Muller‐Bolla 2013.

Methods	Trial design: Split‐mouth design, sealant tooth randomly assigned among tooth pair Follow‐up: 12 months
Participants	Location: Children were recruited from elementary schools (n = 16) located in the low socio‐economic zones of Nice, France (school‐based dental sealant (SBDS) program) Inclusion criteria: Children had to have 1 or 2 tooth pairs of totally erupted permanent first molars without caries (ICDAS codes 0 to 2). Age at baseline: mean 6.4 (SD ± 0.4) years Gender: 133 girls, 143 boys Baseline caries: mean d3‐6mft 2.8 (SD ±3.3); mean D3‐6MFT‐M1 0.2 (SD ±0.5). At baseline, 33.1 % of the first graders were totally caries free. However, 90% of children were classified to have high caries risk at baseline, although they regularly used fluoride toothpaste, and none drank soft drinks or ate snacks apart from the three main meals and the classical 4 o'clock snack. Caries risk was considered high when children had one or more carious lesions (ICDAS codes 3‐6) on temporary or permanent teeth, visible dental plaque in large amount without disclosing agent (score 3 of plaque index de Löe and Silness), or a positive salivary test result (caries risk salivary test consisted in the collection of stimulated saliva samples to assess the Streptococcus mutans and Lactobacillus counts). Number randomly assigned: 276 children with 457 tooth pairs Number evaluated: 253 children with 421 tooth pairs
Interventions	Comparison: resin‐based sealant versus no sealant Tooth pair: occlusal surface of 1 tooth sealed with resin‐based sealant (light‐curing Delton plus containing fluoride); occlusal surface of the other tooth of the tooth pair served as a control without sealant. Sealants were applied to completely erupted occlusal surfaces of permanent first molars by 1 dentist assisted by a sixth‐year dental student. Sealing was performed in the first or second grades. No resealing. Co‐interventions: The children were educated on the importance of considering dental caries as a localised disease, toothbrushing with fluoride toothpaste, and adopting healthy dietary habits
Outcomes	Sound or carious occlusal surface of molar. Caries status was recorded using visual methods and tactile methods when necessary, after toothbrushing performed by the examiner. Examinations were performed in the school's infirmary using portable equipment that included an air‐water syringe, disposable intraoral mouth mirrors, and a LED headlight for a visual assessment. Adverse events
Notes	Intra‐evaluator reliability: Kappa co‐efficient 0.75 for diagnosis of caries (1 investigator). Funding source: Dentsply, the city of Nice, the Conseil General des Alpes Maritimes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The random allocation sequence was generated using block of four by one of the authors". Correspondence from the author: "A block corresponded to 4 children with parental consent and examined in alphabetical order in one class (AABB, ABBA, BAAB, BBAA, ABAB, BABA). In case of one tooth pair, A indicated sealant in cadran 1 or 3 (sealant on 16 for pair 16‐26, and on 36 for pair 36‐46); B indicated sealant in cadran 2 or 4 (26 for pair 16‐26, and 46 for 36‐46). In cases where both pairs were included, the upper pair (16– 26) was used as a reference for randomization. When a maxillary permanent molar was randomly assigned to be sealed, the mandibular permanent molar to be sealed was on the opposite side (16– 36 or 26– 46 were sealed)." Comment: Although the information on sequence generation was incomplete (how the 6 alternatives of blocks and their order were created), this domain was graded as low risk of bias because we saw that in split‐mouth studies the risk of selection bias is in any case minimal
Allocation concealment (selection bias)	Low risk	Comment: Although the method of allocation of a tooth to an intervention within a tooth pair was incomplete, this domain was graded low risk of bias because we saw that in split‐mouth studies the risk of selection bias is in any case minimal
Blinding? (Outcome assessors)	High risk	Comment: this domain was graded as having high risk of bias because we saw that blinding of outcome assessor in clinical trials of this nature cannot be performed, as sealants are visible
Incomplete outcome data? (Caries efficacy outcomes)	Low risk	Missing data: 23 (6.7%) children after 1 year. Quote: "One year later, 23 children (6.7%) had left the school or were absent on the examination day". Comment: Missing data rate under 25%
Selective reporting (reporting bias)	Low risk	Outcomes reported: incidence of dentinal carious lesion on treated occlusal surfaces of molars, retention Comment: Pre‐specified caries outcomes (in methods) were reported in the pre‐specified way
Free of other bias? Comparability of the groups	Low risk	Comment: Split‐mouth design with similar conditions among the teeth during the follow‐up
Free of other bias? Co‐interventions	Low risk	Comment: Similar co‐interventions among the teeth during the follow‐up