Forsman 1974a.

Methods	Trial design: 3‐armed, double‐blind, active/placebo‐controlled RCT Location: Sweden Number of centres: not reported. Schools in Ljungby, Sweden Recruitment period: study commenced in/before 1970
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 12.90 DMFS (DMFS Gp A: 12.90; Gp B: 13.08; Gp C: 12.74). Baseline characteristic (DMFS) "balanced" Age at baseline (years): range 10 to 12 years (not reported by group) Sex: 184 F:210 M (Gp A: 59 F:71 M; Gp B: 66 F:66 M; Gp C: 59 F:73 M) Any other details of important prognostic factors: background weekly supervised exposure to fluoride mouthrinse (NaF 1000 ppm), continued fortnightly throughout study. Community water supply naturally fluoridated (< 0.2ppm F) Number randomised: 469 (group numbers not reported) Number evaluated: 394 at 2 years (present at final assessment. Gp A: 130; Gp B: 132; Gp C: 132) Attrition: 16% dropout after 2 years. Reasons for attrition described with respective total numbers: change of residence/school, orthodontic treatment, did not wish to continue; no differential group losses reported (but not assessable)
Interventions	Comparison: FT (2 groups) versus PL Gp A (n = 130 evaluated): SMFP 250 ppm F; calcium carbonate abrasive system; home use/unsupervised, daily frequency assumed Gp B (n = 132 evaluated): SMFP 1000 ppm F; calcium carbonate abrasive system; home use/unsupervised, daily frequency assumed Gp C (n = 132 evaluated): placebo; calcium carbonate abrasive system; home use/unsupervised, daily frequency assumed
Outcomes	Primary: 2‐year DMFS increment ‐ (NCA) cl; (BLMD‐DFS) cl; (MD‐DFS) xr; proportion of children with new smooth surface caries (at 2 years) Secondary: none assessed Assessments irrelevant to this review's scope: none assessed Follow‐up duration: 2 years
Notes	Adverse effects: not reported Funding source: materials provided by the manufacturer, Barnängen Company, Stockholm. Financial support provided by Barnängen Company, Stockholm and the Swedish patent revenue research fund (Patentmedelsfonden för odontologisk profylaxforskning) Declarations/conflicts of interest: not reported Data handling by review authors: same trial report as Forsman 1974, intervention differed solely according to abrasive system Other information of note: clinical (VT) caries assessment by 1 examiner, diagnostic threshold = NCA. Radiographic assessment (postBW) by 1 examiner, diagnostic threshold = ER. State of tooth eruption included not reported. Diagnostic errors not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "From lists for girls resp. boys in all classes each fourth child on the Vaxjo lists and each third child on the Ljungby lists was randomly selected for the respective groups" Comment: not enough information provided
Allocation concealment (selection bias)	Unclear risk	No information provided
Blinding (performance bias and detection bias) All outcomes	Low risk	Quotes: "The toothpaste was delivered in tubes with the word 'Toothpaste' printed in different colours. During the period of investigation, only the manufacturer knew the code" and "... study was designed as a double‐blind experiment" Comment: blind outcome assessment and use of placebo described
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Overall dropout for length of follow‐up: 16% (75/469) in 2 years. Dropout by group: not reported. Reasons for losses: orthodontic treatment (27), moved away (22), did not wish to continue (26, not reported by group) Comment: numbers lost are not unduly high for length of follow‐up. It is unclear if there were any differential losses, and if reasons for missing outcome data are acceptable and balanced. Caries data used in the analysis pertain to participants continuing the study up to year 2 (children completing tests)
Selective reporting (reporting bias)	Low risk	Outcomes reported: DMFS increment ‐ (NCA) cl, reported at 2 years follow‐up (BLMD‐DFS) cl (MD‐DFS) xr proportion of children with new smooth surface caries Comment: trial protocol not available. All pre‐specified outcomes were reported and were reported in the pre‐specified way
Baseline characteristics balanced?	Low risk	Prognostic factors reported: DMFS: 13.08 FT 1, 12.90 FT 2, 12.74 PL dental age: 20.72 FT 1, 21.21 FT 2, 21.24 PL Comment: initial caries appears balanced
Free of contamination/co‐intervention?	Low risk	Quote: "The dentifrice was distributed every second month in amounts calculated to meet the needs of the whole family, to ensure as far as possible that the participants did not have access to other toothpastes" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention