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An Orthodontic Device toCapitalize on the Rigid Fixation ofOsseointegrated Implants

Markus L. Wetti. DDS'Edmond O. Mukama!. DDS"Adrian Jurim, COT'"

Extraction of maxiiiary and mandibuiar first molars frequentty resutts in tip-ping of the terminai motars. Ideat treatment invotves uprighting the inclinedteeth prior to restoration. If a single-tooth impiant restoration will be used foreplace the missing molar it can aiso be used as anchorage to upright thetipped or drifted teeth. Careful pianning is necessary to make sure theimplant is positioned property for an ideai final resutt (Int J Periodont RostDent 1998:18:241-247.)

"Privóte Practice of Penoaontics and implantoiogy, Cedorhurst,New Vork.

••Private Practice of General and Prosthetic Dentistry,

Woodmere. New Vork.'"JurIm Dentai Labcrotories, Great Neck, New Vork,

Reprint requests: Dr Markus L. Weitz, 657 Central Avenue,Cedarhurst New York 11516, e-maii: mlweitz@yahoa.com

The coiiapse or shiffing of poste-rior teeth usuGliy occurs whenspoces ore ieff unresfored fol-lowing foofh loss. In the heolthydentition, the isoiated loss of amoxillary or mondibulor firstmolar that is not restored com-monly leads to tipping qnd/armesial drifting of the terminaimolor(s). When restoration af ftieedentulous space is finallyplonned, the srtuotian may pre-senf a difficult challenge ta therestorative dentist. Restoration afseverely t ipped abutmentsrequires substantial taath reduc-tion for odequate crown prepa-ration, sometimes resulting inpulp exposure. In addition,tipped teeth may have soft tis-sue and osseous periodontaldefects. In these situations,orthodontic therapy to uprightthe tipped teeth can substan-tially improve the periodontal sit-uation and enhonce fhe finalrestorative result,'

In the case of a missingmqxiliary or mandibular firstmolar, once the terminal molaris uprighted, traditional restara-

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Fig 1 Radiograph at initial presenfa-tion with the missing mandibuiar rightfirst moiar and mesioi tipping of thesecond molar into the edentulousspace. Although 8 mm of inferdentaispace (between the second premolarand second moiar) existed at the levelof osseous crest aniy 3.5 mm af infer-dentai space was presenf af fhe ievelof their cantact paints.

tion of the edentulous spancould be occompiished with athree-unit fixed portiai dentureor. alternativeiy, with a resin-bonded prosthesis. With theintroduction of osseointegration,singie-tooth impiant-supportedrestorations have been used torepiace fhe missing molar.^ Thepurpose ot this sfudy was torefine fhe technique andsequence of using a single-tooth implant-supported res-toration to repiace a missing firstmoiar when mesiai tipping ofthe distai terminal molar(s) hasoccurred. A new device to sim-plify the involved orthodonticuprighting by capltaiizing on fheImplant's immobiiify was used.

Orthodontic tooth move-ment fundomentaiiy requires a

relafiveiy stable anchoragepoint either within or outsidethe mouth. As eariy as 1945,researchers reported usingintraorai dentai impiants asanchorage units. This was fur-ther expiored by Lini<ow in1969.3 Gray et ai,'' Oreei<moreand Ei<lund,̂ and Kraut ef ai"̂reported successfui. pre-dictable tooth movement with-out bone ioss around theimplants. Higuchi and Slaci<'reported using estimated farcesof up to 400 g without notice-able bone ioss around the fix-tures. Once the osseointe-grated impianfs had finishedtheir function as orthodonticanchorage, they were buriedas "sieepers." Stean^ conciudedin 1993 that impiants cculd be

successfuiiy incorporated into atreatment plan that would usethem both as anchorage unitsand subsequentiy as correctiypiaced fixtures for fixed pros-thetic tooth repiacemenf.

