Zacherl 1972.
| Methods | Trial design: 2‐armed, double‐blind, placebo‐controlled, stratified RCT Location: Canada Number of centres: not reported. Elementary schools, Jasper Place, Alberta, Canada Recruitment period: study began in/before 1969 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 11.7 DMFS (Gp A: 11.40 (SE 0.682); Gp B: 12.09 (SE 0.733)). Baseline characteristics (DMFS, DMFT) "balanced" Age at baseline (years): range 6 to 15 years, mean 10 years (Gp A: 10.22 years; Gp B: 10.17 years). Baseline characteristic (age) "balanced" Sex: 321 F:356 M (Gp A: 163 F:185 M; Gp B: 158 F:171 M). Baseline characteristic (sex) "balanced" Any other details of important prognostic factors: background exposure to fluoride: none reported. Community water supply fluoridated < 0.1ppm F Number randomised: 677 (Gp A: 348; Gp B: 329) Number evaluated: 447 at 2 years (available at final examination) (Gp A: 231; Gp B: 216) Attrition: 34% dropout after 2 years (study duration = 2 years). Reasons for attrition not reported; no differential group losses | |
| Interventions | Comparison: FT versus PL Gp A (n = 348): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed Gp B (n = 329): placebo; abrasive system: not reported; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 2‐year DMFS increment ‐ cl + xr; DMFT (at 1 , 2 years) Secondary: none assessed Assessments irrelevant to this review's scope: n/a Follow‐up duration: 2 years | |
| Notes | Adverse effects: not reported Funding source: not reported Declarations/conflicts of interest: institutional affiliations reported only Data handling by review authors: n/a Other information of note: clinical (VT) caries assessment by 1 examiner, diagnostic threshold not reported. Radiographic assessment (5 to 10 BW) by 1 examiner, diagnostic threshold not reported. 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) | Low risk | Quote: "... subjects were classified by age, sex and DMFS. The subjects were then assigned by random number to one of the two dentifrices, identified only by code letter" |
| Allocation concealment (selection bias) | Unclear risk | Insufficient information provided |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quotes: "A double blind investigation..." and "The control dentifrice was the same as the test dentifrice except that it had no active ingredients..." Comment: use of placebo described but blind outcome assessment not clearly described, although it was probably done as earlier report by same author clearly described blind outcome assessment |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Overall dropout for length of follow‐up: 34% in 2 years. Dropout by group: 117/348 FT, 113/329 PL. Reasons for losses: not reported Comment: numbers lost were not unduly high for the length of follow‐up with no differential losses between groups. It is unclear if reasons for missing outcome data are acceptable and balanced. Caries data used in analysis pertain to participants present at final examinations |
| Selective reporting (reporting bias) | Low risk | Outcomes reported:
DMFS increment ‐ cl + xr, reported at 1 and 2 years follow‐ups
DMFT 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: 12.10 FT, 12.44 PL DMFT: 6.27 FT, 6.33 PL age: 10.22 FT, 10.17 PL Comment: initial caries appears balanced |
| Free of contamination/co‐intervention? | Unclear risk | No information provided |