Bravo 2005.

Methods	Trial design: cluster‐randomised design, where 15 school classes were randomly assigned to 3 treatment arms. School classes were conducted at 5 primary schools, which were selected at random from a group of 21 schools. Mean number of teeth per child was 3.5 (a child was an additional cluster) Follow‐up period: 9 years: 4‐year caries preventive programme, plus 5 years after active programme Study was started in 1990
Participants	Location: Spain, a non‐fluoridated city (0.07 ppm F ion in tap water) Children were from middle or lower‐middle socioeconomic status families Inclusion criteria: children with sound permanent first molars Age at baseline: 6 to 8 years (average age 7 years) Gender: girls 68% in sealant group, 47% in varnish group Baseline caries: sealant group: mean dft 2.24 (SD 2.59); fluoride varnish group: 2.42 (SD 3.26) Number randomly assigned: 362 (112 in sealant group; 115 in fluoride varnish group; 135 in control group) Number evaluated: 75 (37 in sealant group; 38 in fluoride varnish group; 45 in control group). Only children who (1) had at least 1 completely erupted and sound permanent molar at any period during the active programme, and (2) were examined at 4‐year follow‐up were included in the analysis at 9 years
Interventions	Comparison: resin‐based sealant vs fluoride varnish Group 1: visible‐light‐polymerised opaque Delton Sealants were applied to completely erupted occlusal surfaces of permanent first molars by 1 dentist plus an assistant, who used portable equipment. After 6, 12, 18, 24 and 36 months, sealant was applied to molars that had not previously erupted and was replaced if partial or total loss had occurred since the previous examination Group 2: fluoride varnish (Duraphat, sodium fluoride (NaF)) Varnish was applied to partially or fully erupted occlusal surfaces of permanent first molars by 1 dentist plus an assistant, who used portable equipment. After 6, 12, 18, 24, 30, 36 and 42 months, varnish was also applied to newly erupted molars and was reapplied to all those that were still sound Group 3: control group without treatments (Only sealant and fluoride varnish groups were used in this review) Co‐interventions: none reported
Outcomes	Sound or carious occlusal surface of molar Outcomes were assessed by a dentist. Examinations were made with an exploration probe and a flat mirror Number of visits to the dentist for repair of sealant or fluoride varnish application Adverse events
Notes	Inter‐rater agreement: Kappa coefficients for intra‐examiner and inter‐examiner reliability > 0.68 in all measurements Sealant retention: complete sealant retention 63% at 4‐year follow‐up and 39% at 9‐year follow‐up Funding source: Spain Ministry of Education and Science. Study authors were from the university
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote from author correspondence: "Each school‐class was numbered. By using a list of random numbers from a statistical book each school‐class was assigned to the 3 groups. When 1 group was full of children (i.e. the sum of the children in the assigned school‐classes was above the sample size needed for a group), then that group was excluded for new random assignations. The school classes allocation was not completely random, since it had some restrictions: For example, the total number of children should be at last more or less equilibrated between the three groups (thus, after the first random assignment, the following were conditional)" Comment: Randomisation procedure was not completely random
Allocation concealment (selection bias)	High risk	Comment: The non‐random method used for sequence generation would likely not allow for allocation concealment
Blinding of outcome assessor (detection bias)	Unclear risk	Quote: "A different dentist examined the subjects in a blinded fashion" Outcome assessor dentist did not have access to previous records (information was obtained from study authors) Comment: Blinding of outcome assessor was intended, but it remains unclear whether outcome assessor had information on study design
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Missing data: 18% for all 3 groups combined at 4 years (drop‐out rates by group not detailed) Comment: This domain was graded as having 'unclear' risk of bias because no information on drop‐outs was provided by group at 4 years of follow‐up At 9 years of follow‐up, this domain was graded as having 'high' risk of bias because proportion of participants assessed and included in the analysis was 33% (only children who had at least 1 completely erupted and sound permanent molar at any time period during the active programme, and were examined at 4‐year follow‐up, were included in the analysis at 9 years)
Selective reporting (reporting bias)	Low risk	Outcomes reported: caries response and sealant retention Comment: Pre‐specified outcomes (in methods) were reported in a pre‐specified way
Other bias	Low risk	Comparability of groups: Comment: Detailed description of demographic characteristics and caries risk level at baseline was given for groups available at 4 years and 9 years, and groups were assessed to be comparable Baseline mean dft in sealant group was 2.24 (SD 2.59) and in fluoride varnish group 2.42 (SD 3.26). Mean age in sealant group was 7.3 years, and in varnish group 7.6 years. Proportion of girls was 68% in sealant group and 47% in varnish group. Although proportion of girls was bigger in sealant group than in fluoride varnish group, assessment revealed that groups were in balance at baseline Co‐interventions: Quote: "The children received no toothbrushing, fluoride rinse, or fluoride tablet programs" Comment: This domain was graded as having 'low' risk of bias because no co‐interventions were included in the protocol