The Relationship Between the Gonial Angle, Ramus Height, And the Type of Third-Molar Impaction: A Panoramic Radiographic Study

Tooth impaction refers to the failure of a tooth to properly emerge in its expected position within a given timeframe. Several local factors influence the occurrence of tooth impaction, one of which is the specific morphometric characteristics of the mandible. The objective of this study is to examine the association between these factors and the type of impaction observed in the mandibular third molar.

In this Cross-sectional study, 186 impacted mandibular third molar from patients with 20 to 30 years of age were evaluated. The mandibular third molars were categorized according to Pell and Gregory classification into A (third molar is at the same level as the occlusal plane of the second molar), B (third molar is between the occlusal plane and Cementoenamel junction (CEJ) of the second molar) and C (third molar is below the CEJ of the second molar) groups. The Chi-square test was used for statistical analysis of the data. The relation between gonial angle and ramus height with third molar impaction type was assessed using a Pearson correlation test.

The mean±SD for gonial angle in A, B and C groups were 121.05±6.33, 120.24±5.43 and 119.67±5.17 respectively. The mean±SD for ramus height in A, B and C groups were 58.51±5.01, 57.63±5.14 and 57.38±4.51 respectively. There was no significant relation between mandibular third molar impaction type and gonial angle and ramus height (P>0.05).

There was no significant relationship between the gonial angle and ramus height and the type of mandibular third molar tooth impaction according to Pell & Gregory classification as well as eruption and impacted state of mandibular third molar. The results of this study can be used by dentists to assess the difficulty of mandibular third molar extraction prior to their surgeries.