip makesup one-third of the lower third of the face. Thelower two-thirds extend from this point to the chin.The vermilion border of the lower lip is midwaybetween the base of the nose and the chin.11 Ordi-narily the corners of the mouth fall almost halfwaybetween the outer limits of the alae and the pupils.(Pupil planes are established by drawing a line throughthe inner and outer canthi of each eye and droppingperpendiculars through the pupil.) A narrow mouthwill approach the width of the nose, while a widemouth may extend to just below the pupils.11 Inprofile and with the facial muscles relaxed, the lipsshould be very slightly parted and the lower lip shouldlie only just posterior to the upper lip.

Bishara and coworkers13 sought to establish longi-tudinal standards for the following soft-tissue param-eters of the facial profile:

• facial convexity including the nose

• facial convexity excluding the nose

• Holdaway soft-tissue angle

• Merrifield’s Z angle

• Rickett’s aesthetic plane relative to the upper lip

• Rickett’s aesthetic plane relative to the lower lip

The upper lip should rest 4mm posterior to atangent drawn between the soft-tissue chin and thetip of the nose. Adult male upper lips are slightlymore retracted than female upper lips, although males5–17 years old consistently demonstrate a more


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protrusive upper lip than females. This observationis important in treatment planning, arguing againstapplying adult standards to adolescents. The lowerlip is ideally situated 2mm posterior to the nose-chinplane in adult female subjects and slightly more pos-terior in male subjects. The lower lip becomes moreretrusive with age in both sexes.

Chin. The strength of a face is usually a functionof the degree of prominence of the chin relative tothe neck.11 Ricketts14 notes that the lips are con-tained within a line extending from the tip of thenose to the most prominent part of the chin (soft-tissue pogonion). A vertical line from the lower-most point of this line upwards should touch thevermilion of the upper lip (Fig 4). The skeletalposition of the chin is illustrated in the section oncephalometrics and further defined in the sectionon genioplasty.

Fig 4. Nose-lip-chin relationships: Left, prognathic mandible;Center, orthognathic mandible; and Right, retrognathic man-dible. (Reprinted with permission from Ricketts RM: Esthetics,environment, and the law of lip relation. Am J Orthod 54:272,1968.)

Nose. The nose has been described as the focalpoint of the face.11 Together with the maxilla, thenose dominates the middle third of the face. Theangle of projection of the nose from the face rangesfrom 30° to 36° (Fig 5), while the columella-lip anglevaries from an average of 90° in men to 95°–110° inwomen (Fig 6). In profile, a 2–3mm-wide segmentof columella should be seen below the rim of theala. The nostrils are oval and their long axes shouldincline towards the tip.11

PHOTOMETRICS

Standardized photogrammometry complementsdirect clinical measurements and supplies clinical tem-plates that are useful in formulating a treatment plan.Farkas4 states that photogrammometry, even underthe most standardized conditions, offers only a lim-ited number of reliable measurements because ofdistortion in the two-dimensional photographs. Oth-ers15-19 have found photometric analysis to be a use-ful adjunct in planning surgical skeletal changes ofthe face.

The basis for standard positioning of the patient isthe Frankfort horizontal line. This is a line passingthrough an imaginary plane touching four points:the two infraorbital rims and the two superior posi-tions of the external auditory canals.20 A good studiochair is necessary for the subject’s comfort and opti-mum positioning. The subject may be asked to applylight pressure to the lumbar region while in an upright

Fig 5. Range of nasal dorsal angles. (Reprinted with permissionfrom D’Ottaviano N and Baroudi R: Surgical and esthetic aspectsof the facial profile. Int J Oral Surg 3:243, 1974.)

Fig 6. Range of columella-labial angles. (Reprinted with permis-sion from D’Ottaviano N and Baroudi R: Surgical and estheticaspects of the facial profile. Int J Oral Surg 3:243, 1974.)


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sitting position. Unusual forward or backward bend-ing will distort the image and produce a bad photo-graph.21 One should also remember that as thesubject gets closer to the lens, the amount of lightreaching the film decreases.

To obtain a good film frame and subject position-ing, plastic surgeons can use the reproduction scale:eg, one-tenth life size on the film is equivalent to a1:10 reproduction ratio. A viewfinder screen with agrid is helpful in obtaining a proper image, particu-larly when the tone is outside the standard view.Viewing 25 forward in a lighter view may highlightthe opposite eyebrow, whereas 25 back may com-press the eyebrow view. To obtain other views, thepatient is rotated around the head central axis. In allright/left or superior/inferior views, the patient shouldbe rotated along the appropriate axis with an equaldegree of change on either side. The anatomic partof interest should be the focus of the image—forinstance, if the objective of the photograph is toevaluate the nose, the nasal tip should be centeredin the frame.22

The data gathered through photometric analysiscan be both valuable and reliable provided the fol-lowing criteria are met:

• A standard 90–105mm lens is used to minimizeperipheral distortion.

• A ruler is held in the field to guarantee accurateenlargement.

• The head position is stabilized with a cephalostator equivalent method.

• The prescribed subject-to-camera distance is kept.

• Critical soft-tissue landmarks are marked or oth-erwise identified.

• Only those landmarks that are exactly perpen-dicular or parallel to the lens are measured. Thisexcludes distances involving depth-of-field, suchas nasal length on AP view.

In 1983 Kinnebrew and colleagues16 offered thefollowing simple guidelines for photometric analysis.They used a projected 35mm slide which is sized toa cephalometric tracing. The dysmorphic parts wereadjusted and used as a guide in treatment planning.Phillips and associates23 questioned the validity ofthis projection–superimposition technique on the basisof errors in enlargement factors between photographsand x-ray films discovered on grid analysis.

Butow17 describes a lateral photometric analysismethod founded on Leonardo da Vinci’s facial thirdsthat incorporates mathematically computed trianglesof the facial plane and nasal structures. Unfortu-nately, the aesthetic “norms” were established frommeasurements of only one man and one womanconsidered to have normal features.

Sen Savara and coworkers24 advocate biostereo-metric photography for evaluating craniofacial malfor-mations. The basic principle of stereophoto-grammetry involves the juxtaposition of twostereophotographs so that the left eye sees the leftphotograph and the right eye sees the right photo-graph, both in proper relation. The result is theperception of depth as clearly as if the object wereseen directly. The technique of stereophotographyis adapted from methods used in topographic fieldmapping: An acrylic control frame is constructed tofit over and around the subject’s head and targetsare affixed to the control frame to establish intercon-necting distances and arrive at X and Y coordinatesgeometrically. The X-Y-Z measurement thus obtainedprovides a contour map that is true to within 0.1mm.

The degree of accuracy possible with stereopho-tography, together with control of the magnification,allows exact correlation of soft-tissue values with thoseobtained by cephalometrograms and CT scans beforesurgery. Postoperative surface alterations in responseto movement of the underlying bony structures canbe precisely quantified to within 0.3mm.

More recently, computer programs have beendeveloped to collect three-dimensional coordinatesdirectly from digital cephalograms, eliminating theneed for hard tracing of mouse-based, X-Y digitizingtablets.25

COMPUTER IMAGING

Modern patient imaging involves the use of two-dimensional images captured and manipulated byreadily available office-based computers. These sys-tems have found extensive use in hair styling andmakeup, landscaping, home remodeling, interiordesign, orthodontics, cosmetic dentistry, and plasticsurgery. Computer imaging technology has evolvedfrom an esthetic marketing tool to a realistic surgicalcommunication device. Critics view computer imag-ing as sophisticated gadgetry designed to lure patientsinto surgery with the promise of tantalizing results.While imaging systems can undoubtedly be misused


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to deceive unsuspecting patients, the issue remainsan ethical one. Computer-based analyses are usedto predict surgical outcome by comparing scaled,undistorted images and the same images after modi-fication by measured, scaled adjustments. Both thepatient’s acceptance of a proposed surgical resultand the surgeon’s ability to attain that result can bejudged from a comparison of before-and-after images.

Null26 reviews the essentials of computer imagingfrom a manufacturer’s viewpoint. All commonlyavailable computer imaging systems have three basiccomponents: (1) input or image acquisition; (2) imagealteration or manipulation; and (3) image output.

Input. The image may be acquired from slide orprint scanners, moving video, or still video. Scannersoffer the highest image resolution that is necessaryfor high-quality, high-resolution output. The processinvolves preliminary photography with production ofa finished 35mm slide or photographic print, andautomatically means two patient visits, one for thephotograph and another for the imaging.

Moving video input can be achieved with stan-dard video cameras and is the least expensive way ofobtaining images. A software image-grabber cap-tures the single frame that is to be manipulated.Problems with moving video input have to do withthe wide-angle lenses common to video cameras,which can distort the image by a “fishbowl” effect.In addition, the distances and magnifications involvedwith video cameras must be standardized and rigidlymaintained. Image resolution is the lowest of thethree alternatives—in the range of 200–300lpi—which translates into an adequate screen image buta blurred output.

Still video works in much the same way as a 35mmSLR camera. The input is captured on a small dis-kette within the camera, which is then imported tothe computer. Resolution is approximately 400lpiand output quality is intermediate between movingvideo and scanned image. The video sources havethe advantage of one patient visit for consultationand imaging.

Manipulation. After the image is imported intothe computer, any of several software packages areavailable for image manipulation in either Mac orPC platform. A high-resolution color monitor withminimal pixel distortion is recommended for view-ing. Some custom-made programs include cephalo-

metric scales that facilitate precise incrementalchanges.

Output. The image may be sent to the outputdevice in its original, imported form or after enhance-ment or reduction through the software program.The screen resolution is much less than acceptablefor most output purposes, and is used only in themost inexpensive systems. The output results fromdirect electronic transport of the image to the outputdevice. Image output is in the form of color orblack-and-white prints or 35-mm slides. Slide-generating devices can be connected directly to thecomputer and will produce 35mm slides of the pre-operative and altered images. Alternatively, a colorprinter may be used to render an intermediate-resolution (300–600dpi) print of the altered image.

The ease and speed of diagnosis possible withoffice imaging and the usefulness of communicatingwith prospective patients in visible, graphic terms27

has led to extensive use of these systems.

COMPUTER-AIDED SIMULATION

Computer-aided simulation is a rapidly evolvingtechnology. Not long after the first computerizedtomography (CT) scanner appeared in 1972, clini-cians realized a stack of CT sectional images couldbe used to generate 3D information. In the early1980s researchers began looking at craniofacialdeformities, and the first 3D imaging simulation soft-ware was developed for craniofacial surgery in 1986.

Today, three-dimensional imaging has evolved intoa discipline of its own. It deals with the various formsof visualization, manipulation, and analysis of multi-dimensional medical structures.28,29 Surgeons usethe computerized technology as a tool in preopera-tive planning and prototyping of surgical procedures.The prototyping models simulate the patient and thesurgical procedure allowing surgeons to cut the modelsin a way that is similar to the final operation. Com-puterized protocols have been described for distrac-tion osteogenesis30 and for intraoperative navigationin maxillofacial surgery.31

Limitations

Along with rapid advances in technology comeindications and limitations. Since the 1980s, CTscans have been the imaging modality of choice for


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the assessment of hard tissues. More recently,reconstructed CT images have been used in plan-ning surgical manipulations in the craniofacial skel-eton. Cavalcanti et al32,33 studied cadaver headswith spiral CT scans and showed the accuracy of 3Dimages was better than for 2D. Meyer and col-leagues34 compared the outcomes of hard-tissue ma-nipulations in virtual surgery against live surgery, andshowed a close correlation of the virtual surgery withthe actual operation. The authors do note, how-ever, that despite the extensive experience of theircraniofacial surgeons, it seemed difficult to transferthe simulated surgery to the real operation.

Another limitation of computer-aided virtual sur-gery is the need for accurate registration of the softtissues following hard-tissue manipulations. Registra-tion methods such as skin markers, implanted mark-ers, and markers on templates and splints have beenused but are too imprecise. For example, skin mark-ers have an average application accuracy of 2–7mm,due either to marker dislocation or movement of themarker with the skin.35,36 Dental splints used as mark-ers are accurate within 1–2mm. Titanium screws arehighly precise markers for surgical registration, butthey require an additional surgery for insertion beforecomputerized data acquisition and the craniofacialprocedure. Another issue with marker-based regis-tration is that the markers themselves fall betweentwo slices of a CT data set. These false measure-ments can lead to translations and, even worse, rota-tions of the data set.

In an effort to improve soft-tissue registration,newer generations of video and laser-based systemscompute skin area and surfaces rather than a singlepoint. In fact, the laser-based system registers 200,000skin surface points. Marmulla and colleagues37 believethis greatly improves the accuracy of registration forsurgical navigation.

Benefits

Computer simulation has also been helpful topatients. Sarver et al38 evaluated the results of treat-ment 4 months after surgery and found that 89% ofpatients thought the image predictions were realisticand the desired results had been achieved. Com-puter simulations also helped 83% of patients with thedecision whether to undergo orthognathic surgery.

Three-dimensional CT provides superior bonedetail and is a useful adjunct in the characterization

of craniofacial deformities and for presurgical plan-ning. As with any new technology, however, onemust weigh its benefits and limitations for every indi-vidual patient.

CEPHALOMETRICS

The cephalometric landmarks are illustrated anddefined by Lehocky3 (Fig 7).

Numerous methods have been devised to assessthe spatial arrangement of the cranium, facial bones,and teeth relative to each other.39 Six major rela-tionships have been described, as follows:40,41

• maxilla to cranium

• mandible to cranium

• maxilla to mandible

• maxillary teeth to maxilla

• mandibular teeth to mandible

• maxillary teeth to mandibular teeth

Traditional cephalometric analyses use the sella–nasion or Frankfort horizontal planes as referencelines42 (Fig 8).

Other methods favor the natural head positionover the Frankfort or sella–nasion planes.43 Downs44

and Ricketts45 claim that the sella is totally unrelatedto the face. Ellis and McNamara46 also state that thesella’s position varies with head posture, bothanteroposteriorly and vertically. From our review ofcephalometric analyses, we conclude that any of thesemethods can yield consistent and reproducible resultsas long as it is accurately applied.

The cephalostat holds the head in a standard,fixed position. A pair of ear rods enter the externalauditory meatus and minimize side-to-side changesin head position. The head is further stabilized witha rod resting passively on the soft-tissues over theinferior orbital rim or nasofrontal suture to preventhead rotation along the sagittal plane. The x-raycassette is held at a constant distance from the mid-line of the cephalostat and head. The radiograph istraced on a standard x-ray light or flat slide sorterusing a fine-point (0.5mm) lead pencil. A matteacetate sheet is attached to the radiograph, and bothare affixed to the viewbox. Skeletal landmarks47 areidentified and used to plan the surgical correction.48

Cephalometric analysis can be static—comparingthe patient at any one point in time against standards


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Fig 7. (Below, left) Cephalometric landmarks. (Reprinted with permission from Lehocky B: Anthropometry and Cephalometric FacialAnalysis. In: Mathes SJ (ed), Plastic Surgery, 2nd ed. Philadelphia, Elsevier, 2006. Vol 2, Part 1, Ch 41, pp 1-30.)

Fig 8. (Above, right) Cephalometric reference planes. (Reprinted with permission from Lehocky B: Anthropometry and CephalometricFacial Analysis. In: Mathes SJ (ed), Plastic Surgery, 2nd ed. Philadelphia, Elsevier, 2006. Vol 2, Part 1, Ch 41, pp 1-30.)


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derived from other individuals, or dynamic—comparing the patient against himself at variousintervals. Regardless of the specific system one uses,the goal is the same: to obtain information aboutjaw-to-jaw and tooth-to-jaw relationships.48–52 Forpractical reasons the method should be clinicallyworkable, diagnostically realistic, and simple ratherthan cumbersome.

The analysis consists of four parts: 1) verticalmidface measurements; 2) horizontal midface mea-surements; 3) horizontal lower face measurements;and 4) dental measurements. The segmentalapproach allows the clinician to view and evaluateeach component alone and to relate the variouscomponents to one another and to the entire cran-iofacial complex.53

Normal Values

Tables 1 and 2 from Zide, Grayson, and McCarthy54,55

demonstrate the range of normal values for male andfemale subjects 16 years of age or older.

Table 1Vertical Midface Analysis

Table 2Horizontal Midface Analysis

(From Zide B, Grayson B, McCarthy JG: Cephalometric analysisfor upper and lower midface surgery: Part II. Plast Reconstr Surg68:961, 1981.)

Numerical values for earlier ages may be extrapo-lated from the growth charts published in An Atlas ofCraniofacial Growth by Riolo and associates.56 Com-puterized data analyses show that female subjectsgenerally complete 90% of their mandibular APgrowth by age 9, 95% by age 13, and 98% by age15. In contrast, male subjects attain 84% of man-dibular AP growth by age 9 years, 90% by age 13,

and 98% by age 19 years.57 The overall vector offacial bone growth is downward and forward, asillustrated by Enlow42 (Fig 9).

Fig 9. Diagrammatic representation of facial growth showingdownward and forward expansion of the whole face relative tothe cranial base. (Reprinted with permission from Enlow DH:The Human Face. New York, Harper & Row, 1968.)

Vertical Midface Analysis

Zide, Grayson, and McCarthy48 recommend thefollowing vertical measurements in cephalometricanalysis preliminary to surgery (Fig 10):

Me–N—anterior total face height (TFH), can be sub-divided into

N–ANS—anterior upper face height (UFH) andANS–Me—anterior lower face height (LFH), whichis in turn subdivided into

ANS–SD—increased in vertical maxillaryexcess—long face syndrome. It isreduced in short face syndrome andfollowing dental extraction andalveolar remodeling

ANS–UIE—changes with dental extractionand inclination of the incisors

Me–LIEMe–ID—is increased in mandibular defi-

ciency syndrome and reduced fol-lowing extractions and results inalveolar crest remodeling

InterincisalAr–Go—posterior lower face height


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Horizontal Midface Analysis

Measurements SN, SNO, O⊥NA, and SNA areused to evaluate the midface in a horizontal plane48

(Fig 11).

SN—The distance from the center of the sella turcicato the frontonasal suture, representing an approxi-mation of the length of the anterior cranial base.This dimension is significantly reduced in the cran-iofacial synostosis syndrome.

SNO—This measurement represents the internalangle between the lines connecting sella to nasionand nasion to orbitale. A reduced angular mea-surement may reflect retropositioning of the orbitalrim—ie, deficiency of the upper midface. Oldangular measurements relative to the cranial baseare affected by abnormalities of the latter.

O⊥NA—Linear measurement from orbitale along aline perpendicular to the NA; describes the posi-tion of the inferior orbital rim relative to the facialplane, NA.

SNA—Represents the internal angle between the linesconnecting sella to nasion and nasion to A point;describes the position of the anterior limit of the

maxillary apical base (A) in relation to the uppercraniofacial complex. It is generally increased inmaxillary hyperplasia and reduced in maxillaryhypoplasia.

Horizontal Lower Face Analysis

Grayson53 recommends the following measure-ments in presurgical cephalometric analysis (Fig 12):

Ar-Pg, Ar-B, and Ar-LIE—oblique mandibularmeasurements from the articulare at three lev-els.

Go-Pg, Go-B, and Go-LIE—linear measurements fromthe Go that describe mandibular body length atthree levels.

Ba-Pg—linear measurement from the Ba to the mostanterior point on the symphysis.When compared to the measurements of Ba-ANS and Ba-N, the relative AP position of thesestructures may be evaluated with respect to Ba.

SNB (angular ratio of the point B to anterior cranialbase)—increased in mandibular protrusion andreduced in mandibular micrognathia. The SNPg

Fig 10. Vertical measurements for cephalometric analysis. (Re-printed with permission from Zide B, Grayson B, McCarthy JG:Cephalometric analysis: Part I. Plast Reconstr Surg 68:816,1981.)

Fig 11. Horizontal measurements for cephalometric analysis.(Reprinted with permission from Zide B, Grayson B, McCarthyJG: Cephalometric analysis: Part I. Plast Reconstr Surg 68:816,1981.)


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(angular relationship of pogonion to anteriorcranial base) is increased in macrogenia andreduced in microgenia.

ANB (angular ratio between points A and B)—increased in maxillary protrusion or mandibu-lar retrusion and decreased in maxillary retru-sion or mandibular protrusion.

Angular Analysis

SN/MP—angular relationship between the inferiorborder of the mandible and the anterior cranialbase (Fig 13). Measurements of the SNA, SNB,and ANB angles and of the lower facial heightdescribe the downward and forward projec-tion of the face and define one side of thedental quadrangle extending from ANS–PNSplane to SNA–SNB plane to GO–GN plane toGO–PNS plane.47

Grayson53 details his system of cephalometricanalysis for the plastic surgeon, including howto obtain tracings, various analyses and theirmeaning, treatment planning, and predictingsurgical outcome. The author points out thatbecause of image distortion in routine radio-graphs and errors in tracing measurements, thecephalometric drawing is, at best, only an ap-proximation of the actual craniofacial structuresunder study. Given the variability in cephalom-etric values between and within populations,Grayson believes cephalometric analysis shouldbe used only to suggest, not dictate, a surgical-orthodontic procedure.

Basic Line

According to Sassouni,51 five basic planes canbe determined from the lateral cephalometrogram,namely

(1) the orbital plane, drawn from the anterior clinoidprocess to a line tangential to the roof of the orbit

(2) the parallel plane, which is simply a line parallelto the orbital plane through the base of the sellacontinued posteriorly

(3) the palatal plane, drawn from anterior nasal spineto posterior nasal spine

Fig 12. Top, Horizontal midface measurements. Pt-M may beused when the posterior nasal spine (PNS) is missing or affectedby the presence of a palatal cleft. Bottom, Horizontal lower facemeasurements. (From Grayson BH: Cephalometric analysis forthe surgeon. Clin Plast Surg 16(4):633, 1989 (top); and Zide B,Grayson B, McCarthy JG: Cephalometric analysi: Part I. PlastReconstr Surg 68:816, 1981 (center and bottom); with permis-sion.)


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(4) the occlusal plane, representing the occlusal lineof the patient’s teeth, and

(5) the mandibular plane.

In the ‘perfect’ face, lines (2) through (5), if con-tinued posteriorly, would pass through a commoncentral point. This is rarely the case, however, andPhillips58 suggests using the center (O) of a circle 1cmin diameter bound by the four lines (Fig 14).

Fig 14. Cephalometric analysis using a center point of reference(O) around which four lines converge. (Reprinted with permis-sion from Phillips JG: Photo-cephalometric analysis in treatmentplanning for surgical correction of facial disharmonies. J MaxillofacSurg 6:174, 1978.)

The Wits Appraisal

The Wits appraisal is a simple and reliable methodof relating the maxilla to the mandible. It consists ofdropping perpendiculars from points A and B ontothe occlusal plane (Fig 15).

In Class I malocclusion, points AO and BO gener-ally coincide. In Class II malocclusion, BO point isbehind AO. In Class III malocclusion, BO point isahead of AO.59 Patients with normal occlusions mayexhibit jaws that are retrognathic, orthognathic, orprognathic (Fig 16).

Fig 13. Angular measurements for cephalometric analysis. (Re-printed with permission from Zide B, Grayson B, McCarthy JG:Cephalometric analysis: Part I. Plast Reconstr Surg 68:816,1981.)


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Fig 16. Relative position of the lower jaw in retrognathia andprognathism. (Reprinted with permission from Jacobson A: Theproportionate template as a diagnostic aid. Am J Orthod 75:156,1979.)

Applications

Among the most useful relationships in cephalo-metrics is the anterior-posterior position of the jawsin reference to the cranium. Are the lower facialstructures of correct height and in proportion to eachother?

Obwegeser and Marentette60 use cephalometricmeasurements to determine the exact size, location,and relative position of the anterior cranial base,

maxillary base, and mandibular base as the first stepin facial analysis. They initially ignore the nose, lips,teeth, and chin, which, though influencing the pro-file line, are not crucial to a diagnosis. The authorsbelieve the three bases of the facial skeleton definethe profile ‘type,’ and it is the profile type, not theocclusion, that directs the treatment plan. They iden-tify three aesthetically balanced profile types (Fig 17)and introduce terminology pertinent to the diagnosisand treatment of related facial abnormalities.

CT ANALYSIS

Improvements in medical imaging based onadvanced computer technology have facilitatedanalysis of the facial skeleton. Axial computedtomography and reformatted periaxial images of theskull produce plainer images that represent tissueslices of finite thickness. The anatomic detail oneach individual sliced image can be exquisite. Com-puter graphics reformat the serial CT scans into athree-dimensional (3D) structure, but only an expe-rienced operator can interpret the spatially integratedslices.

Given the surgical ability to make large correctionsof the jaws in three planes of space, treatment plan-ning has become increasingly important. Predictiveplanning systems have evolved from simple “cut andpaste” tracing methods to more elaborate comput-erized techniques based largely on the lateral cepha-lometric radiograph. More recently, video and 3Dimaging techniques have become widely available.

Herman61 presents a general overview of the usageand technical terminology of imaging. He discussesimaging on a CT or MRI scanner using software thatruns on the scanner’s computer. The 3D98 softwareis designed for the GE CT/T 9800 scanner and isintended for 3D imaging of craniofacial cases. Marshand colleagues62 review the applications of computer-assisted medical imaging in the management of cran-iofacial deformities. Improved diagnosis and treat-ment planning are the result, and quantitative record-ing of changes of surgery and growth is made possiblethrough the use of CT imaging.

Bite and coworkers63 favor 3D CT imaging forassessing orbital volume and predicting response aftersurgery for enophthalmos. Because the referencepoint of the lateral orbital rim is frequently displacedin post-traumatic deformities, they suggest a new“fixed” bony reference point for measuring degree

Fig 15. The Wits appraisal for cephalometric analysis. (Reprintedwith permission from Jacobson A: The proportionate template asa diagnostic aid. Am J Orthod 75:156, 1979.)


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of enophthalmos. Posnick and colleagues64 use CTscans to quantitatively evaluate the intracranial vol-ume before and after surgical correction of cranio-synostosis. The accuracy of the computer-generatedanalyses was validated by comparing direct mea-surements of intracranial volumes in dry skulls withindirect values calculated by means of 1.5mm and4mm slice intervals from actual scans. The sameindirect scan data were used pre- and postopera-tively on patients operated on for craniosynostosis.Surgical findings confirmed that suture release andsimultaneous resecting procedures did in fact increasethe intracranial volumes.

Advances in CT imaging have led to integratedprograms for computer-aided treatment planning andsurgical simulation.65,66 An internal bony moulage isfabricated from the CT image and, aided by thismoulage, computer-derived implants are designedto fit the bony contour precisely and to satisfy thesoft-tissue needs. When asymmetries are involved, amirror representation can be used.

Cutting and associates66 describe a system thatoperates on a 3D database derived from combinedPA and lateral cephalograms of the patient plus theBolton normative standards. This system can beused to help plan craniofacial surgical procedures. Asurgical simulation program based on the CT datacan also be linked to the cephalometric-based pro-gram. After the clinician has selected the numberand type of osteotomies to be performed, an auto-mated optimization program computes the postop-

erative positions of the fragments that best fit theappropriate normal cephalometric form. The sur-geon then interactively modifies the design to accountfor such variables as bone graft resorption, relapsetendency, occlusal disparities, and condition of theoverlying soft-tissue matrix.

Eales and colleagues67 evaluated the accuracy ofcomputerized prediction of the soft-tissue profile afterLe Fort I osteotomy. The computer package usedwas Dentofacial Planner 5.32 software (DentofacialSoftware Inc, Toronto). The authors were surprisedat how well the computer package was able to pre-dict soft-tissue altlerations in relation to surgical move-ments of the maxilla, associated autorotation of themandible, and after genioplasty. No statistically sig-nificant differences were noted between the com-puter-predicted change and what actually occurredin 22 of 33 profile variables examined. The com-puter was less consistent when predicting changesabout the nose and upper lip, where variability inthe size, thickness, and morphology of the soft tis-sues affected the calculations.

The diminished accuracy in cleft lip/palate caseswas attributed to the different movements that wererequired and to the scarred soft-tissues. The deter-mining factor governing the response in CLP patientswas the degree of inferior repositioning of the max-illa during surgery. The degree of movement thatactually occurred was generally greater than pre-dicted by the computer. The software translated theoriginal shape of the upper lip to a new forward

Fig 17. The three esthetically balanced face types. Left, straight anteface. Center, straight retroface. Right, average face. (Reprinted withpermission from Obwegeser HL, Marentette LJ: Profile planning based on alterations in the positions of the bases of the facial thirds.J Oral Maxillofac Surg 44:302, 1986.)


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position, which changed lip shape and created prob-lems in the prediction plot. Significant differenceswere found for vertical labrale superius, horizontalstomium superius, and lip thickness measurementbetween the predicted and the actual values. In theupper lip, the governing factor determining the rela-tion of hard- to soft-tissue change is the initial lipthickness.68

Imai and Tajima69 evaluated the normal skull byCT scan and obtained reference data for thefrontoorbital region. The authors used angles andmeasurements taken from the dorsum sellae to thefrontoorbital region as a standard for advancing andreshaping forehead and orbital rims.

With improved imaging technology and com-puter algorithms, there has been a proliferationof computer software programs to aid with theplanning of orthognathic surgery.70–82 Like theimaging programs used in facial aesthetic surgery,these programs can be used to visualize potentialhard- and soft-tissue changes after maxillary and/or mandibular procedures. Most of these newimaging programs use 3D CT scanning technol-ogy to facilitate or replace the traditional tech-niques of cephalometric tracings and model sur-gery, which can be time-consuming and com-plex. For instance, Okumura et al71 have usedthis technology to combine the cephalometric dataand the dental study casts into a 3D virtual imagefor simultaneous evaluation of skeletal movementsand occlusal relationships in orthognathic proce-dures (Fig 18).

