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Surgical extraction of mandibular third molar in pterygomandibular space: a case report

Young-Kyu Lee1, Sung-Soo Park1,2, Hoon Myoung1,3

Department of Oral and Maxillofacial Surgery, 1School of Dentistry, Seoul National University, Seoul, 2Korean Armed Forces Capital Hospital, Seongnam, 3Dental Research Institute, Seoul National University, Seoul, Korea

Abstract (J Korean Assoc Oral Maxillofac Surg 2013;39:242-245)

Impacted mandibular third molars are located between the second mandibular molar and mandibular ramus. However, ectopic mandibular third molars with heterotopic positions are reported in the subcondylar or pterygomandibular space. The usual cause of malposition is a cyst or tumor, and malposi-tion without a pathology is rare. This case report described an impacted mandibular third molar in the pterygomandibular space without any associated pathology.

Key words: Third molar, Pterygomandibular space[paper submitted 2013. 8. 9 / revised 2013. 9. 9 / accepted 2013. 9. 11]

II. Case Report

A46-year-oldmalepatientvisitedtheDepartmentofOral

andMaxillofacialSurgery,SeoulNationalUniversityDental

Hospital,complainingofswellingandpainintherightpreau-

ricularregion.Hewaspreviouslytoldbyageneraldentistat

alocalclinicthathehadamalposedtoothintherightman-

dibleandwasadvisednottohavethetoothextracteduntil

symptomsappear.Apanoramicradiographshowedathird

molarlocatedhighintheascendingramusoftherightman-

dible.(Fig.1)Toidentifytheexactlocationofthetooth,com-

putedtomography(CT)wastaken,showingthethirdmolar

inthepterygomandibularspaceassociatedwitharadiolucent

lesion.(Fig.2)Theradiolucentlesionwasevaluatedascystic

lesionsuchasodontogenickeratocystordentigerouscystor

secondaryinflammationaccompaniedbysofttissueinvolve-

ment.

Thesurgerywasperformedundergeneralanesthesiavia

theintraoralapproach.Anincisionwasmadeovertheright

externalobliqueridgeandextendedfromthesecondmolar

totheposterosuperiormandibularascendingramus.Subperi-

ostealdissectionwasdonesuperiorly,exposingtheanterior

borderoftheramusfromtheretromolarareaalmosttothetip

ofthecoronoidprocess.Medialsubperiostealdissectionpro-

ceededposteriorly,exposingthelingulaandinferioralveolar

neurovascularbundleuptothecondyleneck.Osteotomywas

I. Introduction

Thesurgicalextractionofanimpactedmandibularthird

molar isoneof themostcommonproceduresperformed

byoralandmaxillofacialsurgeons.Mostmandibularthird

molarsareimpactedinthemandibularramusareanearthe

secondmolar,andthelevelofdifficultyofextractionisclas-

sifiedaccordingtothedegreeofimpaction,positioninthe

mandibularramus,andangulationofthelongaxisofteeth.

Usually,athirdmolarimpactedfarawayfromitsoriginalsite

isaffectedbyacystoratumor.Onlyafewcasesofectopic

mandibularthirdmolarintheregionofpterygomandibular

spacewithoutassociationofcysticlesion--suchasodonto-

genickeratocystanddentigerouscyst--havebeenreported1,2.

Wereportacaseofmandibularthirdmolarlocatedinthe

pterygomandibularspacethatseemstohavebeendisplaced

byneithercystnortumor.

CASE REPORThttp://dx.doi.org/10.5125/jkaoms.2013.39.5.242

pISSN 2234-7550·eISSN 2234-5930

Hoon MyoungDepartment of Oral and Maxillofacial Surgery, Dental Research Institute, Seoul National University, 101, Daehak-ro, Jongno-gu, Seoul 110-749, Korea TEL: +82-2-2072-3059 FAX: +82-2-766-4948E-mail: myoungh@snu.ac.kr

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 Ⓒ 2013 The Korean Association of Oral and Maxillofacial Surgeons. All rights reserved.

Surgical extraction of mandibular third molar in pterygomandibular space

243

sitewasprimarilysutured,with4/0vicrylapplied.Thepost-

operativewoundhealingwasuneventful,withnonervedam-

agesymptom.Asmallfollicularspaceenvelopingthecrown

ofthetoothwasalsoidentified,suggestinginflamedgranula-

tiontissue.(Fig.5)Aconnectiontotheperiodontalspaceof

themandibularsecondmolarwasdetected.Inviewofthe

scleroticchangeoftheunderlyingmandible(Fig.2)andden-

talcaries(Fig.3B),weassumethattherehadbeenprolonged

communicationwiththeoralcavity.Thisultimatelyledto

theinfectiousprocess.

III. Discussion

Severalstudieshavereportedectopicmandibularthirdmo-

lar in themandibularramus3,4,mandibularcondyle5-7,and

coronoidprocess8.

The true incidenceandetiologyofectopicmandibular

thirdmolar remainunknown9.Anaberranteruptionpat-

ternhasbeensuggestedtooccurwhenthetoothhasbeen

displacedbyalesion,usuallyanodontogeniccyst3,10,11.Den-

tigerouscyst is themostcommonbenignlesionrelatedto

performedwitharoundburonthemedialsideoftheman-

dible.Thetoothwasexposedandcarefullyremoved.(Fig.

