Reliability of caries data in three clinical trials

Abstract

The reliability of caries data obtained during 3 clinical trials is presented. Each of the 3 trials, conducted by different examiners, lasted 3 yr and involved children aged 12-15 yr. Reliability was quantified in terms of reliability coefficient and error variance, which allowed the effect of error upon the efficiency of each study to be measured. Reliability tended to be reduced when precavitation (initial) lesions were included in the DMFS [decayed-missing-filled filled surfaces] count, but there was little difference between the reliability coefficients for each of 4 different surface-types. Error was more important in 3-yr incremental rather than prevalence data, but had a rather small influence upon sample size estimation or confidence limits of percent caries reductions.