In Vivo Comparison of Laser Fluorescence, Near-Infrared Transillumination, and Conventional Methods for Approximal Caries Detection

Background/Objectives: The aim of this in vivo study was to compare the diagnostic performance of conventional methods, including visual examination according to the International Caries Detection and Assessment System II (ICDAS II) and digital bite-wing radiography, with laser fluorescence (DIAGNOdent Pen) and near-infrared transillumination (DIAGNOcam and VistaCam iX-Proxi head) for the detection of non-cavitated approximal caries and to evaluate inter-examiner agreement. Methods: A total of 76 non-cavitated posterior teeth/surfaces from patients aged 15–60 years were independently assessed by three investigators. Enamel caries validation was based on combined ICDAS II and bite-wing radiographic findings, whereas dentin caries validation was established by cavity opening and direct clinical assessment. Diagnostic performance was evaluated using sensitivity, specificity, predictive values, accuracy, and receiver operating characteristic analysis. Inter-examiner agreement was assessed using the kappa coefficient, and diagnostic performance was compared using the McNemar test (p < 0.05). Results: Sensitivity ranged from 7.5% for visual examination to 94.3% for DIAGNOdent Pen, whereas specificity ranged from 12.6% to 100.0%. Bite-wing radiography demonstrated the highest diagnostic performance (accuracy: 87.7%; AUC: 0.775), followed by DIAGNOcam (accuracy: 86.0%; AUC: 0.738) and VistaCam (accuracy: 84.2%; AUC: 0.720). Although DIAGNOdent Pen showed high sensitivity, its specificity and overall accuracy were low (31.6%; AUC: 0.535). Inter-examiner agreement was substantial for visual examination, bite-wing radiography, and DIAGNOcam, moderate for VistaCam, and slight for DIAGNOdent Pen. Conclusions: Within the limitations of this study, combining visual examination, digital bite-wing radiography, and near-infrared transillumination methods may improve the detection of approximal caries, particularly at an early stage.