Clinical Examination

Dryland Vig and Ellis83 discuss a systematicapproach to the diagnosis and management ofdentofacial deformities. The clinical examination isa very important component of the diagnostic workupof a surgical-orthodontic patient. Critical to the treat-ment plan are measurements of the face and intraoralstructures including the occlusion and a functionalanalysis of the dynamic aspects of jaw movement.The facial proportions are evaluated with the patientfacing the examiner and holding the lips and man-dible at rest. Bilateral facial profile analysis is alsoindicated, especially if an asymmetry is present. Kentand Craig84 summarize the structural analyses rec-ommended for patients with suspected craniofacialdeformities (Table 3).

Fig 18. 3D virtual imaging of maxillofacial skeleton. Top,Preoperatively. Middle, After sagittal split ramus osteotomy.Bottom, Simulated occlusal relationship. (Reprinted with permis-sion from Okumura H, Chen L-H, Tsutsumi S, et al: Three-dimensional virtual imaging of facial skeleton and dental mor-phologic condition for treatment planning in orthognathic sur-gery. Am J Orthod Dentofacial Orthop 116:126, 1999.)


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In assessing vertical facial balance, the absolutenumbers are not as important as the relationshipbetween the upper, middle, and lower facial thirds.Dentofacial deformities are most commonlyexpressed in the lower face, which is often subdi-vided into an upper one-third—extending betweenthe subnasale and lip contact (stomion)—and a lowertwo-thirds—measured between the stomion andmentum. Vertical macrogenia will typically increasethe distance between stomion and mentum, whereasvertical maxillary deficiency may decrease the dis-tance between subnasale and stomion.

Evaluation of transverse facial symmetry shouldpay particular attention to the cant of the maxillaryocclusal plane, eyes, eyelid position, and interpupil-lary distance. The following instructions are excerptedfrom Dryland Vig and Ellis.83

The nose should be assessed for any asymme-tries regarding the dorsum, tip, or alar base. Thewidth of the alar base should be measured,especially if maxillary surgery is anticipated. Forthe mouth, the amount of maxillary incisorsshowing at rest should be recorded, as should anygingival display. This measurement is repeatedduring function, especially smiling, when exces-sive gingival display may be one of the patient’s

concerns. Normal maxillary incisor show at rest is2–3mm; during smiling, all crowns should bevisible. While this is considered the estheticnorm, the actual tooth display will be related tothe length of the upper lip.

The length of the upper lip from the sub-nasale to the mucocutaneous junction (15mmfemale; 17mm male) and from the subnasale tostomion (20mm female; 22mm male) should berecorded. This will assist in identifying thoseindividuals whose upper lip is short, as it may beunwise to attempt a normal tooth-to-lip relation-ship with vertical maxillary impaction. Decreasingthe vertical dimension of the lower face tocorrect the amount of incisor display may result inloss of vertical facial balance if a short upper lip ispresent. If the upper lip has a thin vermilion,maxillary surgery may further decrease thevermilion.

At rest the upper and lower lips are usuallyin contact, but an interlabial gap may be present.An increase in lower facial height may result in lipincompetence. This is often characteristic ofvertical maxillary excess, where the mandible isrotated downward and backward with apparentretrusion of the mandible. The effort to maintainlip contact results in a lip apart posture at rest and

Table 3Frontal Soft- and Hard-Tissue Assessment

(From Kent JN, Craig MA: Secondary autogenous and alloplastic reshaping procedures for facial asymmetry. In: Atlas of the Oral andMaxillofacial Surgery Clinics of North America, Vol 4, No 1, March 1996.)


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this resting lip posture is often confused withmouth breathing.

The chin: the relationship of the chin to thefacial midline and lower dental midline helpsdetermine whether there is a skeletal or dentalasymmetry of the mandible. A vertically longchin is characteristic of patients with anterioropen bite. Excessive stippling of the soft tissuechin indicates activity in the mentalis muscle,which contracts to elevate the lower lip andproduces lip contact when lip apart posture exists.

It is important when assessing the patient’sprofile that the patient is looking straight ahead inrelaxed posture. If a patient with a normallypositioned mandible looks slightly downward, thechin will appear retruded. Conversely, a patientwith mandibular retrusion can appear morebalanced with the head tilted upwards. Specifi-cally, one should assess the forehead to supraor-bital rims; globes, orbital rims and nose; nasola-bial angle. It is important to realize that a combi-nation of dental position and nasal tip projectionwill contribute to an acute or obtuse nasolabialangle. [Full] sagittal protrusion of the maxillaryincisors will reduce this angle and an upturnednasal tip will increase the angle. . . . The antero-posterior and vertical position of the chin, inrelation to the face, should be in sagittal balancewith the forehead and nose. The form of thesubmental area is included in the lower facialthird.

The intraoral evaluation [assesses thedentition, presence or absence of periodontaldisease, and the occlusal relationship.] Theocclusal relationship is evaluated after an assess-ment of each dental arch for crowding or spacingof the dentition. The horizontal incisor overjetand vertical overbite should be noted, and if anopen bite is present, whether it is located anteri-orly or involves the posterior teeth. To providethree-dimensional evaluation of dentition, anytransverse discrepancy, usually identified as acrossbite, should be noted. . . . [Finally, signs ofdysfunction should be investigated and temporo-mandibular joint (TMJ) disorders excluded.]

Dryland Vig and Ellis (1989)

PRESURGICAL ORTHODONTICS

Patients whose malocclusion reflects as severe skel-etal discrepancy require combined evaluation by botha surgeon and an orthodontist. The dentoalveolarcomponent of the malocclusion is to be treated by

conventional orthodontic appliances to position theteeth in the correct relationship to the upper andlower jaws. Such orthodontic treatment is notintended to correct any occlusal malrelationshipbetween the opposing dental arches. Rather, it shouldbe considered a temporary or intermediate maloc-clusion by decompensating the dental camouflage,for the skeletal discrepancy makes the original mal-occlusion worse. This presurgical phase of orthodontictreatment facilitates surgical correction of the skeletaldiscrepancy and is followed by a short phase of post-surgical orthodontic treatment to refine the occlusion.This combination of orthodontics and surgery yieldsthe best possible dentofacial esthetics and function.

ORTHOGNATHIC SURGERY

Rosen85 states: “It should be evident that if themagnitude of facial skeletal imbalance increases, theextent of change required to correct it increases, andtherefore the need for an osteotomy increases.”What is perhaps not so evident is that an estimated5% of white adults in the United States have a devel-opmental imbalance of the facial skeleton that typi-cally manifests as malocclusion during adolescence.86

Many of these youths will be treated orthodonticallyand as a result will have normal occlusion withresidual skeletal disproportion. It is these peoplewho, once they become adults, will seek plastic sur-gery to improve their facial appearance. Osteotomyis most frequently indicated in these patients, becausethe extent of change required is greater than whatcould be reliably obtained by surface contouring. Inaddition, the vector of change is frequently in thevertical dimension and the location of the osteotomyrequired is usually in the maxilla or chin, where themorbidity is acceptably low.

Facial osteotomies are designed to permit move-ment of the whole or part or the facial complex.The displaced segment may be advanced or set backin any combination of three planes. The movementmay incorporate rotation as well as any desired alter-ation in transverse dimension. A 3D concept, there-fore, is fundamental to the plan of any osteotomy.The soft-tissue attachments are important to thedesign of osteotomies, as they are the source of bloodsupply to the mobilized part. These same attach-


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ments are likely the main restriction to movement ofthe part, and can contribute to relapse.

Sagittal osteotomies stabilize the osteotomy site ina transverse plane while allowing anterior-posterior,superior-inferior, and rotational movement. Steposteotomies allow AP movement and a change inthe transverse dimension but provide vertical stabil-ity. A wedge ostectomy or wedge bone grafts addedto the osteotomy stabilize it against rotation.

Krekmanov87 reviews orthognathic maxillary andmandibular procedures, including their evolution tocurrent standards of rigid fixation. The bibliographicreferences are extensive and a good source of infor-mation on any specific topic.

In cases requiring large movements of the maxillaor mandible, the technique of distraction osteogen-esis may be useful. This technique stretches the soft-tissue attachments that otherwise would restrict theskeletal movement and cause relapse. Cope et al88

review the basic science of distraction osteogenesis,its history, evolution in mandibular surgery, and meth-ods of distraction in current use. Table 4 comparesthe protocols used by different authors for mandibu-lar lengthening and widening as well as their prob-lems and complications. This article provides a use-ful overview of the subject and is worth reviewing.

Distraction osteogenesis has been used primarily inpatients with congenital anomalies such as hemifacial

Table 4Reported Osteodistraction Parameters for Mandibular Lengthening and Widening

(Modified from Cope JB, Samchukov ML, Cherkashin AM: Mandibular distraction osteogenesis: a historic perspective and futuredirections. Am J Orthod Dentofacial Orthop 115:448, 1999.)


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microsomia, cleft-related maxillary hypoplasia, mi-crognathia (eg, Pierre Robin sequence), ormidfacial hypoplasia (eg, Apert’s or Crouzon’s syn-dromes).89–94 There may be a role for distractionosteogenesis in carefully selected patients under-going orthognathic surgery to correct more com-mon developmental imbalances of the facial skel-eton.

Van Sickels95 points out some of the advantagesand disadvantages of distraction versus traditionalorthognathic surgery. He notes that distractionmay be useful when large advancements of themaxilla or mandible are required. Traditionalorthognathic surgery, on the other hand, is moreversatile for moving the maxilla or mandible inseveral dimensions in space, such as with multi-piece maxillary osteotomies. The final occlusionafter orthognathic surgery tends to be more pre-cise than with distraction. Unlike the case withtraditional orthognathic surgery, patient compli-ance and cooperation are more important to thesuccess of distraction procedures.

MANDIBULAR OSTEOTOMIES

The issue of orthognathic surgery during facialgrowth is an important one to consider. Tradi-tionally surgery is postponed until growth is com-plete. However, in selected cases delaying treat-ment is not the best option due to pain and prob-lems with speech, airway, anatomy, occlusion,mastication, aesthetics, and psychosocial factors.96

Wolford et al96 review the more common man-dibular deformities and the techniques that canbe predictably and safely used in the growingpatient.

The TMJs and the tongue are important factors toconsider when contemplating surgery, as pathologicconditions such as condylar hyper- or hypoplasia ormacroglossia influence the growth of the mandible.Wolford and colleagues96 discuss mandibular hypo-plasia, hyperplasia, anterior dentoalveolar deformi-ties, mandibular body deformities, and chin defor-mities. The surgical options for treatment in caseswith deficient growth rates, normal growth rates, andaccelerated growth rates are also described.96 This isan important article that should be read by any sur-geon who is considering doing orthognathic surgeryin a growing patient.

Class III Prognathism

Rakosi and Schilli97 discuss the pathogenesis ofClass III malocclusion and its presentation duringthe deciduous, mixed, and permanent dentitionphases. The authors distinguish between dentoal-veolar Class III malocclusions, characterized by anormal mandibular base, lingually tipped maxil-lary incisors, and labially positioned mandibularincisors, and Class III malocclusions having a largemandibular base. The former can usually be man-aged successfully by orthodontics, while the latteralmost always require surgical treatment becauseof the large articular and gonial angles. The pres-ence of maxillary hypoplasia as a cause of Class IIIrelationship must be excluded, as these casesecessitate maxillary as well as mandibular proce-dures.

Lines and Steinhauser98 offer additional insight intothe treatment of Class III malocclusions. They notethat, in most instances of combined maxillary retru-sion and mandibular protrusion, the mandibulardefect is more responsible for the malocclusion thanthe maxilla. The exception to this is the maxillaryhypoplasia and pseudoprognathism seen in cleft pal-ate patients.

The amount of chin prominence often deter-mines the extent of surgical retrusion that is indi-cated, that is, whether the body of the mandibleshould be set back or just the anterior dentoalveo-lar complex. The entire body of the mandible isusually set back in cases where the chin is promi-nent, the vertical dimension is high, or there is pos-terior crossbite.

Takahashi and Tsuruki99 advocate a surgicalapproach that is based on the type and severity ofthe mandibular prognathism. The authors reserveretropositioning of the lower anterior dentoalveolarsegment for cases of mild mandibular prognathismwithout open bite. If there is open bite, they preferposterior upward movement of the lower anterioralveolar segment and interpositional bone graftingusing a piece of osteotomized chin. For moderatemandibular prognathism, with or without open bite,sagittal splitting of the Obwegeser type I orObwegeser-Dal Pont is recommended. Severe caseswith open bite are best treated by an Obwegeser IIsagittal split osteotomy with partial resection of themandibular angle100 (Fig 19).


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Parker and colleagues101 review proposed tech-niques for the correction of mandibular prognathism.Various methods involve external vertical subcondylarosteotomy (EVSO), intraoral vertical subcondylarosteotomy (IVSO), and sagittal split osteotomy. Theauthors note that intraoral VSO is the preferred pro-cedure for correction of uncomplicated mandibularprognathism. External subcondylar osteotomy is useful

when >10mm of setback is anticipated. Verticaland horizontal correction usually demands sagittalsplit osteotomy. A saggital split osteotomy is alsopreferred in the event both the mandible and maxil-lary must be corrected or rigid fixation is desired.

Minimally invasive techniques to treat prognathismare being developed. Troulis et al102 have demon-strated the feasibility of performing endoscopic verti-cal ramus osteotomy for mandibular setback inminipigs. Such techniques may ultimately find aplace in clinical orthognathic surgery.

Minimal Prognathism

Minimal prognathism without open bite can betreated by subapical osteotomy. If there is a smallanterior open bite, subapical osteotomy comple-mented by a graft from the chin effectively elevatesthe segment while reducing chin projection. Somepatients cannot tolerate orthodontic treatment of longduration, and in these cases Satoh and associates103

often do an anterior mandibular segmental osteotomyto correct minor degrees of prognathism. Their tech-nique is called the Kölle procedure,104 and is safewhen performed below the apices of the teeth andabove the mental foramina. Although the prognathicfacial skeleton and malocclusion can be corrected bysegmental osteotomy alone, a prognathic contourremains in the lower part of the mandible. The authorsreport on 11 patients with minor degrees of prog-nathism in whom they performed segmental osteotomyfor correction of occlusal problems, double horizontalosteotomy for reduction and recession genioplasty,and decortication of the intact middle portion of theosteotomies, in the symphysis and laterally beyondthe mental foramen. The maximum amount of set-back possible with this technique is 4–5mm.

Moderate Prognathism

Moderate prognathism with enlargement of themandibular base deserves a vertical ramus osteotomy.This is a simple procedure less risky to the inferioralveolar nerve than the traditional sagittal splitosteotomy, but is not indicated when vertical rota-tory movements are necessary because it producesdisplacement and poor bony contact along theosteotomy margins. Moderate prognathism associ-ated with open bite is corrected by a sagittal splitosteotomy designed through the ramus.

Fig 19. Management options in mandibular prognathism.


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Severe Prognathism

Neither a sagittal split nor a vertical osteotomy issufficient for correction of severe prognathism due toextreme telescoping of the segments and little or nobony interface at the osteotomy site. In this casemost authors prefer the Obwegeser II modification,which involves lateral sagittal ostectomy with removalof a segment commensurate with the amount ofsetback, and simultaneous ostectomy of the medialsegment through the angle while preserving the infe-rior alveolar nerve. Mandibular body ostectomiesare possible, but generally require dental extractions.

Bell and Jacobs105 focus on the 3D aspect of man-dibular prognathism and analyze the rotational effectof the mandible at the temporomandibular joint whenthe maxillary height is altered. Resection of verticalmaxillary excess causes the chin to rotate anteriorlyand cephalad, increasing mandibular protrusion.Conversely, moving the maxilla inferiorly opens themandibular angle, lengthening the face but decreas-ing prominence of the pogonion. Chronic mouth-breathing during growth contributes to the long-facesyndrome and may be a factor in relapse afterorthognathic surgery. When reconstructive surgeryis contemplated for this deformity, preliminary stepsshould be taken to enhance nasal respiration.

Posnick and colleagues106 note that the potentiallate complications of sagittal split or chin osteotomies“include relapse, residual malocclusion, less than idealfacial esthetics, temporomandibular joint disorders,and residual damage of the inferior alveolar-mentalnerve. During the sagittal split procedure, while com-pleting the cortical cuts or during the actual splittingof the mandible into proximal and distal segments,laceration of the inferior alveolar nerve (partial orcomplete) may occur. Traction injury to the nerve(especially when the neurovascular bundle remainsattached to the proximal segment after the split) andnerve compression during fixation of the segmentsrepresent additional risks to the nerve.” In theirstudy the authors sought to document sensory alter-ations of the chin, lower lip, and gingiva after sagittalsplit and chin osteotomies in adolescents. Threeexperimental groups were evaluated 1 year afterorthognathic surgery: Group II consisted of patientswho had had bilateral sagittal split osteotomies of themandible (14 nerves); Group III had undergone anosteoplastic genioplasty (40 nerves); and Group IVhad combination bilateral sagittal split osteotomy andosteoplastic genioplasty (42 nerves). Compared withcontrols (Group I, normal unoperated adolescents,

134 nerves), subjective residual numbness wasrecorded in 2/7 patients in Group II, 2/20 patients inGroup III, and 14/21 patients in Group IV.

Jaaskelainen et al107 monitored inferior alveolarnerve function continuously while doing bilateral sag-ittal split osteotomies in 13 patients. Adverse effectson the sensory nerve action potentials were detectedthat prompted the authors to change their surgicaltechnique, to use finer instruments and to limit theduration of medial opening to less than 10 minutes.The authors conclude that intraoperative monitoringof the nerve prevented nerve injury during splittingand fixation. If the improved outcome is confirmedby randomized clinical studies, nerve monitoring mayindeed prove valuable in orthognathic surgery withsagittal split osteotomy.

Timing

The timing of surgery for mandibular prognathismis based on the severity of the malocclusion,108 butthe patient’s age influences the treatment plan. Incases of severe disharmony, early surgery may beindicated in hopes of stimulating normal growththrough physiological factors, but in most patientscorrective surgery can be delayed until after thepubertal growth spurt. In cases of mild deformity,surgery can be further deferred until the late teens.

Freihofer109 reviewed the surgical outcome in 12adolescents who had backward displacement of themandibular anterior segment. By the end of theirgrowth period, 33% of patients showed markedocclusive relapse of the retropositioned segment. Incontrast, the rate of relapse after segmental osteotomyin fully grown patients has been variously reported as0–9%.110 Similarly, 15/31 adolescent patients exhib-ited “considerable occlusal relapse” after retro-positioning of the mandible, prompting reoperationin 8 patients.109 Comparable rates in adults are 5–15%. In Cook and Hinrichsen’s series111 all patientswho had significant relapse were under 19 years ofage. Most authors currently recommend delayingcorrection of prognathism until after growth hasstopped.

Class II Mandibular RetrognathiaClass II mandibular retrognathia is much more

common than Class III prognathia.66 The cause ofthe retrognathia may be congenital, developmental,or acquired; examples of congenital occurrencesinclude Treacher Collins and Pierre Robin syndromes


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and Romberg’s disease. Developmental causes suchas birth trauma, TMJ injury, infection, muscle imbal-ance and improper nutrition are more common thancongenital retrognathia Acquired mandibular defi-ciency is also seen after resection for carcinoma orafter facial trauma such as an automobile accidentor gunshot wound.

Mandibular retrognathia has also been implicatedin the etiology of obstructive sleep apnea. Zucconiand coworkers112 studied 100 consecutive habitualsnorers; of these, 55 had an apnea–hypopnea index(AHI) >10, which qualified them as severe. Cepha-lometric and otolaryngologic variables were com-pared between these subjects and the 45 personswhose AHI indexes were less than 10. The twogroups were found to be significantly different inmeasures of mandibular plane-to-hyoid bone dis-tance, SNB angle, SNA angle, posterior airway space,tongue size, and body mass. Nevertheless, thesevariables together explained only 33% of the vari-ance of the AHI in the total sample. The authorsconcluded that the lack of association between cepha-lometric variables and mild sleep apnea suggests thatthe difference in these variables may be the conse-quence, rather than the cause, of habitual snoringand the obstructive sleep apnea syndrome.

Riley and colleagues113 reviewed the outcome of306 patients consecutively treated for obstructive sleepapnea. All were evaluated by physical examination,cephalometric analysis, fiberoptic examination, andpolysomnography before and after treatment. A two-phase surgical protocol was used for reconstructionof the upper airway: Phase 1 consisted ofuvulopalatopharyngoplasty (UPPP) for palatalobstruction and genioglossus advancement with hyoidmyotomy-suspension for base-of-tongue obstruction.Patients who failed phase 1 were offered phase 2reconstruction, which consisted of maxillary-mandibu-lar advancement osteotomy. The overall successrate was 76.5%, and among 91 patients who under-went phase 2 the success rate was 97%. The authorsconclude that a comprehensive presurgical evalua-tion is necessary to plan a logical approach to recon-struction of the upper airway, and patients who com-plete the surgical protocol have a greater than 95%chance of long-term relief of their symptoms.

Fox and Tilson114 reviewed the literature of man-dibular advancement. Early techniques mainlyinvolved step osteotomies of the mandibular body;these were followed by horizontal and oblique

osteotomies of the ramus. Today, inverted-L and Costeotomies of the ramus and sagittal split osteotomypredominate in the correction of mandibular defi-ciency (Fig 20).

Fig 20. Management options in Class II mandibular retrognathia.

Hull and Smith115 prefer the C osteotomy over thesagittal split technique because the former is associ-ated with fewer complications. Farrell and Kent,116

on the other hand, reserve the C osteotomy for casesin which the only requirement is for mandibularadvancement. If an increase in posterior facial heightis needed, they recommend an inverted-L osteotomy.Analysis of their results reveals variable degrees ofrelapse after mandibular advancement: 5% decreasein posterior facial height and 31% anterior collapsewith the inverted-L osteotomy and 23% relapse withthe C osteotomy (straight advancement). Most ofthe relapse occurred in the first 6 months postopera-


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tively and was more significant in the younger agegroups (<20yo).

While the design of the inverted-L and C osteoto-mies eliminates the effect of the masticatory musclepull, the sphenomandibular ligament antagonizesadvancement and restricts any increase in posteriorfacial height. The suprahyoid muscle group is placedunder tension during correction of open bite andmandibular retrognathia, and this is thought to con-tribute to skeletal relapse.117 Wessberg, Schendel,and Epker,117 however, compared the results of man-dibular advancement with and without suprahyoidmyotomy, and showed no significant difference inlong-term relapse between the two groups.

Lines and Steinhauser98 prefer the Dal Pont modi-fication of the Obwegeser sagittal split technique forfull mandibular advancement. Patients who appearchinless and have steep mandibular plane angles(>40°) are ideal candidates for this procedure.Anticipating 20–25% relapse, the authors recommendovercorrection and possible anterior alveolar advance-ment in patients with prominent chins and relativelynormal mandibular bases, because of the tendencyfor relapse seen with full advancement. They admitto a frequent need for bone grafting, extensive orth-odontia, or fixed bridgework with anterior alveolaradvancements.

Rosen118 points out that, in patients with severemandibular micrognathia, the rami are usually defi-cient vertically and the mandibular bodies are alsodeficient. Thus there is a deficient posterior facialheight, an obtuse gonial angle, overly steep occlusaland mandibular plane, and a compensatory increasein anterior facial height with clockwise rotation ofthe entire maxillary-mandibular complex. Failure tocorrect the rotational deformity results in inadequateprojection of the lower face, further reducing theposterior facial height, and no change in the steepocclusal mandibular planes.

Rosen118 reports his results in 11 patients withextreme mandibular micrognathia who had cor-rection of the occlusal plane. The techniqueinvolved rotation of the occlusal plane to its nor-mal level relative to the Frankfort horizontal. A LeFort I osteotomy is performed to shorten the ante-rior maxilla and a sagittal split ramus osteotomy isperformed to advance and rotate the mandibularbody counterclockwise. Together, they close theopen bite created or worsened by Le Fort Iosteotomy. Rosen found that mandibular rotation

yielded a mean 17mm of sagittal displacement atthe B point, compared to just 10mm at the firstmolar. Adequate projection of the lower face wasachieved when the osteotomy was accompaniedby a modest sliding genioplasty (mean 7mm). Amean 25mm of total advancement was achievedat the pogonion. The posterior facial height waspreserved and the mandibular and occlusal planeswere normalized to mean angles of 27° and 10°respectively (Fig 21).

Fig 21. Preoperative (solid line) and immediately postoperative(dashed line) cephalometric tracings demonstrate leveling ofocclusal plane by anterior maxillary intrusion, making the openbite worse, and counterclockwise rotation and advancement ofmandibular body. Sliding genioplasty has advanced the pogonion31 mm. (From Rosen HM: Occlusal plane rotation: aestheticenhancement in mandibular micrognathia. Plast Reconstr Surg91:1231, 1993; with permission.)

A follow-up of 40 months showed a mean sagit-tal relapse at the B point of only 2mm. The authornotes superior aesthetic results but cautions thatlonger followup is needed to confirm the stability.He concludes that in cases of mandibular underde-velopment, a small subset of patients with verticaldeficiency of the mandibuar ramus and deficientposterior facial height will remain undercorrectedby traditional orthognathic procedures—simple man-dibular advancement—unless the occlusal planedeformity has been normalized.


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Timing

The appropriate timing of surgical advancement isarguable. Nanda and colleagues119 studied facialgrowth subsequent to Le Fort I osteotomies in ado-lescent monkeys. Two groups of animals were stud-ied: Group I had a Le Fort I advancement of 4mm,while Group II had a 5mm advancement and a2.5mm impaction. The findings indicated that growthchanges in the maxilla and mandible were related tothe extent of injury caused by the maxillary surgery.The largest increments in rates of growth wereobserved in the control subjects, Group I, and GroupII, in that order. Interestingly, analysis showed thatmandibular growth patterns followed maxillary growthpatterns in both interventional groups.

Schendel and colleagues120 reviewed the surgicaloutcome of 12 children aged 8–16yo who had amean mandibular advancement of 5mm. Theauthors conclude that early surgery in the growingchild promotes harmonious mandibular growth andstability of the correction.

Huang and Ross121 disagree, reporting severegrowth disturbance and no subsequent gain in man-dibular length following advancements of >10mmand <9mm. While these alarming results were asso-ciated with rather large advancements, caution iswarranted when contemplating surgery on the grow-ing child.

Ellis and associates122,123 note that the muscle andconnective tissue within the suprahyoid complexlengthen with mandibular advancement surgery.Posteriorly directed forces created by lengthening ofthese tissues have been implicated in postsurgicalrelapse. A possible consequence of rigid fixation forcentral ramus advancement osteotomy is that forcesgenerated within the stretched perimandibular con-nective tissues must be countered by the temporo-mandibular joint (TMJ). If the TMJ cannot counterthis force, the condyle may move posteriorly withinthe fossa.

Rotskoff124 documented resorption along theanterior surface of the postglenoid spine and resorp-tion of the posterior condylar cartilage after thecondyle is placed posteriorly in the fossa during cen-tral ramus advancement osteotomies.

Ellis and Sinn125 review 63 patients who had sagit-tal ramus advancement osteotomies to correct classII dental relationships. The results of this study indi-cated that orthopedic forces are generated by theperimandibular connective tissues following advance-

ment by the mandible. These posteriorly directedforces are exerted on the advanced distal segment.The same forces are thought to be important in caus-ing postsurgical relapse following mandibularadvancement and dental fixation.

Mandibular distraction osteogenesis has been usedsuccessfully in infants with severe retrognathia whoare tracheostomy-dependent or who have obstruc-tive sleep apnea.126,127 McCarthy et al89 reportedsuccessful decannulation in 4 of 4 patients treatedwith distraction osteogenesis. Cohen et al126 reportedsuccessful decannulation in 7/8 patients and improve-ment in the signs and symptoms of obstructive sleepapnea in 7/8 patients who had been tracheostomycandidates.

Judge et al128 reported distraction of the mandiblein a neonate with Pierre Robin sequence and Klippel-Feil syndrome who had acute airway obstruction atbirth. In addition, distraction osteogenesis has beenused for correction of mandibular hypoplasia andasymmetry in patients with hemifacial microsomia.89,92

CHIN

Anterior horizontal osteotomy of the mandible iscurrently the procedure of choice for correcting skel-etal chin deformity. The sectioned anterior man-dible can be advanced either on a wide pediclewhile maintaining soft-tissue attachments129 or as afree segment by completely detaching the soft tissuesfrom the graft.130 The soft-tissue attachments help tostabilize the skeletal alteration, make for a more pre-dictable soft-tissue change, and minimize postopera-tive osseous resorption.131 It was Ellis132 who reportedthat pedicled grafts underwent less resorption thannonpedicled grafts in the monkey. This was morerecently investigated in humans and confirmed byVedtofte and colleagues133 (Table 5).

Lateral cephalometric evaluations are used todetermine the desired horizontal and vertical dimen-sions of the chin. Wolford and Bates134 use relation-ships between the N-B line, A-Po line, subnasalevertical, and Burstone’s angle of facial convexity topredict the chin’s position in all three dimensionspostoperatively. McCarthy135 proposes a systembased on angles and distances measured from linesdrawn through reproducible cephalometric land-marks.

Hoffman and Moloney131 note that irrespective ofthe analytic criteria used, it is important to realize


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that significant differences can occur between clini-cal evaluation of the patient’s appearance and thenumerical values obtained from cephalometricassessment. They write: “It has been stated thatwhen such a disparity does occur between subjectiveclinical assessment and objective cephalometric analy-sis, experienced surgeons will usually rely on theformer, using the latter as a ‘guideline’ rather than asa ‘yardstick’ in the diagnostic phase of treatment.”

