Fluoride intake and alveolar bone loss in periodontal disease-susceptible mice

The effect of fluoridation and its discontinuation on fluoride profiles in the alveolar bone of rat

We investigated the effect of fluoridation and its discontinuation on fluoride content in the alveolar portion of the mandible in rats. Drinking water with three different fluoride contents (0, 50, 100 ppmF) was given to rats for three different periods (4, 13 and 25 weeks). Fluoride concentrations were measured in the crest, the middle, and the apical parts of the alveolar bone and in the body of the mandible. Furthermore, after fluoridated drinking water was given to rats for 4 or 13 weeks, distilled water was given to them for 21 or 12 weeks respectively; and the effect of the discontinuation on fluoride profiles was investigated. Layer samples were analyzed by abrasive microsampling. Fluoride and phosphorus concentrations were determined by ion-specific electrode and colorimetric procedures, respectively. There was an increase in fluoride concentrations in the mandible in proportion to the fluoride content in the drinking water and the duration of fluoridation. After fluoridation was discontinued, fluoride concentrations in the surface layers of the mandible presented a decrease. Among the four different parts of the mandible, the upper part of the alveolar bone and the alveolar crest part presented the highest rates of reduction. The relative reduction rate of fluoride concentration was closely related to the duration of discontinuation. The alveolar crest was affected most by the discontinuation of fluoridation, presenting the greatest reduction.

Effect of fluoride on root resorption caused by mechanical injuries of the periodontal soft tissues in rats

The present study was carried out to investigate histologically and histometrically the effect of fluoride on root resorption induced by mechanical injuries of the periodontal soft tissues in rats. Resorption lacuna in the root surface of the molar in animals given both mechanical injuries and fluoride administration was significantly smaller in length and area than that in animals given only mechanical injuries. Moreover, resorption lacuna in the former animals contained fewer odontoclasts than that in the latter. The results of the present study might suggest that the administration of fluoride suppressed root resorption induced by mechanical injuries of the periodontal soft tissues.

Effects of fluoride intake on the mineral content, acid solubility and resorption caused by experimental periodontitis of rat alveolar bone

Adult rats were given either distilled water or drinking water containing 100 parts/10(6) of fluoride. The alveolar bone of rats given fluoride for 90 days showed an increased mineral content and decreased acid solubility compared to the bone of rats given distilled water. Experimental periodontitis was initiated in both groups after 110 days of treatment to cause alveolar bone resorption. Fourteen days later, the rats were killed and it was found that the alveolar bone resorption caused by experimental periodontitis was significantly smaller in the rats given fluoride in their drinking water than in those given distilled water. The findings suggest that fluoride intake might have a protective effect on rapidly progressing alveolar bone resorption.