Reliability of the Nyvad criteria for caries assessment in primary teeth Mariana C. SØllos, Vera M. Soviero Department of Preventive and Community Dentistry, School of Dentistry, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil One of the purposes of diagnosing dental caries is to detect and classify the lesions, in order to select the most appropriate treatment for each tooth surface (1). Con- sidering the slower rate of dental caries progression in contemporary populations, the assessment of non- cavitated lesions is of great importance for measuring the effectiveness of preventive approaches in longitudinal studies (2–6). If caries detection is restricted to counting the number of tooth surfaces with cavities, the early stages of the disease process are not considered. There- fore, caries prevalence is underestimated and the behaviour of individual caries lesions cannot be moni- tored (7, 8). Many studies have confirmed that high interexaminer and intra-examiner agreement can be achieved even when precavitated lesions are recorded (8–12), and since the 1950s, the inclusion of non- cavitated lesions has been recommended (13–18). However, the World Health Organization decided not to include enamel caries lesions in their caries index, mainly because the diagnosis may not be reliable when the diagnostic threshold is set at the non-cavitated level, just as it was considered that the inclusion of enamel caries lesions would make a comparison of the caries situation amongst countries worldwide more difficult (19). Besides the inclusion of lesions at the non-cavitated stage, the assessment of lesion activity is of major importance. The decision on clinical treatment will vary depending on the classification of the lesion as being active or inactive. Inactive or arrested lesions may not need any intervention, whereas active lesions have to be treated using non-operative procedures (such as oral hygiene improvement and topical fluorides) or operative treatment (6, 7, 20). The Nyvad caries diagnostic system was the first classification system to define clear criteria for the activity assessment of both non-cavitated and cavitated lesions (8). Recently, an International Caries Detection and Assessment System (ICDAS) has been suggested (4). This system is focused on the estimation of lesion depth and does not include lesion activity in their primary caries codes. A second score system to assess activity has been suggested for use in combination with the primary ICDAS codes (21). Clinical studies have shown that the Nyvad classifi- cation system has construct validity because activity assessment reflected the expected effects of fluoride toothpaste on caries lesions (11, 22). Moreover, it has also been observed that caries activity assessment has predictive validity because active non-cavitated lesions have a significantly greater risk of progressing to cavity than do inactive lesions (22). With the diagnostic threshold set at active vs. inactive lesions, the criteria have also been shown to be reliable, with kappa coeffi- cient values in permanent teeth ranging between 0.68 and 0.80 for intra-examiner agreement and between 0.74 and 0.78 for interexaminer agreement (8). So far, the Nyvad caries classification system has been used successfully in clinical studies (11, 22–24), but more studies on its reli- ability in both permanent and primary teeth are needed. The purpose of the present clinical study was to assess the interexaminer and intra-examiner reliability of the Se´llos MC, Soviero VM. Reliability of the Nyvad criteria for caries assessment in primary teeth. Eur J Oral Sci 2011; 119: 225–231. Ó 2011 Eur J Oral Sci 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 prev- alence, 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 226.5 s (SD = 128.5). The use of the Nyvad caries diagnostic criteria in primary teeth showed reliable results. The examination time was acceptable. Prof. Vera Mendes Soviero, Faculdade de Odontologia, Clínica de Odontopediatria, Universidade do Estado do Rio de Janeiro – UERJ, Av. 28 de Setembro, 157 (2/ andar), Vila Isabel, 20511-030 Rio de Janeiro RJ, Brazil Telefax: +55–21–28686372 E-mail: verasoviero@gmail.com Key words: dental caries; diagnosis; primary teeth; reliability Accepted for publication March 2011 Eur J Oral Sci 2011; 119: 225–231 DOI: 10.1111/j.1600-0722.2011.00827.x Printed in Singapore. All rights reserved Ó 2011 Eur J Oral Sci European Journal of Oral Sciences