32

Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry

Jae-Won Lee, Moon-Key Kim, Sang-Hoon Kang

Department of Oral and Maxillofacial Surgery, National Health Insurance Service Ilsan Hospital, Goyang, Korea

Abstract (J Korean Assoc Oral Maxillofac Surg 2014;40:32-36)

Preoperative surgical simulation in orthognathic surgery has progressed in recent years; the movement of the mandible can be anticipated through three-dimensional (3D) simulation surgery before the actual procedure. In this case report, the mandible was moved to the intended postoperative oc-clusion through preoperative surgical 3D simulation. Right-side condylar movement change was very slight in the surgical simulation, suggesting the possibility of mandibular surgery that included only left-side ramal osteotomy. This case report describes a patient with a mild asymmetric facial profile in which the mandibular menton had been deviated to the right and the lips canted down to the left. Before surgery, three-dimensional surgical simu-lation was used to evaluate and confirm a position for the condyle as well as the symmetrical postoperative state of the face. Facial asymmetry was resolved with minimal surgical treatment through unilateral intraoral vertical ramus osteotomy on the left side of the mandible. It would be a valuable complement for the reduction of the surgical treatment if one could decide with good predictability when an isolated intraoral vertical ramus osteotomy can be done without a compensatory osteotomy on the contralateral side.

Key words: Surgical simulation, Orthognathic surgery, Three-dimensional simulation surgery, Intraoral vertical ramus osteotomy, Facial asymmetry[paper submitted 2013. 9. 10 / revised 2013. 10. 7 / accepted 2013. 10. 23]

ramusosteotomy(USSRO)canbeconsidered.Although

thereareslightrotationalchangesinthenon-operatedcon-

dyleafterUSSRO,theinterocclusalrelationship,teethoc-

clusion,andmandibularjointfunctionmustbemaintainedin

theiroriginalstatewithoutcomplicationssuchastemporo-

mandibularjoint(TMJ)disorders1.

Preoperativesurgicalsimulationinorthognathicsurgery

hasprogressedinrecentyears;themovementofthemandible

canbeanticipatedthroughthree-dimensional(3D)simulation

surgerybeforetheactualprocedure.

Predictingthepositionofthemandibleinamannerthat

reflectsocclusioninformationis important inestablishing

plansfororthognathicsurgery,becausethemandibularposi-

tionduringorthognathicsurgeryisdirectlyinfluencedbythe

plannedpostoperativeteethocclusionaftersurgery.

Inthiscase,themandiblewasmovedtotheintendedpost-

operativeocclusionthroughpreoperativesurgical3Dsimula-

tion.Right-sidecondylarmovementchangewasveryslight

inthesurgicalsimulation,suggestingthepossibilityofman-

dibularsurgerythatincludedonlyleft-sideramalosteotomy.

UnilateralIVRO(UIVRO)wasperformedtosuccessfully

resolvethefacialasymmetry.

I. Introduction

Clinicalevaluationandimageevaluationincludingcom-

putedtomography(CT)arenecessarytotreatfacialasymme-

try.Dentomaxillofacialevaluationofteethocclusion,bone

structure,andsofttissueisfollowedbyatreatmentdecision,

whichusuallyincludesmethodssuchasorthodonticsoror-

thognathicsurgery.Forpostoperativestabilityandaesthetic

reasons,LeFortIosteotomyinthemaxillaandbilateralsag-

ittalsplitramusosteotomy(SSRO)orintraoralverticalramus

osteotomy(IVRO)inthemandiblearegenerallyusefulin

orthognathicsurgeryforpatientswithfacialasymmetry.

Especiallyinthecaseofmildfacialasymmetrywithami-

norlateraldeviationofthemandible,unilateralsagittalsplit

CASE REPORT

Sang-Hoon KangDepartment of Oral and Maxillofacial Surgery, National Health Insurance Service Ilsan Hospital, 100, Ilsan-ro, Ilsandong-gu, Goyang 410-719, KoreaTEL: +82-31-900-0267 FAX: +82-31-900-0343E-mail: omfs1ksh@hanmail.net

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

CC

Copyright Ⓒ 2014 The Korean Association of Oral and Maxillofacial Surgeons. All rights reserved.

