Robertson 2013.

Methods	Randomised controlled trial
Participants	414 women (new mothers) and their infants were randomised. Inclusion criteria: woman located in the selected study communities, able to provide informed consent, with at least 20 natural teeth and unrestored caries or a previous child with documented early childhood caries; and with a child between 4.5 and 6.0 months of age (with or without teeth) Exclusion criteria: presence of orthodontic appliance and pregnancy Setting: local Indigenous Health Service (IHS) or tribally operated community dental clinics in four different American Indian communities in Oregon, Washington and Arizona USA (recruitment and study dates not reported) Important health characteristics reported: high prevalence, severity, and morbidity from ECC in the included. AI/AN communities
Interventions	Group 1 (n = 204 women randomised) Women received a 10% chlorhexidine (CHX) dental vanish treatment. Treatments (six) were applied by a trained hygienist or dental assistant after a brief rubber cup prophylaxis. They were applied in two stages: Stage 1 contained 10% CHX diacetate w/v suspended in a solution of Sumatra benzoin and alcohol. Stage 2 was a proprietary aqueous dispersion of inert methacrylate approved for use by the FDA under license K023671. The stage 2 coating was designed to prolong the contact time between the CHX and the tooth. The mean dose of CHX at each application visit was 37.4 mg (14); the cumulative mean dose was 224 mg. Group 2 (n = 210 women randomised) Women received placebo treatment which consisted of Sumatra benzoin and alcohol solution, delivered by the same providers and in the same setting as the active treatment. Intervention timing: intervention started between 5.5 to 6.0 months after birth (4 weekly treatments), with two further treatments one year and 18 months later (> 6 months intervention duration). Theory or model used as a basis for intervention: authors claimed: "extensive literature on the use of CHX‐containing products in different vehicles and concentrations to prevent caries"; no specific theory or model reported All participants: mothers' caries restored at enrolment
Outcomes	Data in meta‐analysis for: primary outcome: caries presence in primary teeth; secondary outcomes: none Additional narrative text for: none Tabulated data for: none Additional outcomes that had not been prespecified: Child: none reported. Mother: none reported
Notes	Funding: HRSA grant R40MC03621. CHXTechnologies, Inc., Toronto, Canada, provided the study products (Prevora® and placebo) without charge plus initial training for study staff. Declarations of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Study sites received consecutively numbered boxes of the study product which were numbered by the research pharmacist prior to shipment. Each box contained separate vials for each study visit. As participants were enrolled, they were assigned the next numbered product box".
Allocation concealment (selection bias)	Low risk	Boxes with study product and group assignment were numbered by the research pharmacist prior to shipment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Because the active and placebo study products were identical in colour, smell, taste, and viscosity, neither the participants nor study staff knew whether the product was active or placebo".
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	188/204 (92%) infants of mothers randomised to the treatment group, and 179/210 (85%) infants of mothers randomised to the control group, had a post‐baseline caries assessment.
Selective reporting (reporting bias)	Unclear risk	Unable to assess this domain without access to the study protocol
Other bias	High risk	No data showing similarity of groups on key characteristics provided. Additionally, possible intervention infidelity as the authors reported unequal application of intervention treatment across the groups.