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Cranialshapeevaluation613TRIGONOCEPHALYThefourPCsthatexposedthelargestdifferencefortrigonocephalypatientandcontrols wereselected ThesePCscorresponded withasmaller forehead temporalnarrowingreducedfrontalbossingandadecreasedorbitalwidthThevaluesofthefourPCsaredisplayedbytheboxplotsinFigure4ThesummedabsolutevaluesofthesefourPCsresultedinameanof31(SD12)forthecontrolsandameanof97(SD27)forthetrigonocephalypatientsThisdifferencebetweenthecontrolpopulationand the trigonocephalypatients wasstatisticallysignificant(p<0001;95%confidenceinterval51–80)Themeanvaluesofthe4PCsfortrigonocephalywereusedtosimulatethemorphologicaleffectThecolourmapinFigure6demonstratestheeffectofthesefourPCsin3DDISCUSSIONThecombinationof3DstereophotogrammetryandtheevaluationwiththeuseofPCAprovidesanewmethodforanobjectiveandautomaticcharacterizationofthecranialmorphologyPCAwasappliedonadatasetof3DphotographstofindandisolatecranialshapevariationsinanormalpopulationUsingthesevariationsthecranialshapeofscaphocephalyandtrigonocephalypatientscouldbedistinguished fromanormalcranialshape Thismethodprovidesanobjective toolfor thephysician todetect whetheracranialshapeisnormalorcanbeclassifiedasscaphocephalyortrigonocephalyusinga3DphotographSince Virchowdescribedtheabnormalshapeoftheheadin1851therehasbeenawidevarietyinmethodstoevaluatethecranialshape15AstandardmethodfordocumentationofthecranialshapehasnotbeenadoptedThemostcommonmethodsincludeclinicalobservationsand(calliper)anthropometricsdirectlyonthepatient’shead1617Wilbrandetalarguedthatcallipermeasurementsprovidehighlypreciseinformationaslongasastrictlystandardizedprotocolisfollowed;thepatientshouldbeinastandardpositiontheexaminershouldbetrainedandthepatientshouldbecooperative18Becauseoftheseconditionsexactmeasurementsanddocumentationarechallenging1619Inadditionthesemeasurementsaretwo–dimensionalandthereforedonotprovideanadequatedescriptionofthe3Dcranialshape