Three-dimensional diagnosis of facial asymmetry with a new system

  • 郭 子彥

Student thesis: Master's Thesis


The aim of this study was to establish a new system to diagnose classify and quantify facial asymmetry In clinical facial asymmetry is one of the most common chief complaints However diagnosis of asymmetry was usually by the etiologies These pathologic diagnoses just provide clinicians an impression of the facial asymmetry without further information about the facial features and severity of the deformities Currently some CT-based 3D analysis methods are developed in which landmarks are used These methods lack proper reference plane and are inappropriate or inefficient in characterizing the asymmetry The OSP analysis is a self-developed system to examine symmetry in which optimal symmetry planes (OSP) are established for midface and mandible for reference in 3D The present study was divided in three parts In part I study we enrolled 35 patients to compare 2D postoanterior cephalometry (PAC) and OSP analysis In part II 49 patients were enrolled and the relation between condyle dimension and OSP analysis was examined In part III 51 patients were enrolled and conventional frontal facial photographs of 51 patients in natural head position were taken Then five raters who were residents from our oral surgery and orthodontic department were instructed to evaluate each picture for six facial asymmetry features on a scale from 1 to 5 Correlation coefficient and regression analysis were calculated to study the relation between rating of facial asymmetry feature and OSP analysis In part I we found the conventional 2D PAC analysis was significantly different from the OSP analysis and was usually under-estimated Part II study indicated association between condyle dimensional discrepancies and OSP analysis were positive and statistically significance In part III study the result showed that OSP analysis and objective rating of symmetry were correlated significantly (P < 05) except for horizontal deviation angle and lip canting Regression analysis of OSP analysis and soft tissue features were calculated and the regression function could be used to predict severity of facial asymmetry When the rating of 3 (observable asymmetry) was used as the cutting point for asymmetry the correspondingly predicted OSP data as followings: 3 35?for 3DDA 2 1?for FDA 4 7mm for ADD and 2 04mm for PDD The predicted values could help surgeon to determine the plan of surgery
Date of Award2015 Jul 30
Original languageEnglish
SupervisorJia-Kuang Liu (Supervisor)

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