Qvist 2017.

Study characteristics
Methods	RCT, parallel group Duration of study: 84 months Setting: 9 dental hospitals in Copenhagen
Participants	521 children, 521 permanent teeth Age: 6–17 years, mean 11.9, SD 2.2 years ≥ 1 permanent molar with caries limited to half of the dentin without pulpal involvement Inclusion criteria: ≥ 1 occlusal lesion requiring restorative treatment clinically or radiographically assessed; radiographic depth of lesion limited to half of the dentine Exclusion criteria: the occlusal lesion had communication with an approximal caries lesion or occlusal/approximal restoration; tooth was hypomineralised; serious chronic diseases that affect caries experience and activity
Interventions	2 treatment arms Group 1 (368 participants, 368 teeth): sealing over caries. Group 2 (153 participants, 153 teeth): composite resin restorations; extent of caries excavation not reported.
Outcomes	Primary outcome Survival of fissure sealant until replaced by a restoration and longevity of sealants and restorations until retreatment Secondary outcome Caries progression beneath sealing or restoration
Notes	Funding: University of Copenhagen; 3M ESPE, Danish Employees Dentists Organization, Ivoclar Vivadent, Stiftelsen Patentmedelsfonden för Odontologisk Profylaxforskning and VOCO for donation of materials and/ or financial support for presentations.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Allocation sequence described in detail. Central randomisation at University of Copenhagen, sequentially numbered, sealed envelopes.
Allocation concealment (selection bias)	Low risk	Central randomisation at University of Copenhagen, sequentially numbered, sealed envelopes.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "Blinding was not possible." Blinding not possible – operator knew caries removal technique.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Blinding not confirmed, all teeth were restored with different materials, which probably looked different in the treatment arms.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All randomised teeth were included in analyses.
Selective reporting (reporting bias)	High risk	Although all expected outcomes were reported, and the lesions were grouped into those limited to enamel and those extending into dentine in the baseline characteristics table, the results tables presented data for enamel and dentine lesions together and there was insufficient information to extract the data based on lesion extent and only include the dentine lesions that were restored.
Other bias	Low risk	No other biases detected.