Arrestment of caries in rats by adding fluoride and magnesium to the diet

90 weanling Osborne-Mendel rats were divided into six groups of 15 animals each. Half of them received a modified MIT 200 control diet in which one third of the sucrose of the original formula was replaced by high-extraction wheat fluor, magnesium content reduced to 360 parts/10(6) and phosphorus content increased NaH2PO4 . 2H2O to 0.49%. For the experimental diet, an additive containing 75 parts/10(6) fluoride as (NaF) and 50 parts/10(6) magnesium (as MgO) was mixed into the above composition. Each diet was given to three experimental or three control groups for 25, 40, or 55 d. Caries involving dentin-enamel junction was significantly reduced through the F+Mg addition by 37%, 51%, and 61% on the 25th, 40th, and 55th day, respectively. Caries involving dentin was significantly reduced by 58%, 68%, and 70%, respectively. Caries arrestment was observable in both the control rats and rats fed the F rMg additive but in the latter animals the reduction meant an arrestment at a lower level than in controls. This arrestment resembles an early caries arrestment obtained recently in a clinical trial by fluoridation of dietary sugar products. The growth of the animals was only temporarily retarded by the additives.