Laser fluorescence is a predictor of lesion depth in non-cavitated root carious lesions - an in vitro study.

Background: This in vitro study was designed to compare the assessment of carious root surfaces using laser fluorescence or visual assessment and µCT.

Methods: A total of 107 extracted human teeth were included in the study. For the subsequent assessment, a clinical evaluation according to Ekstrand and Nyvad criteria, laser fluorescence measurements (DIAGNOdent-Pen©), and µCT imaging (Bruker Skyscan 1172) of the included root surfaces were performed. For cavitated lesions, the surface was reconstructed on µCT. Target parameters were: clinical appearance, laser fluorescence reading (0-99), and lesion depth in µm (µCT). The statistical analysis included chi² and Spearman-Rho tests.

Results: Laser fluorescence values were significantly higher (p < 0.01) in leathery non-cavitated (median [IQR]: 73.50 [48.00]) and cavitated (88.50 [29.00]) surfaces than in hard intact surfaces (7.00 [35.00]). In addition, laser fluorescence values showed a significant correlation with lesion depth for non-cavitated surfaces (0.750; p < 0.01). Further statistically significant correlations were not detectable. Regression analysis showed that the laser fluorescence values increased with increasing demineralization depth (β: 0.648, CI95: 0.631-1.053; p < 0.01).

Conclusion: Laser fluorescence measured by DIAGNOdent© is a predictor for the depth of demineralization in carious root caries lesions with intact surfaces. Considering the limitations of this in vitro study, laser fluorescence is suitable for assessing the depth extent of (non-cavitated) root caries lesions and is a tool for clinical diagnosing and assessing the course of lesion development.