CHRONIC EXPOSURE TO SODIUM MONOFLUORPHOSPHATE POST-DENTAL EXTRACTION IMPAIRED ALVEOLAR BONE REPAIR

Sodium fluoride (NaF) and sodic monofluorphosphate (Na2FPO–MFP) are extensively used as sources of fluoride (F-) in human therapeutics. Some evidence indicates that F- bioavailability is greater when MFP is administered; it is important to minimize doses and to decrease adverse effects. F- produces biological and physical-chemical effects on the bone tissue depending on the dose and the form of ion administration. OBJECTIVE: To study the effect triggered by chronic exposure to MFP during the active bone resorption phase occurring post-first molar extraction, on the structural properties of alveolar bone and metabolic parameters. METHODS: Young male Wistar rats (n=4-6 per group) were anaesthetized and the first mandibular molar on the left side was extracted. Post-extraction, rats were divided into two experimental groups that were given water containing different concentrations of F- for 4 weeks: Controls (0.3 mg/L F-) and treated with MFP (22 mg/l F-). Plasma samples were obtained to determine phosphocalcic metabolism parameters. Urinary F- was determined using an ion selective electrode. Complete hemimandibles were histologically processed to obtain buccolingual sections. On digital microphotographs, bone volume formed [BV/TV (%)] in the post-extraction socket was measured using Image Pro Plus software. All results were expressed as mean ± SE and analyzed using Student’s “t” test considering significant differences at p<0.05. RESULTS: No significant differences were observed in water intake or body weight gain due to treatment. Urinary F- was higher in chronically MFP exposed rats than in control rats (p<0.05). Calcemia and phosphatemia increased in treated animals (p<0.05), with no changes in total alkaline phosphatase (ALP) between groups. BV/TV (%) in the extraction socket was lower in treated animals compared to controls (p<0.05). CONCLUSIONS: Fluoride uptake in the form of MFP during the immediate post-tooth extraction period produced an alteration in phosphocalcic metabolism and a decrease in alveolar bone volume, suggesting a negative effect on the dental bone repair process.