Heymann - Implantable Devices as Orthodontic Anchorage.pdf

J O U R N A L O F E S T H E T I C A N D R E S T O R A T I V E D E N T I S T R Y68

*Graduate orthodontic resident, Department of Orthodontics, University of North Carolina School of Dentistry, Chapel Hill, NC, USA†Distinguished professor and chair, Department of Orthodontics, University of North Carolina School ofDentistry, Chapel Hill, NC, USA

Implantable Devices as Orthodontic Anchorage: A Review of Current Treatment Modalities

GAVIN C. HEYMANN, DDS*

J. F . CAMILLA TULLOCH, BDS, D. ORTH.†

ABSTRACT

Recently, there has been a dramatic increase in the use of implantable devices as direct adjunctsto orthodontic treatment. Whereas the use of conventional dental implants has been researchedextensively, the body of literature associated with the more recent uses of implantable devices inorthodontics is relatively small. Currently, a limited number of such devices are used to aid inorthodontic treatment. The options include conventional titanium endosseous dental implants,palatal implants, titanium miniscrews (also known as micro- or mini-implants), and mini–boneplates.

Integration of dental implants or implantable devices into contemporary orthodontic practicehas the following possible advantages: serving as a means of increasing orthodontic anchorage,virtually eliminating patient compliance issues with regard to wearing of appliances, decreas-ing overall treatment time, and occasionally permitting orthodontic treatments previouslythought to be impossible without surgery.

CLINICAL SIGNIFICANCEThis article is a review of the currently available options for use of implantable devices as sourcesof temporary skeletal anchorage in orthodontics.

(J Esthet Restor Dent 18:68–80, 2006)

Over the past 20 years dentistryhas seen a dramatic increase

in the use of dental implants. Whatwas once an “experimental” orunproven treatment modality isnow supported by an extensiveresearch base. The vast majority ofdental implant research is centeredaround the use of endosseousimplants for replacement of missingteeth. Recently, the application ofimplants for use in other specialtieshas been explored. Previously, the

use of dental implants within thespecialty of orthodontics was lim-ited to integration of implants intotreatment plans strictly to facilitatetooth replacement. The orthodontictreatment that has traditionallybeen involved in treatment plansincluding dental implants has beenlimited to creating space or aligningroots for subsequent placement ofimplants. The use of dentalimplants as a direct adjunct toorthodontic treatment has been

more limited until recently, but thepotential exists for implants to playan important role in enhancing suc-cessful treatment outcomes. Inte-gration of dental implants orimplantable devices into contempo-rary orthodontic practice has thefollowing possible advantages: serving as a method of increasingorthodontic anchorage, virtuallyeliminating patient complianceissues with regard to wearing ofappliances, decreasing overall treat-

DOI 10.2310/6130.2006.00013

H E Y M A N N A N D T U L L O C H

V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 69

ment time, and occasionally permit-ting orthodontic treatments previ-ously thought to be impossiblewithout surgery.

The practice of clinical orthodon-tics is largely dependent on theavailability of anchorage. Anchor-age, by definition, is a body’s resis-tance to displacement. Newton’sthird law states that for everyaction there is an equal and oppo-site reaction. Thus, orthodonticappliances are designed with thislaw in mind, the goal being to resistunwanted tooth movement.According to Proffit, in treatmentplanning of orthodontics,

it is simply not possible to consideronly the teeth whose movement isdesired. Reciprocal effects through-out the dental arches must be care-fully analyzed, evaluated, andcontrolled. An important aspect oftreatment is maximizing the toothmovement that is desired, while min-imizing undesirable side effects.1

In orthodontic movement of teeth,segments of teeth that resist move-ment and serve as “anchors” areused to pull against other segmentsthat are intended to be moved. Usu-ally, the anchor segment will containmore teeth or teeth with greaterroot surface area than the segmentof teeth that are to be moved. Thisconcept of differential anchorage isimportant in most orthodonticcases, especially more complex situ-ations. In fact, treatment of certain

malocclusions is often limited ordefined by the available anchorage.There are numerous ways in whichorthodontics has tried to augmentanchorage, including auxiliarydevices such as headgear, trans-palatal arches, and other appliances.Many of these appliances are awk-ward or uncomfortable for patients,often leading to less than desiredlevels of compliance. Thus, treat-ment outcomes can become com-promised. Only recently has theconcept of using dental implants assources of anchorage been widelyaccepted as a successful adjunct toorthodontic treatment.

