Association of the Vertical and Sagittal Growth Patterns of Jaws with the type of Third Molar Impactions: A Radiological Analysis

Abstract

Objective: To evaluate if the jaw growth patterns are associated with third molar impactions.

Design: Cross-sectional study.

Study setting: Orthodontics Department, Islamic International Dental College & Hospital Islamabad, Jan to Jun 2018.

Methods: We analysed the records of 300 mandibular and maxillary third molars with specific criteria. Orthopantomogram Xrays were used to identify impactions and were classified by Pell and Gregory (P&G) and Winter lines. In addition, lateral cephalograms were assessed for sagittal classes and vertical growth patterns.

Results: Angles of impaction (Winter lines) of mandibular M3s were significantly associated with sagittal growth patterns(p=0.021), with most mesioangular impactions found in Classes I and II. High-angle subjects resulted in the highest impactions in the vertical growth patterns. High angle was followed by low angle and normal angle in mandibular M3s and normal angle and low angle in maxillary M3s. Levels of maxillary M3s (P&G) and vertical patterns showed a significant association (p=0.016), with the highest M3s at level C. The maximum number of impacted M3 coexisted with P&G Class- II and level B for both jaws.
Conclusion: Significant associations were found between mandibular M3 angles, sagittal patterns, and levels of maxillary M3s and vertical patterns. Results conclude that facial growth patterns and M3 impactions are not completely independent and may help predict impaction status in adolescence and aid in orthodontic treatment.