Page 35 - Demo

Normalcranialevolution332shapeofthehardtissue(CT-HT)andsofttissue(CT-ST)usingMaxilimsoftware(MedicimNV,MechelenBelgium) Three-dimensionalshapeswithclearartefactswereremovedfromtheCT-HTandCT-STgroupsSincetheplagiocephalometrymethodtoexcludeasymmetriccranialshapeswasdesignedforsofttissueonlyacorrelationandoffsetfactorwascalculatedtomaketheplagiocephalometrymethodalsoapplicabletohardtissueDetailsoftheplagiocephalometrymethodandoffsetcalculationaregivenintheAppendixFinallyatotalof94CT-HTshapesand76CT-STshapeswereusedinthisstudy(Figure1)TheCT-HTgroupwas52%(n=49)maleandtheCT-STgroupwas50%(n=38)maleDetailsofthesexdistributionaregivenin Table1DATAPROCESSINGThequalityofall3DphotographswasassessedandminorartefactswererepairedusingMeshMixer3Dsoftware(AutodeskIncSanFranciscoCAUSA)Similartomethodspresentedpreviouslynineland-marksweremanuallymarkedonthetextured3Dphotographs(Table2;Figure2)andusedtoautomaticallyprealignthe3Dphotographsinareferenceframe(tragus–nasionorientation)11Thecomputedcranialfocalpoint(CCFP)wasusedtoautomaticallypositionthe3Dphotographsinidenticalreferenceframes(sellaturcica–nasionorientation)usingMatLabv2017a(TheMathworksIncNatickMAUSA)12The3DphotographswerecheckedforrotationalandpositionalvariancesandadjustedifnecessaryForfurtheranalysisall3Dphotographswerenormalizedtocreatemeshdatawiththesamenumberofvertices(datapoints)1011AnannotationtoolwascreatedinUnityv560(Unity TechnologiesSanFranciscoCAUSA)tomanuallyposition21landmarksontheCT-HT(Table2)LandmarksandtheCCFPmethodwereusedtoautomaticallypositionthe3Dshapesinthesellaturcica–nasionorientationInthesamewayasforthe3Dphotographsrotationalandpositionaldifferenceswereeliminatedandthe3D-CTshapeswerenormalizedforfurtheranalysisMEASUREMENTSThe3Dphotographsweregroupedintosevenpredefinedagecategoriesandthemeancranialshapewascalculatedforeverygroup1011ThemeangrowthwascalculatedasthedifferencebetweenameancranialshapeandtheconsecutivemeancranialshapeandvisualizedwithagrowthmapTheCT-HTshapesweregroupedsimilartothe3Dphotographswithtwoadditionalagegroupsof36and48months Thecraniallengthwasgivenbythemostanteriorandposteriorpoint