Lu 1980.
| Methods | Trial design: 2‐armed, double‐blind, placebo‐controlled and stratified RCT Location: USA Number of centres: not reported, University of Oregon Health Sciences Center Recruitment period: study commenced in/before 1978 | |
| Participants | Inclusion criteria: good health, in possession of at least 16 natural teeth excluding 3rd molars Exclusion criteria: gross dental neglect, ill‐fitting prosthetic appliances or extensive full coverage restorations of their teeth Baseline caries: 38.6 DMFS (Gp A: mean 38.23 (SE 0.931); Gp B: mean 38.96 (SE 0.885)). Baseline characteristic (DMFS) balanced Age at baseline (years): range 18 to 78 years (Gp A: 33.4 years; Gp B: mean 33.7 years). Baseline characteristic (age) balanced Sex: 704 F:401 M (Gp A: 355 F:203 M; Gp B: 349 F:198 M). Baseline characteristic (sex) balanced Any other details of important prognostic factors: background exposure to fluoride: none. Community water supply < 0.05 ppm F Number randomised: 1337 (Gp A: 669; Gp B: 668) Number evaluated: 1105 at 1 year (present at final assessment. Gp A: 558; Gp B: 547) Attrition: 17% dropout (for all study groups combined) after 1 year (study duration = 2 year). Reasons for attrition not reported; no differential group losses | |
| Interventions | Comparison: FT versus PL Gp A (n = 669): SnF2 1000 ppm F; abrasive system: Ca pyrophosphate; home use/unsupervised: daily frequency assumed Gp B (n = 668): placebo; abrasive system: Ca pyrophosphate; home use/unsupervised: daily frequency assumed | |
| Outcomes | Primary: 1‐year DMFS increment ‐ cl + xr; DMFS increment (at 1 year) Secondary: none Assessments irrelevant to this review's scope: none Follow‐up duration: 2 years | |
| Notes | Adverse effects: not reported Funding source: Procter & Gamble Declarations/conflicts of interest: none reported Data handling by review authors: n/a Other information of note: analysis of covariance undertaken. Clinical examination by 1 examiner. Clinical (VT) caries assessment by single examiner according to Radike criteria and FOTI, diagnostic threshold not reported; radiographic (7 BW) caries assessment by single examiner, diagnostic threshold not reported | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Comment: stratified allocation undertaken by trial statistician. Industry sponsored and other trials randomised. Probably done |
| Allocation concealment (selection bias) | Unclear risk | Comment: insufficient information |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quotes: "The dentifrices were identical except for the absence of the active ingredient...." and "double blind" |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Comment: no reasons for attrition reported but low attrition rate 18% overall. No differential group losses |
| Selective reporting (reporting bias) | Unclear risk | Comment: DMFS increments over 1 year, of stated 2‐year trial. Unable to identify 2‐year report |
| Baseline characteristics balanced? | Low risk | Comment: balance of age, sex, DMFS at baseline. Adjusted analysis (analysis of covariance) |
| Free of contamination/co‐intervention? | Low risk | Quote: "Cohabiting adults were assigned to the same treatment group in order to avoid the presence of two different dentifrices in the same household" Comment: contamination unlikely |