Sintes 1995.

Methods	Trial design: parallel (2 arms) Location: schools in the metropolitan area of San José, Costa Rica Number of centres: 17 schools Recruitment period: not stated
Participants	Inclusion criteria: 8‐ to 10‐year‐olds (however, children younger than 8 years yet at the scholastic third grade level, or older than 10 years yet still at the scholastic fifth grade level, were accepted if they met the following criterion); minimum of one DFS Exclusion criteria: not stated Baseline caries: (DFS) Gp A: mean 5.6 (SD 2.9); Gp B: mean 5.5 (SD 3.0) Age at baseline: unclear due to first inclusion criterion above but stratified by age Gender: not stated but stratified by gender Any other details of important prognostic factors: the water supply had a fluoride concentration of less than 0.1 ppm; fluoridated table salt was introduced in Costa Rica around the time the study began, but availability was equal for all participants Number randomised: 2630 (not reported by group) Number evaluated: 1677 (Gp A: 840; Gp B: 837)
Interventions	Comparison: xylitol plus fluoride toothpaste versus fluoride toothpaste Gp A (n = 840 evaluated): twice daily brushing for 1 minute with toothpaste containing 10% xylitol plus 0.243% sodium fluoride (1100 ppm fluoride); participants were instructed to spit out the slurry after brushing and rinse thoroughly with water; eating/drinking was discouraged for at least 30 minutes following brushing; application of toothpaste to toothbrush was supervised Gp B (n = 837 evaluated): as above but without xylitol Duration of treatment: 3 years
Outcomes	Caries: DFS increment. Assessed at 2 and 3 years Adverse effects
Notes	Sample size calculation: the authors state that the study met the sample size requirements of the American Dental Association (ADA) guidelines for clinical trials of anticaries toothpaste efficacy (minimum 80% power to detect 10% difference) Adverse effects: none observed Funding source: several authors employed by Colgate‐Palmolive Declarations/conflicts of interest: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Each child was randomly assigned to use either..." Comment: insufficient information on the method of sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote: "Each child was randomly assigned to use either..." Comment: allocation concealment not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Product was provided in plain white tubes (identified only by a solid colour‐coded label) in order to maintain the double‐blindness" Comment: participants and personnel would not know to which group a participant was assigned
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Product was provided in plain white tubes (identified only by a solid colour‐coded label) in order to maintain the double‐blindness" Comment: outcome assessment appears to have been adequately blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	36% of randomised participants were not included in the final analysis (not reported by group). If the missing participants had higher mean caries increments in one group than the other, as the attrition rate increased, so would over/understatement of the mean difference
Selective reporting (reporting bias)	Low risk	Appropriate outcome measures were considered and reported in full, as described in the methods section
Other bias	Low risk	Caries evaluations were carried out by a single dentist who was calibrated before and during the study. We consider that the risk of differential diagnostic activity was low