3)Thetoothwaseasilyremovedfromtheareabetweenthe

lingulaandthesigmoidnotch.Thepostoperativepanoramic

radiographshowedtheremovalofectopicmandibularthird

molar.(Fig.4)Sharpareasweresmoothened,withthesite

curettedandcleanedwithsterilesalinesolution.Thesurgical

Fig. 1. Panoramic view of ectopic mandibular third molar in the right ascending ramus of the mandible.Young-Kyu Lee et al: Surgical extraction of mandibular third molar in pterygomandibu-lar space: a case report. J Korean Assoc Oral Maxillofac Surg 2013

Fig. 2. Axial image (A) and coronal im-age (B) of computed tomography (CT). CT scans show that the mandibular third molar is located in the pterygo-mandibular space. The sclerotic change of the mandible around the mandibular third molar is consistent with chronic infection.Young-Kyu Lee et al: Surgical extraction of mandibu-lar third molar in pterygomandibular space: a case report. J Korean Assoc Oral Maxillofac Surg 2013

Fig. 3. A. Intraoperative view of the os-tectomy site in the medial aspect of the ascending ramus of the mandible. B. Removed ectopic mandibular third mo-lar whose crown was blackened.Young-Kyu Lee et al: Surgical extraction of mandibu-lar third molar in pterygomandibular space: a case report. J Korean Assoc Oral Maxillofac Surg 2013

J Korean Assoc Oral Maxillofac Surg 2013;39:242-245

244

Surgicalextractionismostlyperformedbyanintra-oral

approach.Extra-oralapproachisdoneinextremelydisplaced

impactedtoothcases.Whenteetharelocatedneartheman-

dibularcondyle,thepreauricularapproachcanbeused.The

approachhastheadvantageofgoodexposureofthesurgical

sitebutmayresultincomplicationssuchasextraoralscar,

damagetotemporomandibularjoint,andfacialnerveinjury11.

Theintraoralapproachmayavoidtheseproblems,butaccess

toandviewoftheseverelydisplacedtoothmaybelimited;

thusmakingthesurgerydifficult.Inthiscase,theimpacted

toothwaslocatedonthelingualsideofthepterygomandibu-

larspace,andthesurgerywasperformedusingtheintraoral

approach.During thesurgery, the inferioralveolarnerve

shouldbeprotected.Moreover,excessivegrindingof the

coronoidprocessormandibularcondyleshouldnotbedone

topreventfracture.

Nowadays,most thirdmolarextractionsareperformed

whenthepatientsareintheirtwenties,sothedislocationbe-

comesrarer.Moreover,theremaybepatientswithectopic

toothwithoutclinicalsymptoms,notknowingthattheyhavea

dislocatedtooth.Therefore,annualpanoramicradiographtak-

ingfromchildhoodisrecommendedfortheearlydetectionof

ectopicthirdmolaranditspathologicchangessuchascystfor-

mationandinfection.Impactedteethdiagnoseduponroutinera-

diographicexamination--andwhicharenotassociatedwithany

pathology--usuallydonotrequiretreatment,buttheyshouldbe

removedtopreventcystformation,infection,andweakeningof

thebonepredisposingtofracture7.Thesurgicalextractionofthe

ectopicthirdmolarshouldbecarefullyplannedandperformed

tominimizecomplicationsinducedbysurgery.

impactedmandibularthirdmolar12.Overtime,thepressure

exertedbytheintracysticfluidontheocclusalaspectofthe

thirdmolarmaycauseitsdisplacement,sometimesfromits

originallocation3,4,13.

In thepresentcase, themandibular thirdmolarwasnot

displacedbyacysticlesionbutbyanuncertaincause.The

developmentof the toothgerminanaberrantpositionor

aberranttoothgermeruptionpatternmaybethemostlikely

etiology.Otherwise,primaryandtotaldislocationoftooth

basemaybethecause8.Intheprocessofmandibularskeletal

growth,boneis typicallyaddedalongtheposteriorramus

borderandresorbedalongtheanteriorborder;mandibular

condyledevelopsasaresultofboneappositionintheposte-

riorramus14.Inthiscase,thepresenceofdentalcariesimplies

thattoothdislocationoccurredafteritsexposuretotheoral

cavity.

KerosandSusić8reportedtheectopicmandibularthirdmo-larinthecoronoidprocessandassumedthattheboneform-

ingthemandibularbaseinchildhoodmayshifttotheregion

beneaththecoronoidprocessinadulthood,withtheectopic

mandibular thirdmolarembedded.Following thenormal

growthpattern,thethirdmolarcrownmovedupward,even-

tuallyreachingthecoronoidprocessofthemandibleinnon-

invertedstate.

Nonetheless,theetiologyofectopicimpactionandmigra-

tionoftoothisstillunclear.Peck15reportedthattheintraos-

seousmigrationofimpactedmandibulartoothisrelatedto

geneticdeterminants.AccordingtoMarksandSchroeder16,

regionaldisturbanceinthedentalfolliclemightleadtolocal

defectiveosteoclasticfunction,withanabnormaleruption

pathwaybeingformed.Sutton17believedthatanabnormally

strongeruptionforceorachangeaffectingthecryptofthe

toothgermmightleadtoerroneouseruption.

Fig. 4. Postoperative panoramic radiograph showing the removal of the ectopic third molar in the pterygomandibular space.Young-Kyu Lee et al: Surgical extraction of mandibular third molar in pterygomandibu-lar space: a case report. J Korean Assoc Oral Maxillofac Surg 2013

Fig. 5. Histopathologic imaging (H&E, ×200).Young-Kyu Lee et al: Surgical extraction of mandibular third molar in pterygomandibu-lar space: a case report. J Korean Assoc Oral Maxillofac Surg 2013

Surgical extraction of mandibular third molar in pterygomandibular space

245

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