Foley 2004.

Study characteristics
Methods	RCT, parallel groups Duration of study: 24 months Setting: 1 University in Scotland, UK
Participants	44 children, 79 primary teeth Age: range 3.7–9.5 years, mean 6.8 years Caries experience: any caries depth, as long as lesions having reached the pulp of the tooth Inclusion criteria: children requiring ≥ 1 pair of restorations in their primary molar teeth; teeth had to be in different quadrants and had to be clinically and radiographically asymptomatic Exclusion criteria: previously restored cavities
Interventions	3 treatment arms (we did not include data from group 1 as Black Copper Cement is not commonly available or used) Group 1 (36 teeth): participants given option for local anaesthesia; isolation with cotton wool rolls and saliva ejector; instrumentation of cavitated lesions limited to gaining access to caries, removal of gross soft caries only and the preparation of a cavity, sufficient to allow an adequate bulk of restorative material to be placed (i.e. ≥ 3 mm); for non‐cavitated lesions, access to the carious dentine was made using a small, round, high‐speed diamond bur to penetrate through the enamel layer, followed by minimal use of the slow speed handpiece to make the cavity retentive; no other instrumentation was undertaken (i.e. PCR); for occlusal cavities, the cavity was lined with a thin mix of Black Copper Cement and restored with a conventional GIC (Chemfil Superior); covering of the restoration with petroleum jelly. Group 2 (43 teeth): caries treatment as described for group 1. Restoration with a conventional GIC (Chemfil Superior); covering of the restoration with petroleum jelly. Group 3 (41 teeth): participants given option for local anaesthesia; isolation with cotton wool rolls and saliva ejector; conventional preparation (i.e. removal of all carious dentine); restoration of the operator's choice, usually either a conventional glass ionomer cement or an amalgam restoration (where an amalgam restoration was placed, the cavity was also made mechanically retentive).
Outcomes	Clinical or radiographic failure (or both) after 24 month
Notes	Inconsistency in reporting of failed teeth: 7 + 7 + 10 failed teeth did not equal overall 31 failed teeth; some teeth with restoration failure had been excluded from analysis. Funding: Tattersall Scholarship, University of Dundee and the Carnegie Trust for the Universities of Scotland.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Molar pairs were randomly assigned using computer‐generated random numbers.
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding of participants/operators.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Only radiographic assessment blinded.
Incomplete outcome data (attrition bias) All outcomes	High risk	Teeth with restoration failures were excluded from study. (6 molars were withdrawn from the trial due to restoration failure and abscess formation.)
Selective reporting (reporting bias)	High risk	Not all relevant outcomes clearly presented (e.g. exact number of failed teeth). No information on outcome measure for clinical assessment of restorations.
Other bias	Low risk	No other biases detected.