TurkJMedSci 34(2004)59-66 ©TÜB‹TAK CLINICALINVESTIGATION AsymmetricMaxillaryFirstMolarDistalizationwiththe TranspalatalArch SerhatEYÜBO⁄LU,AliOsmanBENG‹,ArifÜmitGÜRTON,ErolAKIN DepartmentofOrthodontics,DentalSciencesCenter,GülhaneMilitaryMedicalAcademy,Ankara-Turkey Received:September22,2003 Abstract: ThepurposeofthisstudywastodeterminethedentoalveolarandskeletaleffectsofaGoshgariantranspalatalarch(TPA) inunilateralmaxillaryfirstmolardistalization.Thetreatmentgroupconsistedof15patients(6femalesand9males)between10.8 and12.1yearsofage.Themaxillaryfirstmolars,whichwereinadentalClassIrelationship(anchoragemolars),weretheanchorage units,whilethemolarsinClassIIrelationship(distalizedmolars)weredistalizedusingaTPAwith150g.offorce.Lateral head films,studymodelsandclinicalphotographsofallthepatientsweretakenbeforeandafterdistalization.Thedifferencesbet ween themeasurementswereevaluatedwithapairedsamplesttest.Themeanunilateralmolardistalizationwas2.067mm,with3.733º distaltippingand4.800ºdistopalatinalrotation.Anchoragemolarsweremesialized0.367mmwith0.400°mesialtippingand showedamesiobuccalrotationof9.400º.Thedistalizedmolarsandanchoragemolarswereextruded0.267mmand0.533mm, respectively.A0.467mmbuccalmovementwasobservedinthedistalizedmolars;however,theexpansivemovementofthe anchoragemolarswasnotstatisticallysignificant.TheresultsshowedthattheTPAwaseffectiveintheasymmetricdistalizati onof themaxillaryfirstmolars. KeyWords: Unilateral,asymmetric,molardistalization,transpalatalarch Introduction rotationofthemaxillaryfirstmolarsistypicalinthe ThetreatmentofClassIImalocclusionsfrequently majorityofClassIIcasesandagainof1-2mmarch requiresthedistalizationofmaxillarymolarsandithas lengthpersidecouldbeachievedfollowingthecorrection beenshowninanumberofstudiesthatmaxillarymolars ofmesialrotationoftheseteeth.Earlylossoftheupper canbeeffectivelydistalizedwithvariousnon-compliance seconddecidiousmolarsincreasestheseverityofthe treatmentmodalities(1-9).However,thesemethodscan mesialrotationandcausesmaxillaryfirstmolarstoseem alsocausemesialmovementofthemaxillarypremolars asiftheywereinaClassIIrelationship,fromabuccal andcanines.Inaddition,thelossofanterioranchorage aspect.However,sincethemesiolingualcuspsof oftenleadstorelapseofthemaxillarymolarsduringthe maxillarymolarsstillfitinthecentralfossaeof correctionofthecaninerelationship,overbite,and mandibularmolars,aClassIrelationshipcanbeobtained overjet.Ontheotherhand,thetranspalatalarch(TPA)is withjustthecorrectionofmolarrotation.The awidelyusedapplianceinorthodontictreatmentsand, biomechanicalprinciplesoftheTPAareadequateforthe besidesseveralotherfunctionsincludingstabilizationand correctionofmolarrotations,andlimiteddistalizationof anchorage(10),correctionofmolarrotations(11), themaxillarymolarscanalsobeachievedthrough verticalmolarcontrol(12-14)andtreatmentofunilateral sequentialactivationoftheappliance(17,18).Sincethe molarcrossbites(15,16),itisalsoanalternativetothe introductionofTPAtherehavebeenfewarticlesinthe othertreatmentregimenforthecorrectionofthemolar orthodonticliteraturethathavedealtdirectlywiththe relationshipwhenthemaxillarymolarspresentaslight clinicalmanagementofthistypeofappliance.Studies