Obeservations on association between third molar agenesis and craniofacial morphology

Area of Science:

• Dentistry
• Orthodontics
• Human Genetics

Background:

• Third molar agenesis is a common dental anomaly.
• Understanding its association with skeletal morphology is crucial for orthodontic diagnosis and treatment planning.

Purpose of the Study:

• To investigate the relationship between third molar agenesis and craniofacial skeletal morphology in a Chinese cohort.
• To identify specific cephalometric parameters associated with the absence of third molars.

Main Methods:

• Analysis of panoramic radiographs and cephalograms from 1043 patients.
• Assessment of third molar agenesis based on gender, jaw, and side.
• Comparison of linear, angular, and proportional cephalometric measurements among different agenesis groups using statistical tests (Pearson χ², ANOVA, Student-Newman-Keuls).

Main Results:

• The prevalence of third molar agenesis was 28.7%, more frequent in the maxilla and on the right side, with no significant gender difference.
• Individuals with third molar agenesis exhibited smaller SN-GoGn and Y-axis-FH angles, and a larger S-Go/N-Me ratio.
• Third molar agenesis was less frequent in Class II malocclusion and more common in hypodivergent growth patterns.

Conclusions:

• A significant association exists between third molar agenesis and craniofacial skeletal morphology, encompassing both sagittal and vertical dimensions.
• These findings can aid in predicting potential agenesis based on skeletal patterns and vice versa.