Dental implants have the ability toaid in anchorage either directly orindirectly. Celenza and Hochmandescribed two different types ofanchorage as pertaining to the useof implants in orthodontics.2 Directanchorage refers to any situation inwhich forces that originate from theactual implant itself are used toaugment anchorage. An examplewould be a restored dental implantwith an orthodontic bracketbonded to the restoration. If con-ventional orthodontic appliancesare used in conjunction with thesurrounding teeth and the restoredimplant, the implant will serve as astable “anchor.” That is, theimplant will not respond to theforces generated by the orthodonticwires in the same way that the nat-ural teeth do. The implant simplyremains stationary while surround-ing teeth move.

The second type of anchorage, asdescribed by Celenza and Hochman,is known as indirect anchorage,which refers to a situation in whicha dental implant stabilizes multipleteeth, which then serve as an anchorunit. The most common method ofachieving indirect anchorage is byplacing a dental implant, commonlyin the midpalatal or retromolarregions, and then linking theimplant to the natural teeth bymeans of a wire or other rigid fixa-tion device, such as a transpalatalarch. The result is a stable anchor-age unit composed of multiple teeththat are tethered together by meansof a dental implant that serves asadditional anchorage. The highlevel of stability provided by eitherapproach makes it promising forthe practice of orthodontics.

There are numerous situations inwhich additional anchorage wouldenhance treatment success. Exam-ples of orthodontic treatment ofmalocclusions that would particu-larly benefit from dental implant useare as follows: closing edentulousspaces in first molar extraction sites,midline correction when no poste-rior teeth are present, retracting andrealigning anterior teeth with noposterior teeth present, intruding orextruding teeth, stabilization ofteeth with reduced bone support,reestablishing the proper transverseand anterior or posterior position ofisolated molar abutments, protrac-tion or retraction of one arch, andperhaps many more applications.3


I M P L A N T A B L E D E V I C E S A S O R T H O D O N T I C A N C H O R A G E

The high level of stability gainedfrom the types of implants placed inretromolar or midpalatal regions isderived largely from the fact thatthe implants are osseointegrated.Initial concerns about disruption ofosseointegration by orthodonticloading were proven to beunfounded by several studies.Roberts and colleagues reportedusing two-stage conventional tita-nium implants in the retromolarregion to help augment anchoragewhile protracting molars to closeextraction sites.4 The implants wereremoved using a trephine followingthe conclusion of orthodontic treat-ment and were subsequently histo-logically analyzed. Roberts andcolleagues found that approxi-mately 80% of the endosseous por-tions of the implants were in directcontact with mature bone. Thus,this case study indicated that a rela-tively high level of osseointegrationwas maintained despite loading theimplant with orthodontic forces.Another study by Turley and col-leagues also pointed to the stabilityof two-stage titanium implants usedfor orthodontic traction in dogs.5 Alater study by Wehrbein and col-leagues used the StraumannOrthosystem (Straumann HoldingAG, Basel, Switzerland) in mid-palatal and retromolar areas inhumans for anchorage purposes.6

The implants were subjected tocontinuous orthodontic loading andwere removed and analyzed follow-ing treatment. The findings fromthe histologic evaluation of the

include conventional titaniumendosseous dental implants, palatalimplants (such as onplants and theStraumann Orthosystem [Andover,MA, USA]), titanium miniscrews(also known as micro- or mini-implants), and mini–bone plates.

Conventional Implants Conventional titanium endosseousdental implants can be used assources of absolute or directanchorage for orthodontic treat-ment. This approach can be usedwhen edentulous spaces existwithin an arch and adjacent oropposing teeth are not positionedideally. In such cases when therestorative treatment plan involvesa dental implant, it may be benefi-cial to use the implant itself asanchorage for treating concomitantorthodontic problems (Figure 1). In1991 Higuchi and Slack reportedcorrecting malocclusions in sevenadults using Brånemark implants assources of direct anchorage.8 LaterSchweizer and colleagues reportedthe use of conventional endosseousimplants in orthodontic therapy in1996.9 The authors stressed theimportance of double use (com-bined orthodontic and prosthodon-tic treatment modalities) of theimplant system because once theimplant has been placed, no move-ment will occur owing to osseointe-gration. In 1995 Smalley noted theimportance of using a pretreatmentdiagnostic wax-up to aid in the pre-cise placement of implant(s) priorto orthodontic treatment.10 This

implants indicated that they hadbeen well integrated, again despiteorthodontic loading. It seemsapparent that when subjected to therelatively low continuous forcesthat are used in orthodontic ther-apy, implants have little difficultymaintaining osseointegration.Therefore, the question must beraised: is osseointegration desirableor even necessary for orthodonticanchorage? In a review of studiesexploring implantable orthodonticanchorage, Favero and colleaguesasked a similar question:

Some studies have shown thatimplants loaded early on,although not presenting intimatebone-to-bone contact [osseointe-gration] because of the formationof a pseudo-peri-implant fibrousligament, appeared to be suffi-ciently stable and capable of sus-taining the function of anchoragewith normal orthodontic forces.Did these represent failures,because osseointegration did notoccur, or successes, because theanchorage was achieved anyway?7

It seems that the question does nothave a definitive answer, and untilspecific parameters of success aredefined, it would be prudent to usethe existing body of research todetermine success.

