Ingraham 1970.

Study characteristics
Methods	Study design: 5‐arm parallel‐group RCT (3 relevant arms used), non‐placebo controlled Study duration: 2 years
Participants	119 children analysed at 2 years (available at final examination) Participants randomised (N = 155) Age range 6‐11 years (average = 9) Surfaces affected: 2.4 DMFS Exposure to other fluoride: none assumed Year study began: 1965 Location: USA Setting of recruitment and treatment: school
Interventions	FG (2 groups) + ptc vs NT + ptc (APF groups 1 and 2, concentration(s) NR) Operator applied, with tray (beeswax vs foam rubber), once a year (data extracted from Bryan 1968 (in Bryan 1970), applied for 4 min Prior to application = tooth cleaning performed Postop instruction = refrain from eating and drinking for 30 min
Outcomes	2‐year net DMFS increment ‐ (CA) Reported at 1 and 2 year follow‐ups NetDMFT(CA) Nausea/vomiting on application seen as a reaction according to type of tray used (no data). Dropout
Declaration of interest	No information provided.
Source of funding	No information provided.
Notes	Clinical (VT) caries assessment by 1 examiner; diagnostic threshold = CA; state of tooth eruption included NR; diagnostic errors NR
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quotes: “Children ... were randomly assigned to control and treatment groups ...” Comment: Not enough information provided.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quotes: “Controls also received a prophylaxis, but no fluoride applications.” Comment: No placebo described.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quotes: “Controls received a prophylaxis.” “... the examiner did not know the group assignment of the children at the time of the examination.” Comment: Blind outcome assessment, but no placebo described.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Overall dropout for length of follow‐up: 23.23% in 2 years. Dropout by group: 17/73 (23.3%) FG, 19/82 (23.2%) NT. Reasons for losses: Not reported Comment: Numbers lost not unduly high for length of follow‐up with no differential losses between groups. It is unclear if reasons for dropout are acceptable and balanced. Caries data used in analysis pertain to participants present at all examinations.
Selective reporting (reporting bias)	Low risk	Outcomes reported: DMFS increment ‐ (CA), reported at 1 and 2 year follow‐ups DMFT(CA) Nausea/vomiting on application seen as a reaction according to type of tray used (no data). Comment: Trial protocol not available. All pre‐specified outcomes (in Methods) were reported and were reported in the pre‐specified way.
Baseline characteristics balanced?	Low risk	Prognostic factors reported: DMFS: 2.32(3.57) FG, 2.55(3.66) NT DMFT: 1.29(1.68) FG, 1.49(1.76) NT Comment: Initial caries appears balanced between groups.
Free of contamination/co‐intervention?	Unclear risk	No information provided.