Mandibular Lingual Concavity: A Cross-sectional Analysis using Cone Beam Computed Tomography

Abstract

Introduction: Cross-sectional analysis using Cone Beam Computed Tomography (CBCT) is appropriate for assessment of lingual undercuts and prevention of lingual cortex perforation and subsequent complications. Aim: This study aimed to assess the mandibular lingual undercut in the first molar site on CBCT scans to prevent lingual cortex perforation during implant insertion. Materials and Methods: This cross-sectional study was conducted on 164 CBCT scans (77 males and 87 females with a mean age of 43.9±12.3 years). The following information was collected: Type of ridge morphology (U: lingual undercut, C: convex, P: parallel), ridge width, ridge height, the angle between the lingual surface and the line drawn above the canal, distance between the deepest point in the lingual surface and the line drawn perpendicular to the lingual surface, distance between the most prominent point of the lingual surface and the ridge crest and distance between the most prominent point in the lingual surface and the inferior border of the mandible. Analysis of variance and t-test were used to compare mean values of CBCT measurements between gender and age groups. Results: Type U (50%) was the most common type followed by type C (26.2%) and type P (23.8%). No significant correlation was noted between age and depth of lingual undercut or type of ridge morphology or between ridge morphology and gender (p>0.05). Ridge height (p=0.002) and distance between the most prominent point of the ridge and the ridge crest (p=0.021) were significantly greater in males than in females. Conclusion: Type U ridge morphology had the highest prevalence. Mandibular lingual concavity must be taken into account during implant placement to prevent accidental perforation of lingual plate.

Keywords

• first molar
• imaging
• mandibular lingual undercut
• lingual cortex