Date of Award
Summer 2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Marinho Del Santo
Second Advisor
Dawei Liu
Third Advisor
Shengtong Han
Abstract
Objective: This research aims to investigate the impact of dentoalveolar heights on craniofacial growth and the development of Class I and Class II malocclusions in untreated subjects aged 6-18 years. The study seeks to establish relationships between dentoalveolar heights and anterior and posterior facial heights. The findings contribute to understanding the dynamic interplay between dentoalveolar growth, mandibular rotation, and facial height establishment, shedding light on critical aspects of craniofacial development. Materials and Methods: The study draws upon cephalograms from the University of Michigan Growth Study, encompassing untreated Class I and Class II subjects aged 6-18 years. A subsample of 408 cephalograms from 55 subjects, meeting specific inclusion criteria, was selected from the AAOF Craniofacial Growth Legacy Collection. The research design, approved by the Marquette University Institutional Review Board, features a mixed-longitudinal approach and excludes orthodontic interventions, allowing for a natural exploration of malocclusion development. The study explores the role of four independent variables (U6, L6, U1, L1) in three separate phases of development (phase A, phase B, and phase C) in determining anterior and posterior facial heights. Cephalograms were processed using Viewbox 4 software, and statistical analyses, including multiple linear regression models, were conducted to examine the relationships between dentoalveolar heights and facial height dynamics. Results: For Class I subjects, the multiple linear regression models for anterior facial height (AFH) and posterior facial height (PFH) exhibited significant goodness of fit, with the distance from the upper molar to the palatal plane (U6-PP) emerging as a crucial determinant variable. In contrast, Class II subjects showed no statistically significant role for the four independent variables except for the distance from upper incisors to the palatal plane (U1-PP) in phases B and C. The study emphasized the intricate interplay between dentoalveolar heights, mandibular rotation, and facial height establishment, revealing distinct patterns between Class I and Class II malocclusions. Conclusion: The research concludes that AFH is more influenced by dentoalveolar heights than PFH in Class I subjects, emphasizing the significance of the upper molar's distance to the palatal plane. The late mixed dentition period introduces challenges in assessing craniofacial growth. In Class II subjects, less consistent dentoalveolar growth may contribute to non-ideal facial heights, with the relationship between upper and lower incisors complicating the cause and effect relationship between mandibular rotation and molar eruption. Despite limitations, the study underscores the pivotal role of dentoalveolar heights in facial height establishment and offers valuable insights into craniofacial growth and development.