Sample Chapter Multidisciplinary Appraisal of Treacher Collins Franceschetti Syndrome, 1e by HASAN...

Introduction

Th e role of an orthodontist in the management of Treacher Collins –Franceschetti syndrome (TCOF) patient is to fulfi l functional need of mastication and overall aesthetics. Th e diagnostic records (study models, orthopantomogram [OPG], lateral cephalogram and photographs) of the patient are usually done. Intraoral periapical radiograph (IOPA), posteroan-terior cephalogram, occlusogram, ultrasonography, cone-beam computed tomogram and magnetic resonance imaging may be required according to patient need. Various cephalometric analysis (Down’s, Tweed, Holdaway, Bjork’s, etc.) are done to detect skeletal, dental and soft tissue problems. Individualized cephalometric analysis (quadrilateral analysis) is preferred to analyse the regional dysplasia of jaws for planning of orthognathic surgery. Growth modifi cation is the ideal treatment approach to prevent the retrusion of lower jaw and to develop anterior open bite in growing individuals. Corrective orthodontics (dental camoufl age) is a valid option in mild to moderate dentoskeletal problems. Distraction osteogenesis and orthognathic surgery are terminal and defi nitive treatment approach after growth completion in severe cases.

Diagnostic Records

Orthodontic diagnosis requires a broad overview of the patient’s status. Th e purpose of diagnostic records is twofold: to document the patient’s initial condition and to supplement the diagnostic information obtained from the interview and clinical examination. Th e records can be divided into three major categories: dental casts, photographs and radiographs.

Above records are described on a patient named N.M., an 18-year-old female, affl icted with TCOF syndrome.

Chapter 6

Orthodontic Diagnosis and Management of Treacher

Collins SyndromeGyan P. Singh, Sneh Lata Verma and Vijay P. Sharma

Chapter-06.indd 29Chapter-06.indd 29 12/18/2012 2:06:59 PM12/18/2012 2:06:59 PM

30 Multidisciplinary Appraisal of Treacher Collins Syndrome

DENTAL CASTS

Dental casts or study models for orthodontic purposes diff er from those taken for other dental purposes in two ways: (1) Th e impressions are extended maximally to allow as much as possible of the alveolar process and teeth to be displayed. (2) Th e casts are trimmed with a symmetric base to allow better visualization of asymmetries in arch form and tooth position. Casts should be trimmed to centric (habitual) occlusion. Orthodontic study models consist of two parts. Anatomic part of the study model consists of the actual impression of the dental arch and its surrounding structures and is usually made in stone plaster (Fig. 6.1). Artistic part of the study model consists of a symmetrical plaster base that supports the anatomic portion and helps in analysing the occlusion and orientation of the study models

(Fig. 6.1). Patient’s particulars are clearly inscribed on the back of the study model bases (name, age, sex, registration number, date of the impression and stage of the treatment).

(a) (b)

(c) (d)

Fig. 6.1: Orthodontic study models of a female patient (N.M., 18 years) affl icted with TCOF: (a) frontal view, (b) right lateral view, (c) left lateral view and (d) back of the study model.


Orthodontic Diagnosis and Management of Treacher Collins Syndrome 31

Study model enables a more accurate assessment of the malocclusion and facilitate measurements of the dental arches, size of teeth and calculation of the space required for the correction of malocclusion. Pretreatment study models also serves as a replica of the occlusion and dentition to objectively record traits of malocclusion such as overjet, overbite, canine relation and buccal segment rela-tion. Study models help in assessing the nature and severity of the malocclusion and are valuable aid in total space analysis, being an essential requisite for this invaluable diagnostic procedure. Discrepancy in arch perimeter and tooth size can help in calculating amount of crowding or spacing, and further infl uence extraction decision. Molar relation can be assessed from the lingual aspect also and this is an advantage, as occlusion cannot be assessed from lingual aspect when examining the patient clinically. Study model helps in explaining the treatment plan to the patient and parents and is also helpful in the assessment of the treatment progress and in motivating the patient.

FACIAL PHOTOGRAPHS

Evaluation of facial photographs essentially involves recording of the fi nd-ings on clinical examination for future reference and confi rmation of the clinical observation though a detailed analysis. Th e clinical photographs are essentially grouped as extraoral and intraoral.

EXTRAORAL PHOTOGRAPHS

Th e following views (frontal, left lateral, right lateral, oblique and smiling) are taken for orthodontic diagnosis and treatment planning (Fig. 6.2).

INTRAORAL PHOTOGRAPHS

Intraoral photographs supplement clinical fi ndings of occlusion which are also recorded through the dental study models. In addition, the intraoral photos help review hard and soft tissue fi ndings that exist before treatment. Th ese include white spot lesions, fl uorosis, hyperplastic areas and gingival clefts. Th e following views are taken (Fig. 6.3):

Frontal �

Right and left buccal views �

Occlusal view of the maxilla and mandible �

ORTHOPANTOMOGRAM

It provides an overview of the bony structures of the jaws and teeth includ-ing the temporomandibular joint (TMJ) and dentition.



Evaluation of the OPG (Fig. 6.4) involves an assessment of the following:

1. Th e bony structures and the symmetry (mandible, midface and TMJ) 2. Dentition and associated structures 3. Vertebra and parts of the skull 4. Soft tissues

Evaluation of the mandible can begin with the observation of the TMJ and its compartments. It is necessary that a comparison be made between left- and right-side structures. While examining the body of the mandible, one should look for the anatomical structures such as the external oblique ridge, the mental foramen and the mandibular canal. From an orthodontic point of view, the right and left sides should be symmetrical for ramus height, corpus length, gonial angle and overall shape of the mandible. Presence of a sharp and accentuated antegonial notch is an indicator of the

(a) (b) (c)

(d) (e)

Fig. 6.2: Photographs of a female patient (N.M., 18 years) affl icted with TCOF: (a) frontal (b) right lateral, (c) left lateral (the profi le image should be taken in natural head position), (d) oblique view and (e) the frontal posed smiling view.



hampered growth of the mandible. A prominent antegonial notch is often seen in cases of TCOF.

Evaluation of the midface involves an assessment of symmetry of the structures between the left and the right side. Th e structures that are readily seen on the OPG are as follows:

Contours of the maxilla �

Pterygomaxillary fi ssure �

Zygomatic buttress �

Orbital rims and infraorbital foramen �

Maxillary sinus �

(a) (b) (c)

(d) (e)

Fig. 6.3: Intraoral photographs of a female patient (N.M., 18 years) affl icted with TCOF: (a) frontal, (b) right lateral, (c) left lateral, (d) upper occlusal and (e) lower occlusal.

Figure 6.4: Pretreatment OPG of a female patient (N.M., 18 years) affl icted with TCOF shows deep antegonial notch and root canal treated maxillary left central incisor.



An OPG provides a bird’s eye view of the entire dentition and its sup-porting bone. It is important to ascertain the number, size and eruption status of the teeth, and missing or supernumerary teeth. OPG gives an overview of the presence of caries, restorations, bone loss, impacted teeth, retained roots and also the path of eruption of the teeth. Dental anomalies are seen in 60% of TCOF patients. Th ese anomalies consist in tooth agen-esis (33%), enamel deformities (20%) and malplacement of the maxillary fi rst molars (13%). In some cases, dental anomalies in combination with mandible hypoplasia result in a malocclusion; this can lead to problems with food intake and the ability to close the mouth.

LATERAL CEPHALOGRAM

Cephalogram of an individual helps to establish the severity of dental and skeletal malocclusion (Fig. 6.5). It also helps in identifying the location of dysplasia. It aids in treatment planning and decision on extraction/growth modifi cation/surgical orthodontics. Stage and the posttreatment cephalograms are taken to monitor the progress of the treatment outcome. Serial cephalo-gram can be used to monitor the growth changes of the individual.

Th e lateral cephalometric radiograph in TCOF shows hypoplasia of the facial bones, like the malar bone, mandible and mastoid.

Roberts et al. studied the eight TCOF patients on longitudinal basis to fi nd out the cause of facial convexity and retrusion of the mandible. He

Fig. 6.5: Pretreatment lateral cephalogram of a female patient (N.M., 18 years) affl icted with TCOF shows the peculiar broad curvature of the mandible.



fi nally concluded the upper anterior facial height (N-ANS) was relatively constant through growth period of aff ected individuals almost same to that of adult but the total anterior facial height was commonly found more and considered to be the cause of developing anterior open bite and backward position of the mandible.

In TCOF patients, there was absolute defi ciency of the ramus and body length of the mandible resulting in shorter posterior facial height and the body of the mandible curved in downward and backward direction to provide the functional room for the dentition. Th ough the antegonial notch depth was increased and the gonial angle becomes more obtuse as seen in those aff ected by TMJ trauma at early age and in juvenile rheumatoid arthritis.

Open bite is defi ned as a lack of vertical overlap of the anterior teeth in centric occlusion. Generally two forms of open bite can be distinguished: dental and skeletal open bites. Dental open bite occurs when the abnormali-ties are confi ned to the dentoalveolar region. Th is type is usually related to environmental factors, such as thumb sucking, and can be treated suc-cessfully by orthodontic treatment alone. Th e prognosis of a dental open bite is favourable, provided the environmental factors can be controlled. Th e second type of open bite is skeletal open bite, which occurs when the patient has an open bite that is not limited to the dentoalveolar region, but the aetiology lies in the underlying skeletal structure of the jaws. In skeletal open bites, the aetiology may be related to the vertical facial form as a result of excessive vertical growth. Th is skeletal pattern has been described as long face syndrome, high angle case or hyper divergent growth pattern.

Skeletal open bites tend to have greater molar and incisor eruption whereas dental open bites are a result of intrusion of anterior teeth. If patient had an open bite and an upper anterior facial height to lower anterior facial height ratio less than 0.65, then the open bite is considered skeletal and could not be corrected by orthodontic treatment alone. Skeletal open bite cases have some of the following characteristics: increased mandibular plane angle, increased total facial height, decreased posterior facial height, tipping of the palatal plane and a retrognathic mandible.

Orthodontic Diagnosis

Convex facial profi le with the prominent dorsum of the nose, retrusive lower jaw and chin are commonly present in fully expressed TCOF patients. An antimongoloid slant of palpebral fi ssure due to colobomata, hypoplasia of the lower lids and partial absence of the eyelid cilia are present in eyes. Hypoplasia of the malar bones and hypoplastic zygomatic complex are the most cardinal sign of the syndrome. Th e mandible and the maxilla are also



hypoplastic with more or less aff ected TMJ and muscles of the mastica-tion. Angle’s Class II Division 1 malocclusion with open bite is commonly found in these patients. A reduced cranial base angle is also found in TCOF patients.

On the basis of the questions of the patient, clinical examination and evalu-ation of the diagnostic records, the following diagnosis is made as follows:

An 18-year-old female patient, named N.M., had the chief complaints of unaesthetic appearance as well as inability to incise from the front teeth. Th e patient was born with the Treacher Collins syndrome. In familial history her mother has the traits of the same. Milestones during the development of the patient were that normal patient had a history of trauma at 14 years of age in which there was a loss of vitality of maxillary right central incisor and subsequent periapical pathology. On growth evaluation the patient’s height was 153 cm and the weight was 45 kg. Growth status was normal and recorded at stage 5 in cervical vertebrae maturation index where only 5% growth was left.

On extraoral clinical examination (Fig. 6.2), the head shape was dolichocephalic, facial form was leptoprosopic and apparently bilaterally symmetrical. Patient had convex profi le, nasolabial angle and mentolabial sulcus was measured less than normal. In lips analysis, the lips were incom-petent at postural rest position, interlabial gap was 5 mm and the maxillary incisors’ show at rest was 50% (half of the total clinical crown length). Smile analysis revealed consonant smile arc, less buccal corridors and more than normal smile line (gingival display). Intraoral examination (Fig. 6.3) showed fair oral hygiene, but oral mucosa was pigmented showing black-ish pink colour. She had all permanent teeth present except third molars (Fig. 6.4). Both maxillary fi rst permanent molars were carious; left central incisor was discoloured and hypoplastic. Both maxillary and mandibular arches were ‘U’ shaped. Spacing was present in maxillary anterior region, while mandibular arch was crowded (Fig. 6.1). Anteroposteriorly molars showed Angle’s Class III Subdivision left. Anterior open bite is 3 mm and maximum mouth opening 43 mm was present. Temporomandibular joint examination was found normal.

Th e evaluation of the OPG (Fig. 6.4) reveals that the patient has the typical deep antegonial notch, suggestive of the prominent feature of the TCOF. Th e maxillary left incisor was root canal treated and periapical pathology in relation to it. Lower right third molar is missing. Mental foramina are quite prominent. Restorations are observed on lower left premolars and on the fi rst molar. Th e mandible is small (63 mm) and bowed up to accommodate the teeth. Th e angle of the mandible is obtuse; the ramus appeared shortened, which in the body is seen as a ‘downward curve of the horizontal ramus’.



Th ere is crowding in the lower arch due to small mandible. Teeth in arch are normal except the hypoplastic maxillary incisors.

On the basis of cephalometric analysis (Table 6.1), the patient was found vertical grower and soft tissue problems included incompetent lips, protrusive upper and lower lips, increased upper incisor show at rest with interlabial gap of 5 mm. Th e maxilla is poorly developed and has small antra and shallow orbital fl oors. Th e orbital margins are thin. Th e posterior portion of the maxilla is shortened vertically. Th e malar bones are hypoplastic. Th ere was a decrease in the cranial base angle. It is attributed the defi cient growth at the spheno-occipital synchondrosis.

Cephalometric analyses including the quadrilateral analysis are done for the aff ected patient. Linear and angular variables are taken to diagnose the involved skeletal unit (Fig. 6.6). Cervical vertebrae maturation index is selected to know the skeletal growth status of the patient (Fig. 6.7). Th ese variables are given as follows:

1. Maxillary base length, Max. Lth.: It is measured in millimetre (mm), horizontally between the two points projected on to the palatal plane. Th e anterior limit of the maxillary base length is determined by

Table 6.1: Cephalometric Values of Affected Female Patient

S. no. Variables N.M., 18 years

1 Maxillary base length 57 mm

2 Mandibular base length 63 mm

3 (ALFH + PLFH)/2 56 mm

4

5 Angle of convexity 150°

6 Jarabak ratio 55%

7 App–Bpp 14 mm

8 Basal plane angle 39°

9 ANB angle 12°

10 Wits appraisal 10 mm

11 Depth of antegonial notch 16 mm

12 Nasofrontal angle 148°

13 Saddle angle 117°

14 Articular angle 155°

15 Gonial angle 138°

16 Sum of Bjork angles 410°

17 CVMI stage 6 (Completion)



projecting a perpendicular from subspinale (point A) upward to the palatal plane (ANS–PNS), while the posterior limit of the maxillary base length is determined by projecting a perpendicular from the most inferior portion of the pterygomaxillary fi ssure (Ptm) downward to the palatal plane.

