Effects of Aging on Jawbone Mineral Density in Rats

Objectives: Bone mineral density (BMD) decreases with aging and menopause, particularly in orthopedic bones. However, those effects on jawbone BMD have not been fully investigated. Thus, this study aimed to examine whether ovariectomy (OVX)-induced estrogen deficiency affects mandibular BMD in an aged rat model.
Methods: Following IACUC approval, 24 female Sprague Dawley rats were divided into three groups: 10 sham-operated rats (3 months post-surgery at 6 months old), 9 OVX rats (3 months post-OVX at 6 months old), and 5 aged OVX rats (2 months post-OVX at 12 months old). Mandibles were dissected and scanned using micro-computed tomography. Teeth and non-bone voxels were digitally segmented to isolate the whole bone (WB), alveolar bone (AB), and basal cortical bone (CB). Mean tissue mineral density (TMD) was assessed for each region. Analysis of variance (ANOVA) followed by Tukey HSD post hoc tests was used to compare the mean TMD between the rat groups. Significance was set at p<0.05.
Results: The mean WB TMD value of the aged OVX group was not significantly different from those of the young sham and OVX group (p>0.12). The mean AB and CB TMD values were significantly higher in the aged OVX group compared to the young sham and OVX group (p<0.02).
Conclusions: These findings suggest that jawbone mineral density may remain relatively unaffected by aging and estrogen deficiency.