The effect of aging and ovariectomy on mandibular condyle in rats

Abstract

Statement of problem. It is important for dentists to understand the effect of systemic hormonal change on the osseous oral structures. Purpose. This study examined the effect of aging and ovariectomy on rat mandibular condyle. Material and methods. Seventy-two 120-day-old female Fischer rats were killed at 7, 14, 30, and 60 days after bilateral ovariectomy or sham surgery. As the baseline control group, eight animals were killed on day 0 without surgeries. Changes in the bone mineral density and bone marrow area were detected through dual-energy x-ray absorptiometry and soft x-ray photography, respectively. Results. No significant difference of bone mineral density was found between the bilateral ovariectomy and sham surgery groups with dual-energy x-ray absorptiometry, probably because the thickness of cortical bone obscured any possible changes in trabecular bone. Age-related osteosclerotic changes were found in the sham group with soft x-ray photography. In contrast, the bilateral ovariectomy group showed little change in bone marrow area in relation to time course; on the other hand, the value of their bone marrow area became significantly larger than that of the sham surgery group from 14 days after ovariectomy onward. Conclusions. It was inferred that estrogen deficiency caused the significantly large marrow area found in the rat mandibular condyle. Although much more research is necessary, this study allowed us to speculate that osteoporotic changes may occur in the mandibular condyle of postmenopausal women. (J Prosthet Dent 1998;79:685-90.)