A V A I L A B L E I M P L A N T S Y S T E M S

Currently, only a limited number ofimplantable devices may be used inorthodontic treatment. The options


V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 71

wax-up must simulate the positionof the teeth following orthodontictreatment, and from this informa-tion a surgical stent may be fabri-cated to aid in the placement of theimplant(s). In 1996 Kokich alsoemphasized the importance of inter-disciplinary treatment planning toensure successful treatment out-comes when using implants asanchors. According to Kokich, “itis impossible to accomplish thistype of interdisciplinary treatmentwithout good communicationbetween all members of the team.In most orthodontic patients, inter-disciplinary planning is not neces-sary. However, in the partiallyedentulous patient, it is mandatory.11

The Schweizer and colleagues articlesuggests several specific situationsthat are ideally suited for using dental implants in this manner, forexample, cases in which teeth aresupererupted after the loss ofopposing teeth. In such cases ortho-dontic intrusion is required in addi-

tion to the prosthodontic replace-ment of the missing teeth. Once theimplant(s) is placed, it can be usedfor anchorage to achieve intrusionand to obtain adequate occlusalclearance for future restorations.The advantage of this method oftreatment is that the definitiverestorations can also facilitateorthodontic treatment. The disad-vantage of this modality is thatimplants can be inserted only inedentulous areas with adequatebony support. Also, since this treatment must be coordinated bymultiple specialists (including aperiodontist or surgeon, a prostho-dontist or restorative dentist, andan orthodontist), this option ismore complex and perhaps moretime consuming.

Palatal ImplantsOne of the limitations of usingimplants for orthodontic anchorageis having adequate bone. Conven-tional root-form implants require

adequate thickness of bone forplacement, thus limiting their useto edentulous areas. Severalauthors have reported the mid-sagittal area of the hard palate as a suitable site for a short implant.Block and Hoffman devised a sys-tem that allowed placement ofosseointegrated implant anchors inthe midpalatal region of the max-illa.12 In 1989 they designed theOnplant system (Nobel Biocare,Göteborg, Sweden). The device inthis system is a thin (2 mm thickand 10 mm in diameter) titaniumalloy disk that has a textured sidethat opposes bone and is coatedwith a 75 µm layer of hydroxyap-atite. The side facing soft tissue issmooth titanium alloy with athreaded hole in the center intowhich abutments are placed. Origi-nal designs of the disks included asharp (90°) angle at the periphery,but this design was later altered toprevent adverse soft tissue reac-tions at this margin (Figure 2A).

Onplants are placed subperiosteallyon the posterior aspect of the hardpalate. A “tunneling” procedure isused to place these anchors. A full-thickness mucoperiosteal incision ismade on the anterior aspect of thehard palate, and tunnels are reflectedposteriorly. These tunnels allow theonplant to be placed away from theincision, thus reducing the potentialfor soft tissue reactions that preventosseointegration. A healing screw isplaced, and 10 to 12 weeks areallowed for integration. After this

Figure 1. Illustration of a conventional endosseous implant used asa source of direct anchorage.



healing period, a small amount oftissue is removed over the healingscrew, which is replaced by an abut-ment (Figure 2B).

Block and Hoffman conducted twostudies using their Onplant system.The first study was performed withmongrel dogs and the second withmonkeys. In the canine study,springs were extended from theonplant abutment to the first pre-molar and activated to exert11 ounces of force. Measurementsof tooth movement were made peri-odically, and after 5 months thedogs were euthanized. The maxillaswere retrieved and sectioned, andosseointegration was assessed. Asoft tissue dehiscence developedover one of the onplants at thesharp margin, causing failure of theonplant to integrate. The otheronplants did integrate and wereloaded with the springs. At the con-clusion of the study, measurements

indicated that the onplants did notmove in relation to the incisors ormolars. The premolars attached tothe onplant abutment exhibitedmovement ranging from 4 to 8 mm.Histologic examination showedthat bone directly opposed the tex-tured, hydroxyapatite-coated sur-face. Onplants were also placed inthe mandible to examine the shearforce required for removal. Theresults indicated that 160 to162 pounds of “push-off” forcewas required to dislodge theonplants from the mandible.