The purpose ct this repcrf isto introduce a new device fhafuses the rigid fixation ot anendosseaus impiant as anchor-age far moior uprighting.

Case report

A 47-year-oid heaithy man pre-sented tor comprehensivetreatment. At fhe time of pre-sentation, he was missing hismandibuiar right tirst moiar. As aresuit ot this ioss, the secondmoiar had tipped forward and

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also drifted mesially (Fig 1). Thispresented a multitude ofrestorative dilemmas, includingperiodontal involvement of thefirst molar, less than ideal occlu-sion, and insufficient ponticspace. Ideal treatment wouldinvolve uprighting and distaliz-ing the second molor and sub-sequent prosthetic restorationof the edentulous space withan endosseous implant.

Since the patient declinedthe recommended complete-crch banding, a custom castdevice was designed to incor-porate an intimate tit with thedistai tooth and the two ante-rior teeth. A crank and gear sys-tem that would expand whenactivoted by the patient wasincorporoted in the middle ofthe new device (Figs 2 to 6).The patient was instructed toactivate the crank one turndaily, which translated into0.25-mm of movement (towardan upright and distal position)of the terminal moiar daily.After 3 weeks enough spacewas created for installation ofan endosseous implant; how-ever. Class li mobility of the twopremoiars was present (Figs 7and 8),

An Implant innovationswide-body implant that mea-sured 6 x 1 3 mm was ploced inthe area of the mandibularright first molar. Considerationwas given to the anticipatedfinal position of the molar. Theimplant was placed closer tothe terminal distai tooth than

figs 2 to s Custom cast device désignée re .o.:ú<poioíeoo .rwmoie :•: •.•/irn :na Ü'J¡"Q'tootti and the two anterior teeth. A crank and gear system that expands when acti-vated by the patient is incarparated in the middle of the new device. Model (top left);castings and gear device (top right),- device assembly (bottom left),- and finai deviceconstructian (bottom right).

Fig 6 Custom cast device in piace.

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Fig 7 At 3 weei<s fhe expansion device was removed. Fig 8 Ten miiiimefers of inteidenfai space existed af the ieveiof osseous crest, and 8 mm of inferdentai space was presenfaf fhe ievei cf their canfacf poinfs. Enough ciinioai interdentalspace existed fo aiiaw far instailafion of a wide-diameterImplant. The impiant was positioned cioser to fhe distai moiarto compensate for future distaiizafion of fhis foofh.

Fig 9 A one-sfage approach was used and a transgingivaiheaiing abutment was piaced at the fime of stage-onesurgery.

Fig W Af 4 monfhs a transfer impression was fai<en. Theimpianf was ioaded by a new space expander and a customcast device was designed.

the mesiai tooth. A cne-stageapproach was used and afransgingivai healing abutmentwas p iaced at the time otstage-one surgery (Fig 9).Sutures were removed at 1weei< and uneventfui healingensued. A space maintainerwas cemented between the

second molar and the secondpremolar to preserve fhe inter-dehtai space.

Af 4 monfhs, a transter im-pressioh at the ievei of theimpianf hex was taken to allowtor iaboratory reproduction ofthe implant-fcoth relationships.A "space expander" was de-

signed to capitaiize on theimpianfs immobility. A customcast device was designed toincorporate an intimate fit wifhfhe impiant (engaging the hexto iimif rofation), a hoie tor screwtixation fo the impiant, a crani<thaf could be acfivated by thepatient, a gear sysfem that

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Fig f J Radiographic view at final restoratian. Twelve mmt:ietween the second premolar and second motor exist at thelevel of the osseous crest and 10 mm of interdental space ispresent ot their contact points.

Fig 12 Unguai view of final restoration.

Fig 13 Buccal view of fino! resforofion

would expand when activoted,and a positive seat against themesioi surface of the tooth tobeuprighted (Fig 10).

