Caries risk assessment in school children using a reduced Cariogram model without saliva tests

BACKGROUND To investigate the caries predictive ability of a reduced Cariogram model without salivary tests in schoolchildren. METHODS The study group consisted of 392 school children, 10-11 years of age, who volunteered after informed consent. A caries risk assessment was made at baseline with aid of the computer-based Cariogram model and expressed as "the chance of avoiding caries" and the children were divided into five risk groups. The caries increment (DeltaDMFS) was extracted from the dental records and bitewing radiographs after 2 years. The reduced Cariogram was processed by omitting the variables "salivary mutans streptococci", "secretion rate" and "buffer capacity" one by one and finally all three. Differences between the total and reduced models were expressed as area under the ROC-curve. RESULTS The baseline caries prevalence in the study population was 40% (mean DMFS 0.87 +/- 1.35) and the mean 2-year caries increment was 0.51 +/- 1.06. Both Cariogram models displayed a statistically relationship with caries development (p < 0.05); more caries was found among those assessed with high risk compared to those with low risk. The combined sensitivity and specificity decreased after exclusion of the salivary tests and a statistically significant reduction of the area under the ROC-curve was displayed compared with the total Cariogram (p < 0.05). Among the salivary variables, omission of the mutans streptococci enumeration impaired the predictive ability the most. CONCLUSIONS The accuracy of caries prediction in school children was significantly impaired when the Cariogram model was applied without enumeration of salivary tests.