Blinkhorn 1983.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 10% drop out after 3 years (study duration = 3 years). Reasons for attrition described with respective total numbers: 57 left school, 12 withdrawn by parents, 6 absent at final examination; no differential group losses.
Participants	368 children analysed at 3 years (available at final examination). Age range at start: 11‐12 years. Surfaces affected at start: 8.2 DMFS. Background exposure to fluoride: none reported. Year study began: 1972. Location: UK.
Interventions	FT versus PL (SMFP group = 1000 ppm F). School use/supervised, daily, for 1 min, post‐brushing water rinse done (appropriate toothpastes also provided for home use). Abrasive system: IMP (main abrasive).
Outcomes	3yNetDFS increment ‐ (E+U)(CA)cl+(DR)xr. Reported at 3 years follow up. PF‐DFS. MD‐BL‐DFS. MD‐DFS. postMD‐DFS. DFS (U). DMFT. anterior DMFT. posterior DMFT. DMFT (U).
Notes	Participants randomised (N = 410). Baseline characteristics (DMFS, DMFT, SAR) 'balanced' (DFS baseline data NR). Clinical (V) caries assessment by one examiner, diagnostic threshold = CA. Radiographic assessment (1 postBW) by one examiner; diagnostic threshold = DR. State of tooth eruption included = E/U. Intra‐examiner reproducibility checks for incremental clinical and radiographic caries data in 10% sample (icc score 0.9).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear