[Distribution pattern of fluoride concentration in the bones of the rabbit and the rat]

The authors previously reported that the concentration of fluoride in the thigh-bone of the rat was higher at the endosteum than the periosteum (Narita et al., Aichi-Gakuin J. Dent. Sci., 26(1): 213-221, 1988). This result was opposite from the findings the rabbit by Weidmann and Weatherell (1959). The present study, therefore, was undertaken to determine whether or not the fluoride distribution profile in the bones of the rabbit and the rat really differed from each other. The animals used were four 4-month-old rabbits and five 4-month-old rats. The fluoride distribution of the femur bone in each specimen was analysed from the periosteum to the endosteum by using the abrasive micro-sampling technique described by Weatherell et al. (1985). The results obtained were as follows: 1) In both the rabbit and the rat, fluoride concentration in the bones was high at the periosteum and the endosteum, and then decreased gradually towards the interior of the bone tissue. In harvasian and interstitial lamellae, it was lower than the outer and inner lamellae. 2) The distribution pattern of fluoride concentration in the cortical bone was roughly the same in both the rabbit and the rat, while their fluoride levels differed, probably due to the fluoride content of each diet. 3) The discrepancy between Weidmann and Weatherell's results and our previous paper, was evidently due to the difference in thickness of the analysed samples: the former being thick and the latter being thin.