Mergele 1968.
| Methods | Trial design: 4‐armed, double‐blind, placebo‐controlled, stratified RCT Location: USA Number of centres: not reported. Public schools in North‐East Houston, Texas, USA Recruitment period: study began in/before 1964 | |
| Participants | Inclusion criteria: not reported Exclusion criteria: not reported Baseline caries: 6.5 DMFS (Gp A: 6.42 DMFS (SD 6.30); Gp B: 6.52 DMFS (SD 6.25)) (evaluated participants only). Baseline characteristics (age, SAR, DMFS, DMFT) "balanced" Age at baseline (years): range 10 to 13 years, mean 11 years (Gp A: 10.88 years; Gp B: 11.04 years) (evaluated participants only) Sex: 365 F:357 M (groups relevant to this review: 192 F:195 M. Gp A: 97 F:100 M; Gp B: 95 F:95 M) (evaluated participants only) Any other details of important prognostic factors: background exposure to fluoride through community water supply (1.0 ppm F) Number randomised: 929 (group distribution not reported) Number evaluated: 722 (groups relevant to this review: 387 at 3 years (available at final examination) (Gp A: 197; Gp B: 190)) Attrition: 22% dropout (for all study groups combined) after 3 years (study duration = 3 years). Reasons for attrition: natural losses to follow up; any differential group losses not assessable | |
| Interventions | Comparison: FTa versus PL Gp A (n = evaluated 197): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised, daily frequency assumed Gp B (n = evaluated 190): placebo; abrasive system: IMP; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 3‐year net DMFS increment ‐ cl; DMFT (at 3 years) Secondary: not assessed Assessments irrelevant to this review's scope: n/a Follow‐up duration: 3 years | |
| Notes | Adverse effects: not reported Funding source: not reported Declarations/conflicts of interest: not reported Data handling by review authors: aNa N‐lauroyl sarcosinate/SMFP toothpaste groups not considered (additional non‐F active agent used in this group only) Other information of note: clinical (VT) caries assessment 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) | Unclear risk | Quote: "... population was stratified according to examiner, sex, age, permanent teeth present, past caries experience, oral hygiene rating and prior fluoride history. This stratified population was divided by means of random numbers into 4 balanced groups" 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: "All 4 dentifrices were packed in plain white tubes.... the labelling was identical except for the name of the subject" "One group used a control toothpaste... did not contain active agent" and "All clinical exams performed without reference to previous records" 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% 207/929 in 6 years (for all 4 groups). Dropout by groups: not reported. Reasons for losses: moved away Comment: numbers lost were not unduly high for the length of follow‐up. It is unclear if there were any differential losses, and if reasons for missing outcome data are balanced, although the reasons are acceptable. Caries data used in the analysis pertain to participants present at final examinations |
| Selective reporting (reporting bias) | Low risk | Outcomes reported:
DMFS increment ‐ cl, reported at 3 years follow‐up
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: 6.42 (6.30) FT, 6.52 (6.25) PL age: 10.88 FT, 11.04 PL DMFT: 3.95 (2.85) FT, 3.99 (3.02) PL SAR: 86.30 (29.17) FT, 87.17 (28.88) PL Comment: initial caries appears balanced between groups |
| Free of contamination/co‐intervention? | Low risk | Quote: "Additional dentifrice was provided for the family of a subject as were brushes" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention |