Fluoride Profiles in the Periosteal and the Endosteal Regions of the Cortical Bone in Different Aged Female Rats

The fluoride concentration in the bone of the non-fluoridated female rats increased slowly with age. Up to the age of 12 weeks, the fluoride distribution across the cortical bone was low and showed non-variation from the periosteal region to the endosteal region. From 24 weeks, however, the fluoride concentration in the periosteal and endosteal regions was a little higher than that of the middle region of the cortex. The fluoride concentrations in the bone of the female rats using water containing 100 ppm fluoride increased markedly with age. Six-week old rats showed increased fluoride concentrations in the endosteal region. At 24 weeks, both the periosteal and endosteal regions were higher than the middle region. At 48 weeks, the fluoride concentration in the periosteal region was significantly higher than that of the endosteal region. In conclusion, in younger rats (4, 6, 12, 24 weeks old), the fluoride concentration was lower in the periosteal than in the endosteal region, whereas in older (48 weeks old) rats, the fluoride concentration was higher in the periosteal than in the endosteal region. There were some-what different findings from those on the rat molar cementum in which fluoride was mainly taken up from the cementum surface.