Marthaler 1970a.

Methods	Random allocation; indication of blind caries assessment (C); placebo‐controlled; 30% drop out (for all study groups combined) after 4 years (study duration = 4 years). Exclusions based on: use of orthodontic bands, and presence in all follow‐up examinations; any differential group losses not assessable.
Participants	43 children analysed at 4* years (present for all examinations). Age range at start: 7‐9 years (average = 8). Surfaces affected at start: 2.3 DMFS. Background exposure to fluoride: salt (suboptimal). Year study began: 1966. Location: Switzerland.
Interventions	FT versus PL (AmF group = 1250 ppm F). Home use/unsupervised, twice/three times a day/800 times a year estimated. Abrasive system: IMP.
Outcomes	2y*NetDFS increment ‐ (CA)cl+(DR)xr. Reported at 2 and 4 years follow ups. 1stmPF‐DFS. 1stmMD‐DFS.
Notes	Participants randomised (numbers for relevant groups NR). Baseline characteristics (age, DMFS, 1stmDMFS) 'balanced' (DFS baseline data NR). Clinical (V) caries assessment by two examiners; diagnostic threshold = CA and NCA; state of tooth eruption included NR. Radiographic assessment (2 postBW) by two examiners; diagnostic threshold = DR and ER; partial recording. "Sufficient agreement of examiners known from earlier work". *F solution used by all children after 2 years (final 4 years results not considered).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear