Mandible bone loss in osteoporosis rats

Change in the mandible during the development of osteoporosis has not been studied extensively. Thus, the present study was undertaken to clarify the target loci in the mandible during the development of experimental osteoporosis in aged female rats. Experimental osteoporosis was studied in 76 Wistar strain female rats, 35 weeks old, by means of ovariectomy and dietary calcium deficiency. The rats were divided into the following three groups: (1) group 1, unoperated basal control (Basal), maintained on a diet containing 1.0% calcium; (2) group 2, sham-operated (Sham), maintained on a diet containing 0.01 % calcium; and (3) group 3, ovariecomized (OVX), maintained on a diet containing 0.01 % calcium. Fifteen rats of each group, except the basal rats (10 and 6 rats), were killed at 3 and 6 months following ovariectomy, respectively. The mandible was extracted, cleaned, and then subjected to bone mineral content (BMC) and bone mineral density (BMD) analyses using a peripheral quantitative computed tomography (pQCT) bone scanner. Each mandible was scanned from the mesial margin of the first molar to distal margin of the second molar. The results showed that dietary calcium deficiency and ovariectomy caused significant decreases of trabecular and cortical BMCs and BMDs in Sham and OVX rats compared with Basal rats. Decreases due to dietary calcium deficiency were greater than those caused by ovariectomy. However, significant age-related changes were not observed in BMC and BMD in Sham and OVX rats for 3-6 months. In addition, the cortical and trabecular BMCs and BMDs obtained were found to relate to location in the mandible for each group.