Howat 1978.

Methods	Random allocation; double‐blind (A); placebo‐controlled; 12% drop out after 3 years (study duration = 3 years). Reasons for attrition described with respective total numbers (56 left school, 7 withdrawn by own choice, 2 lack of co‐operation); any differential group losses not assessable.
Participants	495 children analysed at 3 years (available at final examination). Age range at start: 11‐12 years. Surfaces affected at start: 7.4 DMFS. Background exposure to fluoride: none reported. Year study began: in/before 1974. Location: UK.
Interventions	FT versus PL (SMFP group = 1000 ppm F). School use/supervised, daily, for 1 min (appropriate toothpastes also provided for home use). Abrasive system: silica zerogel.
Outcomes	3yNetDMFS increment ‐ (E) (CA)cl+(DR)xr. Reported at 3 years follow up. antDMFS. postDMFS. PF‐DMFS. MD‐DMFS. MD‐BL‐DMFS. DMFT.
Notes	Participants randomised (N = 560); numbers by group NR. Baseline characteristics (DMFS, DMFT, SAR) 'balanced'. Clinical (VT) caries assessment by one examiner; diagnostic threshold = CA; state of tooth eruption included = E/U; radiographic assessment (2 postBW) by one examiner; diagnostic threshold = DR. Reproducibility checks done in 10% sample clinically and radiographically (icc of incremental data between 0.96 and 0.99).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear