Muhler 1962.
| Methods | Trial design: 2‐armed, placebo‐controlled, stratified RCT Location: USA Number of centres: (Not specifically reported but indicated to be as in Muhler 1955.) 1 centre. Dental clinic at Indiana University, USA. Participants from Bloomington area of Indiana Recruitment period: study began in/before 1958 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 13 DMFS (Gp A: 13.08 DMFS; Gp B: 12.98 DMFS). Baseline characteristics (DMFS) comparable Age at baseline (years): range 6 to 18 years, mean 11 years (group mean age not reported) Sex: 178 F:149 M (Gp A: 93 F:72 M; Gp B: 85 F:77 M) (evaluated participants at all assessments only: n = 327) Any other details of important prognostic factors: background exposure to fluoride in community water 0.05 ppm F Number randomised: 492 (Gp A: 242; Gp B: 250) Number evaluated: 343 at 3 years (available at final examination) (Gp A: 174; Gp B: 169) Attrition: 30% dropout (for all study groups combined) after 3 years (study duration = 3 years). Reasons for attrition: not stated; no differential group losses | |
| Interventions | Comparison: FT versus PL Gp A (n = 242): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed Gp B (n = 250): placebo; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 3‐year DMFS increment ‐ cl; DMFS increment; DMFT increment; cumulative caries increment; DMFS increment (children present at every examination); DMFT increment (children present at every examination); proportion developing caries (at 3 years (6 months, 1 year, 18 months, 2 years, 3 years)) Secondary: not assessed Assessments irrelevant to this review's scope: compliance Follow‐up duration: 3 years | |
| Notes | Adverse effects: not reported Funding source: grant from intervention (Crest) manufacturer, Procter & Gamble Declarations/conflicts of interest: sole author employed by Indiana University Data handling by review authors: n/a Other information of note: clinical caries assessment by 1 examiner. 3% aged 17‐18 years at start of study (Gp A: n = 16; Gp B: n = 14) | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "... assigned at random to study groups after stratification" |
| Allocation concealment (selection bias) | Unclear risk | Comment: insufficient information |
| Blinding (performance bias and detection bias) All outcomes | High risk | Quote: "Elements of blindness were compounded in that subjects from several different tests being conducted simultaneously appeared for examination in mixed order" Comment: dentifrices were different. Test was described as "standard factory product" |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Comment: moderate dropout (36 months 32% control 28% test), and balanced between the groups. No reasons for dropouts given |
| Selective reporting (reporting bias) | Low risk | DMFS and DMFT increments |
| Baseline characteristics balanced? | Low risk | Comment: stratified on dental age, past caries, age and sex. Balance for baseline sex, age and disease comparable |
| Free of contamination/co‐intervention? | Unclear risk | Comment: unclear but as dentifrices were very different it is unlikely that errors occurred over their use |