Method: 7-week-old, DBA/2J mice (n=24), genetically susceptible to root resorption, were randomly divided into 2 groups: 12 mice administered 100ppm [F-] fluoridated (NaF) water and 12 mice administered deionized (DI) water for 4 weeks. At 11 weeks of age, each animal experienced 4g of orthodontic force by a NiTi closed coil spring between the left maxillary first molar and incisors for 10 days. After sacrifice, the maxillae were scanned using micro-computed tomography and total tooth volume and density were digitally quantified using Mimics software. Wilcoxon signed rank tests were used to compare the total tooth volume and density between the treated and control teeth. Wilcoxon rank sum tests were used to compare the same measurements between fluoridated and DI water groups. Maxillary left first molars were extracted and analyzed for total tooth fluoride content.
Result: All teeth that experienced orthodontic force displayed significant root resorption, but the teeth of animals that consumed fluoridated water did not demonstrate significantly less root resorption. The maxillary first molars of the mice administered fluoridated water contained significantly higher amounts of fluoride than the molars of mice administered DI water.
Conclusion: The evident genetic predilection to orthodontically-induced root resorption, specifically, a reduction in radiographic volume and density, cannot be overcome by systemic fluoride administration nor higher fluoride concentration in the teeth of genetically susceptible mice.