Muhler 1955.
| Methods | Trial design: 3‐armed, double‐blind, placebo‐controlled, stratified RCT Location: USA Number of centres: 1 centre. Dental clinic at Indiana University, USA. Participants from Bloomington area of Indiana Recruitment period: study began in/before 1954 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 9.3 DMFS (evaluated participants only) (Gp A: 9.7 DMFS; Gp B: 10.0 DMFS). Baseline characteristics (DMFS) "balanced" Age at baseline (years): range 6 to 15 years (group means not reported) Sex: not reported Any other details of important prognostic factors: background exposure to fluoride: data not available for fluoridation status of site Number randomised: 852 (groups relevant to review: 568 (Gp A: 290; Gp B: 278)) Number evaluated: 656 at 1 year (available at final examination) (groups relevant to review: 444 (Gp A: 219; Gp B: 225)) Attrition: 23% dropout after 1 year (study duration = 1 year). Reasons for attrition not reported; differential group losses | |
| Interventions | Comparison: FTa versus PL Gp A (n = 290): SnF2 1000 ppm F; abrasive system: heat‐treated Ca orthophosphate; home use/unsupervised, daily frequency assumed Gp B (n = 278): placebo; abrasive system: heat‐treated Ca orthophosphate; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 1‐year DMFS increment ‐ cl + xr; DMFT (at 6 months and 1 year) Secondary: none assessed Assessments irrelevant to this review's scope: n/a Follow‐up duration: 1 year | |
| Notes | Adverse effects: not reported Funding source: intervention manufacturer, Procter & Gamble Declarations/conflicts of interest: 2 of 4 authors (AW Radike, WH Nebergall) employed by the manufacturer. Remaining authors employed by Indiana University Data handling by review authors: aNaF‐heat treated Ca orthophosphate toothpaste group not considered (abrasive system known to be incompatible with NaF) Other information of note: clinical (VT) caries assessment by 1 examiner, diagnostic threshold not reported. Radiographic assessment by 1 examiner, diagnostic threshold not reported. State of tooth eruption included not reported. Criteria for caries diagnosis reported to have been carefully standardized, diagnostic errors not reported | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "After the initial exam of a subject, his total previous caries experience in terms of DMFS... was corrected by a factor corresponding to his dental age. This factor is one of a series of ratios.... The corrected term was taken as an indication of caries expectancy and the subject assigned to one of nine classes on this basis. Within each class, he was assigned to one of the three treatment groups at random" 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 examiner had no information about any child relative to group assignment, previous exam data, and so on" and "The control dentifrice had no fluoride content" 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: 22% in 1 year. Dropout by group: 71/290 FT, 53/278 PL. Reasons for losses: not reported Comment: numbers lost were not unduly high for the length of follow‐up, with differential losses between groups (24.5% FT, 19.1% PL). It is unclear if reasons for missing outcome data are acceptable and balanced. Caries data used in analysis pertain to participants present at final examination |
| Selective reporting (reporting bias) | Low risk | Outcomes reported:
DMFS increment ‐ cl + xr, reported at 6 months and 1 year 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 factor reported: DMFS: 9.5 FT, 9.1 PL Comment: initial caries appears balanced between groups |
| Free of contamination/co‐intervention? | Low risk | Quote: "The entire family of each child was supplied with the dentifrice assigned to the child. Although this increased the cost of the study considerably, it provided additional assurance that the child would use only the dentifrice assigned" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention |