Weisenstein 1972.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 42% drop out after 1.8 years (study duration = 1.8 years). Reasons for high drop out described: change of residence, absent on examination day; no differential group losses.
Participants	402 children analysed at 1.8 years (available at final examination). Age range at start: 5‐15 years (average = 9.5). Surfaces affected at start: 6.8 DMFS. Background exposure to fluoride: none reported. Year study began: in/before 1969. Location: USA.
Interventions	FT versus PL (NaF group = 1000 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: Ca pyrophosphate.
Outcomes	1.8yDMFS increment ‐ cl+xr. Reported at 9 m, 1.4 and 1.8 years follow ups. DMFT.
Notes	Participants randomised (N = 694). Baseline characteristics (age, gender, DMFS, DMFT) 'balanced'. Clinical (VT) caries assessment by two examiners, diagnostic threshold = NR. Radiographic assessment (7 BW) by two examiners; diagnostic threshold = NR. State of tooth eruption included = NR. Diagnostic errors NR. Results of one examiner chosen.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear