Actual caries development compared with expected caries activity.

In 18 schoolboys, 16 years old, the actual caries development during 1 year was compared with the expected caries activity which was predicted from evaluations of four selected tests: (1) the buffer capacity, (2) the titer of Streptococcus mutans in stimulated whole saliva, (3) clinical evaluation of rate of plaque formation, and (4) a quantitation of a salivary agglutinin reacting with a serotype c strain of S. mutans. According to previous experiences the estimated value for each factor was classified for each individual either as a negative (carries-provoking) or as a non-negative factor. The score of negative factors could thus vary between 0 and 4 for each individual. A good relationship was observed between the caries increment during 1 year and the sum of the scores from the tests representing expected caries activity. This observation indicates the possibility of selecting the most caries susceptible individuals in a population by using the four parameters. A selection can be made from two or three of the tests but then the degree of differentiation becomes lower. No parameter could singly be used as an indication of the potential caries activity in the individual test.