Relationships between mutans streptococci and perceived treatment need of primary root-caries lesions.

A total of 447 primary root-caries lesions from 169 dental patients was studied to determine the relationships between mutans streptococci and the perceived treatment need of primary root-caries lesions. Samples of this altered dentine for microbiological culture were obtained. Lesions were classified into 5 treatment categories; soft and restore, leathery and restore, leathery and debride of caries, leathery and treat chemotherapeutically, and hard, to receive no treatment. The total numbers of mutans streptococci decreased significantly with decreased treatment need. The percentage of mutans streptococci from lesions requiring no treatment was significantly less than from lesions requiring treatment. The frequency of isolation of mutans streptococci was significantly greater from lesions requiring more treatment. Significantly more lesions containing > 10² mutans streptococci were distributed in the groups with a greater perceived treatment need or with larger dimensions occlusogingivally and/or mesio-distally or bucco-lingually or with a closer proximity to the gingival margin.