Effect of diagnostic threshold on the validity and reliability of epidemiological caries diagnosis using the Dundee Selectable Threshold Method for caries diagnosis (DSTM)

Objectives: To develop a method for recording dental caries at the D-1 (enamel and dentine) diagnostic threshold (without loss of D-3 information) and assess its reliability, 'benchmark' validity and potential effects on reported caries prevalence and needs assessment. Methods: Multi-examiner training, calibration and validation trial. Two groups of 10 dental examiners were trained to diagnose dental caries at the D-1 (enamel and dentine) diagnostic threshold under the conditions of a caries prevalence survey, prior to a calibration trial being undertaken. Results: Where 'experienced examiners' were trained to examine at the D-1 (enamel and dentine) diagnostic threshold, under the conditions of a cross-sectional epidemiological survey, there was no significant deterioration in inter-examiner agreement on the assessment of teeth and a significant difference in one of two comparisons on the assessment of surfaces using the kappa statistic. Assessed against a benchmark examiner, there was no significant loss of sensitivity at the D-1 diagnostic threshold compared with the D-3 threshold and, although there was a significant loss of specificity at the D-1 threshold, all specificity values could be considered to be high. Conclusions: Modifying the diagnostic criteria typically used in surveys of caries prevalence (to allow assessment of the levels of enamel caries which could benefit from preventive care as well as dentinal caries requiring restorative care) in adolescents does not adversely affect the reliability or benchmark validity of experienced examiners to a significant degree.