Characteristics of intrabony nerve canals in mandibular interforaminal region by using cone-beam computed tomography and a recommendation of safe zone for implant and bone harvesting.

BACKGROUND: Cone-beam computed tomography can accurately show anatomic structure of intrabony nerve canals in mandibular interforaminal region. PURPOSE: The aim was to evaluate the characteristics of intrabony nerve canals in mandibular interforaminal region by using cone-beam computed tomography (CBCT) and determine a safe zone for implant and bone harvesting. MATERIALS AND METHODS: Hemimandibles (824) CBCT images were obtained. The length of the anterior loop (AL), the length and diameter of the mandibular incisive canal (MIC) and its spatial distance in various landmarks were measured. RESULTS: The prevalence of the AL was 93.57%, and the MIC was 97.33%. The mean lengths of the anterior extension of the anterior loop (aAL), caudal extension of the anterior loop (cAL) and the MIC were 2.53 +/- 1.27 mm, 6.04 +/- 1.66 mm, 9.97 +/- 5.15 mm, respectively. The MIC was closer to buccal border and inferior margin of mandible. The length of the AL and diameter of the MIC varied with gender. CONCLUSIONS: The safe zone recommended for implant surgery is 4 mm anterior and 8 mm inferior to the mental foramen, and 10 mm above the inferior margin of mandible. The chin bone should be harvested at least 10 mm below the tooth apices along with a limited depth of 4 mm.