The monkey study examined theeffectiveness of the Onplant systemto anchor molars during anteriordental retraction. In addition, thisstudy introduced onplants withtapered margins and comparedthem with the original sharp-margined onplants. Bands wereplaced on the first molar on oneside and the second molar on the

contralateral side. The bands wereconnected to the onplant abutmentwith either wire or a cast bar. Bothpremolars were extracted bilater-ally, and stainless steel springs wereextended from each canine to theipsilateral first molar. Measure-ments at the conclusion of thisstudy yielded an average of1.2 ± 0.2 mm movement of theanchored molars toward the centralincisors. The nonanchored molars,however, moved an average of4.1 ± 1.4 mm toward the centralincisors. The canines on both theanchored and nonanchored sidesmoved an average of 1.9 mm awayfrom the central incisors. Soft tissuedehiscences were observed over theoriginal onplant design but werenot observed in the tapered margindesign. This study concluded that“the onplant can provide sufficientanchorage to molars to preventanterior migration in situationsrequiring maximum anchorage.”

A B

Figure 2. A, Illustration of an onplant (Nobel Biocare, Göteborg, Sweden) as described by Block and Hoffman. B, Diagram ofplacement of the onplant connected to a transpalatal arch.


V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 73

In addition to requiring less bonedepth for placement compared withendosseous implants, onplants canbe loaded after a shorter healingperiod. The onplant system cutsthis healing period approximatelyin half. Despite these advantages,one area of concern with this sys-tem is removal of the onplant.Block and Hoffman described usingosteotomes for removal of thedevices.12 Although this techniqueis obviously atraumatic to a eutha-nized dog, performing it on ahuman could be uncomfortable tothe patient. Removal of the onplantalso requires removal of a largeportion of soft tissue, which couldbe uncomfortable postoperativelyfor a patient.

Like Block and Hoffman, Strau-mann has devised an implant sys-tem that can be placed in areas ofdecreased bone thickness.13 In 1996Wehrbein and colleagues describedthis system in a pilot study.14 TheStraumann Orthosystem incorpo-rates screw-type endosseousimplants that can be placed in thepalate and subjected to orthodonticforce without migration or loss ofosseointegration. In addition to themedian palate, the Orthosystemimplant can be placed in retromolarpositions owing to its design. Theself-tapping Orthosystem implantitself has a diameter of 3.3 mm andis available in 4.0 and 6.0 mmlengths. A 4.0 mm diameterimplant is also available for usewhen drilling errors have occurred.

The surface of the Orthosystemimplant is Straumann’s sand-blasted, large-grit, acid-etched sur-face (Figure 3).

Lateral cephalometric analysis isrequired prior to placement todetermine the ideal site for place-ment and the appropriate length ofimplant. Under palatal local anes-thesia, the palatal mucosa at theimplant site is removed. The site isprepared using a series of drillsrotated at no more than 750 rpmunder saline irrigation. The implantis hand-turned as far as possible,and a ratchet is used to tighten theimplant into its final position. Ahealing cap or healing screw is

placed for the next 10 to 12 weeks,after which time the impression ismade. The impression is sent to alaboratory for fabrication of theprescribed orthodontic appliance.After completion of orthodontictreatment, the implant is removedby drilling down two-thirds of theimplant length with the explorationtrephine and pulling out theimplant with extraction forceps and gentle rotation.13 Currently, use of this system is approved bythe US Food and Drug Administra-tion (FDA) for midpalatal place-ment in adults only owing toconcerns about the effects on themidpalatal suture in youngerpatients (Figure 4).

Figure 3. The Orthosystem implant (courtesy of Straumann,Basel, Switzerland).



In 1998 Wehrbein and colleaguespublished a study examining bone-to-implant contact of implants fol-lowing orthodontic loading inpatients.6 In this study, fourpatients were treated for Class IImalocclusion using StraumannOrthosystem implants for anchor-age instead of conventional extrao-ral anchorage aids. Orthosystemimplants were placed in the mid-palatal area of the maxilla and theretromolar areas of the mandible.Midpalatal implants were used to

anchor the posterior teeth for ante-rior dental retraction after premolarextraction. In one patient, the mid-palatal implant was used for bothanterior and posterior anchorage inpremolar mesialization. The retro-molar implants were used for bilat-eral molar distalization.

