Mergele 1968.

Methods	Stratified random allocation; double‐blind ('A'); placebo‐controlled; 22% drop out (for all study groups combined) after 3 years (study duration = 3 years). Reasons for attrition: natural losses to follow up; any differential group losses not assessable.
Participants	387 children analysed at 3 years (available at final examination). Age range at start: 10‐13 years (average = 11). Surfaces affected at start: 6.5 DMFS. Background exposure to fluoride: water. Year study began: in/before 1964. Location: USA.
Interventions	FT** versus 'PL' (SnF2 group = 1000 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: Ca pyrophosphate in fluoride toothpaste, IMP in control toothpaste.
Outcomes	3yNetDMFS increment ‐ cl. Reported at 3 years follow up. DMFT.
Notes	Participants randomised (numbers for relevant groups NR). Baseline characteristics (age, SAR, DMFS, DMFT) 'balanced'. Clinical (VT) caries assessment by one examiner, diagnostic threshold = NR. State of tooth eruption included = NR. Diagnostic errors NR. **Na N‐lauroyl sarcosinate/SMFP toothpaste groups not considered (additional non‐F active agent used in this group only).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear