Interproximal caries detection: near-infrared light transillumination (NILT) compared to bitewing radiograph


Dental caries is the most prevalent chronic disease worldwide. In its early states caries is reversible so early diagnosis monitoring and management are important. Caries detection via a visual-tactile approach is routinely used although frequently supported by radiography. However, the sensitivity and accuracy of bitewing radiographs is not high particularly for enamel lesions, so a variety of light-based alternatives have been tested.  Near-infrared light transillumination (NILT) is a photo-optical method used for caries detection by employing a long-wave light against the side of the tooth.

The aim of this review was to evaluate the accuracy of the near-infrared light transillumination (NILT) for the detection of interproximal dental caries in permanent dentition when compared to bitewing X-ray (BW).


Searches were conducted in the Medline/PubMed, Scopus, Web of Science, Cochrane Central Register of Controlled Trials, LILACS/BBO and Opengrey databases.  In vivo studies comparing near-infrared light transillumination (NILT) and bitewing (BW) radiography for the detection of inter-proximal primary caries lesions in permanent human teeth were considered.  Two reviewers independently selected studies with data being extracted by a single reviewer before been verified by a second reviewer.  Risk of bias was assessed using the QUADAS-2 checklist. Sensitivity and specificity was pooled using a random effects model summary receiver operator characteristics (SROC) curves were constructed, and the area under the SROC curve (AUC) was calculated.  certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system .


  • 13 studies (12 cross-sectional, 1 retrospective cohort) published between 2010 and 2019 were included.
  • 4 Studies were published in Germany 2 each in the USA, Italy and Turkey and one each in Switzerland, Bulgaria and the United Arab Emirates.
  • 6 studies were considered to be at low risk of bias, 3 at high risk and 3 at unclear risk
  • 6 studies contributed to the meta-analysis
    • pooled sensitivity = 0.97 (0.96 to 0.98)
    • pooled specificity = 0.91 (0.91 to 0.92)
    • Symmetric (0.9837) and asymmetric (0.9836) SROC showed a high discrimination and determination effect of NILT.


The authors concluded: –

… in the clinical setting the accuracy of NILT is reasonably comparable to that of BW for detection of interproximal carious lesions in the permanent dentition. However, standardization among further in vivo studies is required to strengthen the certainty of the conclusion.


The authors have searched a good range of databases identifying 13 relevant studies. The main reference standard for the study was bitewing radiographs (BW) and when interpreting the findings of the review this needs to be taken into consideration as BW themselves are a far from ideal diagnostic test.  Three of the included studies involved cavity opening and visual confirmation as the reference standard which may be more appropriate but is a destructive process and would involve ethical considerations particularly in the case of early enamel lesions.  In assessing diagnostic test disease prevalence will influence the sensitivity and specificity as will the size and extend to lesions so ideally new diagnostic test should be tested against a board spectrum of disease. The authors indicated that at least 3 studies were at high risk of spectrum bias. The findings suggest that NILT performs to a similar level to BW although only a small number of studies could be included in the meta-analysis. Additional well conducted studies across  a range of disease prevalence, settings, and age groups would be helpful to better  understand the role of NILT in caries diagnosis.


Primary Paper

Ortiz MIG, de Melo Alencar C, De Paula BLF, Magno MB, Maia LC, Silva CM. Accuracy of near-infrared light transillumination (NILT) compared to bitewing radiograph for detection of interproximal caries in the permanent dentition: A systematic review and meta-analysis. J Dent. 2020;98:103351. doi:10.1016/j.jdent.2020.103351

Review protocol on PROSPERO






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