Light-based tests for early caries detection


While other approaches are available visual and tactile dental examinations is the mainstay of caries detection. Three types of illumination device mainly defined by wavelength, optical coherence tomography (OCT), near- infrared (NIR), and fibre-optic technology, including digital fibre optics (FOTI/DIFOTI) have potential for use in dental examination.

The main aim of this Cochrane review was to estimate the diagnostic test accuracy of different illumination tests for the detection and diagnosis of enamel caries in children or adults.


Searches were conducted in the Medline, Embase US National Institutes of Health Ongoing Trials Register and the World Health Organization International Clinical Trials Registry Platform databases and the reference lists of systematic review articles. In vitro and in vivo diagnostic accuracy studies comparing the use of illumination-based devices against a reference standard (histology, enhanced visual examination with or without radiographs, or operative excavation) were considered.  Studies involving participants with caries in dentine or frank cavitation were excluded. Two reviewers screened and selected studies and extracted data independently and in duplicate. Study quality was assesses using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Summary points of sensitivity and specificity with 95% confidence regions were determined.


  • 24 datasets from 23 studies evaluating 16,702 tooth surfaces were included.
  • 10 datasets (1171 tooth surfaces) evaluated OCT, 8 datasets (14,858 tooth surfaces) evaluated FOTI/DIFOTI, and 6 datasets (673 tooth surfaces) NIR.
  • 14 studies were judged to be of high concern for participant selection, due to selective participant recruitment, a lack of independent examiners, and the use of an in vitro study design.
  • For all included illumination devices, the summary estimates were: –
    • Sensitivity = 0.75 (95%CI; 0.62 to 0.85)
    • Specificity = 0.87 (95%CI; 0.82 to 0.92)
    • Diagnostic odds ratio = 21.52 (95%CI; 10.89 to 42.48).
    • This means that examination a 1000 tooth surfaces with a prevalence of enamel caries of 57% you would expect 142 tooth surfaces to be classified as disease free when caries was present (false negatives), and 56 tooth surfaces to classified as carious in the absence of caries (false positives).
  • Analysis indicated a difference in the sensitivity of the different devices (Chi2(2) = 31.24, P < 0.01) with a higher sensitivity = 0.94 (95%CI; 0.88 to 0.97) for OCT compared to NIR =0.58(95%CI; 0.46 to 0.68) and FOTI/DIFOTI = 0.47 (95%CI; 0.35 to 0.59), but no meaningful difference in specificity.
  • The certainty of the evidence was rated as low.


The authors concluded: –

Of the devices evaluated, OCT (optical coherence tomography) appears to show the most potential, with superior sensitivity to NIR and fibre-optic devices. Its benefit lies as an add-on tool to support the conventional oral examination to confirm borderline cases in cases of clinical uncertainty. OCT is not currently available to the general dental practitioner, and so further research and development are necessary. FOTI and NIR are more readily available and easy to use; however, they show limitations in their ability to detect enamel caries but may be considered successful in the identification of sound teeth.

Future studies should strive to avoid research waste by ensuring that recruitment is conducted in such a way as to minimise selection bias and that studies are clearly and comprehensively reported. In terms of applicability, any future studies should be undertaken in a clinical setting that is reflective of the complexities encountered in caries assessment within the oral cavity.


This diagnostic test accuracy review is one of a series of caries diagnosis reviews being undertaken by Cochrane Oral Health using the same generic protocol. This review looks at a number of illumination-based devices that transmit various wavelengths of light though the tooth which are then observed or recorded in some way. The reviews have undertaken an extensive search and restricted inclusions to only those studies providing sufficient information to construct 2×2 tables to properly assess true positives, true negatives, false positives, and false negatives. The findings indicate that these devices may be valuable. However, there are concerns regarding the quality of the included studies in particular the prevalence of caries in the samples. For example, it was noted by the reviewers that the OCT device which has the highest sensitivity demonstrated higher accuracy when the caries prevalence was higher which could have been influenced by the sample measure.  In addition, 11 of the data sets were from in vitro studies which may raise concerns related to the clinical translation of the findings.


Primary Paper

Macey R, Walsh T, Riley P, Hogan R, Glenny A-M, Worthington HV, Clarkson JE, Ricketts D. Transillumination and optical coherence tomography for the detection and diagnosis of enamel caries. Cochrane Database of Systematic Reviews 2021, Issue 1. Art. No.: CD013855. DOI: 10.1002/14651858.CD013855.

Other references

Cochrane Oral Health Blog – Light‐based tests for the detection and diagnosis of early tooth decay

Dental Elf – 6th Jan 2021

Fluorescence devices for caries detection

Dental Elf – 14th Dec 2020

Root caries: detection and diagnosis





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