Lind 1974.
| Methods | Trial design: 2‐armed, double‐blind, placebo‐controlled and stratified RCT Location: Denmark Number of centres: not reported. Vordingborg School Dental Health District, South Zealand Recruitment period: study commenced in 1970 | |
| Participants | Inclusion criteria: not reported
Exclusion criteria: not reported
Baseline caries: 5.1 DMFS (Gp A: 5.06 DMFS/3.60 DMFT; Gp B: 5.08 DMFS/3.57 DMFT). Baseline characteristics (DMFS, DMFT) "balanced"
Age at baseline (years): range 7 to 12 years, mean 10 years (Gp A: 9.95 years; Gp B: 9.93 years). Baseline characteristic (age) "balanced" Sex: 583 F:584 M (Gp A: 302 F:290 M; Gp B: 281 F:294 M) (evaluated subjects only) Any other details of important prognostic factors: background exposure to fluoride in community water supply (naturally fluoridated: 1.2 to 1.4 ppm F) Number randomised: 1407 (Gp A: 719; Gp B: 688) Number evaluated: 1167 at 3 years (present at intermediate and final assessments. Gp A: 592; Gp B: 575) Attrition: 17% dropout rate after 3 years (study duration = 3 years). Main reasons for dropout: moved away, sickness; exclusions based on presence in 1 interim examination; no differential group losses |
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| Interventions | Comparison: FT versus PL Gp A (n = 719): SMFP 2400 ppm F; abrasive system: Al oxide trihydrate; home use/unsupervised, daily frequency assumed Gp B (n = 688): placebo; abrasive system: Al oxide trihydrate; home use/unsupervised, daily frequency assumed | |
| Outcomes | Primary: 3‐year net DMFS increment ‐ (E + U) (CA) cl + (DR) xr; DMFT; ECSI (at 1, 2 and 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: Unilever Research Laboratories, England Declarations/conflicts of interest: acknowledgements indicate Unilever staff provided "assistance" throughout the study in addition to financial support, although it is not stated how they were involved Data handling by review authors: n/a Other information of note: clinical (VT) caries assessment by 2 examiners, diagnostic threshold = CA/NCA; radiographic assessment (2 postBW) by 2 examiners, diagnostic threshold = ER/DR; state of tooth eruption included = E/U. Inter‐examiner diagnostic error reported to have no effect on results; reversal rates small and similar in both groups | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "... children were stratified according to age, sex... The experimental and control groups were formed using random assignment. Children from the same household were allocated to the same treatment group to ensure that only one type of dentifrice entered the household during the trial period" Comment: not enough information provided |
| Allocation concealment (selection bias) | Unclear risk | No information provided |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quote: "The trial was in... a double‐blind design... The only persons who, of necessity, knew the allocation code of the dentifrices were the factory personnel who manufactured the dentifrices. The packages containing the dentifrices differed only in the color of the neutral text" 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: 17% in 3 years. Dropout by group: 127/719 FT, 113/688 PL. Reasons for losses: sickness, change of address and exclusions from analysis due to presence at the 1st, 4th and at least 1 other intermediate examination (not reported by group) Comment: numbers lost were not unduly high given the length of follow‐up, and show no differential loss between groups. Reasons for missing data are acceptable, but it is unclear if they are balanced. Caries data used in the analysis pertain to participants present for the first, last and at least 1 other follow‐up exam |
| Selective reporting (reporting bias) | Low risk | Outcomes reported:
DMFS increment ‐ (E + U) (CA) cl + (DR) xr, reported at 1, 2, and 3 years follow‐ups
DMFT
ECSI Comment: trial protocol not available. All pre‐specified outcomes were reported and were reported in the pre‐specified way |
| Baseline characteristics balanced? | Low risk | Prognostic factors reported:
DMFS: 9.32 FT, 9.24 PL Mean age: 10.04 FT, 9.99 PL DMFT: 5.51 FT, 5.44 PL Comment: initial caries appears balanced between groups |
| Free of contamination/co‐intervention? | Low risk | Quote: "Children from the same household however, were allocated to the same treatment group to ensure that only one type of dentifrice entered the household during the trial period" Comment: there is sufficient indication overall of prevention of contamination/co‐intervention |