Evaluation of salivary tests and dental status in the prediction of caries increment in caries-susceptible teenagers.

We evaluated caries increment in connection with salivary caries-related findings and dental status in teenagers by carrying out a retrospective follow-up, lasting on average 28 months. A total of 66 adolescents, mean age 15.2 years, were selected by their susceptibility to caries, as clinically defined at a routine checkup. Their baseline DMFT was 5.7, compared to 4.3 in the root population of 230 patients. Increment of caries on selected surfaces (delta DFSs) included new caries reaching the dentine and new fillings done due to such caries. Delta DFSs > 0 was taken as the validation criterion to define a caries case. Screening criteria for salivary tests were set as follows: flow rate of unstimulated saliva less than 0.2 ml/min, and of stimulated saliva less than 1.0 ml/min; buffering capacity: final pH below 4.5, mutans streptococci (SM) score of 2 or 3 (> or = 10(5) CFU/ml), and lactobacilli (LB) score of 5 or 6 (> or = 10(5) CFU/ml). Mean delta DFSs per subject was 1.1, with 70% of these new DF findings being on occlusal surfaces. Delta DFSs was correlated with LB (0.31) for both genders, for boys only with buffering capacity (-0.34), and for girls only with flow rate of stimulated saliva (-0.28) and DMFT (0.35). The highest sensitivities of salivary tests for caries were shown by LB (0.82) and SM (0.64), their specificities being 0.63 and 0.59, respectively. Positive predictive values of the five tests varied between 0.69 and 0.89. Predictions based on DMFT showed a sensitivity of 0.87 for DMFT > 3, but only of 0.33 for DMFT > 7, the corresponding specificities being 0.44 and 0.81.