Date of Award
Summer 2024
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Marinho Del Santo
Second Advisor
Dawei Liu
Third Advisor
Shengtong Han
Abstract
ABSTRACT Morphology of the Cranial Base of Untreated Class I and Class II Subjects Ethan Just, DMD Marquette University, 2024 Objective: Cranial base and facial growth are related. although good attention has been dedicated to this theme, there is no consensus about the role of cranial base growth on facial growth. The morphology of the cranial base aroused early interest among orthodontists but doubts about the validity of the methodologies used to assess its possible correlations with facial growth have been constant. For some authors there is no correlation between the cranial base angle and presented malocclusion. In contrast, other authors have stated that the development of the facial skeleton is closely related to the cranial base dimension and flexure. Materials and Methods: A total sample of 98 subjects drawn from the AAOF website from which a subsample of 55 subjects including 408 cephalograms that matched the inclusion criteria. The subsample included 40 male and 15 female subjects, being 45 presenting Class I malocclusion (33 male and 12 female subjects) and 10 presenting Class II malocclusion (7 male and 3 female subjects). The main selection criteria for such sample reduction were the selection of cases which present at least one cephalogram in all the three phases considered (phase A, B and C), which guarantees a longitudinal coverage from 7 to 16 years of age. Results: Based on the values identified and evaluated by landmarks Basion, Sella and Nasion at phases A, B and C for the Class I and Class II malocclusion groups, no significant differences observed in the cranial base angle between Class I and Class II subjects. An evaluation of Sella, Nasion, and Basion by a cartesian plane based on the true vertical showed a significant difference in the location of Basion between subject groups. Basion drifts downward and backward 2.38 mm in the Class I group but only downward and backward 0.53 mm in the Class II group. Conclusion: The lack of conclusions on the difference between the cranial base angle (Na-S-Ba) reported in previous studies is probably due to geometrical and sample size limitations. In this study, the position of the landmarks Nasion and Basion were also independently assessed in a cartesian plan (X and Y components). The proposed null hypothesis of no difference in cranial base between Class I and Class II subjects is rejected. Basion drifts downward significantly more in Class I subjects than in Class II untreated subjects.