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The aims of this in vitro study were: 1) to evaluate two fluorescence methods, laser fluorescence (DIAGNOdent) and QLF, for quantification of white spot lesions adjacent to fixed orthodontic appliances; 2) to determine the inter-observer agreement for DIAGNOdent and QLF methods for quantification of incipient enamel lesions adjacent to fixed orthodontic appliances. Forty-one premolar teeth with visually sound smooth surfaces or various stages of non-cavitated natural caries lesions were included in the study. Orthodontic brackets were fixed adjacent to the lesions to simulate the clinical conditions during orthodontic treatment with fixed appliances. In order to quantify the severity of the lesion adjacent to the brackets, all teeth were measured both with DIAGNOdent and QLF. For DIAGNOdent the highest readout was registered whereas the mean fluorescence loss was registered for QLF. Furthermore, twenty samples were randomly selected and measured repeatedly by four operators both by DIAGNOdent and QLF. The teeth were sectioned into 300 µm thick slices using a water-cooled diamond saw and the slices were then manually ground to 80-100 µm thickness. Microradiography was performed to provide a gold standard for verification of mineral loss. Pearson's correlation coefficient was employed to assess the correlation between the two fluorescence methods and the gold standard. Intra-class correlation coefficient (ICC) was calculated for assessment of the inter-observer agreement for DIAGNOdent and QLF, respectively. The correlation coefficients between mineral loss and the two methods were 0.64 and 0.84 for DIAGNOdent and QLF, respectively. The ICC values were 0.80 and 0.93 for DIAGNOdent and QLF. Thus it can be concluded that QLF may be the favourable method for quantification of incipient carious lesions around fixed orthodontic appliances. |