Osteoporosis is suspected as a risk factor in periodontal disease, but previous studies have failed to establish a relationship. Possible explanations for this could be lack of precise methods for assessment of osteoporosis in the jaws and confounding of the result by other factors such as age, gender, or smoking. In the present study 12 female patients with osteoporotic fractures (Group O) and 14 normal women (Group N) were examined clinically for plaque (VPI), gingival bleeding (GBI), and loss of attachment on the 6 Ramfjord index teeth. Bone mineral content (BMC) of the mandible and forearm was determined by dual photon scanning. Results were presented as arithmetic means +/- standard error, and differences between groups were tested by 2-sample t-test. The two groups were comparable with respect to age (O: 68.3 +/- 1.8 years, N: 68.1 +/- 1.5 years), menopausal age (O: 47.5 +/- 1.8 years, N: 47.2 +/- 1.3 years), and smoking habits (O: 4 smokers, N: 3 smokers). The osteoporotic women had significantly lower BMC values than controls in the mandible (O: 0.63 +/- 0.04 in U/cm2; N: 0.78 +/- 0.02 in U/cm2, P < 0.01) and forearm (O: 1.05 +/- 0.05 in U/cm; N: 1.28 +/- 0.05 in U/cm, P < 0.01). No significant differences were found with respect to plaque (O: 46.67 +/- 10.00%, N: 36.67 +/- 6.67%) and gingival bleeding (O: 46.67 +/- 11.67%, N: 43.33 +/- 10.00%), whereas significantly greater loss of attachment was seen in osteoporotic women (O: 3.65 +/- 0.18 mm, N: 2.86 +/- 0.19 mm, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal models in which microbiological and immunological aspects of periodontal disease can be studied prospectively seem well warranted. The rat bears much resemblance to man with respect to periodontal anatomy, development and composition of dental plaque, histopathology of periodontal lesions, and basic immunobiology. Furthermore, reproducible methods are available for assessment of periodontal disease in rats, and detectable periodontal destruction can be induced in a few weeks in these animals without traumatizing periodontal tissues with ligatures. Experimental periodontitis studies in germ‐free rats have confirmed the pathogenicity of several suspected periodontal pathogens (Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Capnocytophaga sputigena, Eikenella corrodens, and Fusobacterium nucleatum). The studies also suggest that the number of periodontal pathogens may be higher than generally believed, since species like Streptococcus sobrinus and Actinomyces viscosus are associated with periodontal bone loss in rats. Studies in rats with congenital or induced immune defects indicate that generalized or selective immunosuppression at the time of infection with periodontal pathogens may aggravate periodontal disease. Studies in immunized rats indicate that periodontal disease can be prevented by immunization against periodontal pathogens. However, it is also possible by immunization to induce periodontal destruction; i.e., the immune system has a destructive potential which should not be overlooked. In the future, the rat model may prove valuable for initial screening of antigen preparations and immunization regimens in the search for a periodontitis vaccine. J Periodontol 1991;62:59–73.

The aims of the present study were to examine possible effects of age and sex on energy expenditure independent of differences in body composition, and to develop prediction equations for individual estimation of energy expenditure. The study is based on 235 female and 78 male subjects ranging in age from 15 to 64 y and with body mass indexes (in kg/m2) ranging from 16.9 to 50.5. Basal metabolic rate (BMR), sleeping energy expenditure, and 24-h energy expenditure were measured with standardized protocols by indirect calorimetry in respiratory chambers. Anthropometric data were also recorded. Spontaneous physical activity (SPA) was estimated by a radar system during the chamber stay. About 90% of the variation in 24-b energy expenditure could be explained by differences in fat-free mass, fat mass, SPA, and duration of exercise (SEM: 526 kJ/d), whereas age and sex did not contribute significantly. When comparing energy expenditure adjusted for body composition and activity between two age groups (20-30 y, n = 98 and 50-65 y, n = 39), BMR was 4.6% lower in the older group (P = 0.04) and there was a tendency toward a lower sleeping energy expenditure in the older group (P = 0.06). No sex difference in any energy expenditure measurement could be found after differences in body composition and activity were taken into account. In conclusion, no sex effect and no linear decrease in energy expenditure was found with increased age and the middle-aged subjects had lower BMR than younger subjects independent of body size, body composition and activity.

Kiausen B^ Evans RT, Sfintescu C; Two eomplenientary methods of assessing periodontal bone level in rats. Scand J Dent Res 1989; 97: +94-9.Abstract -SeveraJ methods have been applied to measure periodontal disease in rats. The purpose of the present study was to test the reproducibility of a morphometric and a radiographic method and to describe tiie correlation between the two methods. Periodontal bone loss on 25 defleshed rat heads was assessed under microseope by measuring the distances from the cementoenamel junctiots tO' the alveolar bone crest at 36 buccal sites in each animal. On magnified radiographs from 25 rat mandibles periodontal bone support was expressed by the ratio apes-deepest bony defect: apex-ctisp tip distally on first molars. .All measurements were performed blind and in duplicate on two separate occasions. The bilateral 95% confidence limits for the error of method of measurement were estimated from the /-distribution. In a second experiment 50 rat heads were assessed by both methods, and the correlation between the recordings was estimated by the Spearman rank correlation analysis. Compared to the considerable total variation in the material, tbe variations due to error of methods of measurement were small^ i.e. the reproducibility of both methods was satisfactory. A significant correlation was found between tbe methods. Since the morpbometric method mainly measures horizontal bone loss, whereas the radiographic method detects intrabony interproximal defects, it is concluded that future studies would benefit from applying both methods to assess alveolar bone loss in rats.

Adhesive fimbriae from Porphyromonas gingivalis are cell surface structures which may be important in the virulence of this oral pathogen and thus may serve as a critical or target antigen. Immunization with highly purified 43-kDa fimbrial protein protected against periodontal tissue destruction when tested in the P. gingivalis-infected gnotobiotic rat model. A similarly highly purified 75-kDa cell surface component did not provide protection. Heat-killed whole-cell and sonicated cell surface extracts which contain the 43-kDa protein as well as the 75-kDa component were protective also. This study indicates that the fimbrial protein may serve as a model for the development of effective vaccines against periodontitis, a major human oral disease. * Corresponding author. cultured on modified 5% sheep blood agar (Trypticase soy agar base supplemented with 0.5% yeast extract, 5 ,ug of hemin per ml, and 5 ,ug of menadione per ml) (56) grown at 37°C in an anaerobic chamber (Forma Scientific, Marietta, Ohio) for 48 h. Estimates of cell numbers were made by measuring turbidity with a spectrophotometer at 480 nm and comparing with known standards obtained by counting P. gingivalis cell dilutions in a Petroff-Hauser chamber. P. gingivalis 2561, used for purified antigen preparation, was grown according to procedures previously described (45, 46). Animals. Male germfree Sprague-Dawley rats (Taconic Farms, Germantown, N.Y.) were kept under gnotobiotic conditions in plastic cages with stainless steel tops in positive-pressure plastic inflatable film isolators (Standard Safety Equipment Co., Palatine, Ill.). Each group of eight animals was kept in a separate isolator. Food pellets (diet L-485; Teklad, Madison, Wis.) and water were available ad libitum. Cage bedding consisted of 1/4-in. (1 in. = 2.54 cm) granules (Bed o' Cobs; Anderson, Inc., Maumee, Ohio) and was changed twice a week to minimize trauma to periodontal tissues from impaction of hair and bedding. All equipment, food, bedding, and water were sterilized by autoclaving. Materials entering the isolator were sprayed with 2% peracetic acid. Fecal and surface swab samples from the isolators were cultured once a week by using both aerobic and anaerobic incubation conditions. Experimental design. Six groups of eight rats each were used. Group A was sham-immunized, uninfected animals used as negative controls, and group B was P. gingivalis sham-immunized, infected animals used as a positive control for infection. The other four groups (C to F) were immunized with selected P. gingivalis antigens and subsequently monoinfected with P. gingivalis 381. Group C was immunized with heat-killed whole cells; group D was immunized with highly purified 43-kDa fimbrial protein from P. gingivalis; group E was immunized with highly purified 75-kDa cell surface component from P. gingivalis; and group F was immunized with a cell surface protein fraction which included the 43-kDa protein, the 75-kDa protein, and other proteins extracted during the purification process.

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Tetracyclines have been widely used as adjuncts in periodontal therapy due to the antimicrobial efficacy of these drugs. Recently, their ability to inhibit host-derived matrix metalloproteinases (collagenase and gelatinase) and bone resorption in organ culture has also been invoked as a therapeutic rationale. The current study was undertaken to determine whether tetracyclines can inhibit alveolar bone loss in vivo due to a non-antimicrobial action of these drugs. Experimental periodontitis was induced by inoculating adult, male Sprague-Dawley rats with P. gingivalis (strain 381) following kanamycin/ampicillin pretreatment. Doxycycline, non-antimicrobial chemically-modified tetracycline (CMT-1) and vehicle alone were administered daily to 3 infected groups of rats (n = 6 rats per group; each group housed in a sterilized inflatable isolator) beginning 10 days after P. gingivalis inoculation. The control group (n = 6; non-infected rats) received only vehicle. After 5 weeks of daily drug administration by gastric intubation, the experiment was terminated and blood samples were taken from each animal to determine antibody levels against P. gingivalis. Plaque samples were collected from each group of animals before and after P. gingivalis inoculation and at the end of the experiment for microbiological examination. The jaws were removed from each rat, defleshed and then analyzed morphometrically and radiographically to assess bone loss. Serum antibody levels against P. gingivalis were significantly elevated in the 3 infected groups compared to the non-infected controls. This, together with the microbiologic findings, indicated that these groups of rats were infected with P. gingivalis.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteroides gingivalis is associated with various forms of periodontal disease. To assess the role of the immune response in modulating B. gingivalis-associated periodontal disease, the effect of immunization of B. gingivalis-induced periodontal bone loss was evaluated in gnotobiotic rats. Male Sprague-Dawley rats immunized with various doses of whole cells or sham-immunized with incomplete Freund's adjuvant were monoinfected with B. gingivalis in carboxymethylcellulose by gavage. Two additional groups served as either sham-immunized or untreated germ-free controls. Forty-two days after infection, all rats were killed, periodontal bone level was assessed morphometrically and radiographically, and gingival proteinase (mammalian collagenase and acid cathepsin) activity was assessed biochemically. B. gingivalis was present in oral samples from all monoinfected rats, and no contaminating bacteria were detected in any oral or fecal sample. Animals immunized with B. gingivalis cells had elevated serum and saliva antibodies to whole cells and partially purified fimbriae from B. gingivalis. Infected sham-immunized rats had significantly more periodontal bone loss than noninfected controls, whereas the periodontal bone level in infected rats immunized with 10(10) B. gingivalis cells was similar to that of the noninfected controls. The activities of gingival collagenase and cathepsin B and L were high in sham-immunized infected rats and low in all other animal groups. In conclusion, it is possible to reduce B. gingivalis-induced periodontal tissue loss in gnotobiotic rats by immunization.