Geometric morphometric analysis of hard tissue and soft tissue in different skeletal patterns of Malaysian Malay adults / Tamana Sazgar

Geometric morphometric is a new method used by anthropologists in examining shape analysis. The traditional measurement of malocclusion relies on cephalometric techniques. Nowadays, the geometric morphometries method (GMM) for shape analysis could provide better perception and capabilities of measuring the size and shape variations of malocclusion in 2D and 3D dimensions. This study aims to investigate the size and shape and its variations of hard and /soft tissue patterns in different skeletal relations in adult Malays using the 2-dimensional (2D) geometric morphometries method from lateral cephalograms. In this study, a total of 188 lateral cephalograms of Malaysian Malay (agel8-40 years) were collected and comprised of Class I, Class II, and Class III skeletal relations with 117 females and 71 males. A total of 21 2D-dimensional hard tissue and soft tissue landmarks were applied on lateral cephalograms using tpsDig2 software version 2.31. The MorphoJ software version 1.07a was used for the data and shape analysis. The data were analysed for shape variation according to skeletal relations and gender groups. As a result, 18 shape variations for soft tissue and 16 principal components (PC) for hard tissue variations were produced. Centroid size was significantly different in genders and skeletal relations by Procrustes ANOVA (P < 0.01). Canonical variate analysis (CVA) showed the highest Mahalanobis distances and Procrustes distances between Class II and III among skeletal relations and between males and females (P < 0.0001). Discriminant function analysis (DFA) among skeletal relations showed the classification was mostly accurate, especially for Class II and Class III with success rates of 92.1% and 88.3%, respectively, after cross-validation. The highest percentages of success rates were 85.4% for females and 87.3% for males after crossvalidation among skeletal relations. In conclusion, there were different ANB angles in different skeletal relations. Class III showed the most protrusive upper and lower lips, while class II demonstrated the most retrusive lower lip. The result of this study could be used to develop an artificial intelligence system for predicting the skeletal and facial morphology of Malay subjects as a guide in diagnosis and treatment planning for orthodontists and maxillofacial surgeons.