The relationship between periodontitis and systemic bone mineral density in Japanese women is undetermined. We tested the hypothesis that periodontitis was more frequent in women with low metacarpal bone mineral density (m-BMD). Subjects were 190 Japanese women (89 premenopausal, 101 post-menopausal). Periodontal status was evaluated according to the Community Periodontal Index of Treatment Need (CPITN). M-BMD was measured by computed x-ray densitometry. The proportion of subjects with periodontitis (CPITN > or = 3) increased as m-BMD decreased in pre-menopausal (18.2%, 36.9%, and 66.6% in the normal, borderline, and very low m-BMD groups, p < 0.02) and post-menopausal women (41.5%, 54.8%, 60%, and 68.4% in the normal, borderline, low, and very low m-BMD groups, p < 0.05). Among post-menopausal women, those with very low m-BMD had fewer teeth present than women with normal m-BMD (19.9+/-7.2 vs. 25.1+/-4.1, p < 0.01). These results indicate that m-BMD loss is associated with periodontitis in Japanese women, and with tooth loss after menopause.

The relationship between oral indicators and bone mineral density (BMD) has been studied by many investigators, with mixed and complex results. The purpose of the present cross-sectional study was to evaluate the associations of periodontal conditions and tooth loss with metacarpal BMD (m-BMD) in a community-based cohort and the usefulness of tooth count as a potential screening tool to detect low BMD. Subjects were 356 Japanese women (171 premenopausal, mean age 37.9+/-8.0 years; 185 postmenopausal, mean age 63.3+/-7.7 years). Periodontal status was evaluated by the Community Periodontal Index of Treatment Needs (CPITN). m-BMD was measured by computerized X-ray densitometry. The proportion of subjects with periodontitis (CPITN 3 or 4) increased as m-BMD decreased. The odds ratio (OR) of osteopenia or osteoporosis in relation to periodontitis was 3.2 (95% confidence interval [CI], 2.0--5.3). After adjustment for age and menopausal status, the OR was 2.0 (95% CI, 1.1--3.7). Among postmenopausal women, those having fewer than 20 teeth were 1.6 times more likely to have low m-BMD than those having more than 20 teeth (chi-square for trend in postmenopausal group, 4.27; P<0.05). Receiver-operating curve (ROC) analysis indicated that number of teeth remaining or CPITN score had a greater than 50/50 chance to correctly identify women with osteoporosis or osteopenia, but the areas under the curve (0.72 and 0.67, respectively) are considered less than highly accurate screening tools. These results indicate that periodontitis and tooth loss after menopause may be useful indicators of m-BMD loss in Japanese women.

The results of the present study suggest that the restraint stress modulates the progression of periodontal inflammation and that this rat model is suitable for investigating the association between stress and periodontal disease.

Periodontitis, an inflammatory disease of periodontal tissues, is characterized by excessive alveolar bone resorption. An increase in the receptor activator of nuclear factor-κB ligand (RANKL) to osteoprotegerin (OPG) ratio is thought to reflect the severity of periodontitis. Here, we examined alveolar bone loss in OPG-deficient (OPG(-/-)) mice and RANKL-overexpressing transgenic (RANKL-Tg) mice. Alveolar bone loss in OPG(-/-) mice at 12 weeks was significantly higher than that in RANKL-Tg mice. OPG(-/-) but not RANKL-Tg mice exhibited severe bone resorption especially in cortical areas of the alveolar bone. An increased number of osteoclasts was observed in the cortical areas in OPG(-/-) but not in RANKL-Tg mice. Immunohistochemical analyses showed many OPG-positive signals in osteocytes but not osteoblasts. OPG-positive osteocytes in the cortical area of alveolar bones and long bones were abundant in both wild-type and RANKL-Tg mice. This suggests the resorption in cortical bone areas to be prevented by OPG produced locally. To test the usefulness of OPG(-/-) mice as an animal model for screening drugs to prevent alveolar bone loss, we administered an antimouse RANKL antibody or risedronate, a bisphosphonate, to OPG(-/-) mice. They suppressed alveolar bone resorption effectively. OPG(-/-) mice are useful for screening therapeutic agents against alveolar bone loss.

These observations suggest that IL-1 is effective for evaluating in detail the state of subgingival inflammation.