Hinds and Kent136 discuss the soft-tissue relation-ships of the chin to the lip and nose and suggestcephalometric analysis of the chin using a combina-tion of Downs’, Steiner’s, and Tweed’s projections.The authors credit Hofer, Obwegeser, and Conversewith most advances in the field of genioplasty andreview the versatile horizontal osteotomy (Fig 22), asfollows:136

a) The sliding oblique horizontal osteotomy is usedto correct excessive chin height as well as chinretrusion. May also be used to increase the verti-cal dimension of the chin in microgenia.

b) The step horizontal osteotomy advances the chinwithout altering its vertical dimension.

c) The horizontal osteotomy for asymmetry allowslateral shifting of the segment for contour align-ment.

d) The sandwich osteotomy makes use of an inter-position graft to increase the height of the chin.

e) The horizontal osteotomy with ostectomy reduceschin height.

Spear, Mausner, and Kawamoto137 report a two-center experience with the sliding genioplasty as an

outpatient procedure. The authors conclude thatthis is a simple bony advancement operation thatcan be safely performed under local anesthesia withgood results. In his discussion of this paper, how-ever, Wolfe138 cautions about the risk of aspirationfrom pooling of blood and secretions in the mouth,and states his preference for intubation. And despitedeep sedation, 20% of patients from UCLA com-plained of discomfort during the procedure, whichfurther argues for general anesthesia when perform-ing a sliding genioplasty.

Wolfe139 reviews the literature of horizontalosteotomy and discusses its applications for shorten-ing and lengthening the chin. The author recom-mends a combination of clinical and cephalometricanalyses to determine the vertical position of thechin, but does not give specific criteria for the variousmodifications based on results of the analyses. Wolfenotes that shortening the chin necessitates boneremoval in a strip ostectomy rather than from thelower border of the symphysis. The lower segment isreattached to the remaining upper mandibular seg-ment, preserving the muscle attachments to the infe-rior border of the chin for improved esthetics. Whenthe chin is lengthened, interposition bone grafts arerequired, for which he favors cranial bone becauseof the relatively high incidence of sequestration andinfection when iliac bone is used.

Rosen140 reports the outcome of eight patientswho had vertical augmentation genioplasty by trans-verse symphyseal osteotomy and interpositionalimplantation of porous, block hydroxyapatite. Sevenpatients in this series also had Class II occlusion andunderwent simultaneous sagittal advancement of the

(From Hoffman GR, Moloney FB: The stability of facial osteotomies. 3. Chin advancement. Aust Dent J 40(5):289, 1995; with permission.)

Table 5Relapse Following Genioplasty by Anterior Horizontal Osteotomy


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chin. Preoperatively all patients had measureddecreases in lower facial height. The mean verticallengthening of the chin was 5.3mm. Follow-up at amean of 11 months revealed complete stability ofthe vertically repositioned symphyseal segments. Themean ratio of vertical soft- to hard-tissue augmenta-tion was 0.89:1.

Rosen141 has carried the concept of vertical elon-gation of the chin to mask apparent deformities ofthe lower face. He notes that sliding genioplasty canbe used to effectively camouflage the visual percep-tion of a “weak chin” in most patients with Class IIskeletal pattern; it cannot, however, correct the retru-sive lower lip. An unnatural, overcorrected appear-ance can be avoided only by recognizing this limita-tion and restricting forward movement of the chin,so as not to advance it beyond the lower lip. Rosenstates: “One must be willing to accept residual facialdisproportion in the sagittal plane, since the chin willremain weak relative to the upper lip and midface.Visual compensation for this [anterior-posterior dis-proportion] can be achieved by creating vertical dis-proportion . . . Excessive height of the lower face canbe esthetically pleasing in the presence of a well-defined labiomental fold unaccompanied by lipstrain.”

Rosen141 astutely notes that a significant numberof patients requesting chin enlargement have lowerface dysmorphology consisting of four components:a recessive chin; a recessive procumbent lower lip;an exaggerated labiomental fold; and a diminishedto normal lower facial height. From a biomechani-cal perspective, as the chin is advanced the labio-mental fold deepens, whereas vertical elongation ofthe chin tends to soften the fold. Aesthetic refine-ments in genioplasty and the role of the labiomentalfold are discussed by Rosen elsewhere.142

Precious and Delaire143 describe a functionalgenioplasty for the correction of anterior vertical man-dibular excess. The indications for the procedureinclude patients with

• lip incompetence with a normal maxillary incisorto lip relationship (who generally have an open-mouth posture and require excessive elevation ofmental soft tissue in order to obtain lip closure)

• thinning of the anterior mandibular alveolus

• flattening of the contour of the chin

• residual or associated cleft lip and cleft palatepathology

• a requirement to adjust lower facial height aftermaxillary and mandibular osteotomies

Fig 22. Horizontal osteotomy techniques. (A) Sliding oblique horizontal osteotomy. (B) Step horizontal osteotomy. (C) Horizontalosteotomy for asymmetry. (D) Sandwich horizontal osteotomy. (E) Horizontal osteotomy with ostectomy. (F) Correction of macrogeniaby horizontal osteotomy. (Reprinted with permission from Hinds E, Kent JN: Genioplasty: The versatility of horizontal osteotomy. JOral Surg 27:690, 1969.)


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The treatment plan is to correct the lower anteriorfacial height to 55% of the total anterior facial height.

The soft-tissue response to genioplasty procedureshas been reviewed by Krekmanov and Kahnberg.144

They studied 65 patients who were assigned to oneof four groups depending on the direction of thegenioplasty. The soft-tissue response was equal tobone movement in anterior repositioning but lesspredictable in the posterior direction or when com-bined with vertical reduction. The authors note that,in many cases of long face syndrome or severe chindeficiency, it was extremely difficult to perform cepha-lometric analysis of the soft tissues because the spas-tic condition of the mental muscle could disturb boththe preoperative position of Pogs and the volume ofsoft tissue in front of the bone. This phenomenon,in combination with soft-tissue tension, makes it dif-ficult to accurately predict soft-tissue movement incases where an additional genioplasty is needed,especially in the vertical dimension.

Occasionally it is necessary to modify the trans-verse dimension of the chin because it is excessivelynarrow. Raffaini and Sesenna145 proposed a hemi-genioplasty technique that allows use of the properlyshaped hemichin as a reference point and thatachieves symmetry in the correct transverse dimen-sion by simple osteotomy of the distorted hemichin.The method is applicable mainly in cases of asym-metry in the transverse plane, even if it allows thesimultaneous correction of small sagittal discrepan-cies (maximum 2–3mm).

Osseous genioplasty to correct chin asymmetry incombination with orthognathic procedures requirescareful and precise preoperative planning. Stefanovaand Stella146 review the geometric considerationswhen planning correction of chin asymmetry anddiscuss their protocol of data collection, model sur-gery, diagnosis, and treatment planning. This is auseful article and should be reviewed by anyonecontemplating chin realignment.

One of the drawbacks of genioplasty is the poten-tial for injury to the mental branch of the inferioralveolar nerve, which results in chin, lip, and toothnumbness or dysesthesia. Clinically recognized injuryto the inferior alveolar nerve (reported frequently asup to 6%) may detract from this procedure.137,140

Ritter and colleagues147 used high-resolution radio-graphs to determine the anterior course of the infe-rior alveolar nerve in 52 hemimandibles. The neu-rovascular canal was found to be highly variable in

its course, particularly with respect to its distancefrom the inferior border of the mandible (Fig 23).The authors conclude that “if the osteotomies forsliding genioplasty were performed at least 6mmbelow the inferior border of the mental foramen,injury to the mental nerve would be reduced.” Thereader is encouraged to study this article.

Fig 23. Measurements correlating the course of the inferioralveolar neurovascular canal with external landmarks show widevariability of the canal in relation to the caudal border of themandible. (From Ritter EF, Moelleken BRW, Mathes SJ, OusterhoutDK: The course of the inferior alveolar neurovascular canal inrelation to sliding genioplasty. J Craniofac Surg 3:20, 1992; withpermission.)

Precious, Armstrong, and Morais148 review the ana-tomic placement of fixation devices in genioplastyand conclude that fixation devices should be placedin areas of future bone deposition. Their reviewbefore, immediately after, and 1 year followinggenioplasty showed a consistent pattern of boneapposition and resorption after advancement genio-plasty. A consistent but inverse apposition-resorptionpattern was observed after reduction genioplasty (Fig24).

DeFreitas and colleagues149 evaluated skeletal sta-bility and the remodeling process of the advancedgenial segment when a single bone plate is used tostabilize the segment after osteotomy of the inferiorborder of the mandible. The results in 39 patients


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were analyzed with cephalometrics and clinicalexamination. Stability of the procedure was notedto be excellent; the pogonion maintained its imme-diate postsurgical horizontal position at longest fol-low-up. Despite the fact that the bone plate cov-ered the areas where most remodeling occurs, theremodeling pattern was similar to that seen with otherforms of fixation.

The plate is much simpler to place than non-rigid means of fixation such as wires. One canreadily select the plate corresponding to the amountof advancement desired and be sure that this iswhat will be produced in the patient. Half theplate is attached to the advanced genial segmentwhile the pull of the soft tissues holds the segmentin position against the mandible. The amount ofadvancement is thus assessed before the remainingscrews are secured to the superior flange of thebone plate. If the posterior extensions of theadvanced genial segment are not equally advanced,the entire segment can be readily twisted to oneside or the other, straightening the chin. If onewishes to increase the vertical dimension of the chinduring the advancement procedure, a longer platecan be selected and unbent to provide the desiredmovement.

According to Collins and Epker,150 when consider-ing augmentation genioplasty the surgeon should alsoevaluate the submental region for the presence ofexcessive fat or an obtuse cervicomental (neck-chin)angle without lipohyperplasia. (The normal angle is100–140º.) When a very obtuse neck-chin angleexists concomitant with a moderately retruded chin,and in the absence of lipohyperplasia, attention mustbe given to the relation of the hyoid bone andsuprahyoid musculature. The relationship of thehyoid bone to the 3rd cervical vertebra and man-dibular symphysis is reproducible and relatively con-stant. The normal hyoid bone is approximately 32mmanterior to the body of C3, 37 mm posterior to thesymphysis, and 5mm below a line drawn from C3 tothe mandibular symphysis.151 If the hyoid bone islow or lying forward, the results of augmentationgenioplasty alone may be compromised. In thesecases, posterior-superior repositioning of the genio-hyoid and anterior digastric muscles may be indi-cated to improve the neck-chin angle.

A common complication of advancement genio-plasty is the hourglass deformity, which consists ofnotching along the inferior border of the mandibleat the osteotomy site. Hobar and Byrd152 correct thisiatrogenic indentation by means of hydroxyapatitegranules mixed into a paste and used as a spacklingcompound to even out the lateral mandibular con-tour.

Wider, Spiro, and Wolfe153 describe their experi-ence in 50 patients with simultaneous osseous genio-plasty and meloplasty with associated posterior plica-tion of the platysma. Complications were minimaland easily corrected, and the postoperative contourwas excellent.

Alloplastic chin implants are a popular techniquefor augmentation genioplasty. They are appropriatein cases of mild retrogenia without vertical or hori-zontal disproportions.138,139 The procedure’s sim-plicity and low morbidity are the main reasons for itspopularity. However, because of reports of foreignbody reaction and infection associated with implants,some surgeons still prefer the use of sliding genio-plasty. Loss of an implant due to infection, extru-sion, or displacement is a concern. If an implant isremoved due to displacement or size discrepancy,generally it is simultaneously and successfully replacedwith a new implant. When an implant is removeddue to extrusion or infection, an interval of 3–6months is allowed to elapse before a new implant is

Fig 24. Pattern of bone resorption (stippled area) and apposition(solid area) observed in all cases of A, advancement genioplastywith or without vertical reduction and B, posterior repositioningof the chin. (Reprinted with permission from Precious DS,Armstrong JE, Morais D: Anatomic placement of fixation devicesin genioplasty. Oral Surg 73:2, 1992.)


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inserted. A failed implant results in additional surgi-cal procedure(s); more important, secondary chindisfigurements can occur after implant removal dueto capsular contracture and abnormal redraping ofthe mentalis muscle.154,155

Silicone, MedPor, and GoreTex have all been usedas implant materials. In cases of implant infection orextrusion, Li and Cheney156 use a sliding genioplastyimmediately after removing the implant. The ratio-nale for this protocol is that as long as its periosteumis preserved, the genial segment is well vascularizedby the genioglossus, geniohyoid, and anterior digas-tric muscles at its inferior and lingual borders, andtherefore it is resistant to infection. Secondary chinptosis, soft-tissue bunching and dimpling, and alteredlip motion can be extremely difficult to correct afterfailed chin implant removal, but these problems canbe avoided by doing an immediate sliding genio-plasty. A surgical strategy reduces the waiting period,cost, and morbidity associated with alternative treat-ment methods.

The concept of immediate genioplasty followingremoval of an alloplastic chin implant has also beenchampioned by Cohen and others.154 The authorsreviewed the clinical records of 10 patients whosealloplastic chin implants had been removed and inwhom secondary chin deformities subsequentlydeveloped. Initial augmentation was performed 2 to20 years before the patients sought advice regardingchin ptosis, soft-tissue pogonial bunching and dim-pling, or asymmetrical lower lip motion. Four patientsunderwent advancement genioplasty with resus-pension of their mentalis muscle, but the deformitiesproved refractory to delayed surgical treatment.According to the authors,154 “Zide and McCarthy155

proposed three pathologic mechanisms leading todisturbance of mentalis function: (1) displacementof [the muscle’s] origin; (2) elongation and redraping;and (3) deficits of muscular bulk. . . . Zide andMcCarthy approached the problem of ptosis byresuspension of the mentalis origin throughtransalveolar drill holes.”

Matarasso and coworkers157 studied 6 patients whohad aesthetically positioned and appropriately sizedSilastic chin implants. All patients exhibited labialincompetence. The authors noted a correlationbetween preoperative baseline labial incompetenceand mentalis muscle hyperactivity and progressivebony erosion. They concluded that “bone erosionoccurs in many patients who have undergone sili-

cone rubber chin implantation. . . . It appears thatthe unrelenting forces exerted by mentalis musclecontraction on a compressible implant material arepredominant factors in the predisposition for contin-ued erosion.”

Guyuron and Raszewski158 retrospectively studiedthe objective and subjective outcomes of osteoplas-tic (34) and alloplastic (42) genioplasties in 76 patients.Their analysis showed that although both groups werehighly satisfied with their surgical result, those whohad osteotomy had a slightly higher satisfaction rate.Morbidity was the same for either procedure. Soft-tissue response was more predictable after osteo-plastic genioplasty than when implants were used.Similarly, the cervicomental angle was more improvedafter osteoplastic genioplasty than after alloplasticgenioplasty.

Recently Guyuron and Kadi159 reviewed the prob-lems following genioplasty. The reader is urged toperuse this article, which outlines the diagnosis andtreatment of the various complications that mightensue from alloplastic genioplasty and osteotomies.

MAXILLARY OSTEOTOMIES

Surgical correction of a maxillary deformity mayinvolve movement in an anterior–posterior, inferior–superior, or transverse direction, and the Le Fort Iosteotomy is the basis for all of these (Fig 25).

Bell and McBride160 give step-by-step instructionson how to do a Le Fort I osteotomy. They stress theimportance of the down fracture to facilitate visual-ization of the superior surface of the maxilla and togain access to the crucial area between the perpen-dicular process of the palatine bone, maxillary tuber-osity, and pterygoid plate. Special mention is madeof techniques for widening and narrowing the max-illa, setback, and advancement.

Kawamoto161 describes in detail and illustratesthe surgical technique of Le Fort I osteotomy (Fig26). The author stresses the importance of preop-erative assessment, especially noting the lip-toothratio and gauging the effect of maxillary movementon alar base width. Management of the anteriornasal spine is also discussed. In cases of verticalmaxillary excess, the spine should be left attachedto the nasal septum to avoid creating a more acuteand unattractive nasolabial angle with intrusion ofthe maxilla.


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Posnick et al162–164 discuss modifications of the LeFort I osteotomy in unilateral and bilateral cleft lipand palate deformities. The technique safely andreliably corrects the maxillary hypoplasia, closesresidual oronasal fistulas, fills bone defects, and con-trols the cleft dental gap. The authors stress twopoints: 1) the need to preserve attached gingiva atthe cleft site and 2) to produce a positive overjet andoverbite. Prosthetics are used to complete the den-tal rehabilitation, and are particularly necessary inbilateral cleft deformities.

Wolford and associates,165 in part 2 of their dis-cussion of orthognathic surgery during growth, reviewthe growth considerations affecting the maxilla. Theythen discuss maxillary hypoplasia, maxillary protru-sion, vertical maxillary hyperplasia, and double-jawsurgery. The LeFort I osteotomy is the primary pro-cedure for treatment of the maxilla in all these situa-tions. The authors emphasize certain key pointsregarding the surgical correction of maxillarydentofacial deformities in the growing patient, as fol-lows:

1. Early surgical correction may be beneficial insome patients for functional, esthetic, andpsychosocial reasons.

2. The TMJs must be functionally healthy andstable for predictable surgical results.

3. The LeFort I osteotomy eliminates further APgrowth of the maxilla.

4. Surgical correction of vertical maxillary hyper-plasia with normal mandibular growth can bepredictably performed during growth.Postsurgically, the vector of facial growth will bein a downward and backward direction.

5. Double-jaw surgery may be predictably per-formed in selected instances for specific jawdeformities.

Wolford, Karras, and Mehra (2001)

Vertical maxillary hyperplasia excluded, more pre-dictable results can be obtained when surgery isperformed close to or after completion of maxillarygrowth growth (approximately age 15 in girls; age17 or 18 in boys). The horseshoe osteotomy pre-serves the attachment of the nasal septum to thehard palate, thus allowing some continued APgrowth while mobilizing only the dentoalveolar struc-tures (Fig 27).

MAXILLARY HYPOPLASIA

Jackson166 emphasizes that a hypoplastic maxillacan be present in association with normal occlusionas well as with malocclusion of the Class III type.Patients who have maxillary hypoplasia with normalocclusion often go unrecognized because theirdeformity may be rather mild; they are often seen inconsultation when they request a rhinoplasty. Thenose may be large or small, but the significant fea-ture is paranasal hypoplasia, frequently localized tothe alar base region and to the superior upper lip; inother words, these patients have a weak midface.Intraoral examination confirms normal occlusion, butthe upper part of the alveolus shelves backwardsinstead of vertically, particularly in the area betweenthe canines. With age, these patients tend to developdeep nasolabial fold and often have a sad or angrylook. Augmentation of the anterior maxilla is anessential element in the treatment of these patients,often complementing rhinoplasty or a facelift proce-dure. Examples of the management of maxillaryhypoplasia in the face of normal occlusion aregiven.166

Jackson166 further discusses maxillary retrusion inconjunction with maxillary hypoplasia. He pointsout that the retruded maxilla may be either hypo-plastic or normal, and the diagnosis plays significantlyin the decision tree for adequate treatment.

Fig 25. Le Fort I osteotomy. (Reprinted with permission fromJackson IT, Munro IR, Salyer KE, Whitaker LA: Atlas ofCraniomaxillofacial Surgery. St Louis, CV Mosby, 1982.)


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Fig 26. Technique of Le Fort I osteotomy. See text for details. (Modified from Kawamoto HJ Jr: Simplification of the Le Fort I osteotomy.Clin Plast Surg 16(4):777, 1989.)


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VERTICAL DEFICIENCY – SHORT FACESYNDROME

Bell167 describes the short face syndrome and itssurgical correction. On frontal projection, the typi-cal patient shows an edentulous-appearing, short,square face. With the jaw at rest or when the patientis speaking or smiling, the maxillary incisors are hid-den behind the upper lip. The upper lip curvesdownward and the corners of the mouth are belowthe midline. The upper third of the face is withinnormal limits. The middle third is characterized by anose with broad alar bases and large nostrils. Thereis decreased facial height localized to the lower third.The posterior part of the face appears wide becauseof prominent mandibular angles. Cephalometricexamination reveals decreased vertical maxillaryheight, a large freeway space, and a low mandibularplane angle, which are pathognomonic of verticalmaxillary deficiency. There is often a Class I or IImalocclusion with a deep overbite. Vertical maxil-lary deficiency may be associated with anterior-posterior maxillary deficiency in patients with man-dibular prognathism or cleft lip and palate. Orth-odontia is sometimes effective in the young and grow-ing child; in adults, surgery is indicated.

Clinical assessment should determine the amountof inferior maxillary displacement that is needed for3mm of maxillary incisor exposure with the upper lipat rest. The surgical goal is to attain acceptable facialproportions, with the lower face assuming approxi-

mately 55% of the total facial height. Cortical-cancellous bone grafts from the iliac crest, sculpturedas dumbbells to the preoperative planned dimen-sions, are inserted in the gap created in the maxillarydefect.167

Bell and Scheideman168 report the long-termocclusal and soft-tissue changes following surgicaltreatment of the short face. Relapse averaging 30%of the correction (approximately 2mm) was repeat-edly seen in the first 2–3 months postoperatively.Some lengthening of the upper lip was noted, butnot to a consistent degree. To accommodate thisupper lip lengthening, the preoperative plan shouldincorporate inferior maxillary repositioning in excessof that considered necessary to achieve a normalincisor-to-lip relationship, that is, aiming for 3–4mmof incisor show.

Hedemark and Freihofer169 noted 50–100%relapse in patients treated with vertical downwardtilting of the maxilla and conventional wire fixation.They concluded that the surgical plan should allowfor this relapse by initial overcorrection, and sug-gested plate osteosynthesis as the method of fixation.

Rosen170 reports his experience with definitive sur-gical correction of vertical maxillary deficiency anddescribes the perioperative course of 9 patients whounderwent inferior maxillary repositioning resultingin no residual bone contact between the down-fractured maxilla and the superior midface. Themean distance of inferior maxillary displacement was6.2mm. Osteotomy gaps were implanted with porousblock hydroxyapatite (Interpore 200), and the max-illa was rigidly fixed in position with miniplates. Nopostoperative maxillary-mandibular fixation was usedand no complications were associated with the pro-cedure. Follow-up was 11–28 months. During thistime there was a mean vertical relapse of 4.3%, whichis significantly better than for other series. Postop-eratively the upper lip was lengthened 20–50% ofthe magnitude of skeletal repositioning, especially ifthe upper lip had been compressed by the lower lipfrom an overrotated mandible. The author’s experi-ence supports the use of rigid miniplate fixation infacial osteotomies and is testimony to the value ofhydroxyapatite as a bone graft substitute.170

VERTICAL EXCESS – LONG FACE SYNDROME

The following are typical features of vertical maxil-lary excess:171,172

Fig 27. Horseshoe osteotomy maintains attachment of horizontalpalate to vomer and lateral nasal walls. Only the dentoalveolus ismobilized. (Reprinted with permission from Wolford LM, KarrasSC, Mehra P: Considerations for orthognathic surgery duringgrowth, Part 2: maxillary deformities. Am J Orthod DentofacOrthop 119:102, 2001.)


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• >3.5mm exposure of the upper anterior teethwith the lips at rest

• lip incompetence with an interlabial gap of>3.5mm

• a convex nasal dorsum

• narrow alar bases in proportion to the remainderof the face

• a nasolabial angle within the limits of normal

• a recessed chin

• increased facial height primarily in the lower one-third

Clinical evaluation of the lip-tooth relationshipforms the basis for projecting the extent of superiorrepositioning that will be needed to effect correc-tion—that is, how far the incisors must be raised.The acceptable amount of upper incisor exposurewith the lip at rest is approximately 2.5mm. Becausethe upper lip will shorten approximately 20% of thedistance the upper teeth and maxilla are moved,compensatory overcorrection of 20% is indi-cated.160,172–174 Other goals of treatment are toestablish a proper relationship with the chin and toachieve good overall lower facial height. To thisend, autorotation of the mandible may be neces-sary. Rotation about the condyle frequently dictatesresection of various amounts of bone from the ante-rior maxilla compared with the posterior segments.

Occlusal analysis of patients with long face syn-drome often reveals a Class II malocclusion with orwithout anterior open bite. The exact occlusal rela-tionships should be determined preoperatively bymeans of dental models and confirmed by cepha-lometry and sketches. With this information, thedegree of correction necessary to obtain the desiredesthetic result and profile changes can be accuratelyplanned.173

To avoid septal buckling or deviation and interfer-ence with superior advancement, a segment of nasalseptum equal to the desired maxillary displacementmust be resected. Because superior maxillary repo-sitioning of >4–5mm will compromise the nasal air-way, the nasal septum is not reduced in height, butrather a horseshoe-shaped osteotomy of the nasalfloor is performed to separate the palatal and den-toalveolar portions of the maxilla. The midpalatalsegment is held passively at the presurgical level bythe nasal septum while the anterior and posterior

dentoalveolar segments are superiorly repositionedaround them.160 Movements >5mm require burr-ing of the margins of the piriform aperture to avoidundesirable elevation of the alar bases.

Kawamoto161 warns of consequences of intrusionof the anterior nasal spine with maxillary impaction.A silver blade is used to make a V-shaped cut belowthe anterior nasal spine in order to leave this struc-ture attached to the nasal septum. This avoids anunpleasant uptilt to the nasal tip.

The transverse dimension of the maxilla is alteredby means of the horseshoe palatal osteotomy orparasagittal osteotomies. If narrowing is desired,parasagittal ostectomies may be added. These seg-mental osteotomies can be executed under directvision by using the down fracture method. Rosen175

notes that sagittal maxillary deficiency and verticalmaxillary excess are frequently accompanied by trans-verse maxillary deficiency. At the time the maxilla isadvanced or impacted, it should be properlysegmentalized to expand it transversely and establishnormal buccal-lingual-dental relationships. In Rosen’sestimation, parasagittal osteotomies can reliably widenthe posterior maxilla 6–8mm. When significantexpansion is required in the canine region, he pre-fers a four-piece Le Fort I osteotomy.

Although the most common type of vertical maxil-lary excess is represented by the “classic” long facesyndrome, Schendel and Carlotti176 identify sixdysmorphic subgroups according to variable degrees ofvertical maxillary excess. In fact, 22% of patients withlong face syndrome in their study did not have verticalmaxillary excess, but instead had short upper lips withnormal maxillae and excessive chin height. The chinexcess is independent of maxillary excess and as suchnot entirely secondary to posterior-inferior rotation ofthe mandible. Proper distinction between these sub-groups has obvious implications to the treatment plan.

Washburn, Schendel, and Epker177 analyzed theresults of superior maxillary repositioning in 16 chil-dren aged 10–16yo. The authors recommend amaxillary alveolar osteotomy, avoiding transection ofthe nasal septum. Stable occlusion and an estheti-cally satisfactory outcome were noted in all. Thestability can be predicted from the available humangrowth studies, which show that maxillary growth isvirtually complete by age 10–13. There is also noevidence to suggest that disproportionate maxillarygrowth continues beyond the normal growth periodin individuals with vertical maxillary excess.177


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In a study of 61 patients treated with surgicalsuperior repositioning of the maxilla and wire fixa-tion, Proffit and colleagues178 report vertical stabilityin 80% during the first postsurgical year, while 20%had 2mm or more postsurgical movement of skeletallandmarks.

Bailey and colleagues179 assessed changes in den-tal and skeletal relationships of 49 patients whosemaxillae had been superiorly repositioned by LeFort I osteotomy 5 years earlier. Most patients whohad changes during the first 6 weeks postopera-tively showed further superior movement of themaxilla, but this was offset by inferior movementfrom the time of fixation release to the 1-yearreporting interval.178 In the short term, therefore,superior repositioning of the maxilla can be consid-ered stable, perhaps the most stable orthognathicsurgical procedure, even without rigid fixation. Theauthors note that

From 1 to 5 years postsurgery, minimalchanges occurred in skeletal and dental land-marks in the majority of patients, but approxi-mately 25% of the patients showed 2 mm ormore of downward movement of the maxillaand/or eruption of maxillary teeth, leading todownward-backward rotation of the mandible. . .. An increase in overbite, resulting from incisoreruption, was noted in 14%, and an increase inoverjet occurred in 12% as the mandible rotated.It appears that modest long term skeletal anddental changes occur in some surgically treatedlong face patients. Only one patient had morethan 1 mm of open bite on long-term follow-up.The likelihood of long-term change was notrelated to the age of the patient, stability duringthe first postsurgical year, or segmentation of themaxilla at surgery.

Bailey et al (1994)

Zarrinkelk and coworkers180 remark that superiorrepositioning of the maxilla also produces a forwardrotation of the mandible that may reduce an appar-ent mandibular deficiency. Patients with either VMEor retrognathia have reduced maximum bite forcesand slightly reduced maximum range of motionbefore treatment.181 Their study compared mor-phology and function of patients with combined ver-tical maxillary excess and mandibular retrognathiawith other controls. The authors also looked at howthese parameters changed after combined maxillaryintrusion and mandibular advancement surgery. Fif-

teen female patients with VME and straightretrognathia were compared with 26 female con-trols before and up to 3 years after orthognathicsurgery. Facial skeletal morphology, mandibularrange of motion, maximum isometric bite force, andEMG activity of selected muscles of mastication weremeasured. At surgery the maxilla was elevated anaverage of 2.8mm and the mandible was length-ened by an average 7.1mm. The authors report that

All of the postoperative morphologic measure-ments were closer to normal values. The pa-tients’ masseter mechanical advantage wassignificantly lower than that of controls bothbefore and after surgery. Surgically inducedchanges in mechanical advantages were verysmall. The patients’ maximum range of motionand excursion during mastication were all lowerthan those of controls before surgery. All mea-surements of mobility decreased immediatelyafter surgery, with a gradual return to preopera-tive values. However, even 3 years after surgery,all of the motion measurements remained smallerthan those of the controls. Before surgery, thepatients had maximum isometric bite forcessignificantly lower than those of controls. Biteforces increased significantly after surgery,approaching normal values within 2 years. Theactivity levels in the muscles of mastication duringisometric bites were not significantly altered bysurgery.

