Muhler 1955.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 22% drop out after 1 year (study duration = 1 year). Reasons for attrition NR; differential group losses.
Participants	444 children analysed at 1 year (available at final examination). Age range at start: 6‐16 years. Surfaces affected at start: 9.3 DMFS. Background exposure to fluoride: data not available for fluoridation status of site. Year study began: in/before 1954. Location: USA.
Interventions	FT** versus PL (SnF2 group = 1000 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: heat‐treated Ca orthophosphate.
Outcomes	1yDMFS increment ‐ cl+xr. Reported at 6 m and 1 year follow ups. DMFT.
Notes	Participants randomised (N = 568). Baseline characteristics (DMFS) 'balanced'. Clinical (VT) caries assessment by one examiner, diagnostic threshold = NR. Radiographic assessment by one examiner; diagnostic threshold = NR. State of tooth eruption included = NR. Criteria for caries diagnosis reported to have been carefully standardised, diagnostic errors NR. **NaF‐heat treated Ca orthophosphate toothpaste group not considered (abrasive system known to be incompatible with NaF).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear