关键词: 下颌第二磨牙, 跨下牙槽神经种植, CBCT, 牙槽骨萎缩

Abstract:

Objective To measure the position of the mandibular nerve canal at the mandibular second molar by CBCT image data, analyze the theoretical implantation range of trans-alveolar implantation, and provide a theoretical solution to insufficiency of posterior mandibular bone volume in clinical practice. Methods Eighty patients with missing mandibular second molars whose vertical bone height of the edentulous area was less than 9 mm were selected for CBCT image measurement, and the distances from the mandibular nerve canal to the buccal cortex, lingual cortex, and alveolar crest were measured to simulate trans-inferior alveolar nerve implantation. The angular range of the buccolingual inclination of the implant was also measured. Results The distances from the mandibular nerve canal to the buccal cortex, lingual cortex and alveolar crest at the mandibular second molar were(6.913±1.222)mm, (2.859±0.891)mm and (7.991±0.783)mm, respectively. The distance from the mandibular nerve canal to the buccal cortex was significantly greater than that to the lingual cortex. And, 75% of the patients could be implanted by the inferior alveolar nerve. The minimum angle of buccolingual inclination of the simulated implant was 19.360°±7.086°, and the maximum angle was 39.462°±6.924°. Conclusion The mandibular nerve canal at the mandibular second molar is inclined toward the lingual side, which ensures sufficient buccal bone volume. Most patients with severe mandibular atrophy can still adopt implants of conventional length by trans-inferior alveolar nerve implantation to keep a safe distance from the nerve canal.

Key words: mandibular second molar, trans-inferior alveolar nerve implantation, CBCT, mandibular atrophy