unilateralClassIIdiscrepancy(17,18). dealingwiththedistalizationeffectsoftheTPAareeven rare.ModifyingCetlin’s(20)technique,Mauderinoand LemonsandHolmes(19)indicatedthatmesial 59 AsymmetricMaxillaryFirstMolarDistalizationwiththeTranspalatalArch Balducci(18)demonstratedunilateraldistalizationofthe thedoubled-overendatthesideoftheAnMandthearm maxillarymolarswith0.032"TMAbars,whicharemore waspusheddistallyuntila150-gforcewasproducedon elasticandresilientthanthestainlesssteelusedinthe theDiM(Figure1d).Theforcewasmeasuredbypulling con-ventionalGoshgarianarch.However,theysuggested backtheDiMendofthearchtothelevelofthelingual extraoralforceatnightstoreinforceanchorage.The sheath,usingadentaurumgauge(006-013-00)(Figure objectiveofthisstudywastoevaluatetheefficiencyof 1c).Approximately30ºofthebuccalroottorquewas theconventionalGoshgarianTPAinunilateralmaxillary incorporatedinthedoubled-overend,whichwasinserted firstmolardistalizationandtodeterminethe intotheAnMsheath. dentoalveolarandskeletaleffectsoftheappliance. ClinicalManagement Aslightexpansionbendwasincorporatedinthe MaterialsandMethods applianceduringthefirstappointmenttopreventan Thestudycomprised6femalesand9males,withan edge-to-edgerelationshipwiththeDiM.Thepatients averageageof11.2years.Thepatientselectioncriteria wereseenmonthlyandtheTPAwasreactivatedby wereasfollows: bendingdistallybeneaththeendinsertedfromthedistal. Themeandistalizationperiodwas5monthsandallthe 1-ClassImalocclusionwithanormalverticalpattern, recordswererepeatedafterthepatientsattaineda 2-UnilateralClassIImolarrelationship(needforfirst bilateralClassImolarrelationship.Theorthodontic molardistalizationnotexceeding1.5-2.5mm), treatmentsofthepatientswerethencarriedoutwith 4-Correctlowerdentalmidline, fixededgewiseappliances.Excessiverotationsand undesiredtippingsofthemaxillaryfirstmolarswere 5-Latemixedorearlypermanentdentition, correctedwithfinishingNi-Tiarchwires(0.017”x 6-Normaloverjetandoverbite. 0.025”)andblueelgiloyuprightingsprings(0.016”x Maxillaryfirstmolarsinthetreatmentgroupwere 0.022”).Intraoralphotographsofapatientbeforeand distalizedunilaterallywithtranspalatalarchesbentfrom afterunilateralmolardistalizationareshowninFigures2 0.9mmstainlesssteelwire.Lateralcephalograms, a-cand3a-d. orthodonticmodelsandclinicalphotographsofthe CephalometricEvaluation patientsweretakenbeforeandafterthedistalization RadiographywasperformedwiththeFrankfort period. Horizontalplaneparalleltothefloor.Individualguiding ConstructionoftheTPA markers(0.017”x0.025”blueelgiloy)wereusedto Buccaltubesandpalatalsheaths(0.9mmx1.8mm) distinguishtheAnMandDiMonthelateralheadfilms. werespotweldedtoappropriatemolarbands.Sheaths StraightmarkersindicatedtheAnM(Figure2b)whilethe wereattachedtothelingualaspectsofthemolarbands hookedmarkersindicatedtheDiM(Figure2c).The atthesameoccluso-gingivalheightandinthesame markerswereplacedintherectangulardoublebuccal mesiodistalpositionasthetubes.Tubesandsheathswere tubesofmolarbandsandorientedverticallybefore solderedtothemolarbands,andanalginateimpression obtainingtheinitialcephalograms.Thentheywere wasmadewiththebandsinplace.Thebandswere removedandkeptforthefinaluseafterdistalization.The transferredtotheimpressionandastudymodelwas