Evaluation of Vertical Components of the Mandible Using Three-Dimensional Radiographs
thesisposted on 27.07.2018, 00:00 by Peyton Harris
Introduction: The purpose of this study was to evaluate the association of various linear and angular parameters of subjects’ mandibles with different craniofacial skeletal patterns, utilizing 3D CBCT images from three private practices in CO and IL, USA. Methods: Pre-treatment 3D CBCT images from 331 non-growing subjects were used. Two-dimensional cephalometric images generated by Dolphin Imaging Software were utilized for categorizing the samples. The samples were categorized into Class I, Class II, and Class III skeletal types; and subcategorized into hyperdivergent, normodivergent, and hypodivergent vertical growth patterns. Dimensions of linear and angular variables from 3D images i.e. ramus height, ramus breadth, condylar length, coronoid process length, anterior mandible height, and convergence angles of the ramus and of the mandibular base, amongst the skeletal categories were evaluated. ANOVA and Student's t-test statistical analyses were conducted to determine differences of the outlined variables amongst the skeletal types, and Pearson correlation was performed to evaluate the correlation of each variable. Results: There was a significant difference in ramus height observed between Class I and III skeletal types, and between males and females. Significant difference in anterior mandibular height was observed between males and females. There were statistically significant mean differences of the studied variables of the mandibles, among the vertical patterns in all skeletal groups. Positive correlation of various parameters of the mandibles was observed most in Class I/normodivergent subjects. Conclusions: This is the first study to compare linear and angular variables of the mandibles in all skeletal types, using 3D CBCT images. This study provides a preliminary 3D norm for all skeletal types and genders. Ramus height can be used as an indicator for gender differentiation.