Torell 1965a.

Methods	Random allocation; double‐blind (A); placebo‐controlled; 20% drop‐out rate after 2 years (study duration = 2 years). Natural losses mainly; differential group losses.
Participants	285 children analysed at 2 years (available at final examination). Average age at start: 10 years. Surfaces affected at start: 11.7 DMFS (from sample randomised). Background exposure to fluoride: none reported. Year study began: 1962. Location: Sweden.
Interventions	FT versus PL (SMFP group = 1000 ppm F). Home use/unsupervised, twice a day instructed but daily frequency assumed, post‐brushing water rinse instructed. Abrasive system: Ca carbonate.
Outcomes	2yDMFS increment ‐ (CA)cl. Reported at 2 years follow up. MD‐DMFS. FS.
Notes	Participants randomised (N = 357). Baseline characteristics (DMFS, MD‐DMFS) 'balanced'. Clinical (VT) caries assessment by one examiner, diagnostic threshold = CA; radiographic assessment (BW) by two examiners; diagnostic threshold = DR. State of tooth eruption included NR. Intra‐examiner reproducibility check done for clinical caries in a sample; 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