Splieth 2001.

Study characteristics
Methods	Trial design: split‐mouth, sealant tooth randomly assigned Follow‐up: 2 years Started: 1995
Participants	Location: a private dental practice, Germany Inclusion criteria: children had to have ≥ 1 pair of equivalent FPMs without carious defects (occlusal surface sound or with initial lesion in enamel) Age at baseline: 5–8 years Sex: no information about boy to girl ratio Baseline caries: mean DMFS 0.2 Number randomly assigned: 98 children with 181 tooth pairs (on average 1.8 tooth pairs per child) Number evaluated: 92 at 2‐year follow‐up
Interventions	Comparison:resin‐based FS plus FV vs FV alone Tooth pair: occlusal surface of 1 tooth sealed with visible‐light activated Fissurit Transparent (VOCO GmbH, Cuxhaven, Germany); occlusal surface of the other tooth of the tooth pair applied with FV (Duraphat, sodium fluoride) FV was applied to all teeth including the sealed tooth Children were examined semi‐annually for 2 years – sealants were resealed if necessary and FV was applied to all teeth at examinations Co‐interventions: children were instructed about better oral hygiene and brushed their teeth under supervision (mean frequency of cariogenic food intake per day was 15, including a large number of sweetened drinks. Oral hygiene was moderate). 5% of the children used fluoride tablets during the study. (Fluoride concentration of public water supply was 0.1 ppm.)
Outcomes	Primary outcome Status of sound/caries in enamel/caries in dentine on occlusal surfaces Changes in DMF scores on whole‐mouth level Caries status was recorded by 1 experienced dentist according to WHO criteria, but without applying pressure to the explorer. Secondary outcome Mean treatment time for sealing and varnish application
Notes	Inter‐rater agreement: not considered Complete sealant retention: 81% at 24 months Funding source: no information
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Coin tossing. Additional information was obtained from study authors. Comment: random sequence generation was adequate.
Allocation concealment (selection bias)	Low risk	Comment: random sequence was adequately concealed up until the moment of allocation by flipping a coin to allocate a particular tooth, within a tooth pair, to be sealed.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding not possible as sealants could be seen; however, we judged it to be unlikely to be a significant source of bias in a study with a split‐mouth design.
Blinding of outcome assessor (detection bias)	High risk	No blinding of outcome assessor was performed. Comment: additional information was obtained from study author.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Missing data: 6/98 (6%) after 2 years. No description of reasons for dropouts. Comment: missing data rate < 25%.
Selective reporting (reporting bias)	Low risk	Outcomes reported: status of sound/caries in enamel/caries in dentine on occlusal surfaces; changes in DMF scores on whole‐mouth level; treatment time; sealant retention; costs. Comment: prespecified outcomes (in methods) were reported in the prespecified way.
Other bias	Low risk	Comparability of groups: Comment: split‐mouth design, which included sound surfaces or surfaces with initial lesions in enamel. With split‐mouth designs, we considered that both surfaces within a tooth pair would eventually be at equal risk for caries because of the long follow‐up (regardless of whether the diagnosis was sound surface or surface with enamel lesion). Co‐interventions: The fluoride concentration of the public water supply was 0.1 ppm. 5% of children used fluoride tablets during the study. Mean frequency of cariogenic food intake per day was 15, including a large number of sweetened drinks. Oral hygiene was moderate. Comment: split‐mouth design. Conditions were the same for both teeth within a tooth pair.