Gish 1966.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 34% drop out after 3 years (study duration = 5 years). Reasons for attrition NR; any differential group losses not assessable.
Participants	328 children analysed at 3 years (available at final examination). Age range at start: 6‐14 years (average = 9). Surfaces affected at start: 3.9 DMFS. Background exposure to fluoride: water. Year study began: in/before 1963. Location: USA.
Interventions	FT versus PL (SnF2 group = 1000 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: Ca pyrophosphate.
Outcomes	3yDMFS increment ‐ cl+xr. Reported at 1, 2, 3, 4 and 5 years follow ups. DMFT.
Notes	Participants randomised (N = 500); numbers by group NR. Baseline characteristics (age, DMFS) 'balanced'. Clinical (VT) caries assessment by two examiners, diagnostic threshold = NR. Radiographic assessment (5‐7 BW); diagnostic threshold = NR. 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