After completion of orthodontictreatment, the implants wereremoved in a bony core using atrephine. These cores were thenpreserved and sectioned through

the implant to examine the bone-to-implant contact. Midpalatalimplants were found to have amean bone-to-implant contact of79.3%, whereas the retromolarimplants exhibited contact of 68%.This study concluded that “the dataof the present histological reportindicate that orthodontic implantsare well integrated into the hostbone even following long periods oforthodontic loading in humans.”6

According to Wehrbein and col-leagues, the advantages of theOrthosystem are that it can beplaced in areas that conventionalimplants cannot, soft tissue irrita-tion is minimal, and anchorage isstable owing to sound osseointegra-tion.14 The disadvantages are thatthe placement process requires asurgeon, loading is not typicallydone immediately, and removal ofthe device often requires the use of a trephine owing to the extent of osseointegration.

MiniscrewsAn alternative approach to achiev-ing anchorage is the use of titaniumminiscrews. These devices are verysmall and can be placed in areaswhere other implantable devicescannot. For example, some minis-crews are so small that they canactually be placed in bone betweenthe roots of individual teeth. Thescrews themselves are similar oridentical to those used forosteotomy fixation followingorthognathic surgery. These mini-

A

B

Figure 4. A, Illustration of a midpalatal implant connected toa transpalatal arch. B, Illustration of placement location for amidpalatal implant.


V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 75

screws are unique because unlikerestorative endosseous implantsthey do not require osseointegra-tion. Instead, these devices rely onmechanical retention to maintainrigidity, which also makes theirremoval relatively simple and non-invasive. They may be loadedimmediately, but biomechanical fac-tors must be taken into considera-tion owing to the increased chanceof loosening associated with thelack of integration and torquing orrotational forces that may occurunder loading. Kanomi publishedone of the preliminary reports ofthis technique in which he referredto the devices as mini-implants.15

Although he referred to the devicesby a different name, his results wereessentially similar to those of othercase reports on the use of mini-screws, such as the one publishedby Costa and colleagues.16 Theirarticle is a case report in which theauthors observed 14 patients with16 screws. The titanium screws thatthey used were manufactured by acompany called Cizeta (Rome,Italy) and had a diameter of 2 mmand a length of 9 mm. The place-ment technique involved insertingthe screws under local anesthesiadirectly through mucosa without amucoperiosteal flap. The screwswere placed in several differentlocations depending on the desiredtreatment and available bone. Theywere reported to be useful in boththe maxilla and the mandible,specifically, on the inferior surfaceof the anterior nasal spine, mid-

palatal suture, infrazygomatic crestof the maxilla, retromolar area ofthe mandible, and mandibular sym-physis and within edentulous areasof the alveolar process. After takinginto account what tooth move-ments were desired, the locationwas decided upon, and the screwswere placed with specific angula-tions to accommodate existinganatomy and deliver forces in thedesired directions. Prior to insertionof the screws, a 1.5 mm diameterhole was drilled into the bone witha slow-speed handpiece using irri-gation. The miniscrews wereinserted by hand with a screw-driver. To apply the desired force,the heads of the screws were joinedto the dental arch or tooth with awire. In cases involving one-dimen-sional force, the head of the screwwas placed so that mucosa wouldcover it and the attached wirewould emerge from the mucosa. Incases that involved the use of multi-dimensional forces, the heads of thescrews were kept above the mucosaso that edgewise wires could beinserted into the specially designedhead of the screw. In this article, theminiscrews were loaded immedi-ately, and after treatment they wereremoved under local anesthesiausing the same screwdriver that wasused during initial placement.

In 2000 Melsen and Costa report-ed the use of a similar device called the Aarhus Achorage screw, whichis manufactured by Medicon (Tuttlingen, Germany).17 This sys-

tem uses a self-drilling titaniumscrew, and the surgical process andclinical applications are not unlikethe previously mentioned systems.This system is FDA approved.

In 2003 Kyung and colleaguesreported the development of amicroimplant for orthodonticanchorage.18 This implant is a small titanium screw known as theAbsoanchor and is manufacturedby a Korean company called Dentos Inc. (Taegu, Korea).According to Kyung and Dentos,the Absoanchor is a particularlyattractive member of the family ofmini-implants because it “has beendesigned specifically for orthodon-tic use and has a button-like headwith a small hole that accepts liga-tures and elastomers. The Absoan-chor’s small diameter allows itsinsertion into many areas of themaxilla and mandible previouslyunavailable—even between roots of adjacent teeth” (Figure 5).18

The stated advantages of minis-crews for use in orthodontic treat-ment are primarily the ease ofinsertion and removal. Comparedwith other systems the surgical pro-cedure for placing and removingminiscrews is very simple and non-invasive. This can allow the proce-dures to be performed by anorthodontist, thereby eliminatingthe need for a surgical referral.Additional advantages are thatloading can occur immediately,which has the potential to shorten



treatment time, and local soft tissueirritation is reported to be limitedcompared with other transmucosaltypes of anchorage and, when pre-sent, is easily controlled with localapplication of chlorhexidine. Thestated disadvantages of the minis-crews as used in the Costa and col-leagues article were the potentialfor infection or local soft tissue irri-tation, the potential for maxillarysinus perforation, infringementupon tooth roots, especially whenplaced in the infrazygomatic crestregion, and, perhaps most impor-tantly, loosening of the miniscrew.16

During the trial reported by Costaand colleagues 2 of the 16 screwswere loosened and lost prior to thecompletion of treatment. Looseningis suggested to be a problem onlywhen the screws are loaded in amanner that results in a force thatis oriented in a direction that

unscrews the screw. If the screw isloaded such that the force is ori-ented in the direction that tightensthe screw, then loosening does notoccur as quickly. This suppositionhelps reinforce the conjecture thatlateral shearing forces are moredetrimental to the stability ofimplantable devices than are otherforces. Miyawaki and colleaguesretrospectively examined the suc-cess rates of titanium screws placedfor orthodontic anchorage in thebuccal alveolar bone in the poste-rior region.19 They concluded that ascrew diameter of 1.0 mm or less,inflammation of periimplant tissue,and a high mandibular plane anglewere associated with the mobility(failure) of the screws. Interestingly,they detected no associationbetween the success rate and lengthof the screw. Miniscrews are avail-able from manufacturers other than

those mentioned in this article, but,in general, the same advantages anddisadvantages exist for all of them.

Miniplates A further approach to the use ofimplantable devices in conjunctionwith orthodontic treatment hasbeen the use of titanium miniplates.Miniplates are frequently used inorthognathic surgery for osteotomyfixation or in the fixation of frac-tures. An early case report by Sherwood and colleagues describedtwo adult patients referred fororthodontic treatment of super-erupted molars.20 The extrudedteeth were in contact with theopposing alveolar ridge. Withoutorthodontic intervention thesupererupted teeth would need tobe reduced occlusally by a consider-able amount, which would haverequired endodontic therapy andsubsequent restoration. The implantplacement involved a surgical proce-dure with a 1.5 cm incision underlocal anesthesia in the buccalvestibule adjacent to the extrudedmolars. A full-thickness mucope-riosteal flap was reflected, and bonewas exposed. An L-shaped titaniumLeibinger (Stryker Leibinger GmbH& Co. KG, Freiburg, Germany)miniplate was contoured over theexposed bone and fixed with twoself-tapping screws of 3 mm length.The last loop of the miniplate wasallowed to project through thevestibular wound adjacent to thesupraerupted molars. The incisionwas closed via sutures, and soft

Figure 5. A, An example of a minis-crew, the Absoanchor (courtesy ofDentos Inc., Taegu, Korea). B, Dia-gram of a possible placement loca-tion of a miniscrew (courtesy ofDentos Inc.).A

B


V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 77

tissue was allowed to heal aroundthe exposed loop for 2 months.During healing the other teeth wereorthodontically leveled, excludingthe extruded molars. Elastic threadswere attached to the exposed loopof the miniplate and tied tightlyover the buccal tube of the extrudedmolar, which was now banded.New elastics were applied and acti-vated every month. This processwas continued until the molars were at the plane of occlusion of theadjacent teeth. This process tookapproximately 6.5 months, andafterward the molars were ligatedto the miniplate loops for retention.

In another case report by Chung andcolleagues the investigators used theminiplate system by Martin MedizinTechnik (Gebruder Martin GmbH& Co KG, Tuttlingen, Germany),but they soldered a round 0.036-inchtube with a hook to one end of the miniplate.21 The authors calledthis device the C-tube, and it wasdesigned to use the tube with ahook instead of an exposed loop or rectangular slot to minimizetorque forces (Figure 6). This spe-cific report involved the treatmentof a 10-year-old female with severecrowding and a Class II skeletal discrepancy. The surgical processwas similar to that described bySherwood and colleagues. One C-tube was placed in each quad-rant. In the maxilla they wereplaced between the second premo-lars and first molars and in themandible between the first and

second molars. The C-tubes wereplaced so that the tube end pro-truded through the mucosa. Theauthors reported good results inretraction of anterior teeth and lev-eling of the occlusal plane followingconnection of C-tubes to the rest ofthe arches via rectangular wires.This case was cut short owing tothe patient moving away, but theresults nevertheless seem to indicatea potential method of achievingskeletal anchorage.

