Fluoride effect in bone repair in dental alveoli in rats

Objectives: the objective of the study was to evaluate comparatively alterations in bone repair of rats chronically exposed to fluoride (F).

Methods: Four groups of 80-day-old Wistar rats (n=5 per group) received for 60 days drinking water containing 0 (control), 5, 15 or 50 ppm F. The incisors of the animals were extracted. After these treatments, the animals were euthanized after 7, 14, 21 and 30 days post-operatively. Dental alveoli were collected for microscopic (stained by Haematoxylin Eosin) and morphometric analysis.

Results: histological analysis showed new bone formation (30 days post- operatively) in animals after treatment with fluoride (5, 15 and 50 ppm F) and control group. The 50 ppm F group showed less new bone formation when compared with the others. The results of morphometric analysis showed increased volume density of new bone, between 7 and 30 days, in groups control (12.2±0.67% to 60.8±6.62%), 5 ppm (3.8±2.70% to 49.4±5.62%), 15 ppm (22.0±1.89% to 62.2±7.32%) and 50 ppm F (6.5±2.20% to 48.7±8.04%). Concomitantly, the volume densities of connective tissue and blood clot decreased, between 7 and 30 days, in groups control (connective tissue 58.1±0.34% to 31.34±5.02%; blood clot 29.6±0.33% to 7.8±1.60%), 5 ppm (connective tissue 55.2±21.41% to 40.9±9.64%; blood clot 40.8±18.81% to 9.7±4.14%), 15 ppm (connective tissue 27.1±0.62% to 35.8±6.76%; blood clot 50.8±1.27% to 1.9±0.58%) and 50 ppm F (connective tissue 20.5±8.40% to 38.0±0.92%; blood clot 73.0±10.6% to 13.3±7.12%). These values correlate to the histological descriptive observations where the dental alveoli in the 50 ppm F group were filled mainly by fibrotic connective tissue plus blood clot and new bone was present in a lesser extent.

Conclusions: Data show that F in high concentrations in the drinking water can impair bone repair and promote decrease in new bone formation in rats.