Streptococci and activities of sucrases and alpha-amylases in supragingival dental plaque and saliva in three caries activity groups.

Thirty-eight young adults participated in the study. They were divided in a caries-inactive group, a low caries activity group and a moderate to high caries activity group. Total cultivable bacteria, Streptococcus salivarius, and S. mutans in plaque and saliva were quantitated on TSA, MS, and MSB plates, respectively. Sucrase activity was determined by measuring reducing sugars in plaque and saliva after incubation with sucrose. alpha-Amylase activity was determined by Pharmacia Phadebas Amylase test. The data were analyzed with the non-parametric Mann-Whitney U test. The only significant difference was observed for plaque alpha-amylase activity between the caries-inactive group and the moderate-high caries activity group (P less than 0.05). The lack of differences concerning the other variables is discussed mainly on the basis of the multifactorial character of dental caries and the possible insufficiency of the applied methods.