The purpose of this study was to study the relationship between genetic diversity within glucosyltransferases of Streptococcus mutans and dental caries.Methods: The isolates were collected from patients of the caries-active group harbored the Streptococcus mutans strains producing higher water-insoluble glucans and patients of the caries-free group harbored the strains with lower water-insoluble ones. The gtfBC (961一5574 bp) of the DNA from isolates was amplified by polymerase chain reaction (PCR) .Genetic diversity of gtfBC~assessed using restriction fragment-length polymorphism (RFLP) with restriction endonucle- ases: Hinf工，Mbo I and Taq I .Results: The differences in the gtf PCR-RFLP patterns among strains~revealed when di- gested with几 rd l.The number of subjects harbored the longest band 1.9 kb pattern in the caries-active group was significantly ~than the caries-free group(P