Zarrinkelk et al (1996)

An earlier study by Upton and associates182 exam-ined the premise that malocclusion and unbalancedskeletal relationships of the facial structures contrib-ute to orofacial dysfunction syndromes.

RETROGNATHIA

Deformities of vertical maxillary deficiency mayalso include some posterior displacement of the max-illa as part of the syndrome. Treatment usuallyinvolves maxillary advancement of <6–7mm,160 andbone grafts in the pterygomaxillary osteotomy aregenerally not required. Bell and McBride160 offerclinical details of wiring and fixation techniques forthe mobilized segment.

A frequent indication for maxillary advancementis the mandibular pseudoprognathism seen in asso-ciation with cleft palate. Maxillary advancements>1cm may be needed, and in these cases bonegrafts in the pterygomaxillary osteotomy are recom-


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mended.160 Lines and Steinhauser98 also recommendovercorrection by at least 25% because of a ten-dency to relapse.

PROGNATHISM

Posterior repositioning of the maxilla may be indi-cated as part of the treatment for vertical maxillaryexcess. The maxilla can be set back 4–5mm byreducing the posterior aspects of the maxillary tuber-osities.160 When the planned posterior movementexceeds the amount of available bone in the tuber-osity, the pterygoid plate is sectioned and fracturedto accommodate the desired positional change.

Wolfe, Lin, and Berkowitz183 state thatMaxillary protrusion may exist by itself or along

with mandibular protrusion in the condition ofbimaxillary protrusion. Surgical approaches to themaxilla, depending on arch form and otherorthodontic considerations, may involve thefollowing:

1. Tooth extractions (usually of premolars) andpremaxillary setback (Wassmund/Wunderer); thesame result can often be obtained by dentalextractions and orthodontic therapy alone,although they require a much longer treatmenttime.

2. Posterior movement of the entire maxilla afterLe Fort I mobilization, by removing bone in themaxillary tuberosity and third molar area.

3. Combination of 1 and 2 for more pronouncedcases: Le Fort I osteotomy, posterior movementof the entire maxilla, maxillary tooth extractions,and segmentation of the maxilla with premaxillarysetback.

Wolfe, Lin, and Berkowitz (1997)

Krekmanov and colleagues184 published what is todate the largest surgical series of posterior reposition-ing of the entire maxilla. Of the 30 patients in thestudy, 29 had associated vertical maxillary hyperpla-sia. Bone was removed from the maxillary tuberos-ity area and the maxilla was trimmed to good con-tact along the osteotomy line. On cephalometricanalysis the mean distance of posterior repositioningwas -2.0 ± 2.1mm, range 0.02 to -8.5mm. In casesof additional superior repositioning, the maxilla wastelescoped in the lateral and posterior regions. Theauthors do not mention removing either of the thirdmolar teeth.

Kawamoto185 states that maxillary retropositioningprocedures are infrequently used because “they tendto give the face an aged appearance. Once theupper lip is robbed of the support of the underlyinganterior teeth, whether by an orthodontic plan ofbicuspid extraction or by surgical setback, unpleas-ant soft-tissue changes can occur. The upper lipmoves back and thins. Fullness of the upper lipvermilion . . decreases. . . . The upper lip alsodescends, which can produce an unflattering lessershow of teeth. In patients with a component ofmaxillary anterior protrusion, the nasal alar bases areburied into the face and the nasolabial folds deepen.”

The classic paper by Freihofer186 on latitude andlimitation of midface movements should be requiredreading for anyone contemplating doing a Le Fort Iosteotomy.

SIMULTANEOUS MAXILLARY ANDMANDIBULAR OSTEOTOMIES

Epker and associates187 review selected dentofacialdeformities that call for simultaneous mobilization ofthe maxilla and mandible in Class III, Class II, andClass I relationships. In general, combined upperand lower jaw surgery should be considered whenocclusal relationships dictate skeletal movement of>10–12mm. Combined surgery is also indicated tomaintain the appropriate relationship between thetip of the nose, upper and lower lip, and chin, whichis frequently impossible when surgery is limited to asingle jaw.

Lindorf and Steinhauser188 discuss the planningand execution of simultaneous mandibular and max-illary surgery. Plate and screw fixation of the mobi-lized parts provides the necessary rigidity for simulta-neous movements, while an intermediate splintenables proper orientation of the mobilized man-dible with regard to the as yet intact maxilla. Oncethe mandibular segments have been stabilized withrigid fixation, the maxilla can be mobilized.

Guyuron189 discusses combined maxillary andmandibular osteotomies and points to problems thatcan arise from previous orthodontic treatment,including missing teeth, alteration of arch form, toothroot resorption, and temporomandibular joint dys-function. The need for accurate evaluation of thepatient’s smile is emphasized. Specifically there shouldbe minimal or no gum show, and the distance


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between the oral commissure and the pupil shouldbe equal on both sides. Guyuron189 details the tech-nique of double jaw surgery and postoperative careof the patient and summarizes the preparation anduse of interocclusal splints in the surgical sequence.Most studies of stability after two-jaw surgery showthe maxilla to be relatively more stable than themandible.190–194

A major problem that may develop from simulta-neous mobilization of the maxilla and mandible isfacial asymmetry. This may be due to torquing ofthe maxilla or mandible, canting of the occlusalplane,195 rotation of the proximal mandibular seg-ment, or malposition of the inferior fragment of thegenioplasty. Schendel196 notes that “asymmetry inthe vertical plane is evidenced by a difference in thevertical position of the maxillary molars from oneside to the other. This cant of the maxillary occlusalplane will produce a similar cant of the mandibularocclusal plane. Orthodontics may be able to correcta mild cant of the occlusal plane. Reoperation isnecessary if a significant facial asymmetry is presentdue to occlusal plane cant.”

CLEFT ORTHOGNATHIC SURGERY

Primary repair of cleft lip and palate during infancyand early childhood often leads to maxillary growthrestriction, secondary deformities of the jaw, andmalocclusion. Orthognathic surgery is performedwhen adolescent patients have a residually cleftedand perforated maxilla. Readers are urged to exam-ine the comprehensive reviews by Marsh and Galic197

and O’Ryan198 on maxillofacial osteotomies forpatients with cleft lip and palate and complicationsof orthognathic surgery, respectively.

Posnick and Tompson199 reviewed the complica-tions and long-term results of jaw surgery in a seriesof 116 adolescents who underwent different palatalrepairs in infancy or childhood. In all cases the basicorthognathic procedure included Le Fort I osteotomy.In addition, 87 patients had osteoplastic genioplastyand 32 had simultaneous sagittal split osteotomies ofthe mandible. Autogenous cortical-cancellous iliacbone grafts were used in all but six patients. Lateralcephalometric radiographs obtained 1 year postop-eratively showed that a positive overjet was main-tained in 97% of patients and a positive overbite in89%. Overall, 89% of residual oronasal fistulas weresuccessfully closed.

Schendel and Mason196 reviewed 6 years oforthognathic surgery at Stanford University duringwhich 315 patients underwent 474 osteotomies.Fourteen patients required surgical revision later. Theauthors give an excellent overview of the adverseoutcomes of orthognathic surgery and the manage-ment of residual problems. Attention is directedtoward difficulties with healing, especially of bone,occlusal relapse, TMJ dysfunction, nerve injury, andother functional impairments such as nasal airwayobstruction. The adverse esthetic outcomes relatemainly to the nose, lips, and cheeks.

PLATE FIXATION

Miniplates have lately become the standard ofcare in the stabilization of facial osteotomies andfractures. Beals and Munro200 described an experi-ence with miniplates in fixation of the skull, maxilla,and mandible in 74 patients. Little if anymaxillomandibular wiring was used. No infectionswere reported, fixation was stable, and only 1% ofplates became exposed and required removal. Tech-nical points emphasized are passive fitting of the platesand precise drilling so as to avoid distraction of themobilized fragments.

Luyk and Ward-Booth201 analyzed their results in11 Le Fort I osteotomies using Champy miniplateswithout bone grafts. Stability was achieved, withpatients showing no relapse at 10 months postop-eratively and an average horizontal maxillaryadvancement of 3.7mm.

Taylor202 reviewed complications of osteotomieswith rigid fixation and concluded that most compli-cations could be traced to technical errors. Ana-tomic variation in the position of the inferior alveolarnerve and poor quality or quantity of bone werecited as complicating factors.

Posnick and Dagys203 reviewed the long-term skel-etal stability and relapse patterns of 35 patients withunilateral cleft lip and palate, maxillary hypoplasia,and class III malocclusion who underwent Le Fort Imaxillary osteotomy. The advanced maxilla was fixedwith miniplates. Clinical follow-up ranged from 1.5–4.5 years (mean 1.5). The authors found no signifi-cant difference in horizontal or vertical surgical changeor relapse between patients who had maxillary sur-gery alone (24) and those who had surgery on bothjaws (11). One year after surgery all patients showeda positive overjet and 86% had a positive overbite.


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Although there was no significant correlation betweenthe amount of advancement/displacement and degreeof relapse, surgical overcorrection and perioperativeorthodontics were performed in anticipation ofrelapse. Posnick and Dagys speculate that the causeof relapse may be multifactorial and may not beexplained by cleft palate scar tissue alone. Theyconcluded that while miniplate-and-screw internalfixation is useful, it does not eliminate relapse inpatients with unilateral cleft lip and palate whoundergo Le Fort I osteotomy.203

Costa and coworkers204 reviewed the literatureregarding stability of the LeFort I osteotomy in maxil-lary inferior repositioning, which is known to have ahigh relapse rate. The authors concluded that infe-rior repositioning stabilized with rigid fixation andbone grafting is the technique of choice because ofits predictability and “acceptable” rate of relapse (35%posteriorly and 15% anteriorly).

Berger and associates205 compared two groups ofpatients undergoing bilateral sagittal split osteotomy(BSSO). One group was treated with transosseouswiring (26) and the other with rigid fixation (28).Despite minimal statistical differences in relapsebetween the groups, the authors state that “thepotential was greater for relapse in patients stabilizedwith transosseous wiring.”

In a 3-year follow-up analysis of 80 consecutivemandibular prognathism patients treated with bilat-eral sagittal split osteotomy and rigid fixation,Mobarak and others206 found BSSO to be a “fairlystable clinical procedure.” The mean relapse rate atpogonion was 26%, and most of the relapse (72%)occurred during the first 6 months after surgery.

A study by Talebzadeh and Pogrel207 of 20 patientstreated with osseous genioplasty with rigid fixationdocumented relapse rates of 0.38mm at pogonion,1.2mm at soft-tissue pogonion, and 1.5mm at soft-tissue B point. Relapse was not related to the amountof advancement. The authors found “essentially nosignificant relapse” 12 months after genioplasty sta-bilized with rigid fixation.

Nemeth and colleagues208 evaluated the risk ofincreased TMJ disorders after rigid fixation of BSSO.The prospective study comprised 127 patients ran-domized to either rigid or wire fixation. At 2 years’follow-up, no statistically significant difference wasdetected between the groups regarding temporo-mandibular joint dysfunction.

Shand and Heggie209 reported preliminary resultsin 31 patients who underwent maxillary, mandibu-lar, or bimaxillary orthognathic procedures stabilizedwith resorbable plates and screws. The follow-upinterval ranged from 2–8 months. Six patients had“mild mobility of the maxilla” in the early postopera-tive period, but stability was “within normal limits” at6 weeks postoperatively. The authors conclude thatresorbable plates represent a “good” fixation methodfor orthognathic procedures. Although this report isencouraging, the data are quite preliminary and mustbe independently confirmed with longer follow-up.The technique is not the current standard of care inorthognathic surgery.

MIDFACIAL AND CRANIOFACIALOSTEOTOMIES

Converse and Wood-Smith210 give detaileddescriptions of the techniques for orbital, paranasal,and maxillary osteotomies and discuss modificationsof the low maxillary osteotomy—Le Fort I; pyrami-dal nasomaxillary or nasoorbitomaxillary osteotomy—Le Fort II; and high maxillary osteotomy—Le Fort III(Figs 28-30).211

The effects of these osteotomies on the facial skel-eton are as follows:Le Fort I osteotomy ¯ Affects the upper lip and thelower fourth of the nose. May alter nasal tip projec-tion, alar base width, and the nasolabial angle. Hasno effect on nasal length, projection of the cheeks,or orbital volume.

Fig 28. Le Fort I osteotomy, showing the burr used to make a U-shaped osteotomy around the palatal vault. (Reprinted withpermission from Jackson IT, Munro IR, Salyer KE, Whitaker LA:Atlas of Craniomaxillofacial Surgery. St Louis, CV Mosby,1982.)


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Le Fort II osteotomy ̄ Allows nasal lengthening andalteration of the dorsal nasal angle and affects pro-jection of the upper lip through the attached maxilla.Allows correction of telecanthus with modificationsin the nasoorbitoethmoidal area. The cheeks andorbital volume are not affected.Le Fort III osteotomy ̄ Alters the orbital volume andthe projection of the cheeks, lengthens the nose andchanges its dorsal angle, and modifies upper lip pro-jection through its attached maxillary component.

When performing a Le Fort I osteotomy on a cleftpatient, Converse and Wood-Smith210 recommenda transverse cut across the posterior portion of thehard palate so as to leave the posterior border of thehard palate and the attachments of the soft palateundisturbed. This averts the possibility of shorteningthe soft palate with resultant velopharyngeal incom-petence.

Converse and Wood-Smith210 also describe modi-fications of paranasal osteotomies to lengthen theforeshortened nose and trace improvements in thedesign of the Le Fort III osteotomy through Tessier’swork. Special reference is made to the inferior andmedial orbital cuts that do not disturb the lacrimalapparatus so that it can move forward with themidface. The authors stress the advantage of split-ting the zygoma and stepping the cut through thezygomatic body to increase lateral stability.

A study of the stability of Le Fort III advancementsin children with Crouzon’s, Apert’s, and Pfeiffer’ssyndromes by Bachmayer and Ross212 concluded thatrelapse was neither occlusion-dependent nor relatedto the amount of forward maxillary advancement,but instead was inversely proportional to the degreeof stability of the midfacial segment, and to this endrecommend rigid fixation. The authors note thatovercorrection in children is necessary to compen-sate for the lack of maxillary growth after Le Fort IIIosteotomy in the presence of a normally growingmandible.

Posnick and associates213 recommend a modifiedocclusal splint that avoids tracheostomy in totalmidface osteotomies. The authors discuss variousmethods for circumventing the restrictions of eitheroral or nasotracheal intubation, including (1) guidingthe orotracheal tube behind the maxillary tuberosity

Fig 29. Le Fort II osteotomy. (Reprinted with permission fromJackson IT, Munro IR, Salyer KE, Whitaker LA: Atlas ofCraniomaxillofacial Surgery. St Louis, CV Mosby, 1982.)

Fig 30. Le Fort III osteotomy. (Reprinted with permission fromJackson IT, Munro IR, Salyer KE, Whitaker LA: Atlas ofCraniomaxillofacial Surgery. St Louis, CV Mosby, 1982.)


