In vitro validity of the Dundee Selectable Threshold Method for caries diagnosis (DSTM)

Objectives: It is not generally possible to assess diagnostic accuracy in dental surveys as no histological 'gold standards' are available, therefore examiner agreement tends to be used as a proxy for accuracy. The aim of this study was to investigate, using extracted teeth in arch models, the in vitro validity of a diagnostic system to assess caries at the D-1 (enamel and dentine) and D-3 (dentine) diagnostic thresholds, for epidemiological purposes. Method: Two groups of 10 dental examiners trained in the use of the Dundee Selectable Threshold Method for caries diagnosis (DSTM) each examined (on two occasions) 160 extracted permanent molar and premolar teeth set in arch models in phantom heads according to the codes and criteria of the DSTM. The teeth were subsequently radiographed and sectioned to provide validation of the diagnoses. Results: Intra-examiner agreement according to the kappa statistic was substantial. In general terms the results of the in vitro validation exercise demonstrated significantly higher sensitivity values at the D-1 diagnostic threshold than were found at the D-3 diagnostic threshold with a consequent toss of specificity. Conclusions: The results of this in vitro validation exercise demonstrate that at the D-1 diagnostic threshold the sensitivity of the DSTM was greater than at the D-3 threshold indicating no loss of diagnostic accuracy at the D-1 threshold.