The aim of this study was to evaluate the reproducibility and differences in diagnostic outcomes by practicing dental clinicians previously inexperienced in using the Nyvad criteria and the ICDAS II criteria with the Lesion Activity Assessment system (ICDAS II + LAA). Four volunteer dentists were randomly allocated to one of two groups. Both groups of dentists examined the same voluntary sample (n = 140) of caries active young adults using Nyvad and ICDAS II + LAA criteria in different sequences. The first group used the Nyvad criteria during period 1, followed by ICDAS II + LAA during period 2; the second group did the examinations in the opposite sequence. Before the period 1 and 2 examinations, dentists from both groups were trained with the Nyvad or ICDAS II + LAA criteria, depending on the group to which they were assigned. Intra-examiner agreement for lesion severity was high for both diagnostic instruments (weighted kappa 0.62-0.80). For lesion activity the intra-examiner unweighted kappa values ranged from 0.31 to 0.61 for ICDAS II + LAA and from 0.36 to 0.51 for Nyvad. The mean number of active non-cavitated caries lesions was significantly higher for ICDAS II + LAA (6.14 ± 5.4) than for Nyvad (3.90 ± 3.9) (p < 0.001). Active cavitated/dentinal caries lesions were significantly higher for ICDAS II + LAA (4.14 ± 4.1) than for Nyvad (2.13 ± 3.1) (p < 0.001). Both the Nyvad and ICDAS II + LAA diagnostic criteria showed high reproducibility for lesion severity assessment. The mean number of active caries lesions among high caries risk subjects was significantly higher using the ICDAS II + LAA criteria, which may subsequently lead to more caries treatment.
Trial registration: ISRCTN65592532.