Ashley 1977.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 12% drop out (for all study groups combined) after 2 years (study duration = 2 years). Natural losses; any differential group losses not assessable.
Participants	489 children analysed at 2 years (available at final examination). Average age at start: 12 years. Surfaces affected at start: 9.1 DFS. Background exposure to fluoride: none. Year study began: 1973. Location: UK.
Interventions	FT versus PL (SMFP group = 1000 ppm F). School use/supervised, daily, 1g applied for 1 min, post‐brushing water rinse done (non‐fluoride toothpaste provided to all for home use). Abrasive system: IMP (main abrasive).
Outcomes	2yNetDFS increment ‐ (E+U)(NCA)cl+(ER)xr. Reported at 2 years follow up. PF‐DFS. MD‐BL‐DFS. MD‐DFS. DFS (U).
Notes	Participants randomised (numbers for relevant groups NR). Baseline characteristics (age, DFS, DMFS, DMFT) 'balanced'. Clinical (V) caries assessment by one examiner (FOTI used); diagnostic threshold = NCA. Radiographic assessment (postBW) by one examiner; diagnostic threshold = ER. State of tooth eruption included = E/U. Intra‐examiner reproducibility checks for incremental caries data (icc for clinical 0.95, for radiographic 0.8); reversal rate between 12% and 7% of observed DFS increment in study groups.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear