Post-Menopausal Women Have Region Specific Mandibular Microarchitectural Bone Loss Compared to Pre-Menopausal Controls

There are conflicting reports on the effects of menopause and decreased estrogen levels on the mandibular bone microarchitecture, especially in humans.1,2 Therefore, the goal of this study was to evaluate the trabecular and cortical bone microarchitecture in the mandibular condyle and alveolar bone by 3-dimensional cone beam computed tomography (CBCT) in post-menopausal women and compare them with pre-menopausal women. This study was approved by the Columbia University Irving Medical Center Institutional Review Board and was carried out in accordance with relevant guidelines. Written informed consent was obtained from all study subjects. A total of 62 females (31 pre-menopausal and 31 post-menopausal) were recruited. Menopausal status was determined by self-report. Each participant had a CBCT of their alveolar bone surrounding the mental foramen and mandibular condyles bilaterally. For condylar bone, 30 consecutive sections without intersection gaps were stacked after skipping the first 20 consecutive sections apical to the cortical bone at the head of the target condyle. Region of interest (ROI) included all trabecular and cortical bone (taken as the negative ROI from isolated trabecular bone) of the bilateral mandibular condyles in each axial sectional image. For alveolar bone, 60 consecutive sections without intersection gaps were stacked after skipping the first 40 consecutive sections posterior to the opening of the mental foramen. The ROI included all trabecular and cortical bone in an 18 x 15 mm rectangle centered on the mandible with the bottom border of the rectangle at the inferior border of the mandible in each coronal sectional image. SkyScan CTan Software (Bruker Corporation) was used to isolate the ROI, convert to binary image form via local thresholding, and perform quantitative 3D microstructure evaluation. See Figure 1 for isolated regions of condylar and alveolar bone, along with a 3D representation of trabecular bone. There were 2 scans per patient for analyzing alveolar bone, for a total of 124 scans across both pre-menopausal and post-menopausal groups. For analyzing condyle bone, there were a total of 106 scans (51 scans for pre-menopausal and 55 scans for post-menopausal) due to poor image quality in 18 of the scans for either the left or right side for these patients. The alveolar and condyle samples that had bilateral scans available were averaged into 1 sample, and the patients that did not have an acceptable contralateral condyle scan were used as a single sample. All statistical analyses were conducted with Microsoft Excel (Microsoft Corporation 2013). Between-group differences in continuous measures were assessed with unpaired t-test, and demographic variables were assessed by chi-square. Data are presented as means ± standard errors. Statistical significance was recorded at P < .05. There was a significant difference in age between pre-menopausal and post-menopausal patients (pre-menopause = 43.9 ± 6.9 vs post-menopause = 57.5 ± 7.6; P < .001), but no difference in race and ethnicity (P = .575). Post-menopausal women had a significant decrease in mandibular condyle trabecular bone volume fraction BV/TV (pre-menopause = 63.7 ± 4.51 % vs post-menopause = 57.95 ± 8.87%; P = .003), increase in trabecular separation (pre-menopause = 0.47 ± 0.11 mm vs post-menopause = 0.59 ± 0.14 mm; P < .001) and decrease in trabecular number (pre-menopause = 1.21 ± 0.19 1/mm vs post-menopause = 1.03 ± 0.18 1/mm; P < .001) compared to pre-menopausal women. There were no significant differences in the alveolar bone microarchitectural parameters. See Table 1 for full parameters of interest and results. Menopause has region specific effects on the mandibular bone, negatively affecting the condyle but having a lesser impact on the alveolar bone. Additional research with larger sample sizes is required to expand the generalizability of these results, which may have important ramifications for treatment planning in older individuals when considering risks of bone loss specific to different regions of the mandible. Table 1Summary of Results for Microarchitectural Parameters of Alveolar and Condylar Bone Open table in a new tab