Lingual Concavities in Posterior Mandible: Retrospective Morphometric Analysis in Relation to Gender and Tooth Loss

To analyze the posterior mandible bone ridge shape in relation to gender and tooth loss. Focusing on the accompanied changes and variations in lingual concavities.

406 cone-beam computed tomography (CBCT) images with dentulous and edentulous 1st and/or 2nd molars (206 females and 200 males, aged ≥20) were examined. Mandibular morphology was classified into U type (undercut), P type (parallel), and C type (convex). The study examined the ridge morphology and dimensions. Lingual concavities angle, area, and the concavity position were measured/reported.

U type bone shape was the most common bone shape 64.1%, then P type was 24.8%, while C type was 11.2 %. U ridge was more frequent in 2nd molar compared to the 1st molar regions (p = 0.04), while C type was statistically related to long extraction time (p = 0.001). Many bone ridge measurements were higher in males (p < 0.05). Other significant differences in measurements were found at 36, 37, 46, and 47 dentate and missing sites (p < 0.05). Lingual concavities were larger in males (p < 0.001) and relatively larger at 2nd molar dentulous ridges; 37 (p = 0.02). Also, they were more statistically frequent at the level of mandibular canal (MC) or above (p = 0.0001).

The U type ridge was the most common in the studied population, occurring more often in the second molars region. Bone ridge and lingual concavities dimensions were varied by gender, tooth loss, and specific tooth. Lingual concavities were significantly related to MC level.