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to exit the oral cavity through incisions in the floor ofthe mouth and submental skin; (2) intraoperativeoral-to-nasal tube switch; and (3) the modified occlusalsplint, which allows both orotracheal intubation andexacting occlusal relationships without the need fordirect contact of the teeth.

SOFT-TISSUE RESPONSE

The correction of dentofacial and craniofacialabnormalities is not complete without considerationof the soft-tissue response to bony manipulation. Thedegree of correlation that exists between changes inthe soft-tissues of the face and their underlying skel-eton determines which adjustments need to be madein the preoperative tracings to bring about the desiredresult. The currently available data on soft-tissueresponse to bony movement are summarized in Table6.98,168,214–217

Willmot214 stresses that, in planning the profileresponse to mandibular surgery, one cannot rely onthe soft tissues of the lips and chin following themandible posteriorly in a uniform 1:1 relationship.In analyzing lip changes following mandibularretropositioning, the author214 concluded that thesoft-tissue pogonion became less prominent in rela-tion to the inferior labial sulcus, and deepening ofthe inferior labial sulcus was mainly due to forwardmovement of the labrale inferius, rather than actualdeepening of the sulcus itself. Changes in total heightof the lower lip from soft-tissue pogonion to labraleinferius were insignificant, but the distance betweenthe inferior labial sulcus and the labrale inferiusdecreased a mean 1.8mm.

Hayes and associates218 quantified the changesseen in the cervicomental angle and the lip-chin-throat angles in response to mandibular advance-ment. The authors concluded that following man-dibular advancement (1) the soft-tissue cervicomentalangle and lip-chin-throat angle decreased; (2) a sig-nificant positive correlation exists between thechanges in the soft-tissue cervicomental angle andthe soft-tissue lip-chin-throat angle after mandibularadvancement; (3) for each degree of reduction inthe lip-chin-throat angle, the cervicomental angledecreases by 0.77°; (4) a decrease of approximately1.5° in the cervicomental angle can be expected foreach 1mm of mandibular advancement.

Shelly and associates219 evaluated the changes inprofile with mandibular advancement in 34 patients.

Pre- and post-treatment cephalograms were used togenerate silhouette images which were then gradedby lay persons and orthodontic residents. All observ-ers agreed on a consistent improvement in profileesthetics for patients with an initial ANB angle of=6°. Improved profile esthetics were recorded only50% of the time when the initial ANB angle was<6°; the other 50% of patients were thought to beworse after surgery. The authors recommend thatonly patients with an initial ANB angle of at least 6°be considered for mandibular advancement surgery.

Hayes and colleagues218 also monitored hyoidbone positional changes in the study. Twenty-fiveyears earlier, Schendel, Wolford, and Epker120 hadnoted that on surgical advancement of the man-dible, the hyoid bone responded with a forwardmovement, but with time tended to return toward itspreoperative position. Hayes et al218 confirmed thatthe hyoid bone moves toward the sella, nasion, andposterior nasal spine after mandibular advancementsurgery; the overall movement can be described assuperior with a slight anterior component. Following

Table 6Soft-Tissue Response to Facial

Skeletal Changes


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an adaptive process that occurs at the bone-tendoninterface,220 the hyoid tends to reside in a positionclose to its preoperative location.

Marino and associates221 reported that the overallsuccess of double-chin correction through soft-tissuesurgery depends on the position of the hyoid bone.A hyoid bone that is located inferior to the 4th cervi-cal vertebra tends to predispose the person to a less-than-ideal treatment result.

Krekmanov and Kahnberg222 reviewed the soft-tissue response to genioplasty in 65 patients. Sub-jects were grouped according to the direction of chinmovement: straight anterior (17); posterior (12);vertical reduction (19); or superior-anterior (17)repositioning. The authors concluded that soft-tissueresponse was equal to bone movement during ante-rior repositioning but less predictable in the posteriordirection or when combined with vertical reduction.However, patients who had vertical reduction of themandible also showed soft-tissue movement equalto the amount of reduction, so that the horizontalrelation between the soft-tissue and the skeletal pogo-nion did not change.

Ewing and Ross223 compared the soft-tissueresponse of mandibular advancement alone and com-bined with genioplasty. When mandibular advance-ment alone was performed, they found a consistent1:1 ratio of soft- to hard-tissue advancement at thepogonion, and predictions could be accurate in bothanterior-posterior and vertical directions. When agenioplasty was added to the advancement, how-ever, the results were much less consistent: the meanratio of soft-tissue to skeletal movement was 0.9:1 atthe pogonion, but the average difference in move-ment between the soft tissues and the skeleton wasapproximately 3mm. Thus when mandibularadvancement is combined with genioplasty, it isimpossible to predict the anterior-posterior soft-tissuechanges that will follow with any degree of accuracy.Changes in vertical dimensions were also moremarked when genioplasty was performed. The lowerlip showed a variable response to surgery particularlyin the genioplasty group, which had a mean 0.5:1ratio of soft-tissue to skeletal change with a range of4mm in either direction. After genioplasty the softtissue pogonion moved inferiorly relative to theunderlying pogonion. The behavior of the lower lipwas significantly different in the nongenioplasty andgenioplasty cases. The lip thinned by 1.4mm and

3.1mm respectively, but there was wide variability inboth groups.224

Van Sickels and colleagues225 studied the interplaybetween vertical and horizontal movement of thebony chin. The authors noted that the farther thechin was advanced, the less the soft tissue followedthe advancement. In addition, vertical movement ofthe chin greatly influenced the overall result. Themore the bony chin is shortened, the thicker thesoft-tissue chin becomes, and the reverse is true whenthe chin is lengthened. Finally, horizontal resorp-tion/stability appears to be influenced by the amountof dissection, rather than the amount of advance-ment.

Freihofer226 compared the soft-tissue response toLe Fort I osteotomy in cleft and noncleft patients andfound no significant difference in the ratio of responsebetween the two groups. Considerable individualvariation was noted, however, and patients with thickfleshy lips seemed to have a less favorable soft-tissueresponse than those with thin lips. Because the soft-tissue response was about 50% that of the bonymovement, it was frequently necessary to place themaxilla at an Angle Class II relationship to obtain thedesired improvement in the profile. The authorstresses the importance of preserving the nasal spineto gain the needed projection of the subnasale.

Hack and others193 reviewed the long-term pre-dictability of soft-tissue changes after Le Fort I sur-gery. The objectives of their study were to deter-mine the stability of soft-tissue changes 5 years afterLe Fort I osteotomy; to find reliable correlations, ifany, of soft-tissue changes to bone movements; andto ascertain the predictability of soft-tissue change asan aid to orthodontic treatment planning. Analysisof the stability data revealed that most horizontaland vertical soft-tissue changes after Le Fort I surgeryoccurred in the first year after surgery. Significant(>10%) change continued to occur over the subse-quent 4 years for subnasale, labrale inferius, upperlip protrusion, lower lip protrusion, and soft-tissueconvexity. Reliable correlations of skeletal change atsurgery to 5-year soft-tissue change could be madefor 10 variables. The authors felt that, given therelatively low reliability of long term correlations, it ispossible that soft-tissue movements may become pro-gressively independent of bony manipulations overtime. Detailed and comprehensive tabulations ofmeasurements for hard- and soft-tissue landmarks at


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three chronological points in the study are includedin the article.

Betts and associates227 looked specifically atchanges in the nasal and labial soft-tissues in responseto surgical repositioning of the maxilla in 32 patientswho were evaluated preoperatively and 1 year post-operatively. The variables examined were age, sex,and whether alar cinch suture, V-Y closure, or con-touring of the anterior nasal spine had been per-formed. The authors concluded that accurate pre-dictions could be made if the patients were groupedby vector-specific maxillary movements. In general,regression analysis showed that the base of the nosewidened in all patients regardless of the vector ofsurgical maxillary movement. Narrow noses wid-ened more than did broad noses, and alar cinchsuture widened the alar base even more. There wasan associated shortening of the nose. The nasolabialangle decreased or remained constant in mostpatients, whereas the upper lip widened and length-ened at the philtral columns. The results indicatethat soft-tissue changes associated with maxillary sur-gery may be affected more by the position of thesoft-tissue incision and by the methods used in clo-sure than by the surgically induced skeletal change.

McCance and colleagues228 reviewed the soft- andhard-tissue changes after bimaxillary orthognathicsurgery in 16 patients with skeletal Class III occlu-sion. Follow-up was at 1 year postoperatively. Aftera Le Fort I osteotomy there was commonly a 1:1ratio of soft-tissue to bone movement in the midline,which increased to 1.25:1 at the alar bases and overthe canine regions bilaterally. There was also a 1.25:1or greater ratio over the chin and mentalis regionsfollowing mandibular setback.

DENTAL EXTRACTION AND FACIAL FORM

The possible effect of dental extractions on thedevelopment of the maxilla and mandible has beendebated for years, particularly in the orthodontic lit-erature. A team of investigators from Ann Arbor229

compared long-term outcomes of orthodontic treat-ment of Class II patients whose premolars had orhad not been extracted. Patients were judged on sixmeasures of protrusion and crowding of teeth andassigned to three prognostic groups: clear-cutextraction, clear-cut nonextraction, and an interme-diate, borderline category. Some 15 years after treat-ment, 62 clear-cut patients (33 extraction and 29

nonextraction) were recalled and examined. Theyfound that both groups underwent essentially thesame change: decreased profile convexity and man-dibular displacement mesially and anteroposteriorly.On the basis of detailed analysis of multiple cephalo-metric variables, the authors concluded that theirfindings failed to support the common belief thatpremolar extraction causes dished-in profiles,distalized mandibles, and craniomandibular dysfunc-tion.

Douglass and coauthors230 looked at cephalomet-ric changes occurring in patients after 20 years ofwearing complete dentures. They found a loss ofvertical dimension on profile; the mandible wasrotated in a counterclockwise fashion that resulted inincreased prognathism; the maxillary alveolus wasstable; the mandibular alveolus resorbed; and thedentures rotated counterclockwise and shifted for-ward slightly. From these observations, the readermay conclude that the effect of teeth on the functionand anatomy of the maxillary and mandibular skel-eton cannot be overlooked.

COMPLICATIONS

El Deeb, Wolford, and Bevis231 offer a thoughtfulreview of the complications of orthognathic surgery.Complications can be broken down into presurgical,surgical, and postsurgical occurrences.

Significant presurgical complications may includea failure to remove maxillary and mandibular thirdmolars prior to orthognathic surgery. The authorssuggest that the third molars should be removed atleast 9–12 months before surgery so as to avoidundesirable splits or fracturing of mobilized segments.In addition, the authors point to the value of thor-ough planning for interdental cuts. This involvesorthodontic manipulation to divert the tooth roots inorder to provide access for the bone cuts. Minimalorthodontics is advocated when the tooth roots areshort due to underdevelopment. The primary orth-odontic goal of positioning teeth over basal bone isemphasized.

Surgical complications include obstruction of theairway, edema, hemorrhage, infection, segmentmobility, hypesthesia and paresthesia, and relapse.The use of rigid fixation eliminates the need for max-illary-mandibular fixation and significantly lessens therisk of airway problems. In Le Fort I maxillary sur-gery the vessels most commonly involved in bleeding


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complications include the posterior superior alveolarartery, descending palatine artery, anterior and pos-terior palatine arteries and veins, the pterygoid plexus,and the maxillary artery or its branches. In man-dibular surgery the most frequently injured vesselsare the inferior alveolar artery and vein, the facialartery and vein, the masseteric artery, theretromandibular vein, and the maxillary artery orany of its branches.

As for postsurgical complications, 8 infections werereported in 600 cases of sagittal split osteotomy—a1.33% rate—reaffirming the value of prophylacticantibiotics. The most important contributing factorsto wound infection in orthognathic surgery are con-tamination during and immediately following sur-gery, age of the patient, length of the surgical proce-dure, and avascular necrosis of bone. CT scans andMRI were useful in detecting infection early in thepostoperative period.

Nerve injury was most common in the mandible.The subcondylar vertical osteotomy was associatedwith a significantly lower incidence of neurosensorydeficit than the sagittal split osteotomy. An 85%incidence of paresthesia was noted immediately aftersagittal split osteotomy, which fell to 9% by 1 yearpostoperatively. Prolonged paresthesia was mostcommon in patients older than 40.

Most often injured during sagittal split osteotomywas the inferior alveolar nerve, and the injuryoccurred primarily during medial retraction of thenerve when performing the medial horizontalosteotomy cut or upon completion of the sagittalsplit, when the nerve adheres to the proximal seg-ment and is stretched. A fine spatulate chisel facili-tates bone splitting and lessens the risk to the inferioralveolar nerve.

El Deeb et al231 also noted reduced maxillary-mandibular opening following orthognathic surgery.This decrease was dramatic in patients treated bysagittal split osteotomy. Takeuchi, Furusawa, andHirose232 investigated the mechanism of paresthesiaassociated with sagittal split mandibular ramusosteotomy. Using 3D CT, they determined that theinferior alveolar neurovascular bundles remainedintact during the sagittal osteotomy in all cases, andconcluded that sensory loss to the mental nerve isdue to compression of the nerve trunk at the man-dibular foramen, which in turn results from posteriormovement of the mandibular ramus. All authorsadvocate a postoperative regimen of muscular and

occlusal rehabilitation to normalize muscle function,condylar movement, and range of mandibularmotion.

Relapse after orthognathic surgery is often sec-ondary to unstable orthodontic movement, whichessentially means that the teeth have been movedoff the basal bone. Takeuchi and colleagues232 stressthe importance of thorough knowledge of theanatomy and meticulous planning to ensure a pre-dictable, safe osteotomy, as well as dealing with seg-mental loss, lack of tooth viability, overimpaction,and fistula formation. Their article is recommendedto all clinicians contemplating orthognathic surgery.

CONCLUSION

A systematic approach to the analysis of facialdeformities is essential to state-of-the-art surgicalresults. The best plan of treatment must take intoconsideration the origin of the deformity and factorspeculiar to these cases.

Preoperative evaluation should involve a clinicalanalysis that emphasizes the relationships amongexisting structures and how they compare to estab-lished acceptable norms. These proportions shouldthen be correlated with the bony morphology asseen in cephalometric testing.

Reference points must be carefully evaluated and,if involved in the deformity, their position must becorrected to enable proper evaluation of the remain-ing parts. These measurements must then be corre-lated with a careful assessment of dental occlusion.

No single system of analysis is applicable to allpatients. The face-bow articulator lets the dentalcasts be arranged in space to duplicate the occlusalrelationships of the patient. Exact model surgery canbe performed, and the three-dimensional alterationsbetween the upper and lower jaw can be visualizedand computed. At this point analysis yields the move-ments needed to achieve the desired bony and soft-tissue changes. (These measurements may differ,however, and the clinical impression must take pre-cedence.) The expected result of surgery is arrived atby translating the measured distances into mock sur-gical tracings after correcting for the ratio of responsebetween the soft and hard tissues. Osteotomies canthen be planned following traditional lines or incor-porating modifications designed for specific adjust-ments of the bony framework.


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