Zacherl 1972a.
| Methods | Trial design: 5‐armed, double‐blind, placebo‐controlled and head‐to‐head, stratified RCT Location: Canada Number of centres: not reported. Leduc County, Alberta, Canada Recruitment period: study began in/before 1969 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 7.3 DMFS (Gp A: 7.32 (SE 0.550); Gp B: 7.19 (SE 0.465); Gp C: 6.79 (SE 0.429); Gp D: 7.05 (SE 0.426); Gp E: 7.80 (SE 0.444)). Baseline characteristics (DMFS, DMFT) "balanced" Age at baseline (years): range 6 to 16 years, mean 9.3 years (Gp A: 9.27; Gp B: 9.30; Gp C: 9.40; Gp D: 9.30; Gp E: 9.19). Baseline characteristic (age) "balanced" Sex: 689 F:726 M (Gp A: 137 F:135 M; Gp B: 134 F:138 M; Gp C: 132 F:134 M; Gp D: 145 F:156 M; Gp E: 141 F:163 M). Baseline characteristic (sex) "balanced" Any other details of important prognostic factors: background exposure to fluoride: water. Naturally fluoridated community water supply, ranging from 1.5 to 3.8 ppm F Number randomised: 1405 (Gp A: 272; Gp B: 272; Gp C: 256; Gp D: 301; Gp E: 304) Number evaluated: 894 at 1.7 years (present for both follow‐up examinations) (Gp A: 174; Gp B: 175; Gp C: 151; Gp D: 184; Gp E: 210) Attrition: 36% dropout after 1.7 years (study duration = 1.7 years). Reasons for high dropout not reported; exclusions based on presence in both examinations; no differential group losses | |
| Interventions | Comparison: FT (4 groups) versus PL Gp A (n = 272): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate in all toothpastes; home use/unsupervised, daily frequency assumed Gp B (n = 272): NaF 1000 ppm F; abrasive system: Ca pyrophosphate in all toothpastes; home use/unsupervised, daily frequency assumed Gp C (n = 256): SMFP 1000 ppm F; abrasive system: Ca pyrophosphate in all toothpastes; home use/unsupervised, daily frequency assumed Gp D (n = 301): APF 1000 ppm F; abrasive system: Ca pyrophosphate in all toothpastes; home use/unsupervised, daily frequency assumed Gp E (n = 304): placebo; abrasive system: Ca pyrophosphate in all toothpastes; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 1.7‐year DMFS increment ‐ cl + xr; DMFT (at 1 year, 1.7 years) Secondary: none assessed Assessments irrelevant to this review's scope: n/a Follow‐up duration: 1.7 years (20 months) | |
| Notes | Adverse effects: not reported Funding source: not reported Declarations/conflicts of interest: institutional affiliations reported only Data handling by review authors: Gps A + B + C + D versus E in analyses 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: "The subjects were arrayed by sex, age and initial visual‐tactile DMFT and then assigned by random number to one of five groups identified only by code letter" |
| Allocation concealment (selection bias) | Unclear risk | No information provided |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quotes: "A double blind clinical investigation..." and "All dentifrices were similar in colour, flavour and other consumer properties" and "All examinations and interpretations were independent of previous records" 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: 36% in 1.7 years. Dropout by group: 98/272 FT, 94/304 PL. Reasons for losses: exclusion based on presence at all examinations Comment: numbers lost were somewhat high for the length of follow‐up. 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 all examinations |
| Selective reporting (reporting bias) | Low risk | Outcomes reported:
DMFS increment ‐ cl + xr, reported at 1 and 1.7 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: 7.63 FT 1, 7.33 FT 2, 6.98 FT 3, 7.28 FT 4, 7.60 PL DMFT: 4.34 FT 1, 4.19 FT 2, 4.00 FT 3, 4.17 FT 4, 4.13 PL age: 9.31 FT 1, 9.28 FT 2, 9.37 FT 3, 9.25 FT 4, 9.17 PL Comment: initial caries appears balanced |
| Free of contamination/co‐intervention? | Unclear risk | No information provided |