Third molar impaction and agenesis: influence on anterior crowding

Area of Science:

• Orthodontics
• Anthropology
• Dental Anatomy

Background:

• The role of third molars in anterior dental crowding is debated, with assumptions of their impact on dental arch space.
• Understanding these relationships is crucial for orthodontic diagnosis and treatment planning.

Purpose of the Study:

• To investigate the association between third molar impaction, agenesis, and anterior dental crowding.
• To analyze these relationships in a specific population: black South African males.

Main Methods:

• Examination of 535 mandibles and maxillae from the Raymond A. Dart Collection of Human Skeletons.
• Assessment of anterior crowding using Little's irregularity index.
• Evaluation of third molar impaction and agenesis.

Main Results:

• Individuals with impacted third molars exhibited more moderate-to-extreme anterior crowding compared to those with agenesis.
• Bilateral presence of third molars was linked to ideal-to-minimal crowding.
• Significant positive correlations were found between crowding and impaction in both mandible and maxilla.
• Increased odds of mandibular crowding were observed in individuals with impacted third molars (OR = 3.22).

Conclusions:

• Third molar impaction is a contributing factor to anterior dental crowding.
• The presence or absence (agenesis) of third molars alone does not explain the absence of crowding.
• Findings highlight the importance of considering third molar status in orthodontic assessments.