Hargreaves 1973a.

Methods	Quasi‐random allocation; double‐blind (A); placebo‐controlled; 5% drop out after 3 years (study duration = 3 years). Reasons for attrition NR; exclusions based on presence in all follow‐up examinations; any differential group losses not assessable.
Participants	284 children analysed at 3 years (present for all examinations). Age at start: 9 years. Surfaces affected at start: 6.3 DFS. Background exposure to fluoride: none reported. Year study began: 1968. Location: UK.
Interventions	FT versus PL (SMFP group = 2400 ppm F). Home use/unsupervised, daily frequency assumed. Abrasive system: Al oxide trihydrate.
Outcomes	3yNetDFS increment ‐ (E+U)(CA)cl+(ER)xr. Reported at 3 years follow up. DFT. DMFS. DMFT. ECSI.
Notes	Participants randomised (N = 298); numbers by group NR. Baseline characteristics (age, TAR, DFS, DMFS, DFT, DMFT, ECSI) 'balanced'. Clinical (VT) caries assessment by two examiners; diagnostic threshold = CA; radiographic assessment (2 postBW) by two examiners; diagnostic threshold = ER. State of tooth eruption included = E/U. Diagnostic errors NR.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	High risk	C ‐ Inadequate