In 2002 De Clerck and colleaguesintroduced and reported success inthe treatment of Class II malocclu-sion using the Zygoma AnchorageSystem.22 The authors adapted aSurgitec zygoma anchor miniplate(Surgitec, Bruges, Belgium) securedwith three screws that had a roundextension arm carrying an attach-ment mechanism (Figure 7). Thesedevices were placed in the inferiorsurface of the zygomaticomaxillarybuttress. The surgical procedure for placement was similar to thatdiscussed for the other miniplatesystems; however, in this case thedevices were loaded immediatelyafter placement. The tooth move-ments reported in this case wereretraction and intrusion for

correction of Class II malocclusion.The specific points addressed by De Clerck and colleagues were the design of the extension arm, the exit of the extension arm at themucogingival junction, and the ver-satility of the attachment apparatus.

The apparent advantages for usinga miniplate system as declared bythe above authors are as follows: along history of biocompatibility, avariety of shapes and sizes, a mini-mally invasive surgical procedure,and little risk of damaging nervesor tooth roots. This approach isindicated by various authors asbeing valuable in aiding patientsneeding intrusion of individual orgroups of teeth, correction ofsevere crowding, correction ofskeletal Class II malocclusion, andmanagement of an anterior openbite.23 The disadvantages are thatplacement of miniplates is moreinvasive than the placement ofminiscrews and requires a surgeonfor the procedure. In the reports of miniplate use as temporaryskeletal anchorage, patientsexperience loosening of the platessecondary to inflammation orexcessive shearing or torsionalforces from the archwire.

Figure 6. The C-tube miniplate (KLS Martin, Tuttlingen, Germany).



C O N C L U S I O N S

It seems apparent that dentalimplants or implantable devices canplay a valuable part in augmentinganchorage for orthodontic move-ment of teeth. However, the ques-tion must be asked: why is thisapproach better than other auxiliary

treatment methods or appliances?One of the most important answersis that most traditional methods ofanchorage rely on patient coopera-tion and compliance:

Clinical experience suggests thatthere is a threshold for force dura-

tion in humans in the 4-8 hourrange [per day], and that increas-ingly effective tooth movement isproduced if force is maintained forlonger durations…Continuousforces, produced by fixed appliancesthat are not affected by what thepatient does, produce more toothmovement than removable appli-ances unless the removable appli-ance is present almost all the time.1

The reality is that many patients,especially adolescents, do not showoptimum compliance, that is, theydo not wear their appliances orhead gear all of the time. The socialimplications of doing so make thisunderstandable, but the result is adelivery of force that is unquestion-ably more discontinuous than usingan implant. The result of usingimplantable devices is that patientcompliance issues are virtually elim-inated and force is delivered contin-uously throughout the day.

With compliance eliminated as afactor in treatment it seems logicalthat treatment times would bedecreased. In the currently availableliterature there are few data in thisarea, and most reports are purelyanecdotal. However, logic wouldsuggest that the use of implantabledevices could significantly increasethe speed of orthodontic treatmentin certain circumstances.

In conclusion, the incorporation ofdental implants into dental treat-ment plans has had a tremendousimpact on virtually the entire field

A

B

C

Figure 7. A, Surgitec boneanchor miniplate (Surgitec,Bruges, Belgium). B, Possibleplacement locations of mini-plates. C, Surgical placementof a miniplate in the zygo-matic buttress region.


V O L U M E 1 8 , N U M B E R 2 , 2 0 0 6 79

of dentistry. With the increasedinterest in the area of implantologyhas come a great deal of credibleresearch exploring the use of dentalimplants. Indeed, evidence-baseddentistry is the basis for sound clini-cal decision making and treatment-planning modalities. Whereas theconventional use of dental implantshas been studied for some time now,the use of implants and implantabledevices as described in this article isrelatively new by comparison.Therefore, the literature is limited inclinical trials and other more rigor-ous evaluation methods. At this timethe body of research associated withthis subject is composed largely ofcase reports and a few small time-limited trials in animals. There is nodoubt that this area will continue tobe explored and researched and willprobably become an indispensablepart of contemporary orthodontictherapy in the future. Purely as amatter of opinion, it seems that theextent to which the use of implantsor implantable devices is acceptedby the field of orthodontics on abroad basis will depend on a fewspecific factors. It seems that thedevices themselves will continue toevolve but will probably move in adirection that supports the bestcombination of ease of placement(able to be placed by orthodontist),least invasive procedure, and bestphysical design properties to deliveroptimum mechanical forces. Per-haps the use of dental implants willprove to be as useful to the field oforthodontics as it has been forother areas of dentistry.

