Neuhaus 2012.

Study characteristics
Patient Sampling	Method of sampling: selected from a pool of extracted teeth Included conditions: visually sound surfaces or signs of demineralisation Teeth: permanent molars Sealants: no Restorations: all selected teeth had Class II amalgam restorations Surface: approximal root surfaces
Patient characteristics and setting	Age: not reported Sex: not reported Ethnicity: not reported Country: Switzerland Setting: "a pool of extracted teeth" Number of participants/teeth/sites: 80 teeth in total, 30 teeth where proximal restoration margins extended onto the root surface, 30 root surfaces Prevalence: 20/30 = 0.67 Concern that this study reports secondary caries which may not be applicable to primary caries setting and therefore differs to our review question
Index tests	Category of test: radiograph (bitewing), laser fluorescence pen Model set up: "The study teeth were mounted in pairs between two sound teeth, whose roots were embedded in composite resin, in order to obtain a tight contact" Sequence of test(s): index tests carried out prior to reference standard Examiner training and calibration: no training or calibration, "Two trained examiners assessed the radiographs independently" Threshold applied: radiographic examination: classified as no radiolucency or radiolucency in dentine; laser fluorescence pen threshold: > 22" Device specifics: "Bitewing radiographs (BW) were taken of all blocks using X‐ray machine (HDX Dental EZ, USA) and double Kodak Insight films (22 mm x 35 mm, Kodak, Rochester, MN, USA) at 65 kV, 7 mA and an exposure time of 0.09 s.The source‐to‐film distance was 6100 mm. Close to the object on the focus side, a 5‐mm‐wide plastic mould was placed to simulate soft tissues"; "LF pen measurements were carried out using... 0.4 mm thickness: TWDG (tapered wedge‐shaped) 0.7 mm width. The device was calibrated before each measurement according to the manufacturer's instructions"
Target condition and reference standard(s)	Category: histology Sequence of index test and reference standard: reference standard followed all index tests Training of examiner: not reported, although 2 examiners were used who reached a consensus Blinding to index test: not reported but assumed to be the case Multiple tests: no Site selection: the teeth were ground longitudinally until 1 mm before the site of measurement Target condition: caries free or root caries
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: not reported Participants receiving both tests but excluded from results: 0
Comparative
Notes	Data from pre‐specified thresholds for tapered wedge‐shaped (TWDG) tip have been used in the analyses
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?	Yes
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?	Yes
If a threshold was used, was it pre‐specified?	Yes
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?			Low concern
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?	Yes
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