Investigating the relation among the needle insertion plane, occlusal plane, mandibular foramen, and mandibular lingula for inferior alveolar nerve block.

Background/purpose: The success rates and incidence of positive blood aspiration during inferior alveolar nerve blocks (IANB) vary. Understanding the relative positions of the mandibular foramen (MF), mandibular lingula (ML), and occlusal plane (OP) is crucial for the effectiveness and safety of IANB. This study evaluates the relationship among needle insertion levels, ML, and OP for IANB. Materials and methods: Cone-beam computed tomography images of 90 participants were analyzed to measure ML and MF distances relative to OP. Participants were categorized into skeletal classes (I, II, and III). The distances from ML to the anesthetic needle positioned 5, 6, 7, 8, 9, and 10 mm above OP were assessed. Comparisons based on gender and skeletal classes were conducted, and correlations among variables were evaluated. Results: The MF and ML were located below OP in 72 (40.0 %) and 5 (2.8 %) sides, respectively. Class II had the highest proportion of MF below OP (16.67 %), followed by Class III (13.33 %) and Class I (10 %). When the needle was inserted 5 mm and 10 mm above OP, ML was below the insertion plane in 27 (15 %) and 116 (64.4 %) sides, respectively. ML-OP distances were significantly greater in Class III (9.75 mm) and Class I (9.62 mm) than in Class II (7.29 mm). Conclusion: Class II exhibited significantly smaller ML-OP and MF-OP distances than Class I and Class III. The needle should be inserted parallel to OP and positioned approximately 6-7 mm above OP for improved safety and anesthesia efficacy.