Short-wave infrared reflection for proximal caries detection

Abstract Objectives This in vitro study analyzed the diagnostic performance of short-wave infrared reflection at 1050, 1200, 1300 and 1550 nm for proximal caries detection. Materials and Methods 250 extracted posterior teeth with sound or carious proximal surfaces were examined using reflection imaging at 1050–1550 nm. Digital bitewing radiography served as an alternative index test and micro-computed tomography as reference standard. Two examiners independently evaluated all images and the reference standard twice using method-specific classification systems. Results The overall accuracy of reflection imaging at 1550 nm and bitewing radiography were similar between 72.4 and 73.2%. Reflection at 1050–1300 nm revealed higher values than bitewing radiography (78.4–80.0%). Short-wave infrared reflection showed increasing sensitivity and decreasing specificity for proximal carious lesions with increasing wavelength. Radiography revealed lower values of sensitivity paired with higher values of specificity than short-wave infrared reflection. Reflection imaging at increasing wavelength revealed increasing false positive and decreasing false negative ratings. Intra- and inter-examiner reliability revealed almost perfect agreement for all assessments. Conclusions Short-wave infrared reflection holds high diagnostic potential for proximal caries detection. At 1050 nm, reflection imaging reveals higher diagnostic accuracy than bitewing radiography and less tendency to overestimate caries than at 1200–1300 nm. The application of wavelengths longer than 1050 nm improves sensitivity and reduces specificity of short-wave infrared reflection. Clinical Relevance: As an alternative to bitewing radiography, short-wave infrared reflection at 1050 nm demonstrated the highest diagnostic potential and proved to be a clinically relevant non-ionizing option for the detection of proximal caries.