Application of two fluorescence methods for detection and quantification of smooth surface carious lesions

Abstract: Early diagnosis of carious lesions is a key factor in prevention and management of dental caries. With non-invasive, quantitative diagnostic methods it should be possible to detect lesions at an initial stage and subsequently monitor lesion changes over time during which preventive measures are introduced. Conventional methods are inadequate for a modern approach to clinical caries management. The need for objective and quantitative methods for detecting and monitoring progression of carious lesions is therefore obvious. Aims The present thesis is aimed at evaluating two fluorescence devices, DIAGNOdent and QLF for detection and quantification of carious lesions on smooth surfaces under both in vitro and in vivo conditions, with special reference to applications in orthodontic patients. Material and methods Validity of DIAGNOdent and QLF: (papers I, IV) The validity of two fluorescence methods, DIAGNOdent and QLF, was evaluated for the purpose of caries detection and quantification on non-cavitated carious lesions on smooth surfaces. In paper I, the performance of these fluorescence methods was validated by microradiographic and histopathological analyses in order to correlate the two methods with mineral loss and lesion depth. In paper IV, the DIAGNOdent and the DIAGNOdent pen were validated by histopathological analysis in terms of Spearman s rank correlation coefficient. Reliability of DIAGNOdent and QLF: (papers I, II, IV) The reliability of DIAGNOdent and QLF in terms of observer agreement on quantification of enamel caries on smooth surfaces was evaluated and compared under in vitro conditions employing Intra-class correlation coefficient (ICC) (paper I, IV). The inter- and intra-observer agreement of the DIAGNOdent method was also tested under in vivo conditions (paper II). Application of DIAGNOdent as a monitoring tool for evaluation of preventive programs: (paper III) The capacity of DIAGNOdent for monitoring caries progression was evaluated in a clinical study where twelve subjects with 127 test teeth were randomly assigned to two caries preventive treatment groups. The lesion changes over a 12 months period were followed by DIAGNOdent. The mean changes of the DIAGNOdent values for the two treatment groups were analyzed by three-way ANOVA. Results In the in vitro studies on comparisons between the fluorescence methods with respect to the correlation with lesion depth, the correlation coefficients for DIAGNOdent and QLF were 0.76 and 0.82, respectively (paper I), and 0.55 and 0.52 for DIAGNOdent and DIAGNOdent pen, respectively (paper IV). The QLF method showed higher correlation with mineral loss, 0.84, compared to 0.64 for DIAGNOdent. The ICC values showed excellent intra-examiner agreement, and good inter-examiner agreement under both in vitro and in vivo conditions. For longitudinal quantification, there was a significant difference in the DIAGNOdent readings between the first and the final evaluation, p=0.025. However, the difference between the two treatment groups regarding the changes of DIAGNOdent values over time was not statistically significant, p=0.87. Conclusions It was concluded that the applied fluorescence methods are reliable and valid for quantification of natural carious lesions on smooth surfaces. The results suggested that it might be feasible to use DIAGNOdent for longitudinal monitoring of carious lesions on smooth surfaces. QLF and DIAGNOdent may aid clinical decision making in caries susceptible individuals, such as orthodontic patients.