radiographiesweretracedby1investigatorwith obtained.TheTPAwasbentsothattheloopwas4mm verificationofanatomicoutlinesandlandmarksbythe abovethepalatalmucosawiththebendfacingthedistal. other3.Thestructuresinquestionwereretracedtothe Theendsofthearchwereformedaccordingtothe mutualsatisfactionoftheinvestigators.Asingleaverage modifiedtechniqueofMauderinoandBalducci(18).One tracingwasmadeininstancesofbilateralstructures.The ofthedoubled-overendsoftheTPAwasinserted parametersweremeasuredbyeachinvestigatortwice,at passivelyfromthedistalintothesheathofthemaxillary differenttimes,toeliminatemeasurementerrorsandthe firstmolarusedasanchorage(AnM),andfromthemesial meanfindingswereevaluatedstatistically.Theangular intothatofthemaxillaryfirstmolartobedistalized(DiM) andlinearmeasurementsusedinlateralcephalogramsare (Figures1a-c).Theappliancewasheldwithpliersbeneath presentedinFigure4. 60 S.EYÜBO⁄LU,A.O.BENG‹,A.Ü.GÜRTON,E.AKIN Figure1.Thedoubled-overendsoftheAnM(b)andDiM(c)andactiveformoftheTPA(d). Figure2.Intraoralphotographsofapatientbeforedistalization. ModelAnalysis intersectionpointwasmarked.Theintersectionpointson Modelanalysiswascarriedouttodeterminemaxillary theAnMandDiMweredefinedasIPAnandIPDi, firstmolarrotationandchangesinintermolardistance. respectively. Themidpalatalsuturesandthetipsofmolarcuspswere Rotationofthefirstmolarswasfoundbymeasuring definedwitha0.5mmpointeddrawingpencilonstudy theanglebetweenthemidline(ML)andthediagonalline models.Modelphotocopieswereobtainedasdescribedby passingthroughthemesiobuccal(MB)anddistopalatinal Champagne(21).Onmodelphotocopies,amidlinewas (DP)cusptips.Thechangesintheintermolardistance drawnalongmidpalatalsutureand2diagonallineswere werefoundbymeasuringtheperpendiculardistances drawnbetweenthecusptipsofthefirstmolarsandtheir fromIPAntoMLandfromIPDitoML(Figure5). 61 AsymmetricMaxillaryFirstMolarDistalizationwiththeTranspalatalArch Figure3.Intraoralphotographsofthepatientduringfixedtreatment(a)andafter(b-d)orthodontictreatment. 2 1 12 3 8 9 11 4 5 6 7 Figure4. Angularandlinearmeasurementsusedincephalometricanalysis.(1)SNAº,(2)SNBº,(3)ANBº,(4)MPº,(5)OPº,(6)AnM- PtV(mm):theperpendiculardistancefromtheinsertingpointoftheAnMmarkertothebuccaltubetoPtV,(7)DiM-PtV (mm),(8)AnM/FHº:theanglebetweenthemarkerofAnMandFH,(9)DiM/FHº,(10)AnM-FH(mm):theperpendicular distancefromtheinsertingpointoftheAnMmarkertothebuccaltubetoFH,(11)DiM-FH(mm),(12)U1/SNº:theangle betweenthelongaxisofthemaxillaryincisorandSN. 62 S.EYÜBO⁄LU,A.O.BENG‹,A.Ü.GÜRTON,E.AKIN withadistaltippingof0.367º(P=0.022).TheDiMsand AnMswereextruded0.533mm(P=0.003)and0.267 mm(P=0.027),respectively.Whenskeletalchanges wereevaluated,asignificantincreasewasobservedatthe SNBangleof0.466º(P=0.010)(Table1). StudyModelFindings ThedistancebetweentheDiMsandthemidlinewas increasedby0.467mm(P=0.014)howeverthe distancebetweentheAnMsandthemidlinedidnot 1 2 changesignificantly.TheDiMsshoweddistopalatinal rotationof4.800º(P<0.001)whileamesiobuccal AnM DiM rotationof9.400º(P<0.001)wasobservedinthe AnMs(Table2). Discussion TheTPAcanbeactivatedtodeliverclinicallyuseful forcesandcouplestomoveand/orrotatemaxillary 4 3 molarsinall3planesofspace.However,itmustbekept inmindthatininstancesofasymmetricactivationthe