Marthaler 1974.

Methods	Trial design: double‐blind (assessor), placebo‐controlled RCT Location: Switzerland Number of centres: not reported. Primary school authorities in Kilchberg, border of Zürich Recruitment period: study began 1966
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 2.6 DMFS (Gp A: 2.54 DMFS; Gp B: 2.59 DMFS) (evaluated participants only). Baseline characteristics (DMFS, DMFT, FS, FT, TAR) "balanced" (DFS baseline data not reported) Age at baseline (years): range 6 to 9 years; mean 7.5 years (Gp A: 7.48 years; Gp B: 7.52 years) (evaluated participants only) Sex: not reported Any other details of important prognostic factors: background exposure to fluoride community water supplies < 0.2 ppm F; 0.3 mg daily dose of salt assumed from F domestic salt, and 44 evaluated participants also received fluoride tablets at home (Gp A: 17; Gp B: 27). Fluoridation of community water supply not reported Number randomised: 161 (Gp A: 81; Gp B: 80) Number evaluated: 109 at 6 years (Gp A: 50; Gp B: 59) Attrition: 32% dropout after 6 years (study duration = 6 years). Exclusions based on presence in all follow‐up examinations; differential group losses
Interventions	Comparison: FT versus PL Gp A (n = 81): AmF 1250 ppm F; abrasive system: IMP; home use/unsupervised, daily frequency assumed Gp B (n = 80): placebo; abrasive system: IMP; home use/unsupervised, daily frequency assumed
Outcomes	Primary: 6‐yeara net DFS increment ‐ (E) (CA) cl + (DR) xr; PF‐DFS; posterior MD‐DFS; anterior MD‐B‐DFS; DFT; proportion of children with new DFS (at 2 and 6 years) Secondary: none assessed Assessments irrelevant to this review's scope: gingivitis; calculus Follow‐up duration: 6 years
Notes	Adverse effects: not reported Funding source: "Gaba AG Basle [sic], for providing and mailing the dentifrices." Funding not specifically reported, although inferred by Elmex's manufacturer (Gaba AG, Basel, Switzerland) providing intervention and placebo materials for the study Declarations/conflicts of interest: not reported Data handling by review authors: aresults at 6 years follow‐up chosen (reported for all outcomes) Other information of note: clinical (V) caries assessment by 2 examiners, diagnostic threshold = CA and NCA; state of tooth eruption included = E. Radiographic assessment (2 postBW) by 2 examiners, diagnostic threshold = DR and ER; partial recording. "Sufficient agreement of examiners known from earlier work"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The children were randomly assigned to either control or fluoride dentifrice. There were 9 pairs of siblings.... each pair received either the control or fluoride dentifrice to avoid the provision of one family with different types of dentifrices" 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 tubes showed no indication whether they contained fluoride or not" and "The type of dentifrice to which the child was assigned remained unknown to the examiner during the whole course of the study"  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: 32.3% in 6 years. Dropout by groups: 29/81 FT, 21/80 PL. Reasons for losses: exclusions based on presence at all follow‐up examinations Comment: numbers lost were not unduly high for the length of follow‐up, with a differential loss between groups (35.8% FT, 26.3% PL). It is unclear if reasons for the missing outcome data are acceptable and balanced. Caries data used in the analysis pertain to participants present at all examinations. Group losses unlikely to be related to intervention
Selective reporting (reporting bias)	Low risk	Outcomes reported: DFS increment ‐ (E) (CA) cl + (DR) xr reported at 2 and 6 years follow‐ups PF‐DFS posterior MD‐DFS anterior MD‐B‐DFS DFT proportion of children with new DFS 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: 2.59 FT, 2.54 PL DMFT: 1.81 FT, 1.74 PL FS: 2.07 FT, 1.80 PL TAR: 10.47 FT, 10.88 PL Comment: initial caries appears balanced between groups
Free of contamination/co‐intervention?	Low risk	Quote: "Two dentifrice tubes were mailed once a month to the children via their parents" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention