Comparison of photothermal radiometry and modulated luminescence, intraoral radiography, and cone beam computed tomography for detection of natural caries under restorations

Objectives: The aim of this ex vivo study was to measure the sensitivity, specificity, and receiver operating characteristic (ROC) area under the curve (AUC) of a caries diagnostic system based on photothermal radiometry and modulated luminescence (PTR/LUM) and compare them with the values for digital intraoral radiography (IR) and cone beam computed tomography (CBCT) in detecting recurrent decay. Study Design: Class 2 composite restorations were prepared on 70 proximal surfaces: 35 with caries and 35 without caries. The gingival floor of the restored surfaces was assessed for caries under the restorations using each of the 3 modalities. Statistical calculations and analysis were performed using the R statistical computing environment. Results: The average scores for sensitivity among the 6 observers were 0.89 for PTR/LUM, 0.38 for IR, and 0.40 for CBCT. Sensitivity for PTR/LUM was significantly greater than sensitivity for IR and CBCT. Average scores for specificity were 0.83, 0.80, and 0.70 for PTR/LUM, IR, and CBCT, respectively. CBCT had significantly lower specificity. The AUC was 0.65 for IR and 0.59 for CBCT, which were significantly different. PTR/LUM had moderate intraobserver agreement. Conclusions: PTR/LUM, which involves non-ionizing radiation, can serve as a sensitive adjunct in early caries detection and monitoring.