Detection of Occlusal Caries by Laser Fluorescence: Basic and Clinical Investigations

Abstract

Summary Objectives: Motivated by the poor sensitivity of visual inspection and radiography in the detection of occlusal caries hidden under a macroscopically sound surface, we explored the implementation of fluorescence as an alternative diagnostic tool. Methods and Results: Fluorescence spectroscopic investigations revealed considerable contrast between sound and carious tooth hard tissue when excited by red (655 nm) light. For this excitation wavelength on inorganic tooth components only negligible fluorescence was observed. Advanced caries, however, show readily detectable fluorescence. The latter, at least in part, originates from porphyrins produced by bacteria. Based on red excited fluorescence a novel caries detector was constructed (DIAGNOdent™, KaVo, Biberach). The system measures fluorescence quantitatively. The minimum amount of protoporphyrin IX that can be detected is approximately 1 pmol. Clinical investigations yielded a sensitivity ≥0.92 in detection of occlusal caries, compared to 0.63 for bitewing radiography, and ≤0.62 for visual inspection. Intra- and interexaminer reproducibility tests resulted in Cohen's Kappa value of 0.93 in vivo. Conclusions: Detection of occlusal caries with the DIAGNOdent™ system has a much better sensitivity than conventional methods. Because the readings are correlated to the status of the carious lesion, treatment decisions can be aided by the measurement. Additionally, excellent reproducibility allows monitoring of lesions over time to facilitate preventive based management of dental decay.