Simon 2016.

Study characteristics
Patient Sampling	Method of sampling: systematically sampled from attending population, no clear reporting of inclusion criteria regarding the caries status in sampled teeth Included conditions: participants scheduled for orthodontic extractions Teeth: permanent premolars Sealants: not reported Restorations: not reported Surface: occlusal and approximal
Patient characteristics and setting	Age: 12 to 60 years Sex: not reported Ethnicity: not reported Country: USA Setting: clinical setting, dental school, followed by extraction Number of participants/teeth/sites: 40 participants teeth, 109 occlusal and approximal sites Prevalence: occlusal ‐ enamel 0.82, dentine not reported approximal ‐ enamel 0.28, dentine not reported
Index tests	Category of test: NIR transillumination Sequence of test(s): index tests in the clinical setting in the following order: (i) conventional photos; (ii) cross‐polarized NIR; (iii) occlusal NIR; (iv) approximal NIR. Digital radiographs followed in the in vitro setting Examiner training and calibration: 1 examiner assessed the NIR and another the radiographs, each was an experienced dentist with over 20 years experience Threshold applied: S ‐ sound; E1 ‐ outer half of enamel; E2 ‐ inner half of enamel; D1 ‐ inner half of dentine; D2 ‐ second half of dentine Device specifics: "Light centered at 1310 nm is generated using a superluminescent laser diode (SLD), Model SLD72 (COVEGA Corporation, Jessup, MD) with 50 nm bandwidth. Fiber optic cables are used to deliver the light into a Teflon diffusing element" Note ‐ high applicability as device is not commercially available; "near‐IR transillumination and near‐IR reflectance probes that we fabricated in our laboratory for both occlusal and approximal lesions"
Target condition and reference standard(s)	Category: histology ‐ polarized light microscopy (PLM) was used for histological examination Sequence of index test and reference standard: index test then reference standard Training of examiner: not reported Blinding to index test: unclear Multiple tests: no Site selection: sectioned teeth Target condition: sound, inner/outer enamel, inner/outer dentine
Flow and timing	Participants with index test but no reference standard: 0 Participants with reference standard but no index test: 0 Time interval between tests: minimal Participants receiving both tests but excluded from results: 0
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Could the selection of patients have introduced bias?		Unclear risk
Are there concerns that the included patients and setting do not match the review question?			Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
If multiple tests were applied were different examiners used for each (in vivo)?	No
Could the conduct or interpretation of the index test have introduced bias?		Low risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			High
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Could the patient flow have introduced bias?		Low risk