[Analysis of mandibular canal in patients with prognathism and its clinical significance].

PURPOSE

The aim of this study was to investigate the position and course of mandibular canal in patients with prognathism using cone-beam CT(CBCT)，and explore its clinical significance.

METHODS

The mandibles of 28 patients with skeletal Class Ⅲ prognathism (10 males and 18 females) and 20 normal people(12 males and 8 females) were analyzed on CBCT. The position and course of mandibular canal from the lowest point of mandibular foramen to the first molar were measured at five specific sections from the mandibular foramen to the mandibular first molar area, including inner and outer diameter, mandibular bone thickness ,distance between mandibular canal and distance to the buccal and lingual bone cortex, and the inferior border of mandible bone. Statistical analysis was performed using SPSS 17.0 software package.

RESULTS

The mandibular bones of patients with prognathism gradually thickened from the mandibular ramus to the forepart of the mandibular angle and thinned forward to the position where the mandibular first molar projected on the mandibular bone. Cortical bone of buccal side of the mandibular ramus thickened forward to the mandibular angle and thinned to the mandibular body. The width of buccal bone marrow cavity and diameter of mandibular bone were statistically different between genders.

CONCLUSIONS

This study found that the difference between the thickness of the mandibular ramus in patients with mandibular protrusion from the controls was mainly due to the difference between the width of the buccal bone marrow cavity. CBCT can accurately locate the mandibular canal and display anatomic structures.