Lenkkeri 2012.
| Methods | Trial design: cluster (5 arms) Location: interventions given in schools in Kotka, Finland; clinical examinations took place in local dental clinics Number of centres: 21 schools Recruitment period: not stated |
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| Participants | Inclusion criteria: not stated but all children were in grade 4 (10 years old) Exclusion criteria: not stated but from the study flow diagram (figure 1) systemic disease appears to be an exclusion criterion Baseline caries: (D₃MFS) Gp A: mean 0.35 (SD 0.8); Gp B: mean 0.27 (SD 0.7) Age at baseline (months): Gp A: mean 123.4 (SD 4.2); Gp B: mean 122.6 (SD 3.6) Gender: Gp A: 45.5% male; Gp B: 47.5% male Any other details of important prognostic factors: "all subjects would have accessed water with a fluoride content not exceeding 1.5 mg/mL"; the study was conducted in a low‐caries prevalence population (i.e. average DMFT of 12‐year‐olds approximately 0.8 for this area, compared to the Finnish average of 1.2) Number randomised: 228 (Gp A: 110; Gp B: 118) (numbers only including the two relevant arms) Number evaluated: 200 (Gp A: 99; Gp B: 101) |
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| Interventions |
Comparison: the 5 arms were as follows: 1) xylitol/maltitol* lozenges for 1 year (excluded: we felt it was more appropriate to use the arm with longer‐term use) 2) xylitol/maltitol lozenges for 2 years (included) 3) erythritol/maltitol lozenges for 1 year (excluded: erythritol is considered, like xylitol, to be caries‐preventive so cannot be used as a control group) 4) erythritol/maltitol lozenges for 2 years (excluded: see arm 3) 5) control (included: no lozenges and no additional prevention) Gp A (n = 110): eight xylitol/maltitol lozenges per day (two in the morning, three after lunch, and three before the child went home) (total dose = 4.7 g xylitol plus 4.6 g maltitol per day) Gp B (n = 118): children received the same comprehensive routine caries prevention as those in the xylitol group, but no lozenges Duration of treatment: children in Gp A received the lozenges for 2 years * Maltitol is considered to be inert (i.e. neither causes nor prevents caries) so we did not consider its inclusion in the lozenges to be a problem |
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| Outcomes |
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| Notes | Sample size calculation: "It was estimated that a 20% difference between the control and each study group...would be clinically relevant...To avoid the risk of a false‐negative result (the type II error) and for the test to have a 90% power to detect a statistically significant difference, even when taking attrition of 10% or less per year into account, one hundred subjects per group were required" Adverse effects: mentioned but no usable data Funding source: CSM Leaf (Turku, Finland) provided the lozenges Declarations/conflicts of interest: the authors stated that they had no conflict of interest |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Quote: "The 21 participating schools were assigned as clusters by means of restricted randomization and blocking into five different groups of approximately the same size" and "After the determination of the groups, they were randomly given a role as one of the four groups receiving colour‐coded lozenges...or a nonlozenge control group, by
drawing lots" Comment: this is an appropriate method of random sequence generation |
| Allocation concealment (selection bias) | Low risk | Quote: "The generation of the random allocation sequence, enrolling the participants, ascertaining treatment assignment and administering the intervention was performed by the Chief Dental Officer of Kotka who did not take part in the clinical examinations. The allocation sequence was concealed until all analyses completed" Comment: it seems that the allocation was performed by someone not involved in the study. We feel that this was probably done properly in this study |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Although the study is described as double‐blinded, we are only interested in the 2‐year xylitol arm and the control group who received no lozenges. Therefore we cannot discount that this would have an effect on the behaviour/motivation (in terms of oral care) of the participants which may affect the results (for example, control group participants 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: "the examining dentist...the dentists interpreting the radiographs...were all completely blinded and not aware of the group the child belonged to until all the data analyses had been carried out" Comment: outcome assessment appears to have been adequately blinded |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 12% of randomised participants were not included in the final analysis (Gp A: 10%; Gp B: 14%). This amount of attrition may be considered low for a 4‐year study. Also, one school of 20 participants in Gp A discontinued the intervention during the first year, but they were included in the analyses on an intention‐to‐treat basis Comment: we do not believe that any of the above could pose a risk of bias significant enough to have led to a distortion of the true intervention effect |
| Selective reporting (reporting bias) | Unclear risk | There were no usable data reported for adverse events. This should be considered an important outcome in xylitol trials |
| Other bias | High risk |
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