Beiswanger 1989.

Methods	Trial design: 4‐armed, triple‐blind, active‐controlled and stratified RCT Location: USA Number of centres: not reported Recruitment period: study commenced 1983
Participants	Inclusion criteria: not reported Exclusion criteria: orthodontic appliances; unsuitable medical history Baseline caries: not reported for all groups (Gp A: mean 1.93 DMFS (SEM 0.075); Gp B: not reported; Gp C: mean 1.87 DMFS (SEM 0.072); Gp D: not reported). Baseline characteristics similar according to DMFS (reported for SMFP 1100 ppm F group and NAF 1100 ppm F group) Age at baseline (years): 6 to 16 years (Gp A: mean 9.07 years; Gp B: not reported; Gp C: 9.02 years; Gp D: not reported). Baseline characteristics similar according to age (reported for SMFP 1100 ppm F group and NAF 1100 ppm F group) Sex: Gp A: 841 F:803 M; Gp B: not reported; Gp C: 831 F:815 M; Gp D: not reported Any other details of important prognostic factors: background exposure to fluoride in drinking water, containing approximately 0.5 ppm F from natural sources Number randomised: 3290 (1100 ppm Gps only. Not reported for 1700 ppm Gps). Gp A: 1644; Gp B: not reported; Gp C: 1646; Gp D: not reported Number evaluated: 4458 at 3 years (present at final assessment. Gp A: 1122; Gp B: 1109; Gp C: 1151; Gp D: 1076) Attrition: overall percentage dropout after 3 years not calculable as numbers randomised at baseline not presented for 1700 ppm groups. Percentage dropout for 1100 ppm F groups 1017/3290 = 31%
Interventions	Comparison: FT versus FT Gp A (n = 1644): SMFP 1100 ppm F; hydrated silica abrasive system; home use (unsupervised) and school use (not clear whether supervised brushing), at least once a day Gp B (n = not reported): SMFP 1700 ppm F; hydrated silica abrasive system; home use (unsupervised) and school use (not clear whether supervised brushing), at least once a day Gp C (n = 1646): NaF 1100 ppm F; hydrated silica abrasive system; home use (unsupervised) and school use (not clear whether supervised brushing), at least once a day Gp D (n = not reported): NaF 1700 ppm F; hydrated silica abrasive system; home use (unsupervised) and school use (not clear whether supervised brushing), at least once a day
Outcomes	Primary: 3‐year net DMFS increment ‐ (CA) cl + DR; DMFS (at 2 and 3 years follow‐ups) Secondary: none assessed Assessments irrelevant to this review's scope: mean number of sealed occlusal surfaces after 3 years Follow‐up duration: 3 years
Notes	Adverse effects: not reported Funding source: not reported, however intervention (Gp C: Crest toothpaste) is manufactured by Procter & Gamble, therefore probable trial was funded by the manufacturer as a co‐author is also employed by them Declarations/conflicts of interest: not reported Data handling by review authors: Gps A + C, and Gps B + D combined in analyses Other information of note: additional information provided in Bartizek 2001. Caries assessment determined by visual‐tactile examinations according to Radike criteria by single examiner and supplemented with radiographs. Diagnostic threshold not stated, CA assumed
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Within each stratum, the subjects were randomly assigned to one of the two dentifrice groups" Comment: random sequence generation not stated
Allocation concealment (selection bias)	Unclear risk	No information provided
Blinding (performance bias and detection bias) All outcomes	Low risk	Quotes: "Both dentifrices were formulated using the same …. And were essentially identical with regard to common excipients" and "At no time during the course of the study did the subjects or the examiner know to which dentifrice group any subject was assigned" Comment: investigators and participants blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: overall dropout for length of follow‐up: not calculable as numbers randomised not provided for all groups. Caries data used in analysis pertain to participants present at final examination
Selective reporting (reporting bias)	Low risk	Outcomes reported: DMFS increment ‐ (CA) cl (DR) xr, reported at 24 and 36 month follow‐up mean number of reversals after 3 years mean number of sealed occlusal surfaces after 3 years Comment: trial protocol not available. Fluoride concentration for 1 group not reported so unable to include in meta‐analysis
Baseline characteristics balanced?	Unclear risk	Prognostic factors reported: age, caries Comment: all appear balanced but only reported for 2 of the 4 FT groups
Free of contamination/co‐intervention?	Low risk	Quote: "Care was exercised to ensure that siblings were assigned to the same treatment group to avoid having different dentifrices in the same household" Comment: contamination not observed