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

Objectives: It is not generally possible to assess diagnostic accuracy in d ental surveys as no histological 'gold standards' are available, therefore examiner agreement tends to be used as a proxy for accuracy. The aim of thi s study was to investigate, using extracted teeth in arch models, the in vi tro validity of a diagnostic system to assess caries at the D-1 (enamel and dentine) and D-3 (dentine) diagnostic thresholds, for epidemiological purp oses. Method: Two groups of 10 dental examiners trained in the use of the D undee 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 DS TM. The teeth were subsequently radiographed and sectioned to provide valid ation of the diagnoses. Results: Intra-examiner agreement according to the kappa statistic was substantial. In general terms the results of the in vit ro validation exercise demonstrated significantly higher sensitivity values at the D-1 diagnostic threshold than were found at the D-3 diagnostic thre shold with a consequent toss of specificity. Conclusions: The results of th is in vitro validation exercise demonstrate that at the D-1 diagnostic thre shold the sensitivity of the DSTM was greater than at the D-3 threshold ind icating no loss of diagnostic accuracy at the D-1 threshold.