Evaluation of the relationship between Gonial angle, mandibular plane inclination, and ramus height with the impaction of mandibular third molar

Mandibular third molar is the most common impacted tooth and craniofacial morphology and facial parameters can be appropriate predictors of impaction of this tooth. The aim of this study was to evaluate the relationship between Gonial angle, mandibular plane inclination, and ramus height with the impaction of mandibular third molar.

This retrospective descriptive-analytical study was performed by analysis of lateral cephalometric radiographic images of 172 patients in city of Zahedan in 2020. The status of eruption of mandibular third molars was determined by clinical examination and assistance of panoramic radiographic images and samples were categorized into four groups: fully erupted (1), partially impacted (2), impacted (3), partially developed (4). Then, the Gonial angle, mandibular plane, and ramus height were measured on lateral cephalometric images of each group and collected data were analyzed by Chi-square test and analysis of variance (ANOVA).

Among the patients, 68.02% were female and 31.97% were male. The difference between the mean values of Gonial angle of four groups was not statistically significant (P>0.05). In the fourth group, the mean value of mandibular plane inclination was significantly higher (29.74) and the mean value of the ramus height was significantly less (49.21 mm) than other groups.

According to the preformed analysis and obtained results, Gonial angle, mandibular plane, and ramus height were not accurate predictors for the impaction of mandibular third molar and further studies should be undertaken in this filed.