BACKGROUND The detection and diagnosis of caries at the initial (non-cavitated) and moderate (enamel) levels of severity is fundamental to achieving and maintaining good oral health and prevention of oral diseases. An increasing array of methods of early caries detection have been proposed that could potentially support traditional methods of detection and diagnosis. Earlier identification of disease could afford patients the opportunity of less invasive treatment with less destruction of tooth tissue, reduce the need for treatment with aerosol generating procedures, and potentially result in a reduced cost of care to the patient and to healthcare services. OBJECTIVES To determine the diagnostic accuracy of different visual classification systems for the detection and diagnosis of non-cavitated coronal dental caries for different purposes (detection and diagnosis) and in different populations (children or adults). SEARCH METHODS Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 30 April 2020); Embase Ovid (1980 to 30 April 2020); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 30 April 2020); World Health Organization International Clinical Trials Registry Platform (to 30 April 2020). We studied reference lists as well as published systematic review articles. SELECTION CRITERIA We included diagnostic accuracy study designs that compared a visual classification system (index test) with a reference standard (histology, excavation, radiographs). This included cross-sectional studies that evaluated the diagnostic accuracy of single index tests and studies that directly compared two or more index tests. In vitro and in vivo studies were considered. Studies that explicitly recruited participants with caries into dentine or frank cavitation were excluded. We also excluded studies that artificially created carious lesions and those that used an index test during the excavation of dental caries to ascertain the optimum depth of excavation. MAIN RESULTS We included 71 datasets from 67 studies (48 completed in vitro) reporting a total of 19,590 tooth sites/surfaces. The most frequently reported classification systems were the International Caries Detection and Assessment System (ICDAS) (36 studies) and Ekstrand-Ricketts-Kidd (ERK) (15 studies). In reporting the results, no distinction was made between detection and diagnosis. Only two studies were at low risk of bias across. There was substantial variability in the results of the individual studies: sensitivities ranged from 0.16 to 1.00 and specificities from 0 to 1.00. For all visual classification systems, the estimated summary sensitivity and specificity point was 0.86 and 0.77, respectively, diagnostic odds ratio (DOR) 20.38. In a cohort of 1000 tooth surfaces with 28% prevalence of enamel caries, this would result in 40 being classified as disease free when enamel caries was truly present (false negatives), and 163 being classified as diseased in the absence of enamel caries (false positives). The addition of test type to the model did not result in any meaningful difference to the sensitivity or specificity estimates, nor did the addition of primary or permanent dentition. The variability of results could not be explained by tooth surface (occlusal or approximal), prevalence of dentinal caries in the sample, nor reference standard. Only one study intentionally included restored teeth in its sample and no studies reported the inclusion of sealants. We rated the certainty of the evidence as low, and downgraded two levels in total for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the in vitro studies, and inconsistency of results. AUTHORS' CONCLUSIONS Whilst the confidence intervals for the summary points of the different visual classification systems indicated reasonable performance, they do not reflect the confidence that one can have in the accuracy of assessment using these systems due to the considerable unexplained heterogeneity evident across the studies. The prediction regions in which the sensitivity and specificity of a future study should lie are very broad, an important consideration when interpreting the results of this review. Should treatment be provided as a consequence of a false positive result then this would be non-invasive, typically the application of fluoride varnish where it was not required, with low potential for an adverse event but healthcare resource and finance costs. Despite the robust methodology applied in this comprehensive review, the results should be interpreted with some caution due to shortcomings in the design and execution of many of the included studies. Studies to determine the diagnostic accuracy of methods to detect and diagnose caries in situ are particularly challenging. Wherever possible future studies should be carried out in a clinical setting, to provide a realistic assessment of performance within the oral cavity with the challenges of plaque, tooth staining, and restorations, and consider methods to minimise bias arising from the use of imperfect reference standards in clinical studies.
