IADR Abstract Archives
Cervical Spine Morphology Related to Malocclusions: A Geometric Morphometric Approach
Objectives: To compare facial-craniocervical morphology between Class II and Class III individuals applying Geometric Morphometric Methods (GMM).
Methods: The sample consisted in 79 lateral cephalometric radiographs of adult patients of the Dental Clinic of the University of Chile. The patients were classified according to Delaire criteria, resulting in 40 Class II and 39 Class III individuals. To assess the pattern of shape variation of cervical spine in relation to skeletal Classes II and III 13 craniofacial and 13 cervical landmarks were digitalized, and Generalized Procrustes (GPA) and Principal Component (PCA) Analyses were carried out. Differences between groups were analyzed through the corresponding thin-plate spline deformation grids.
Results: The first two principal components (PC1, PC2) explained 62% of the total shape variation. The individuals were mainly separated in relation to PC1 (40%). With respect to facial morphology, differences in maxillo-mandibular sagittal relationship can be clearly observed. Additionally, craniocervical features indicate morphological differences related to a decreased cervical lordosis and an anterior inclination of the cervical spine in skeletal Class II individuals compared to the skeletal Class III ones. These differences were statistically significant (expected PC1, PC2 values= 28%, 18%, respectively; observed PC1, PC2 values= 44%, 25% respectively, after applying a Bayesian broken stick model on PC1+PC2+…+ PCn, where n=90% of the total variance).
Conclusions: Despite some overlap between the skeletal classes, the morphological characteristics of the cervical spine, such as its curvature and inclination, are contributing to the observed differences between skeletal Class II and Class III malocclusions. In contrast to traditional morphometric assessment, GMM represent an effective approach to analyze visually and numerically the pattern of shape variation in the facial-craniocervical system.
Methods: The sample consisted in 79 lateral cephalometric radiographs of adult patients of the Dental Clinic of the University of Chile. The patients were classified according to Delaire criteria, resulting in 40 Class II and 39 Class III individuals. To assess the pattern of shape variation of cervical spine in relation to skeletal Classes II and III 13 craniofacial and 13 cervical landmarks were digitalized, and Generalized Procrustes (GPA) and Principal Component (PCA) Analyses were carried out. Differences between groups were analyzed through the corresponding thin-plate spline deformation grids.
Results: The first two principal components (PC1, PC2) explained 62% of the total shape variation. The individuals were mainly separated in relation to PC1 (40%). With respect to facial morphology, differences in maxillo-mandibular sagittal relationship can be clearly observed. Additionally, craniocervical features indicate morphological differences related to a decreased cervical lordosis and an anterior inclination of the cervical spine in skeletal Class II individuals compared to the skeletal Class III ones. These differences were statistically significant (expected PC1, PC2 values= 28%, 18%, respectively; observed PC1, PC2 values= 44%, 25% respectively, after applying a Bayesian broken stick model on PC1+PC2+…+ PCn, where n=90% of the total variance).
Conclusions: Despite some overlap between the skeletal classes, the morphological characteristics of the cervical spine, such as its curvature and inclination, are contributing to the observed differences between skeletal Class II and Class III malocclusions. In contrast to traditional morphometric assessment, GMM represent an effective approach to analyze visually and numerically the pattern of shape variation in the facial-craniocervical system.