The purpose of this study is to evaluate validity of dental caries prediction of modified Alban´ s test and acidic high-sucrose liquid medium test which is bacteriologic dental caries activity test by colorimetric grading method. For this purpose, longitudinal follow up study has been carried out for 4 years, targeting 233 elementary students. The caries experience and caries activity of subjects were examined. The caries examination was repeated after 4 years and caries increment was calculated for each child. Caries increment was calculated by summing up the primary tooth and the permanent tooth. Validity of dental caries prediction was evaluated by dividing into the case to predict the person with caries increment, the case to predict the person of more than the average and the case to predict the 20% persons with the highest 4-yr caries increment. Validating criteria were one or more, two or more and five or more of caries increment for 4 years. Test grade was set as screening criterion in modified Alban´ s test and acidic highsucrose liquid medium test. In accordance with each -screening criterion, sensitivity, specificity, hit ratio, positive predictive value, difference with proportional chance criterion and positive likelihood ratio were calculated and analyzed. After the optimal screening criterion was decided, final validity on corresponding test was evaluated per decided screening criterion.
The obtained results were as follows:
1. In case of predicting the person with caries increment, optimal screening criterion in modified Alban´ s test, was the 96 hour culture testing value of 4. At this time, sensitivity was 70.2%, and specificity was 48.5%. Also, positive predictive value was 79.5%. Optimal screening criterion in acidic high sucrose liquid medium test was the 96 hour culture testing value of 4.8. At this time, sensitivity was 85.9%. Also,
specificity and positive predictive value were 28.6% and 77.0%, respectively.
2. In case of predicting the person with the caries increment of more than the average of study group, optimal screening criterion in modified Alban´ s test was the 96 hour culture testing value of 6. At this time, sensitivity and specificity were 57.6% o and 54.4%, respectively. Also, positive predictive value was 52.3%. Optimal screening criterion in acidic high-sucrose liquid medium test was 48 hour culture testing value of 4.6. Sensitivity at this time was 61.0%. Also, specificity and positive predictive value were 55.3% and 63.2%, respectively.
3. In case of predicting highest 20% of children based on their 4-yr caries increment, the validity of dental caries prediction and acidic high sucrose liquid medium test were low, and thus has little practicability.
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