Sex dependent differences of oral bone mineral density

Objectives: Bone mineral density (BMD) has been assessed using different types of non-invasive X-ray based computed tomography. The objective of this study was to examine whether clinical cone-beam computed tomography (CBCT) can measure the BMDs of various craniofacial anatomical sites to provide any significant clinical information.
Methods: Following the IRB approval, CBCT images of 38 patients (15 male with 51±7 years of age and 23 female with 55±9 years of age) were retrospectively obtained. The CBCT images included both cervical vertebrae and oral bone. After segmentation of bone voxels from non-bone voxels, right and left temporomandibular joint (TMJ) mandibular condyles were digitally dissected from top surface up to 7 mm along with the occlusal plane. Alveolar bone (AB) surrounding lower left premolar (LL4) as well as lower incisors (LL1LR1), and corresponding basal cortical bone (CB) were isolated. Cervical vertebral bodies (C2 and C3) were isolated by removing posterior and lateral processes at 10 voxels from either side of vertebral endplate. Mean values of gray level, which is proportion to BMD, were obtained for all regions. An analysis of variance was tested to compare the mean values of gray level between male and female patients.
Results: The female group had significant greater mean value in premolar cortical bone (LL4 CB) and left condyle of TMJ than the male group (p<0.03).
Conclusions: The current findings indicate that the CBCT based BMD assessment could identify the sexual dimorphism of craniofacial bone. In particular, the significantly higher BMD observed in the female group could result from active bone remodeling at the TMJ. The abnormal BMD level is likely associated with the higher prevalence of TMJ disorder in female population.