Evaluation of facial asymmetry measurements on simulation model

Objective: To study the correlation between 3 types of facial deformation and 2 groups of measurements using (1) ratio parameters and (2) center of mass based parameters, in asymmetric computerized simulation models. Materials and methods: Three groups of facial deformation were constructed which were (1) proportion deformation, (2) shearing deformation and (3) rotation deformation. Computerized facial models were divided into 3 zones which were (1) total zone (maxillo-mandibular complex), (2) upper zone (maxilla) and (3) lower zone (mandible). Three ratio parameters: (1) area ratio, (2) compactness ratio, (3) perimeter ratio, and 4 center of mass based parameters: (1) difference center milieu, (2) Ci milieu, (3) difference milieu and (4) difference vertical milieu were used to measure incremental deformation figures. The results were evaluated using SPSS program. Slope and coefficient of determination (R ² ) values were obtained. Correlation of deformation amount and 7 measurements were considered high and significant if R ² was greater than 0.8 with p-value less than 0.05. Results: For the proportion deformation and shearing deformation, the center of mass based parameters and area ratio were highly and significantly correlated with the deformation amount. However, difference vertical milieu was the only measurement with significant R ² in the rotation deformation group for all 3 facial zones. Conclusion: The correlation of the ratio and the center of mass based parameters can be differently influenced by type of deformations and facial anatomical zones. Center of mass based parameters may be used in conjunction with ratio parameters in order to differentiate type of asymmetry.