A study by Dr. Carmen Gonzales, et al investigated the effect of systemic fluoride intake from birth to 12 weeks on orthodontically induced root resorption and tooth movement in rat molars. Fifty male rats were randomly divided into the following 5 groups: a negative control group that received no sodium fluoride and had no tooth movement; a positive control group that received no sodium fluoride but had tooth movement; and 3 experimental groups that received 45-ppm sodium fluoride from birth to 2, 4, and 12 weeks, respectively. At week 10, a 50-g nickel-titanium coil spring was applied to the maxillary left first molar for 2 weeks. At week 12, movement of the maxillary first molars was measured in relation to the maxillary second molar on digitized cephalometric radiographs. Mesial and distal roots were examined by using scanning electron and 3-dimensional laser microscopes. The study found that fluoride reduced the depth, volume, and roughness of the resorption craters in the experimental groups. Yet, the area was similar to that in the positive control group. The longer fluoride was administered via drinking water, the smaller the amount of tooth movement observed. It concluded that fluoride in drinking water from birth reduced the severity of orthodontically induced root resorption, but the amount of tooth movement was also decreased.
