Rule 1984.

Methods	Stratified random allocation; double‐blind (A); placebo‐controlled; 24% drop out after 2 years (study duration = 2 years). Reasons for attrition not described; exclusions based on presence in all follow‐up examinations; no differential group losses.
Participants	876 children analysed at 2 years (present for all examinations). Age range at start: 9‐12 years (average = 11). Surfaces affected at start: 8.6 DMFS. Background exposure to fluoride: none reported. Year study began: 1977. Location: USA.
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	2yDFS increment ‐ (E+U) (CA)cl+(ER)xr. Reported at 1 and 2 years follow ups. DFT. DMFS. DMFT. O‐DFS. MD‐DFS. Oral soft tissue lesions.
Notes	Participants randomised (N = 1154). Baseline characteristics (age, gender, TAR, DMFS, DMFT, DS, DT) 'balanced' (DFS baseline data NR). Clinical (VT) caries assessment (FOTI used) by one examiner; diagnostic threshold = CA; state of tooth eruption included = E/U. Radiographic assessment (2 postBW) by one examiner; diagnostic threshold = ER. Reproducibility checks done in 10% sample clinically and radiographically.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear