Effects of Fluoride on Condylar Growth and Density

Objectives: Orthodontists commonly use functional appliances to stimulate condylar growth by displacing the mandible forward when treating patients with a mandibular deficiency.  Increased administration of dietary minerals, such as fluoride, has been shown to increase condylar thickness and density.  The cumulative effects of condylar displacement and increased fluoride concentrations have not been previously investigated.  Therefore, the objective of this study was to evaluate the effects of increased fluoride administration during lateral displacement of the condyle in a rat model.  Methods: Thirty-two, 4-week old rats were fitted with a custom maxillary acrylic appliance, which caused their mandibles to permanently shift laterally.  All rats were placed on a soft diet and were randomly assigned to two groups.  One group received distilled water (control), while the other received distilled water with 100 ppm NaF.  For 2 weeks the animals were allowed to eat and drink ad libitum. The effects of fluoridated or DI water and side of the mouth on the measurements were evaluated using analysis of variance (ANOVA). The ANOVA included fixed effects for water, side, and their interaction and a random effect to correlate the two sides within an animal. Results: Significant differences in condylar length, bone volume, bone surface, were observed (p≤0.05) between the distracted and non-distracted condyles, but this difference was independent of the water consumed.  Conclusions: We concluded that lateral displacement of the mandible results in significant changes of the distracted condyle.  Increased fluoride administration, however, did not produce a significant difference in condylar morphology or mineral composition.  Supported, in part, by the Indiana University School of Dentistry Dental Student Research Fund.