CL‐213 1983.

Methods	Trial design: 2‐armed, double‐blind, active‐controlled and stratified RCT Location: Pennsylvania, USA Number of centres: not stated Recruitment period: study commenced in 1979
Participants	Inclusion criteria: male and female schoolchildren in Grades 1 to 6 Exclusion criteria: schoolchildren with a condition which prohibited a thorough oral examination, including orthodontic therapy and extensive prosthetic appliances Baseline caries: not reported Age at baseline (years): range 6 to 11 years Sex: not reported Any other details of important prognostic factors: background exposure to fluoride not reported. Community water supply fluoride < 0.3 ppm Number randomised: not reported Number evaluated: 1197 at 3 years (present for final assessment. Gp A: 582; Gp B: 615) Attrition: unable to calculate due to missing information from number randomised
Interventions	Comparison: FT versus FT Gp A (n = 582 evaluated): NaF 1100 ppm F; abrasive system not reported; home use ad libitum (twice daily, unsupervised assumed) Gp B (n = 615 evaluated): NaF 1700 ppm F; abrasive system not reported; home use ad libitum (twice daily, unsupervised assumed)
Outcomes	Primary: 3‐year DMFS increment ‐ cl + xr Secondary: none reported Assessments irrelevant to this review's scope: none Follow‐up duration: 3 years
Notes	Adverse effects: not reported Funding source: The Procter & Gamble Company Declarations/conflicts of interest: none reported. Procter & Gamble data Data handling by review authors: n/a Other information of note: all clinical (Radike criteria) and radiographic examinations were carried out by a single examiner. "The sponsor decided to begin another study immediately upon completion of the Year 3 examinations. For logistical reasons, it was decided to only perform Year 3 examinations on those subjects who agreed to participate in Study E (approximately 40% to 45% of the subjects who completed Year 2)." Unpublished data on file from The Procter & Gamble Company, published in Bartizek 2001
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "...subjects were stratified based on gender, age and baseline DMFS scores derived from the visual‐tactile examination, and randomly assigned to one of the treatment groups in the study"
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information
Blinding (performance bias and detection bias) All outcomes	Low risk	Quotes: "... double‐blind study" "Subject and examiner blindness to treatment were maintained throughout the study" and "Dentifrices were supplied in plain white tubes"
Incomplete outcome data (attrition bias) All outcomes	High risk	Quotes: "The studies each enrolled approximately 1200 to 2000 male and female schoolchildren per treatment group" and "The sponsor decided to begin another study immediately upon completion of the Year 3 examinations. For logistical reasons, it was decided to only perform Year 3 examinations on those subjects who agreed to participate in Study E (approximately 40% to 45% of the subjects who completed Year 2)" Comment: actual number randomised not reported, so unable to calculate attrition. Selective examination at Year 3
Selective reporting (reporting bias)	Low risk	Comment: results reported traditional increment using clinical and radiographic assessments
Baseline characteristics balanced?	Low risk	Comment: not explicitly stated, but stratified randomisation according to gender, age and baseline DMFS scores with large sample size so probably balanced
Free of contamination/co‐intervention?	Low risk	Quote: "...siblings, all were automatically assigned to the same treatment group as the first sibling to minimise the risk from cross‐usage of assigned dentifrice"