Is there a relationship between mandibular third molar impaction and mandibular morphology?

BACKGROUND

Panoramic radiography is widely used for initial assessment during clinical examinations. It is very useful for clinicians to predict impaction of third molar teeth via certain parameters without relying solely on personal experience. This study aims to examine the relationship between the impaction of mandibular third molar teeth and mandibular morphology. Thus, mandibular third molar tooth impaction estimation can be provided with measurements made on panoramic radiography.

METHODS

The study material consisted of panoramic radiographs of 330 patients. The experimental group with impacted mandibular third molar teeth included 165 patients (mean age 20.62 ± 2.89 years), and the control group with erupted mandibular third molar teeth included 165 patients (mean age 22.23 ± 4.22 years). Nine dimensional, four angular, andone1 proportional parameter were examined on panoramic radiographs via the ImageJ program. The Mann‒Whitney U test, Kruskal‒Wallis H test, chi‒square test and correlation analysis were used for statistical analysis. Intraobserver reliability was examined via the intraclass correlation coefficient (ICC).

RESULTS

Dimensional parameters such as condyle length, coronoid length, mandibular corpus width, sigmoid notch depth, retromolar space distance, and antegonial notch depth were significantly lower in the experimental group than in the control group. The Co/Cr angle was also significantly greater in the experimental group, whereas the alpha angle was significantly greater in the other groups. The ratio of the retromolar space distance to the third molar tooth width was also significantly greater in the control group.

CONCLUSIONS

Mandibular third molar tooth impaction is related to various parameters of mandibular morphology. Certain measurements taken from panoramic radiographs may provide predictions regarding the likelihood of mandibular third molar impaction.