The caries predictive ability of the modified Alban´s test and the acidic high-sucrose liquid medium test were studied longitudinally. The sbjects of study were 306 primary school children and follow-up studies were carried out for 2 years. The caries predictive ability was evaluated by analyzing the validity of test, potentiality as a quantitative test, and the comparative value with respect to other caries activity test. Reliability of test was evaluated by setting the validating criterion of high caries activity group to 3 kinds of criteria, such as more than 1 new DdFfT, to calculate sensitivity, specificity, predictive value, hit ratio, and difference with proportional chance criterion.
The obtained results were as follows:
1. The optimal screening criterion of modified Alban´s test was 96 hours incubation test value, 1 and the sensitivity at this time was 0.86; specificity, 0.25; predictive value, 0.74, and hit ratio, 0.68, while the difference with proportional chance criterion was 0.09. In addition, the optimal screening criterion of the acidic high-sucrose liquid medium test was 96 hours incubation test value, 4.9, and the sensitivity at this time was 0.93; specificity, 0.25; predictive value, 0.66, and hit ratio, 0.68,
while the difference with proportional chance criterion was 0.14.
2. The hit ratio of prediction made on high caries activity group based on past caries experience was higher than that of prediction made based on modified Alban´s test, but lower than that of acidic high-sucrose liquid medium test. Consistency ratio between the results of judgement made on high caries activity group using the past caries experience as the predictive variables and the results of judgment made on modified Alban´s test was 84%, while consistency ratio with the results of judgement made on acidic high-sucrose liquid medium test was 79%.
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