Once installed, the patientwas advised to rotate thecrank one turn daily, thus ex-panding the space betweenthe impiant and the distal

tcoth 0.25 mm daily. Thisresulted in the uprighting anddistaiization ot the terminalmolar. Once adequate inter-dentai space was achieved, atransfer impression was taken tocapture the new position andrelationship of the distai moiarto the impiant. The expansion

device wos left fuliy expondedintraorally to act as a spacemaintainer while o final restora-tion was fabr icated. Oncecompleted, the tinai restorationreplaced the expansion device(Figs 11 to 13).

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Preoperativepianning to

determine idealfinal implant

position

Implantinstallatian

Impressian at hex ievel:fabriootion, place-

ment, and activationot "space expander"

Finaiimpression:

fabrication oftinal orown

3 to 9 monthsQ for

osseointegration

1 tc 2 additionaimonths for

orthodontiouprighting and

distolization

Fig 14 Proper planning and sequencing is of paramount importance when piacinçimpianfs prior to finaiizing tooth position. The impiant is rigid and cannaf move:therefore it must be placed in a position that wiit accommodate future prostheticsand not in the ideat position at time of placement.

Discussion

When using odjacent teeth farmolor uprighting, mobiiity andmigration of feeth is passible ifsfrong forces are used toaquickly, Osseointegrated im-piants provide ideai ancharogebecause of their immobility.When endosseous implants oreused far arfhadontic anchoragewith intentions af using theimplant in the finol prosthesis,careful treatment planning andsequencing is necessary tamake sure fhe finol posifianing iscorrecf (Fig 14). Since implonfsare fixed and cannot mcve,once instaiied they remain sta-

ble, even fhaugh feefh aroundthem can move. A finol freat-ment plan wifh ultimate focthpositicning is necessary beforeimpionts can be insfalled, sofhof implant pasifion relative tothe final prosthesis can bedetermined. Once adequatehealing time for asseointegra-tian has eiapsed (3 fa 9months), implant ioading is per-missibie. Orthodontic movementshouid be completed beforefinai impressioning is perfarmed.Sfabilizatian of fhe maved teethto prevent relapse is necessarybetween the completion oforthodontic mavement andinstallation at the finai prasthesis.

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Summary

Endosseous impionts can beused for both orthodonticanchorage and tooth restora-tions. By using impiants as an-chorage for moiar uprighting,bonding ot additional teeth isnot necessary. Once adequateheoiing for osseainteg ration hastaken place, a space expandercan be screwed into the im-plant and used to upright onddistaiize a terminai moiar. Oncethe necessary orthodonticmovement has been achieved,the impiant can be convertedinto a tunctionai restoration.

6. Kraut RA.HommerHS.WheeierJJ.Useof endosteai impionts os orthiodonticoncfioroge. Compend Contin EducDent 1989.-9; 796-801.

7. Higuchi t<W. Slack JM. The use of tita-nium fiiitures for introorol anohorogeto fooiiitate orthodontio tooth move-ment, in J Orol Maxiilofac Implants1991;ó;338-34d.

8. Stean H. Clinical case report' Animproved technique for using dentolimplants OS orthodontic onohoroge JOrol impiontoi 1993;19;336-340

References

1. Sohlugar 3 Youdelis R. Page R.Johnson R. Periodontai Diseases.Phiiodelphio: Leo S Febiger. IWO'438.

2. Schmitt A. Zorb GA. The longitudinoieffectiveness of osseointegroteddentai impiants for single toothreplacements, int J Prosthodonf1993:6:197-202

3. Unkov/ Li. The endosseous b iadeimpiont ond its use in orttiodontics. IntJOrthod 19ó9:7(4):149-154.

4. Grav JB. Steen ME. King GJ. Clark AE.Studies on the etfioocy ot impiants asorthodont ic onohoroge. Am JOrttiod 1983:83:311-317.

5. Creekmore TD. Ei<lund MK. The possi-biiity of skeletol onchoroge J ClinOrthod 1983:17:266-209.

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