F.J. McClure

EFFECT OF FLUORIDE AND TETRACYCLINE ON ALVEOLAR BONE RESORPTION IN THE RAT.

The results of recent studies recommend consideration of a possible beneficial effect of fluoride on periodontal disease. It has been reported, for example, that the severity of periodontal disease in adults using a drinking water containing 1.2 ppm F is significantly less than in those whose water supply contains 0.1 ppm F (H. R. Englander, R. G. Kesel, and 0. P. Gupta, Amer. J. publ. Hith [in press]). Since this difference was not associated with dental caries status (H. R. Englander, personal communication), the postulate that fluoride might deter the resorption of alveolar bone assumes interest (H. R. Englander, personal communication). Of interest in this regard is the observation that fluoride improves the crystal texture of the mineral apatite of bone (I. Zipkin, A. S. Posner, and E. D. Eanes, Biochem. biophys. Acta, 59:255-58, 1962; A. S. Posner, E. D. Eanes, R. A. Harper, and I. Zipkin, Arch. oral Biol., 8:549-70, 1963). Such improvement in crystal size and/or strain would decrease chemical reactivity and, possibly, susceptibility of bone to resorptive processes. Further, it has been reported that the calcium balance can be improved in other skeletal diseases such as osteoporosis and Pagets disease by the administration of large doses of fluoride (C. Rich and J. Ensinck, Nature, 191:185, 1961; C. Rich and J. Ensinck, Clin. Res., 10:118, 1962 [Abst.]; M. J. Purves, Lancet, pp. 1188-89, December, 1962). The purpose of the present study was to determine the effect of fluoride ingestion on alveolar bone loss in rats. A corollary objective was to investigate also the role of tetracycline, since antibiotics have proved efficacious in reducing the incidence and severity of periodontal disease in rice rats (J. H. Shaw, D. Griffiths, and A. M. Auskaps, J. dent. Res., 40:511-19, 1961). Female Sprague-Dawley rats, 25 days of age, were assigned to one of three experimental groups. Those belonging to Groups I and II were fed an oat-flour diet (F. J. McClure, J. dent. Res., 40: 380, 1961), omitting sodium phytate. (The diet of McClure and an essentially similar diet [M. L. Dodds, J. Nutr., 7:317, 19611 have been shown to produce alveolar bone loss.) Group III animals received the same diet containing 0.01 per cent oxytetracycline hydrochloride. Groups I and III were offered distilled H20 and Group II a solution containing 50 ppm F as NaF. A supplement of 2,000 units of vitamin A and 400 units of vitamin D was provided each week. The animals were sacrificed at the end of 100 days on experiment, and the heads and jaws cleaned of soft tissue by Dermestes lardarius larvae. Groups I, II, and III comprised 15, 13, and 18 animals, respectively. Alveolar bone loss was determined three different times for 56 areas using an arbitrary rating scale of from 0 to 4+ to assess severity (O. P. Gupta and J. H. Shaw, Oral Surg., 9:727-35, 1956). The scores (mean ± S.E.) were as follows: control, 96.9 + 3.4; fluoride, 96.9 ± 4.4; tetracycline, 57.3 + 3.8. It is apparent that fluoride had no effect on alveolar bone resorption. On the other hand, rats fed the tetracycline-containing diet lost significantly less (P < 0.01) bone. Presumably this was the result of a diminished inflammatory response associated with the impaction of oat-hull fibers and hair in the gingival crevices. However, the antibiotic may have affected bone loss per se, as it has been reported that chlortetracycline slowed the rate of mineral depletion from rats fed a rachitogenic diet (N. B. Guerrant, Proc. Soc. exp. Biol. Med., 113:268-70, 1963). Unpublished data indicate that this level of fluoride significantly increases the crystallinity of rat alveolar bone (R. C. Likins, G. Pakis, and A. S. Posner). It appears, then, that improvement in apatite crystal size and/or reduction in crystal strain associated with fluoride ingestion under these conditions was of negligible value in the management of bone loss resulting from inflammatory processes.