Possible effect of medically administered antibiotics on the mutans streptococci: implications for reduction in decay.

The decline in dental caries in children in North America, Scandinavia, Britain, Ireland and many Commonwealth nations is well documented. The multiple uses of fluoride can account for most, but not all, of this reduction. In this investigation, data are provided which suggest a relationship between antibiotic usage for medical purposes and a decline in both mutans streptococci (MS) and caries. Children attending Grades 1 and 2 in the Coldwater, Michigan school system and who reportedly never received antibiotics had significantly higher proportions of MS in the fissure plaques of first molars than subjects who received antibiotics. The level of decay in the primary dentition was inversely related to the reported usage of antibiotics. The frequent usage of antibiotics could reduce the incidence of dental caries by delaying the colonization of the teeth by the MS. This was evaluated by a prospective study in infants to determine what effect reported antibiotic usage would have on the colonization of newly erupting primary teeth. Only 2 of 10 infants cultured at 2 to 3 week intervals for periods up to 1 year after tooth eruption became colonized by the MS. One had never received antibiotics and the second had been on antibiotics for a single 5-day period. Seven of the 8 non-colonized infants had received antibiotic therapy for periods ranging from 10 to 181 days. Both the Coldwater study and the prospective study of infants suggested a relation between frequency of antibiotic usage for medical purposes and the MS levels on the teeth.