Marthaler 1965a.

Methods	Random allocation; double‐blind (A); placebo‐controlled; 66% drop out (for all study groups combined) after 3 years (study duration = 3 years). Main reason for high drop out: children leaving public school on completion of last compulsory year; exclusions based on variation in toothpaste provision and presence in follow‐up examinations; any differential group losses not assessable.
Participants	74 children analysed at 3 years (present for all examinations). Age range at start: 11‐14 years (average = 13). Surfaces affected at start: 18.9 DMFS. Background exposure to fluoride: salt (suboptimal). Year study began: 1958. Location: Switzerland.
Interventions	FT versus PL (AmF group = 1250 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: IMP.
Outcomes	3yNetDFS increment ‐ (CA)cl+(DR)xr. Reported at 3 years follow up. postMD‐DFS. antMD‐DFS. BL‐DFS. O‐DFS. DMFT. FT. FS. MT.
Notes	Participants randomised (numbers for relevant groups NR). Baseline characteristics (age, DMFS, DMFT) 'balanced' (DFS baseline data NR). Clinical (V) caries assessment by one examiner; diagnostic threshold = CA and NCA; state of tooth eruption included NR. Radiographic assessment (2 postBW) by one examiner; diagnostic threshold = DR and ER; partial recording. Diagnostic errors NR.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	A ‐ Adequate