Integrating the Causes of Third Molar Impaction: A Longitudinal Analysis of Multiple Predisposing Traits
Date
2021-01-28
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Doctoral
Abstract
Introduction: Third molars (M3s) very often fail to erupt into function, becoming thus impacted. While sufficient jaw space is important, it does not always guarantee full eruption. Thus, other factors also play a role in this process. This work investigates the multifactorial etiology of M3 impaction as well as this condition’s strongest predictors.
Material and Methods: To address the aforementioned goal, three individual studies were utilized. Study 1 systematically reviews the literature to a) identify key points that are impeding progress in the field, and b) to guide future investigations, including Studies 2 and 3. In Study 2, 324 molar regions of 99 Canadian dental patients aged 6–24 years were assessed on retrospective CBCT scans and panoramic radiographs to test whether timing of M3 development (M3Dev.timing – a traditionally underexplored trait of M3 impaction) is a significantly trait for predicting M3Eruption.status. Lastly, in Study 3, 297 molar regions of 91 patients aged 9–24 years were simultaneously investigated to determine from a pool of multiple traits those that play the greatest role in the prediction of M3Eruption.status, warranting thus particular clinical concern.
Results: Study 1 revealed key limiting points in the field, including a) inconsistent criteria for distinguishing erupted from impacted M3s, and b) a shortage of investigations on preadolescent and adolescent traits of M3 impaction – points that were addressed in Studies 2 and 3. Study 2 revealed that M3Dev.timing is a significant predictor for M3Eruption.status (Wald X2=32.217, p.<0.001), and that the risk of M3 impaction is significantly reduced when M3s develop earlier (Odds=0.71; CI=0.61, 0.83). Study 3 demonstrated that M3Eruption.status was predicted by multiple traits, not just jaw space, and that along with jaw space, M3 developmental stage (Wald X2=20.92, p.<0.001) and patient age (Wald X2=14.21, p.<0.001) were the strongest predictors within each jaw.
Conclusion: M3 impaction is a condition of multifactorial causes which is more accurately predicted by multiple traits than by traits alone. Clinical assessment of multiple traits is thus recommended, particularly M3 developmental stage and patient age which, along with jaw space, are the strongest predictors of this condition.
Description
Keywords
Wisdom tooth, Maxillofacial growth, Digital radiology, 3D imaging, Odontogenesis, tooth impaction, Maxillomandibular development.
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Anatomy and Cell Biology
Program
Anatomy and Cell Biology