Bucco-lingual Orientation of Inferior Alveolar Canal for Implant Osteotomy: A CBCT-Based Study in a Malaysian Population

Introduction: The inferior alveolar nerve can be subjected to iatrogenic injury during surgical procedures if its location and course are not carefully identified. Objectives: The objectives of this retrospective study were to determine the bucco-lingual orientation of the inferior alveolar canal (IAC) and to estimate ethnicity-, side-, sex-, and age-related variations in a Malaysian population. Methods: A total of 121 cone beam computed tomography (CBCT) files were selected using a stratified random sampling method. The bucco-lingual position of the IAC was identified on the cross-sectional view of all the premolars and molars on both sides of the mandible. Buccal bone width (B), canal thickness (C), and lingual bone width (L) were measured at the horizontal canal levels. Kruskal Wallis test, Friedman test, one-way analysis of variance (ANOVA) test, and independent and paired samples t-tests were carried out to evaluate side-, ethnicity-, gender- and age-related variations (p0.05). Results: Overall, the IACs were located on the lingual side in second molar regions (left: 71.9%; right: 71.1%); in the centre in first molar regions (left: 57.9%; right: 47.10%); and exits through the mental foramen before second premolar regions. There was a statistically significant difference in the location of the IAC among the age groups in left (p=0.003) and right (p=0.015) second molar regions and between genders in left second premolar regions (p=0.033). On average, B measurement was the thickest at the second molar regions (left, right: 6.13mm) while L was the thickest at the second premolar regions (left: 4.09mm; right: 4.36mm). Statistically significant differences in these measurements were found, associated with ethnicity (p≤0.035), gender (p≤0.013), age (p≤0.038) and side (p≤0.025). Conclusions: From second molar to second premolar, the IAC stretched from lingual to centre and exited through the mental foramen before the second premolars; mean values of B decreased while L increased. These variations should be taken into considerations prior to surgical procedures involving the mandible to prevent iatrogenic injury. Keywords: Implant treatment, nerve injury, CBCT, Malaysian population