2. Mandibular base length, Mand. Lth.: It is measured in mm, horizontally between the two points projected on to the mandibular plane (Go–Gn). Th e anterior limit of the mandibular base length is determined by pro-jecting a perpendicular from supramentale (point B) downward to the mandibular plane (Go–Gn), while the posterior limit of the mandibular

1. Maxillary base length2. Mandibular base length3. Anterior lower facial height4. Posterior lower facial height5. Angle of convexity

ANSA

51

3

J

2

4

Ptm

PNS

Go

Ar

N

B

Gn

Fig. 6.6 (a): Cephalometric variables: (1) maxillary base length, (2) mandibular base length, (3) anterior lower facial height, (4) posterior lower facial height and (5) angle of convexity.



base length is determined by projecting a perpendicular from point J downward to the mandibular plane.

3. Anterior lower facial height (ALFH): It is measured in mm from the projection of point A on to the palatal plane to the projection of point B on to the Go–Gn plane.

4. Posterior lower facial height (PLFH): It is measured in mm from the projection of Ptm on to the palatal plane to the projection of point J on to the Go–Gn plane. Th ese four measures (maxillary base length, mandibular base length, anterior lower facial height and posterior lower facial height) form the basis for the quadrilateral analysis of the lower face.

Th e quadrilateral analysis indicates that in balanced facial pattern a 1:1 ratio exists between the maxillary bony base length (Max. Lth.) and

6

Me

6

Ptm

PNS

Go

Ar

N

10

9

8

S

6. Jarabak ratio7. App-Bpp8. Basal plane angle9. ANB angle10. Depth of antegonial notch

B

ANSA

7

Fig. 6.6 (b): Cephalometric variables: (6) Jarabak ratio, (7) App–Bpp, (8) basal plane angle, (9) ANB angle and (10) depth of antegonial notch.



the mandibular bony base length (Mand. Lth.); also that the average of the ALFH and the PLFH equal to these bony base lengths.

Simply stated, Max. Lth. = Mand. Lth. = (ALFH + PLFH)/2

5. Angle of facial convexity ALFH and anterior upper facial height (AUFH): Th ey intersect at the projection of point A on the palatal plane. Th is intersection forms an angle defi ned as the angle of facial convexity (165–178°). Th is angle relates the quadrilateral to the cranial base and upper face and is a means of establishing a skeletal profi le assess-ment.

OCC. Plane

14

A

12

N

S

13

Ar

15

GoB

BOAO

11

Me11. Wits appraisal12. Nasofrontal angle13. Saddle angle14. Articular angle15. Gonial angle

Fig. 6.6 (c): Cephalometric variables: (11) Wits appraisal, (12) nasofrontal angle, (13) saddle angle, (14) articular angle and (15) gonial angle.



6. Jarabak ratio: It is the ratio of posterior facial height (S-Go) and ante-rior facial height (N-Me). It indicates the growth pattern of individual. Average value is (62–65%). A higher percentage means a relatively greater posterior facial height and horizontal growth. A small percentage denotes a relatively shorter posterior facial height and vertical growth.

7. App–Bpp: Th e measurement (in mm) between perpendiculars drawn from points A and B to the palatal plane.

8. Basal plane angle: Th is defi nes the angle of inclination of the mandible to the maxillary base, the latter being represented by the palatal plane. Th e angle, therefore, also serves to determine rotation of the mandible. If the basal plane angle is large, the mandible is usually rotated backwards (vertical growth type), and if it is small, mandible is usually rotated forwards (horizontal growth type).

9. ANB angle: Th is angle is formed between points A, N and B. An ANB angle of 2 + 2 was considered Class I. Angles greater than 4° were considered Class II. Angles less than 0° were considered Class III.

10. Depth of antegonial notch: It is the distance along a perpendicular line from the deepest point of notch concavity to a tangent through the two points of greatest convexity on the inferior border of the mandible on either side of the notch. Th e mandibular growth potential is diminished in patients with pronounced antegonial notching. Prominent mandibu-

C2p C2a

C2m

C3up C3ua

C3m

C3lp C3la

C4up C4ua

C4lp C4la

C4m CS1 CS2 CS3 CS4 CS5 CS6

(a) (b)

Fig. 6.7: (a) Cephalometric landmarks for the quantitative analysis of the mor-phologic characteristics of the vertebral bodies of C2, C3 and C4. (b) Schematic representation of the stages of cervical vertebrae.



lar antegonial notching has been seen with acquired and congenital abnormalities of the mandible.

11. Wit’s appraisal: Jacobson described the ‘Wit’s’ (University of Witwa-tersrand) appraisal of jaw disharmony, which is a measure of the extent to which the jaws are related to each other anteroposteriorly. Th e method of assessing the extent of jaw disharmony entails drawing perpendiculars on a lateral cephalometric head fi lm tracing from the point A and point B on the maxilla and mandible, respectively, on to the occlusal plane which is drawn through the region of maximum cuspal interdigitation. Th e points of contact on the occlusal plane from A and B are labelled AO and BO, respectively. It was found that with normal occlusion, point BO was approximately 1 mm anterior to point AO. In skeletal Class II jaw dysplasia, point BO would be located well behind point AO, whereas in skeletal Class III jaw disharmonies, point BO will be forward of point AO.

12. Nasofrontal angle: It is located between a line drawn from the radix tangential to the glabella and a second line from the same point tan-gential to the nasal tip. Th e latter can be tangential to the nasal dorsum as well. A normal nasofrontal angle is 130° ± 7° in men and 134° ± 7° in women.

13. Saddle angle: Th e NS–Ar angle is the angle between the anterior and the posterior cranial base. A large saddle angle indicates a posterior position and a small saddle angle an anterior position of the fossa. If this deviation in position of the fossa is not compensated by the length of the ascending ramus, the facial profi le becomes either retrognathic or prognathic. Th e mean value is 123′ ± 5′.

14. Articular angle: Th e S Ar–Go angle is one of those rare angles that may be altered by orthodontics. If the bite is opened by extrusion of the posterior teeth or by distalization, the angle increases. Whilst mesial movement of the teeth will make it smaller. A large articular angle imposes retrognathic changes on the profi le, while a small angle imposes prognathic changes. Th e mean value is 143 ± 6.

15. Gonial angle: Th e Ar–Go–Me angle is an expression for the form of the mandible, with reference to the relation between body and ramus. A large angle indicates more of a tendency to posterior rotation of the mandible, with condylar growth directed posteriorly. A small gonial angle, on the other hand, indicates vertical growth of the condyles, giving a tendency to the anterior rotation with growth of the mandible. Th e mean value is 128 + 7.

16. Sum of the posterior angles: Th e sum of the three above-mentioned angles (saddle, articular and gonial angles) is 396 + 6 (Bjork). Th is is signifi cant for the interpretation of the analysis. If it is greater than 396,



the direction of growth is likely to be vertical; if it is smaller than 396, growth may be expected to be horizontal.

17. CVMI stage: Th ere are six stages of the CVMI as mentioned below (Fig. 6.7). i. Initiation: At this stage, adolescent growth was just beginning and

80–100% of adolescent growth was expected. Inferior borders of C2, C3 and C4 were fl at at this stage. Th e vertebrae were wedge shaped, and the superior vertebral borders were tapered from posterior to anterior.

ii. Acceleration: Growth acceleration was beginning at this stage, with 65–85% of adolescent growth expected. Concavities were develop-ing in the inferior borders of C2 and C3. Th e inferior border of C4 was fl at. Th e bodies of C3 and C4 were nearly rectangular in shape.

iii. Transition: Adolescent growth was still accelerating at this stage towards peak height velocity, with 25–65% of the adolescent growth expected. Distinct concavities were seen in the inferior borders of C2 and C3. A concavity was beginning to develop in the infe-rior border of C4. Th e bodies of C3 and C4 were rectangular in shape.

iv. Deceleration: Adolescent growth began to decelerate dramatically at this stage, with 10–25% of adolescent growth expected. Distinct concavities were seen in the inferior borders of C2, C3 and C4. Th e vertebral bodies of C3 and C4 were becoming more square in shape.

v. Maturation: Final maturation of the vertebrae took place during this stage, with 5–10% of adolescent growth expected. More accentu-ated concavities were seen in the inferior borders of C2, C3 and C4. Th e bodies of C3 and C4 were nearly square in shape.

vi. Completion: Growth was considered to be complete at this stage. Little or no adolescent growth was expected. Deep concavities were seen in the inferior borders of C2, C3 and C4. Th e bodies of C3 and C4 were square or were greater in vertical dimension than in horizontal dimension.

Role of Orthodontist

Th e treatment of Treacher Collins syndrome should be tailored to the spe-cifi c symptoms and needs of each individual. Th e treatment of individuals aff ected by TCOF needs a multidisciplinary approach and may involve the intervention of various professionals. Orthodontic intervention can be performed during diff erent growth stages.



GROWTH MODIFICATION

Whenever a jaw discrepancy exists, the ideal solution is to correct it by modifying the child’s facial growth, so that the skeletal problem is corrected by the diff erential growth of the eff ected jaw.

Functional appliances are designed to enhance forward mandibular growth in the treatment of distal occlusion by encouraging a functional displacement of the mandibular condyles downwards and forwards in the glenoid fossae. Th is is balanced by an upward and backward pull in the muscles supporting the mandible. Adaptive remodelling may occur on both articular surfaces of the temporomandibular joint to improve the position of the mandible relative to the maxilla.

A skeletal mandibular defi ciency is well established at an early stage of dental and facial development. Th e orthopaedic approach to treatment endeavours to correct the skeletal relationships before the malocclusion is fully expressed in the permanent dentition. Early diagnosis and interceptive treatment aims to restore normal function, and thereby enable the permanent teeth to erupt into correct occlusal and incisal relationships.

Th e prognosis for correction of anterior open bite depends on the degree of skeletal and soft tissue imbalance. Early treatment is frequently eff ective in controlling the functional imbalance associated with adverse soft tissue behaviour patterns.

Twin block appliances are simple bite blocks that are designed for full-time wear. Th ey achieve rapid functional correction of malocclusion by the transmission of favourable occlusal forces to occlusal inclined planes that cover the posterior teeth. Th e forces of occlusion are used as the functional mechanism to correct the malocclusion (Fig. 6.8).

In open bite cases, the twin blocks are made to modify growth with occlusal contacts on all posterior teeth to apply an intrusive force to mini-mize vertical growth. No trimming was done on the blocks.

Anterior open bite is related to unfavourable vertical growth and requires careful management. Th rough treatment, all posterior teeth must remain in

(a) (b)

Fig. 6.8: Occlusal inclined planes are functional mechanism of the natural dentition. Twin block modify the occlusal inclined plane and use the forces of occlusion to correct the malocclusion. The mandible is guided forwards by the occlusal inclined plane.



occlusal contact with the opposing bite blocks to prevent over eruption. It is important to avoid over eruption of posterior teeth, as it would accentuate the vertical growth tendency and tend to open the bite even more. Intru-sion of posterior teeth helps to reduce anterior open bite and encourages a favourable mandibular rotation to close the mandibular plane angle.

For correction of developing open bite at an early age, light masticatory muscle exercises for one minute fi ve times a day can be helpful. Correction suggests that clenching exercises helped to control the vertical dimension and assist in closure of open bite malocclusions.

DENTAL CAMOUFLAGE

Beyond the adolescent growth spurt, despite the fact that some facial growth continues, too little is left to correct skeletal problems. Th e possibilities for treatment, therefore, are either displacement of the teeth relative to their supporting bone, to compensate for the underlying jaw discrepancy or surgical repositioning of the jaws. Displacement of the teeth, similar to the retraction of protruding incisors, often is called camoufl age. Th e name is well chosen, because the objective of the treatment is to correct the malocclusion while making the underlying skeletal problem less apparent. Because skeletal Class II problems often can be camoufl aged rather well, most camoufl age treatment is for Class II patients. With extraction of teeth to provide space for the necessary tooth movement, often it is possible to obtain correct molar and incisor relationships despite an underlying skeletal Class II jaw relationship. For Class II correction, the extraction of upper fi rst premolars alone or upper fi rst and lower second premolars often is the choice. Camoufl age implies that repositioning the teeth will have a favour-able, or at least not a detrimental, eff ect on facial aesthetics. For patients with mild to moderate skeletal Class II problems, displacement of the teeth relative to their bony bases to achieve good occlusion is compatible with reasonable facial aesthetics, and the camoufl age can be quite successful. In more severe Class II problems, it may be possible to obtain good occlusion only at considerable expense to facial aesthetics. If the upper incisors must be displaced far distally and the lower incisors proclined to compensate for mandibular defi ciency, the aesthetic result is increased prominence of the nose and an overall appearance of mid- and lower-face defi ciency. Even if the occlusion is corrected, such a result is unacceptable for two reasons: (1) it did not address the patient’s major problem of facial appearance and social acceptability and (2) the lower incisors are likely to relapse lingually and become crowded.

Once the growth is complete, clinician cannot utilize growth modifi cation to address the skeletal problem. Many nonsurgical options to correct the



open bite includes anterior vertical elastics, posterior bite blocks, high pull headgear, vertical pull chin cups and implants. Nonsurgical options usually require longer treatment time and more patient compliance.

In the above patient (N.M., 18 years, affl icted with TCOF), objective of the treatment was to achieve aesthetically acceptable and functionally optimum occlusion, to correct the proclination of incisors, open bite and molar relation. To achieve the corrections for this maximum anchorage case (closure of the extraction space is mainly the retraction of the anterior teeth to enhance aesthetic of the patient), treatment plan included 022 slot Roth fi xed appliance therapy with banding of all the maxillary and mandibular fi rst molars. Alignment and levelling of the arches followed by the extrac-tion of fi rst premolars in all the upper and lower quadrants. Extraction of the dentition also facilitates the correction of open bite. Finally after fi nishing and detailing of the occlusion the retention of achieved results was accomplished.

DENTAL CARE FOR ORTHODONTICS AND SURGICAL PROCEDURES

Any suggested periodontal or general dental care associated with maintain-ing teeth or improving dental health should be done prior to orthodontics and surgical treatment. Th e aim is to maintain as many teeth as possible and stabilize the periodontium. Restorative work has to be fi nished in sug-gested cases.

ORTHODONTIC TREATMENT BEFORE SURGICAL PROCEDURES

Th e objective of the presurgical orthodontics is to place the teeth in the most suitable position over basal bone in preparation for intended surgery.

Th roughout the presurgical orthodontic phase occlusal detailing is not performed. Th e presurgical orthodontic fi xed appliance will stay in place throughout the surgery and provide fi xation during healing. Preferably the fi xed appliance should be edgewise or straight wire appliance. After surgical fi xation is released, another shorter period (4–6 months) of orthodontics is indicated to detail the occlusion before retainers are fi tted.

Following are the procedures that are undertaken as part of presurgical orthodontics:

1. Tooth alignment within the arches: Th roughout the presurgical orthodontic treatment, rotations, spacing and crowding are to be eliminated. Fixed appliances are favoured as they provide better control, and it is possible to align several teeth. Space may be required for these manoeuvres,



which can be gained by interdental stripping or even extractions. Extractions during presurgical orthodontics are generally undertaken to relieve moderate to severe crowding within the dental arches and to accommodate segmental bone cuts. If space calculations allow to align the arch, it is better to avoid extractions at this stage. Extractions can be done at the time of surgery.

2. Interarch coordination: Any crossbites whether localized or segmental should be corrected at this phase. Crossbites with narrow maxillary arch require some form of arch expansion procedures. As a general rule orthodontic expansion or contraction to coordinate the upper and lower arches should be performed before the surgery so as to provide correct postoperative occlusal interdigitation.

3. Incisor inclinations and decompensation: Majority of the severe skeletal jaw discrepancies are partly compensated by change in axial inclination of the anterior teeth in opposite direction. For example in Class II skeletal conditions, the lower incisors procline to compensate for mandibular ret-rognathism and the upper anteriors retrocline to compensate for maxillary prognathism. Th is is known as natural compensation. In mild skeletal cases, this compensation is further increased by camoufl age through selective extraction of certain teeth which is explained in the previous chapters. In contrast to dental camoufl age, in preparation for orthognathic surgery, it is essential to remove any dental compensation present and to place the teeth in a favourable position with their supporting bone. Th is is known as presurgical decompensation. Th is usually means that the planned move-ment of the teeth prior to the surgery must be in the opposite direction from the movement with dental camoufl age treatment. For example in Class II skeletal malocclusions associated with mandibular retrognathism, there is natural dental compensation in the form of proclined lower anteriors to partially off set or mask the skeletal discrepancy. In such cases, decompensation is represented by maxillary anterior teeth proclination and mandibular anterior teeth retroclination.

Six Year Follow-Up Study of a Family (Father and Son) Afflicted with TCOF

Persons of two generations of a family with TCOF were examined and followed after a 6-year interval for signs traditionally associated with this disorder. Both the father and his aff ected son exhibited eight out of nine features of this syndrome, whereas the mother and two siblings revealed no visible anomalies. Th e clinical fi ndings of the aff ected father and son are summarized as follows (Table 6.2; Figs. 6.9 and 6.10):



Table 6.2: Clinical Findings of Father and Son Affl icted with TCOF

Clinical fi ndings Father Son

EXTRAORAL

Age 46 years 13 years

Facial profi le Convex Convex

Lip competency Incompetent Incompetent

Interlabial gap 10 mm 4 mm

Facial symmetry Deviation of lower jaw

towards left side

Deviation of lower jaw

towards right side

Jaw form Micrognathia of lower jaw Micrognathia of lower jaw

Lip form Everted lower lip Everted lower lip

Chin form Receded Receded

Smile Nonpleasing (Display of

dentition is more)

Pleasing

INTRAORAL

Periodontal condition Poor oral hygiene

Generalized gingivitis

Poor oral hygiene

Localized gingivitis

Dental status Loss of multiple teeth

Due to caries and attrition

Satisfactory

Moral relation Angle’s Class II Div. 1 Angle’s Class II Div. 1

Subdivision

Overjet 8 mm 3 mm

Overbite 4 mm 2 mm

Crowding Mild in lower anterior region Mild in lower anterior

region

Crossbite Right side in posterior region Absent

(a) (b)

Fig. 6.9: Photographs of the father affl icted with TCOF syndrome: (a) extraoral frontal view and (b) intraoral frontal view.



(a) (b)

Fig. 6.10: Photographs of the son affl icted with TCOF syndrome: (a) extraoral frontal view and (b) intraoral frontal view.

Both the affl icted individuals were followed for 6 years. Signifi cant growth changes were observed in the son as he was in a growing stage. Father showed no growth changes after 6 years but the reduction in the anterior lower facial height was noticed due to untimely loss of the lower posterior teeth as the overall bite was collapsed. Th e changes of the cephalometric values were recorded (Table 6.3).

Table 6.3: Cephalometric Values of Father and Son Affl icted with TCOF

S.

no.

Variables Father,

46 years

Father,

52 years

Son,

13 years

Son,

19 years

1 Maxillary base length 52 mm 52 mm 45 mm 48 mm

2 Mandibular base length 55 mm 55 mm 46 mm 55 mm

3(ALFH + PLFH)/2 67 mm 65 mm 56 mm 67.5 mm

4

5 Angle of convexity 150° 155° 153° 157°

6 Jarabak ratio 54.54% 60.60% 50.00% 61.65%

7 App–Bpp 21 mm 18 mm 13 mm 11 mm

8 Basal plane angle 51° 49° 36° 34°

9 ANB angle 15° 11° 10° 9°

10 Wits appraisal 2 –1 1 0

11 Depth of the antegonial notch 13 mm 13 mm 9 mm 9 mm

12 Nasofrontal angle 160° 160° 144° 151°

13 Saddle angle 135° 135° 133° 133°

14 Articular angle 153° 148° 155° 152°

15 Gonial angle 145° 145° 136° 136°

16 Sum of Bjork angles 433° 428° 424° 421°

17 CVMI stages 6 (Com-

pletion)

6 (Com-

pletion)

3 (Tran-

sition)

4 (Decel-

eration)



Quadrilaterals obtained by the analysis of the father and son were super-imposed to observe the changes occurred after the follow-up study (6-year period; Table 6.3 and Fig. 6.11).

A total superimposition of the aff ected son was done to observe the overall growth changes in diff erent parts of the skull as he was in growing stage after the follow-up of 6 years (Fig. 6.12). Superimposition was done on the S–N plane at the sella as the registration point.

Conclusion

Th e current approach to the correction of the deformities associated with TCOF is to stage the reconstruction to coincide with facial growth patterns, visceral function and psychosocial needs. Precise, morphologic and aesthetic analysis of each patient and the recognition for the need of a staged recon-structive approach serve to clarify the objectives of each phase of treatment both for the clinicians and the family. Th e main objective of the study was to off er a means of identifying a subclinical carrier status from lateral cephalograms by establishing cephalometric standards for the syndrome that would then be used as an adjunct for genetic counselling.

1

2

3

4

Initial

After 6 years

1

3

4

2

Initial

After 6 years

(a) (b)

Fig. 6.11: (a) Superimposition of the quadrilaterals of the father affl icted with TCOF: (1) maxillary base length, (2) mandibular base length, (3) anterior lower facial height and (4) posterior lower facial height. (b) Superimposition of the quadrilaterals of the son affl icted with TCOF: (1) maxillary base length, (2) mandibular base length, (3) anterior lower facial height and (4) posterior lower facial height.



N

S

Initial

After 6 years

Fig. 6.12: Total superimposition of the son affl icted with TCOF on S–N plane; registration point at sella.

Glossary of Cephalometric Landmarks

1. N: Nasion. Th e most anterior point of the nasofrontal suture in the median plane.

2. S: Sella. Th e sella point is defi ned as the midpoint of the hypophysial fossa. It is constructed point in median plane.

3. A: Point A, subspinale. Th e deepest midline point in the curved bony outline from the base to the alveolar process of the maxilla. In anthro-pology, it is known as subspinale.



4. B: Point B, supramentale. Most anterior part of the mandibular base. It is the most posterior point in the outer contour of the mandibular alveolar process, in the median plane. In anthropology, it also known as supramentale.

5. Gn: Gnathion. Graig defi nes it with the aid of the facial and the man-dibular plane; according to Graig, gnathion is the point of intersection of these two planes.

6. Go: Gonion. A constructed point, the intersection of the lines tangent to the posterior margins of the ascending ramus and the mandibular base.

7. Me: Menton. According to Krogman and Sassouni, Menton is the most caudal point in outline of the symphysis; it is regarded as the lowest point of the mandible.

8. Ar: Articulare. Th is point was introduced by Bjork (1947). It provides radiological orientation, being the point of intersection of the posterior margin of the ascending ramus and the outer margin of the cranial base.

9. ANS: Anterior nasal spine. Point ANS is the tip of the bony anterior nasal spine, in the median plane.

10. PNS: Posterior nasal spine. Th is is a constructed radiological point, the intersection of a continuation of the anterior wall of the pterygopalatine fossa and fl oor of the nose. It marks the dorsal limit of the maxilla.

11. J Point. It is located at the deepest point of the curvature formed at the junction of the anterior portion of the ramus and the corpus of the mandible.

12. AO. Th e point at which the perpendicular from the A point on func-tional occlusal plane.

13. BO. Th e point at which the perpendicular from the B point on func-tional occlusal plane.

14. App. Th e point at which the perpendicular drawn from the point A on the palatal plane.

15. Bpp. Th e point at which the perpendicular drawn from the point B on the palatal plane.


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