Park 2018.

Study characteristics
Patient Sampling	Method of sampling: selected Included conditions: unclear Teeth: permanent incisors (25), premolars (11) and molars (15) Sealants: not reported Restorations: not reported Surface: smooth
Patient characteristics and setting	Age: not reported Sex: not reported Ethnicity: not reported Country: Germany Setting: extracted teeth Number of participants/teeth/sites: 51 teeth, 133 sites Prevalence: enamel 0.73, dentine 0.05
Index tests	Category of test: spectral domain OCT Sequence of test(s): ordering of tests not clear Examiner training and calibration: examiner was an experienced user of OCT Threshold applied: ICDAS 0‐4 was applied to OCT Device specifics: Telesto II (Thorlabs GmbH, Dachau, Germany); "Technical specifications of the SD‐OCT system were as follows: center wavelength 1310 nm ± 107 nm, sensitivity ≤ 106 dB, axial/lateral resolution < 7.5 (air)/15 μm, field of view ≤ 10 mm × 10 mm × 3.5 mm (pixel size 700 × 700 × 512), imaging speed 48–91 kHz, and A‐scan average 1–5"
Target condition and reference standard(s)	Category: visual Sequence of index test and reference standard: unclear ordering of tests Training of examiner: not reported Blinding to index test: unclear Multiple tests: no Site selection: specified regions of interest Target condition: ICDAS 0‐4
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	3 studies in this paper that could have been included. The first was in vitro, OCT (swept source) versus histology, could not be included as no data were presented. The second, in vitro part (OCT ‐ spectral domain) is included, above. The third in vivo element (OCT ‐ spectral domain) but samples participants with caries up to ICDAS 4, so we had to exclude this study
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	Yes
If multiple tests were applied were different examiners used for each (in vivo)?
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	No
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?		High 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