D I S C L O S U R E A N D

A C K N O W L E D G M E N T S

The authors do not have any finan-cial interest in the companies whosematerials are discussed in this article.

We thank Dr. Nicole Scheffler forstimulating interest in this subject.

R E F E R E N C E S

1. Proffit WR. Contemporary orthodontics.3rd ed. St. Louis: Mosby; 2000.

2. Celenza F, Hochman MN. Absoluteanchorage in orthodontics: direct and indi-rect implant-assisted modalities. J ClinOrthod 2000;34:397–402.

3. Ismail SFH, Johal AS. The role of implantsin orthodontics. J Orthod2002;29:239–45.

4. Roberts WE, Marshall KJ, Mozsary PG.Rigid endosseous implant utilized asanchorage to protract molars and closeatrophic extraction site. Angle Orthod1989;60:135–51.

5. Turley PK, Kean C, Schur J, et al. Ortho-dontic force application to titaniumendosseous implants. Angle Orthod1988;58:151–62.

6. Wehrbein H, Merz BR, Hammerle CHF,Lang NP. Bone-to-implant contact oforthodontic implants in humans subjectedto horizontal loading. Clin Oral ImplantsRes 1998;9:348–53.

7. Favero L, Brollo P, Bressan E. Orthodonticanchorage with specific fixtures: relatedstudy analysis. Am J Orthod DentofacialOrthop 2002;122:84–94.

8. Higuchi KW, Slack JM. The use of tita-nium fixtures for intraoral anchorage tofacilitate orthodontic tooth movement. IntJ Oral Maxillofac Implants1991;6:338–44.

9. Schweizer CM, Schlegel KA, Rudzki-Janson I. Endosseous dental implants inorthodontic therapy. Int Dent J 1996;46:46, 61–8.

10. Smalley W. Implants for tooth movement:determining implant location and orienta-tion. J Esthet Dent 1995;7:62–72.

11. Kokich VG. Managing complex orthodon-tic problems: the use of implants foranchorage. Semin Orthod 1996;2:153–60.

12. Block MS, Hoffman DR. A new devicefor absolute anchorage for orthodontics.Am J Orthod Dentofacial Orthop1995;107:251–8.

13. ITI/Straumann Orthosystem [productbrochure].

14. Wehrbein H, Glatzmaier J, Mundwiller U,Diedrich P. The Orthosystem—a newimplant system for orthodontic anchoragein the palate. J Orofac Orthop1996;57:142–53.

15. Kanomi R. Mini-implant for orthodonticanchorage. J Clin Orthod 1997;31:763–7.

16. Costa A, Raffaini M, Melsen B. Mini-screws as orthodontic anchorage: a pre-liminary report. Int J Orthod OrthognathSurg 1998;13:201–9.

17. Melsen B, Costa A. Immediate loading ofimplants used for orthodontic anchorage.Clin Orthod Res 2000;3:23–8.

18. Kyung HM, Park HS, Bae SM, et al.Development of orthodontic micro-implants for intraoral anchorage. J ClinOrthod 2003;37:321–8.

19. Miyawaki S, Koyama I, Inoue M, et al.Factors associated with the stability oftitanium screws placed in the posteriorregion for orthodontic anchorage. Am JOrthod Dentofacial Orthop2003;124:373–8.

20. Sherwood KH, Burch J, Thompson W.Intrusion of supererupted molars with titanium miniplate anchorage. AngleOrthod 2003;73:597–601.

21. Chung K, Kim Y, Linton JL, Lee Y. Theminiplate with tube for skeletal anchorage.J Clin Orthod 2002;36:407–12.

22. De Clerck H, Geerinckx V, Siciliano S.The Zygoma Anchorage System. J ClinOrthod 2002;36:455–9.

23. Sugawara J, Baik U, Umemori M, et al.Treatment and posttreatment dento-alveolar changes following intrusion ofmandibular molars with application of askeletal anchorage system (SAS) for openbite correction. Int J Adult OrthodOrthognath Surg 2002;17:243–53.

Reprint requests: Gavin C. Heymann, DDS,Department of Orthodontics, University of North Carolina School of Dentistry,Chapel Hill, NC, USA 27599-7450; e-mail:[email protected]©2006 Blackwell Publishing, Inc.

Heymann - Implantable Devices as Orthodontic Anchorage.pdf

Documents

Transcript of Heymann - Implantable Devices as Orthodontic Anchorage.pdf