It may be difficult to recognize composite resin restorations that are correctly shade-matched and well-placed by visual and tactile inspection alone--which can make the replacement of an existing resin restoration challenging. Many composite resins fluoresce under UV light, which can help dentists to detect resin material. This article explores a technique that utilizes a UV LED to cause composite resin to fluoresce. A UV/visible light spectrofluorometer was used to measure fluorescence excitation and emission maxima of 14 composite resin brands. Control samples of dentin and enamel were measured in a similar manner. Subsequently, each brand of composite resin was placed in extracted teeth and relative fluorescence was assessed. The composite resins were then removed and each tooth was inspected using UV light to detect remaining resin. Results from this study indicated that the optimal excitation wavelength was 385-395 nm, while 460 nm was determined to be the mean emission maxima. This study revealed three types of resin: highly fluorescent, moderately fluorescent, and weakly fluorescent. In each instance, the UV light revealed the presence of resin after all resin was believed to have been removed. Based on the results of this study, the use of UV illumination can be a useful technique for determining if composite resin has been removed completely.