The aim of this study was to evaluate the reliability of a laser-induced infrared fluorescence method, DIAGNOdent, for measuring orthodontically induced white spot lesions. The subjects comprised 13 orthodontic patients, aged 13-17 years, who had recently completed fixed appliance therapy: 137 test teeth were selected, with white spot lesions on the facial or buccal smooth surfaces. An initial visual inspection was performed to localise and record the measuring region. The predetermined measuring regions were scanned to locate the sites of the highest reading. The readings and their corresponding sites were registered on the print out photographs. Following the measurement by the first examiner, the second and the third examiners took DIAGNOdent readings independently at the same lesion sites indicated on the photographs, under identical conditions. One week later, DIAGNOdent readings of the same lesions were retaken by the three observers working independently. Intra- and inter- examiner agreements on DIAGNOdent quantification of lesion severity were analysed by Intra-class correlation coefficient (ICC). The ICC values for intra-examiner agreement for the three examiners were 0.91, 0.97, and 0.98, respectively, with a mean value of 0.95, indicating excellent agreement. The ICC values for inter-examiner agreement were comparatively lower: 0.69 and 0.82 for the first and second measurements, respectively. It was concluded that the reliability of the DIAGNOdent readings on white spot lesions associated with orthodontic banding was good. Keywords: fluorescence, caries, smooth surface, reliability