Abstract
This study was designed to clarify the relationship between the mandibular morphology and the status of the eruption of mandibular third molars. All of the subjects, male and female, were classified into three groups according to the condition of eruption of the third molars; full impaction, semi-impaction, and full eruption.
1. In males, the total length of the mandible (M), CdGn, U6-PTV, and L6-MP' proved to be significantly larger in Group C (full eruption) than in Group A (full impaction), and Facial A., and OPMP were significantly larger in Group C (full eruption) than those in Group A (full impaction).
2. In females, the total length of the mandible (M), Cd-Gn, U6-PTV, and L6-MP', were significantly larger in Group C (full eruption) than in Group A (full impaction), and the length of the mandibular corpus (C), the width of the mandibular ramus (R), Go-Me, Xi-L7, ABR-L7, and U7-PP were all significantly larger in Group C (full eruption). The Y-axis was smaller and SNA larger in Group C (full eruption) than in Group A (full impaction).
3. These results showed that in both males and females, the mandible was generally larger in subjects with fully erupted third molars, allowing ample room for the eruption of the mandibular third molar in the post region. These cases were characterized by the opening of the mandible accompanied by the elongation of the first molars.
