Chadwick 2005.

Study characteristics
Methods	Design: RCT with parallel design Number of participants: 508 Setting: children recruited from dental planning areas with high levels of caries and sealants were placed in community clinics, health centres and some in patient homes Country: UK Unit of randomisation: child Unit of analysis: child Follow‐up: mean (range): 1.34 years, SD 0.50 (12–30 months) Dropout: 11.6%
Participants	Number randomised: 508 children Number analysed: 449 children Age: mean 2.02 years, SD 0.29 (range 1–3 years) Sex: 251 (49%) boys and 257 (51%) girls Mean dmft score at baseline: d‐0.72, m‐0.49, f‐0.08 Inclusion criteria: children aged 18–30 months, with caries‐free primary first molars, with or without caries elsewhere in the mouth, at high risk of developing caries Exclusion criteria: unerupted primary molars and primary molars with dentinal caries (additional information provided by the author) Baseline caries risk of participants: high caries risk
Interventions	2 arms Glass ionomer (Ketac‐Fil Plus, Espe). GIC was applied to fissures of the occlusal surface with a flat plastic carver. Isolation method was with cotton wool rolls. No sealant. Study stated "placebo‐controlled" but no indication of placebo treatment. Co‐intervention: standard package of dental health education on feeding and healthy eating was delivered; child‐sized toothbrushes and toothpaste were given for brushing for the participants in both groups.
Outcomes	Study primary outcomes Incidence of fissure caries Sealant retention assessed as number of sealants present at the time of follow‐up examination Study secondary outcome Incidence of caries in other teeth Diagnostic criteria for caries: visual and tactile using BASCD criteria for caries by Pitts and Evans 1997
Notes	Funding: NHS Research and Development Programme in Primary Dental Care Trial register: registered (ISRCTN98615437) (additional information provided by the author) Inter‐evaluator consistency: no information provided Sample size: calculated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Children were randomly allocated to active and control groups." Comment: no additional information was provided by the author.
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided. No additional information provided by the author.
Blinding of participants and personnel (performance bias)‐Participants	High risk	Comment: blinding of participants usually not possible in this study design for sealants as they can see the material on tooth. No information provided on 'placebo.'
Blinding of participants and personnel (performance bias)‐ Operator	High risk	Comment: the operator could not be blinded as sealant was placed on 1 tooth and contralateral tooth served as control.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Comment: blinding of outcome assessor could not be performed in such studies.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Quote: "The overall dropout rate was 11.6%. At follow up, number of subjects in the test group was 221 (drop out rate 8.3%) and control group was 228 (drop rate 10.6%)." Comment: drop‐out similar in intervention and comparator groups but reasons for attrition not reported.
Selective reporting (reporting bias)	Low risk	Comment: all prespecified outcomes reported.
Other bias	Low risk	Comments: no evidence of other bias.