Naylor 1967.

Methods	Trial design: 3‐armed, double‐blind, placebo‐controlled, stratified RCT Location: UK Number of centres: single mobile dental unit attending 14 secondary schools in East and South‐East London districts Recruitment period: study began 1961
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 9.5 DMFS (groups relevant to review: 9.5 DMFS (Gp A: 9.45 DMFS (SD 6.22); Gp B: 9.61 DMFS (SD 6.43)). Baseline characteristics (SAR, DMFS, DMFT, posterior MD‐DFS) "balanced" Age at baseline (years): range 11 to 12 years (group means not reported). Baseline characteristic (age) "balanced" Sex: 813 F:676 M (groups relevant to review: 543 F:430 M (Gp A: 274 F:220 M; Gp B: 269 F:210 M)). Baseline characteristic (sex) "balanced" Any other details of important prognostic factors: background exposure to fluoride in community water supply approximately 0.3 ppm F Number randomised: 1789 (groups relevant to review: not reported. Group distribution unknown) Number evaluated: 1489 at 3 years (available at final examination) (groups relevant to review: 973 (Gp A: 494; Gp B:479)) Attrition: 17% dropout (for all study groups combined) after 3 years (study duration = 3 years). Natural losses; any differential group losses not assessable
Interventions	Comparison: FTa versus PL Gp A (n = 494 evaluated): SnF2 1000 ppm F; abrasive system: IMP (main abrasive); home use/unsupervised, daily frequency assumed Gp B (n = 479 evaluated): placebo; abrasive system: dicalcium phosphate (dihydrate); home use/unsupervised, daily frequency assumed
Outcomes	Primary: 3‐year crude DFS increment ‐ (E + U) (CA) cl + (ER) xr; posterior MD‐DFS; 1st molar MD‐DFS; DMFS; DMFT (at 3 years) Secondary: proportion of children with tooth staining (at 3 years) Assessments irrelevant to this review's scope: subjective oral hygiene rating assessment Follow‐up duration: 3 years
Notes	Adverse effects: staining grades (subjective assessment. Scale 0 to 4, lower better): Gp A: Grade 0 n = 242 (49.0%); Grade 1 n = 124 (25.1%); Grade 2 n = 94 (19.0%); Grade 3 n = 32 (6.5%); Grade 4 n = 2 (0.4%) Gp B: Grade 0 n = 368 (76.8%); Grade 1 n = 70 (14.6%); Grade 2 n = 33 (6.9%); Grade 3 n = 7 (1.5%); Grade 4 n = 1 (0.2%) Funding source: Colgate‐Palmolive provided toothpastes and funding Declarations/conflicts of interest: not reported, authors employed by Guy's Hospital, London Data handling by review authors: aNa N‐lauroyl sarcosinate/SMFP toothpaste group not considered (additional non‐F active agent used in this group only) Other information of note: clinical (VT) caries assessment by 1 examiner, diagnostic threshold = CA; state of tooth eruption included = E/U. Radiographic assessment (2 postBW) by 1 examiner, diagnostic threshold = ER. Reversal rate less than 4% of observed DFS increment in all groups. High accuracy of diagnosis revealed by 10% sample checks (clinically and radiographically)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Subjects were stratified according to age, sex, race.... The stratified population was then divided into three groups A, B and C by means of random numbers"
Allocation concealment (selection bias)	Low risk	Quote: "A sealed envelope containing the allocation of the toothpastes to groups was placed in the safe of the Dean, Guy's Hospital Medical School before the trial began and not opened until analysis of third year results were complete"
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Throughout the trial, each group received the corresponding toothpaste, the formular of which was unknown to both the examiner and the user.." 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: 16.9% (300/1789) in 3 years (for all 3 groups). Dropout by group: not reported. Reasons for losses: "low dropout due to the fact that exams were completed before school leaving age" Comment: numbers lost were not unduly high for the 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 present at final examination
Selective reporting (reporting bias)	Low risk	Outcomes reported: DFS increment ‐ (E + U) (CA) cl + (ER) xr, reported at 3 years follow‐up DMFT DMFS posterior MD‐DFS 1st molar MD‐DFS proportion of children with tooth staining 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: 9.45 (6.22) FT, 9.61 (6.43) PL gender: (55.5% F) FT, (56.2% F) PL DMFT: 5.34 (2.84) FT, 5.51 (2.93) PL SAR: 107.69 (20.46) FT, 106.91 (20.93) PL Comment: initial caries appears balanced
Free of contamination/co‐intervention?	Low risk	Quote: "In an attempt to ensure that the subjects did not use other pastes, enough was sent to provide for the needs of the whole family" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention