CARIOSTATIC EFFECTS OF SODIUM TRIMETAPHOSPHATE WHEN FED TO RATS DURING DIFFERENT STAGES OF TOOTH DEVELOPMENT

Because numerous investigators have reported that phosphates are effective in reducing the development of dental caries when fed in the diets of hamsters and rats, it is important to determine whether phosphates are more effective if ingested at certain stages of tooth development and maturation than at other stages. A factorial design was used to study the effect of 1.31 per cent sodium trimetaphosphate mixed into a caries-producing diet and fed to rats during four stages of tooth development (1) during the last 15 days before birth, (2) during the first 20 days after birth or before completion of the eruption of the molar teeth, (3) during the period from 20 to 40 days of age or immediately following eruption of the molar teeth, (4) during 40-80 days of age, or later in the post-eruptive maturation of the molar teeth. All 16 combinations of these four periods were tested. The rats were sacrificed when 80 days old, and the 12 molar teeth in each rat were scored for caries development. Analysis of variance showed that feeding the phosphate during pregnancy had no influence on dental caries and a slight one when fed during the first 20 days. The supplement was highly effective when offered to rats immediately following eruption from 20 to 40 days or from 40 to 80 days of age. The cariostatic effect in rats appears to be due mostly to a local action of the phosphate. Still greater reductions in caries scores were noted when the phosphate was fed during more than one stage of tooth development. Thus, stage of development of the tooth and the length of the feeding period are of critical importance in evaluating the cariostatic action of phosphates in animals and presumably in human beings. © 1968.