http://dx.doi.org/10.5125/jkaoms.2014.40.1.32pISSN 2234-7550·eISSN 2234-5930

Unilateral IVRO

33

tiveocclusionwasplannedusingthecastmodelsinorderto

obtainproperinformationregardingthepost-surgerymaxil-

larandmandibularpositionsforthesimulation.Theplanned

occlusionwasformedusingthemaxillaandmandiblecast

models.Thecastmodelswerefixedintheplannedpostop-

erativeocclusionstateandwerescannedwiththe3Doptical

scanner.Duringthemandibularsetbacksurgerysimulation,

theCTimageofthemandiblewassetbacktooverlapwith

thescannedmandibularplannedocclusioncastmodel im-

age2,3.(Fig.2)

Thefirst surgicalsimulationwascheckedbyreferring

tothemandibularsymmetry.Duringthesimulation,facial

asymmetrywascorrectedonlywithmandibularsurgery.Au-

thorsfoundthatright-sidecondylarmovementwasslightin

thesurgicalsimulation(Fig.3),suggestingthepossibilityof

mandibularsurgerythatincludedonlyleft-sideosteotomy.

Thefinalsurgicalplanemployedonlyunilateralmandibular

osteotomyintheleftside.(Fig.4)IVROwasconsideredfor

facialasymmetrycorrection,accordingtothesurgeon’spref-

erence.Afterthesurgicalsimulation,thesurgicalwaferwas

producedusingstereolithographytechnology(Eden250;Ob-

jetGeometriesLtd.,Rehovot,Israel).IVROsetbacksurgery

wasperformedonlyontheleftsideofthemandibleusinga

surgicalwafermanufacturedviastereolithography.

Thefinalsurgicalwaferwasmaintainedfor6weeksin-

cluding2weeksmaxillomandibularfixationaftersurgery

tostabilize theocclusionandmandibularsegmentsafter

surgery.Postoperativeorthodontictreatmentmaintainedthe

facialsymmetryobtainedaftersurgery; thedowncanting

oftheliphadimproved.TherewasnoTMJdisorder.The

postoperativeorthodontictreatmentwascompleted6months

aftersurgery.(Figs.5,6)

II. Case Report

A20-year-oldfemalevisitedthehospitalwithchiefcom-

plaintsofanasymmetricmandibleandteeththatwerenotoc-

cluded.Thepatienthadnospecificmedicalanddentalhisto-

ry,includingTMJdisorders.Clinicalexaminationsrevealed

thatthemandiblewasdeviatedtotherightsideandthatthe

leftlipwasdowncanted.Crossbiteoftheincisors,crowding

oftheupperandlowerteeth,classIIIleftsidemolars,and

classIII leftcanineswereobserved.Analysisofthefacial

skeletonrevealedthattheupperjawwasinthenormalposi-

tionoftheA-pointtothenasion(N)-perpendicularline(1.48

mm).Thefinaldiagnosiswasfacialasymmetry.(Fig.1)The

treatmentplanwastolevelandaligntheteethviaorthodontic

treatmentbeforesurgery.Orthognathicsurgerywouldthenbe

performedtosetbackthelowerjawonly,asthepositionof

theupperjawwasnormal.Theocclusionoftheteethwould

besetandcompletedthroughorthodontictreatmentaftersur-

gery.

Orthognathicsurgerywasperformedafter17monthsof

orthodontictreatment,whenthelevelingandalignmentofthe

teethwerecomplete.CTimages(0.7mmslicecut)ofthepa-

tient’scraniofacialareawereusedtoreconstructthe3Dskel-

etalimageswithMimicsversion14.0(Materialise,Leuven,

Belgium).Dentalcastmodelswereusedtoreplaceinaccurate

dentitionintheCTimages.Currentdentalcastmodelsofthe

patientweremadeandscannedusinga3Dopticalscanner

(RexcanDS2;Solutionix,Seoul,Korea).Thescannedimages

ofthemaxillaandmandiblecastswereoverlappedwiththe

3DreconstructedCTimagesusingthesurface-basedregistra-

tionfunctionoftheRapidformXOV2software(INUSTech-

nology,Seoul,Korea).

Inconsultationwiththeorthodonticdepartment,postopera-

Fig. 1. A-C. Initial pretreatment extraoral photographs. D. Intraoral photograph.Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

J Korean Assoc Oral Maxillofac Surg 2014;40:32-36

34

Fig. 2. Mandibular simulation surgery. A. Preoperative three-dimensional (3D) skeletal image overlapped with current occlusion digital cast images. B, C. 3D images of the mandibular setback (blue) repositioning under bilateral ramus osteotomy was simulated and evaluated ac-cording to the planned postoperative occlusion images. D. Images were overlaid consisting of the current mandible image (pink) and the repositioned mandible image (blue) in the 3D surgical simulation with the planned postoperative occlusion state. Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

Fig. 3. A. Discrepancies were color-coded and evaluated in the three-dimensional (3D) image based on the range of difference values in the superimposed preoperative mandibular image and the simulated repositioned mandible. B. Discrepancies of the right condyle were evaluated in the 3D image based on the moved range of 3D coordinate planes in the superimposed preoperative mandibular image (sky blue) and the simulated repositioned mandible (red). Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

Unilateral IVRO

35

affectthefunctionalaspectsoftheTMJ1,6-8.Thischangemay

causeTMJdisorders,includingtheabsorptionofthecondyle,

whichmayresultinareductionintheramalheightaftersur-

gery.

Additionalcomplications,includingunwantedchangesin

teethocclusionfromtherotationofthemandibleafteruni-

lateralramusosteotomyofthemandible,arealsopossible.

Tolerablerangeofthecondylarpositionalchangeafteror-

thognathicsurgeryhavenotbeenverified.Simulatedsurgery

mayyieldaccurateandpredictableresultsforthepostopera-

tivepositionoftheunoperatedcondyle,includingthedegree

ofrotationandtheamountofsetback,increasingthenumber

ofclinicalcasesofunilateralmandibularramusosteotomy.

III. Discussion

Unilateralmandibularramusosteotomyisasurgicalmethod

usedinunilateralcondylarfractures4.Thismethodmayalso

besufficientforfacialasymmetrypatientswhosemandibles

areslightlydislocated,becauseitcanalignthefacialmidline

andchangetheposteriorocclusiontoAngle’sClassI1,5.

Unilateralmandibular ramusosteotomy is a surgical

methodwhichmayalsobesufficientforfacialasymmetry

patientswhosemandiblesareslightlydislocated1.However,

inunilateralramusosteotomyofthemandible,therotational

or transitionalmovementof theoppositecondylecanau-

tomaticallychangeintheglenoidfossa,whichcandirectly

Fig. 4. Final surgical simulation image, with only left mandibular ramus osteotomy. Final surgical simulation with only left mandibu-lar ramus osteotomy (blue) was confirmed, and decided as final surgical plan.Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

Fig. 5. Extraoral photographs (A, B), intraoral photograph (C), and three-dimensional facial computed tomography (D) of the final result.Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

Fig. 6. Discrepancies were color-coded in the three-dimensional image based on the range of difference values in the superim-posed preoperative mandibular image and the final result man-dible.Jae-Won Lee et al: Unilateral intraoral vertical ramus osteotomy based on preoperative three-dimensional simulation surgery in a patient with facial asymmetry. J Korean Assoc Oral Maxillofac Surg 2014

J Korean Assoc Oral Maxillofac Surg 2014;40:32-36

36

toryosteotomyonthecontralateralside.

Conflict of Interest

Nopotentialconflictofinterestrelevanttothisarticlewas

reported.

References

1. WohlwenderI,DaakeG,WeingartD,BrandstätterA,KesslerP,LethausB.Condylarresorptionandfunctionaloutcomeafterunilateralsagittalsplitosteotomy.OralSurgOralMedOralPatholOralRadiolEndod2011;112:315-21.

2. KangSH,KimMK,ParkWS,LeeSH.Accuratecomputerisedmandibularsimulationinorthognathicsurgery:anewmethodforintegratingtheplannedpostoperativeocclusionmodel.BrJOralMaxillofacSurg2010;48:305-7.

3. KangSH,LeeJW,KimMK.Useofthesurface-basedregistrationfunctionofcomputer-aideddesign/computer-aidedmanufacturingsoftwareinmedicalsimulationsoftwareforthree-dimensionalsim-ulationoforthognathicsurgery.JKoreanAssocOralMaxillofacSurg2013;39:197-9.

