健康青年人髁突松质骨结构锥形束CT分析

目的探讨锥形束CT测量下颌骨髁突松质骨结构的可行性，了解下颌骨髁突松质骨结构的分布特点。方法用锥形束CT对40名健康青年志愿者（20～32岁）的80侧下颌骨，获取髁突冠状位正中层面图像，用自行设计的图像分析软件对图像进行二值化处理，并分8区对松质骨结构参数进行分析，包括单位体积内的松质骨体积即骨小梁体积分数、测量范围内骨小梁的平均厚度即骨小梁厚度、单位毫米长度内骨小梁数目及骨小梁间的平均空间距离即小梁分离度。结果髁突上区与中、下区的所有松质骨结构参数值均不同，差异有统计学意义（P〈0．05）；髁突上区骨小梁体积分数最高（52．2％），骨小梁数目最多（1．33mm^-1），骨小梁厚度（393．48μm）和骨小梁分离度（361．59μm）最小；两侧髁突松质骨的结构参数值差异无统计学意义（P〉0．05）。结论下颌骨髁突内部的松质骨结构分布不均，但两侧的分布对称；用锥形束CT结合图像分析技术可以实现髁突松质骨结构的体内定量分析。

A study of trabecular bone structure in the mandibular condlye of healthy young people by cone beam computed tomography

OBJECTIVE: To evaluate the feasibility of cone beam computed tomography (CBCT) for the evaluation of trabecular bone structure in mandibular condyle and to investigate the distribution of the trabecular bone structure within mandibular condyle. METHODS: Eighty condyles from 40 healthy young volunteers (aged 20-32) were scanned by CBCT. A coronoid image was acquired of each condyle and divided into 8 regions where regions of interest were specified. After CBCT images were binarized, four morphological parameters including bone volume fraction, trabecular thickness, trabecular number and trabecular separation were computed. RESULTS: All parameters were significantly different between the superior zone and middle/inferior zone of the condyle (P < 0.05). Superior zone showed the largest bone volume fraction (52.2%), the highest trabecular number (1.33 mm(-1)), the thinnest trabecular thickness (393.48 microm), and the smallest trabecular separation (361.59 microm). Inferior zone showed the smallest bone volume fraction (49.64%). These results were not significantly different between bilateral sides of the condyles (P > 0.05). CONCLUSIONS: Trabecular bone structure was inhomogeneous within the condyle, but symmetrical between bilateral sides of the condyles. CBCT combined with image processing is a feasible tool in evaluating trabecular bone structure of human mandibular condyle.