Oscarson 2006.

Methods	Trial design: parallel (2 arms) Location: public dental clinic in Lycksele, Sweden Number of centres: 1 Recruitment period: not stated
Participants	Inclusion criteria: all healthy 2‐year‐old children, born in 2000 and the first quarter of 2001, attending the public dental clinic in Lyycksele Exclusion criteria: children with severe disabilities; children that did not co‐operate for an oral inspection Baseline caries: not stated Age at baseline: all children were 2 years old Gender: Gp A: 49% female; Gp B: 46% female Any other details of important prognostic factors: not stated Number randomised: 132 (Gp A: 66; Gp B: 66) Number evaluated: 118 (Gp A: 55; Gp B: 63)
Interventions	Comparison: xylitol sucking tablets versus control (no tablets and no additional prevention) Gp A (n = 66): one tablet (0.48 g xylitol) slowly dissolved in the mouth per day, at bedtime after toothbrushing, for the first 6 months, then two tablets (one in the morning and one in the evening) for another year (total dose = 1 g xylitol per day) Gp B (n = 66): children received the same routine prevention and restorative care and advice as those in the xylitol group, but no tablets Duration of treatment: children in Gp A received the tablets for 1.5 years
Outcomes	Caries: dmfs increment. Assessed at 2 years Caries: incidence measured using dichotomous presence of a dmfs increment or not. Assessed at 2 years Microbial counts (not an outcome of interest in this review)
Notes	Sample size calculation: only a post‐investigation sample size analysis was performed Adverse effects: not reported Funding source: grants from: a) the County of Västerbotten; b) the Patent Revenue Fund for Dental Prophylaxis; and c) the Swedish Dental Society Declarations/conflicts of interest: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "the children were randomly assigned" Comment: insufficient information on the method of sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote: "the children were randomly assigned" Comment: allocation concealment not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	It was not possible to blind participants and personnel because the control group had no tablets. Therefore we cannot discount that this would have an effect on the behaviour/motivation (in terms of oral care) of the participants/carers which may affect the results (for example, control group participants/carers may overcompensate by taking extra care of their oral health, or conversely, the xylitol group may feel they do not need to take as much care of their oral health as they usually would due to an expected effect of the xylitol)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "single‐blind" and "Caries was registered by tactile and visual examination in a dental chair by two blinded calibrated examiners" Comment: outcome assessment appears to have been adequately blinded
Incomplete outcome data (attrition bias) All outcomes	High risk	11% of randomised participants were not included in the final analysis, but this was unbalanced with appreciably higher attrition in the xylitol group (Gp A: 17%; Gp B: 5%). If the higher rate of attrition was related to the intervention, then this could be considered a risk of bias
Selective reporting (reporting bias)	Unclear risk	Adverse events should be considered an important outcome in xylitol trials, but were not considered in this study
Other bias	High risk	Confounding: due to the lack of a placebo, we cannot exclude the possibility that some of the effects would be due to salivary stimulation as a result of sucking a tablet Caries was assessed by two blinded calibrated examiners. We consider that the risk of differential diagnostic activity was low