# Short-Wave Infrared Reflectance at 1050–1550 nm for Proximal Caries Detection: An In Vitro Diagnostic Accuracy Study Validated by Micro-CT

## TL;DR

This study evaluates short-wave infrared reflectance imaging for detecting tooth decay, finding that a wavelength of 1050 nm offers the best balance of accuracy and reliability.

## Contribution

The study systematically evaluates the impact of wavelength selection on SWIRR diagnostic accuracy for proximal caries detection.

## Key findings

- SWIRR diagnostic performance varies with wavelength, showing higher sensitivity at longer wavelengths.
- 1050 nm SWIRR achieved the highest overall accuracy (80.0%) compared to digital bitewing radiography (73.8%).
- 1550 nm SWIRR had the highest sensitivity but increased false positives.

## Abstract

Background/Objectives: Short-wave infrared reflectance (SWIRR) imaging is a non-ionising approach for proximal caries detection; however, the diagnostic impact of wavelength selection in reflectance imaging has not been systematically evaluated. Methods: This in vitro diagnostic accuracy study assessed SWIRR at 1050, 1200, 1300 and 1550 nm for proximal caries detection, using micro-computed tomography as the reference standard and digital bitewing radiography (BWR) as the clinical comparator. A total of 250 extracted permanent posterior teeth with sound or carious proximal surfaces were examined. SWIRR and BWR images were independently evaluated twice by two calibrated examiners using method-specific criteria. Diagnostic performance was quantified by sensitivity, specificity and accuracy; examiner reliability was analysed using kappa statistics, and pairwise comparisons were performed using McNemar tests with Holm–Bonferroni correction. Results: Diagnostic performance of SWIRR was wavelength dependent, showing increasing sensitivity and decreasing specificity with longer wavelengths. The highest overall accuracy was observed at 1050 nm (80.0%), exceeding that of BWR (73.8%) while maintaining comparable specificity and higher sensitivity. At 1550 nm, sensitivity was highest but accompanied by an increase in false-positive findings. Conclusions: SWIRR demonstrates high diagnostic potential for proximal caries detection, with 1050 nm providing the most favourable balance between diagnostic accuracy and specificity.