The effect of aging and ovariectomy on mandibular condyle in rats.
BACKGROUND
It is important for dentists to understand the effect of systemic hormonal change on the osseous oral structures.


OBJECTIVE
This study examined the effect of aging and ovariectomy on rat mandibular condyle.


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.
Tanaka
M
M
Department of Removable Prosthodontics, Niigata University School of Dentistry, Japan.
Ejiri
S
S
Kohno
S
S
Ozawa
H
H
D015502:Absorptiometry, Photon; D000375:Aging / Q000502:physiology; D000818:Animals; D015519:Bone Density; D001853:Bone Marrow / Q000000981:diagnostic imaging; D004967:Estrogens / Q000172:deficiency*; D005260:Female; D006801:Humans; D008335:Mandibular Condyle / Q000000981:diagnostic imaging / Q000502:physiology*; D015663:Osteoporosis, Postmenopausal / Q000503:physiopathology*; D010052:Ovariectomy; D011856:Radiographic Image Enhancement; D011877:Radionuclide Imaging; D051381:Rats; D011916:Rats, Inbred F344
D004967:Estrogens