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Quantitative light-induced fluorescence (QLF, Inspektor Research Systems BV, Amsterdam, the Netherlands) has not been applied successfully interproximally. In this study, a multi-axis optical bench was developed and interproximal tooth assemblies were investigated with different angulations for excitation light and camera position. Extracted human premolars with interproximal lesions from the D1 to D3 level were selected (n = 20). Each pair of teeth with the same caries level was mounted in contact, modeling a natural situation, where both adjacent teeth have an interproximal lesion of similar extent and position. An optical bench was designed and built to hold an interproximal model, a video camera and a light guide from a modified QLF system. Camera and light guide could be swiveled around the model in the same plane independently. Images were captured from all models by varying camera and light direction each from 0° (buccal) to 90 ° (occlusal) to 180° (lingual) in steps of 30 ° using PC and software (QLF 1.97 h). The images were examined for the visibility of interproximal lesions. Interproximal lesions could be detected in all teeth, but visibility was strongly dependent on camera angulation and, to a lesser degree, on excitation angulation. No caries could be detected with the camera in the 90-degree position. The lesion was visible from both buccal and lingual directions in 10 teeth, while in the other 10 teeth the lesion could only be seen from either the buccal or lingual direction. Valid quantification of lesion severity using the QLF patch technique was not possible. The QLF system is able to detect interproximal lesions under certain conditions. Quantification is not possible with the current system. |