4. RubensBC,StoelingaPJ,WeaverTJ,BlijdorpPA.Managementofmalunitedmandibularcondylarfractures.IntJOralMaxillofacSurg1990;19:22-5.

5. UekiK,MarukawaK,ShimadaM,HashibaY,NakgawaK,YamamotoE.CondylaranddiscpositionsaftersagittalsplitramusosteotomywithandwithoutLeFortIosteotomy.OralSurgOralMedOralPatholOralRadiolEndod2007;103:342-8.

6. Al-GunaidT,YamadaK,TakagiR,SaitoC,SaitoI.PostoperativestabilityofbimaxillarysurgeryinClassIIIpatientswithmandibu-larprotrusionandmandibulardeviation:afrontalcephalometricstudy.IntJOralMaxillofacSurg2008;37:992-8.

7. UekiK,MoroiA,SotoboriM, IshiharaY,MarukawaK,Yo-shizawaK,etal.Changesintemporomandibularjointandramusaftersagittalsplit ramusosteotomyinmandibularprognathismpatientswithandwithoutasymmetry.JCraniomaxillofacSurg2012;40:821-7.

8. FangB,ShenGF,YangC,WuY,FengYM,MaoLX,etal.Changesincondylarandjointdiscpositionsafterbilateralsagittalsplitramusosteotomyforcorrectionofmandibularprognathism.IntJOralMaxillofacSurg2009;38:726-30.

9. ZhaoQ,HuJ,WangD,ZhuS.Changesinthetemporomandibularjointaftermandibularsetbacksurgeryinmonkeys:intraoralverti-calversussagittalsplitramusosteotomy.OralSurgOralMedOralPatholOralRadiolEndod2007;104:329-37.

10. HashimotoT,FukunagaT,KurodaS,SakaiY,YamashiroT,Takano-YamamotoT.Mandibulardeviationandcantedmaxillaryocclusalplanetreatedwithminiscrewsandintraoralverticalramusosteotomy:functionalandmorphologicchanges.AmJOrthodDentofacialOrthop2009;136:868-77.

Inthecurrentcase,IVROwasusedastheunilateralman-

dibularramusosteotomy.SSROorIVROcanbothbeused

forunilateralmandibularramusosteotomy.Therehavealso

beenreportsofusingIVROin theshiftsideof theman-

dible9,10.IVROwasusedastheunilateralmandibularramus

osteotomy,consideringtheuseofIVROintheshiftsideof

themandible.

Theoutcomemayhaveoccurredbychancealone.There

wasnotestablishedabouttheprotocoltodetermineifsingle

sidedmandibularramussurgerywouldbebiologicallyand

functionallytolerated.Also,criteriaashowmanydegreesof

displacementwouldbeindication,needtobeverified,though

USSROisnotuniqueprocedure1.But,wehadexpected

throughthe3Dpreoperativesurgicalsimulation,theimpact

of thenon-operatedcondylewouldbeminimal. Itwould

beavaluablecomplementforthereductionofthesurgical

treatmentifonecoulddecidewithgoodpredictabilitywhen

anisolatedIVROcanbedonewithoutacompensatoryoste-

otomyonthecontralateralside.

Recentdevelopmentsin3Dimagingtechnology2,3,includ-

ing3Dsimulationsurgery,andthemanufactureofsurgical

wafersviastereolithographyreducethepossibilityoferror

duringorthognathicsurgery.Applicationof3D imaging

technologytounilateralmandibularramusosteotomywill

behelpfulforpredictingthemorphologicalandfunctional

changes in the temporomandibular regionaccording to

changesinthepositionofthecondyle,andthusweexpect

3Dsimulationsurgerytobeutilizedmoreofteninclinical

treatment.

Inthiscasereport,thepatienthadafacialprofileinwhich

themandibularmentonhadbeendeviated to theright.A

stablepositionforonecondyleandasymmetricalpostopera-

tivestateofthefacewereconfirmedusingpreoperative3D

surgicalsimulation.Facialasymmetrywasresolvedwith

minimalsurgicaltreatmentthroughUIVROontheleftside

ofthemandiblewithoutTMJcomplications.

Itwouldbeavaluablecomplementforthereductionofthe

surgicaltreatmentifonecoulddecidewithgoodpredictabil-

itywhenanisolatedIVROcanbedonewithoutacompensa-