Torell 1965.

Methods	Random allocation; double‐blind (A); placebo‐controlled; 13% drop‐out rate after 2 years (study duration = 2 years). Natural losses mainly; no differential group losses.
Participants	668 children analysed at 2 years (available at final examination). Average age at start: 10 years. Surfaces affected at start: 14.5 DMFS (from sample randomised). Background exposure to fluoride: none reported. Year study began: 1962. Location: Sweden.
Interventions	FT (2 groups) versus PL(2 groups) (SnF2 group = 1000 ppm F, NaF group = 1100 ppm F). Home use/unsupervised, twice a day instructed but daily frequency assumed, post‐brushing water rinse instructed. Abrasive system: Ca pyrophosphate in SnF2 toothpaste and its placebo, Na bicarbonate in NaF toothpaste and its placebo.
Outcomes	2yDMFS increment ‐ (CA)cl. Reported at 1 and 2 years follow ups. MD‐DMFS. FS. Proportion of children with new carious lesions (U)xr.
Notes	Participants randomised (N = 766). Baseline characteristics (DMFS, MD‐DMFS) 'balanced'. Clinical (VT) caries assessment by two examiners, diagnostic threshold = CA; radiographic assessment (BW) by two examiners; diagnostic threshold = DR. State of tooth eruption included NR. Inter‐ and intra‐examiner reproducibility checks done for clinical caries in 4 and 2% sample respectively; duplicate examination of x‐rays records done and any discrepancies discussed before final diagnosis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear