Forsman 1974a.

Methods	Random allocation; double‐blind (A); placebo‐controlled; 16% drop out after 2 years (study duration = 2 years). Reasons for attrition described with respective total numbers: change of residence/school, ortho treatment, did not wish to continue; no differential group losses reported (but not assessable).
Participants	394 children analysed at 2 years (available at final examination). Age range at start: 10‐12 years. Surfaces affected at start: 12.9 DMFS. Background exposure to fluoride: mouthrinse. Year study began: in/before 1970. Location: Sweden.
Interventions	FT (2 groups) versus PL (one SMFP group = 250 ppm F, another SMFP group = 1000 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: Ca carbonate in all toothpastes.
Outcomes	2yDMFS increment ‐ (NCA)cl. Reported at 2 years follow up. BLMD‐DFS (clin). MD‐DFS (x‐ray). Proportion of children with new smooth surface caries.
Notes	Participants randomised (N = 469); numbers by group NR. Baseline characteristics (dental age, DMFS) 'balanced'. Clinical (VT) caries assessment by one examiner, diagnostic threshold = NCA. Radiographic assessment (postBW) by one examiner; diagnostic threshold = ER. State of tooth eruption included = NR. Diagnostic errors NR.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear