Powell 1981.
| Methods | Trial design: 4‐armed, double‐blind, placebo‐controlled, stratified RCT Location: Australia Number of centres: not reported Recruitment period: study began 1963 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 21.4 DMFS (from sample developing caries) (Gp A: 21.5 DMFS (SE 1.12); Gp B: 21.2 DMFS (SE 0.90)). Baseline characteristic (DMFS) "balanced" Age at baseline (years): range 12 to 14 years (Gp A: 13.4 years (SE 0.04); Gp B: 13.4 years (SE 0.03)) (from sample developing caries). Baseline characteristic (age) "balanced" Sex: Gp A: 25 F (33%):51 M (67%); Gp B: 43 F (42%):59 M (58%)) (from sample developing caries). Baseline characteristic (sex) "balanced" Any other details of important prognostic factors: background exposure to fluoride in community water supply fluoridated < 0.1 ppm F Number randomised: not reported, nor group distribution Number evaluated: not reported, nor group distribution Attrition: dropout rate not reported nor obtainable (study duration = 4 years). Reasons for attrition not reported; any differential group losses not assessable | |
| Interventions |
Comparison: FT (pp/Plsol) versus PL (pp/Plsol)a
Gp A (n = not reported): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed
Gp B (n = not reported): placebo; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed Gp C (n = not reported): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed; topical SnF2 solution Gp D (n = not reported): placebo; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed; topical SnF2 solution |
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| Outcomes | Primary: progression rate of initial carious lesions in MD surfaces of permanent posterior teeth (caries increment data not reported nor obtainable) (at 1, 2, 3, and 4 years) Secondary: not reported Assessments irrelevant to this review's scope: none Follow‐up duration: 4 years | |
| Notes | Adverse effects: not reported Funding source: not reported Declarations/conflicts of interest: institutional affiliations only Data handling by review authors: aprior prophylaxis with lava pumice followed by professional application of placebo solution performed every 6 months for 2 years in both relevant groups compared. Not included in analyses. 2 other arms in trial ineligible for inclusion due to concurrent fluoride topical fluoride solution Other information of note: radiographic (postBW) enamel caries progression assessment by 1 examiner; state of tooth eruption included = E. High reproducibility of radiographic diagnosis (ICC = 0.91) | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "... subjects were assigned to four groups, using systematic random sampling by age, sex, class, and school" Comment: not enough information provided |
| Allocation concealment (selection bias) | Unclear risk | No information provided |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | Quotes: "To determine the reproducibility of radiographic diagnoses, duplicate readings of radiographs taken at 48 month exam were made by the same examiner. To ensure that the examiner had no knowledge of the group, an independent observer randomly selected the subjects and nominated, at random, one or two lesions from each" and "Participants issued with either test or control dentifrice for the full 4 year period of the study" Comment: blinding of outcome assessor is mentioned but although it appears that only a small sample was assessed blindly for reproducibility |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Overall dropout for length of follow‐up: not reported. Dropout by group: not reported. Reasons for losses: not reported Comment: it is unclear if numbers lost were high for length of follow‐up, 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 who had developed caries at final examination |
| Selective reporting (reporting bias) | Low risk | Outcomes reported: caries increment (data not obtainable) progression rate of initial carious lesions in MD surfaces of permanent posterior teeth at annual intervals (for 4 years) 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: 21.2 (0.90) FT, 21.5 (1.12) PL gender (M): 58 FT, 67 PL age: 13.4 (0.03) FT, 13.4 (0.04) PL Comment: initial caries appears balanced |
| Free of contamination/co‐intervention? | Unclear risk | No information provided |