Reliability of the Nyvad criteria for caries assessment in primary teeth.

This study assessed the interexaminer and intra-examiner reliability of the Nyvad caries classification system in primary teeth and calculated the mean examination time. The criteria were based on visual and tactile examinations to differentiate active and inactive lesions at cavitated and non-cavitated levels. Eighty children (3-7 yr of age) were examined under standardized conditions by calibrated examiners. At the tooth surface level, reliability was expressed as percentage agreement and kappa coefficient, using four diagnostic thresholds: sound vs. diseased; sound or inactive lesion vs. active lesion; intact surface vs. surface discontinuity; and sound or non-cavitated lesion vs. cavitated lesion. Interexaminer and intra-examiner kappa values were, respectively: 0.82/0.86; 0.80/0.86; 0.90/0.94; and 0.95/0.98. At the individual level, reliability of estimates of the caries prevalence and of the decayed or filled surface (dfs) counts were assessed at three diagnostic thresholds: sound vs. diseased; sound or inactive lesion vs. active lesion; and sound or non-cavitated lesion vs. cavitated lesion. For caries prevalence, interexaminer and intra-examiner kappa values were, respectively: 0.84/0.94; 0.69/0.74; and 0.95/0.97. The mean examination time was 226.5s (SD = 128.5). The use of the Nyvad caries diagnostic criteria in primary teeth showed reliable results. The examination time was acceptable.