Tai 2009

Methods	Study design: cluster‐randomised controlled trial Conducted in: Xiling District of Yichang City Hubei Province, China Unit of randomisation: schools Unit of analysis: children Setting: kindergartens Funded by: "The study was supported by the Guangzhou Colgate Palmolive Company Limited, and the National Key Technologies R&D Programme of the Eleventh Five‐Year Plan conducted by the Ministry of Science and Technology of China" Duration of the study: 3 years
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Age at baseline: 6 to 7 years old N (controls baseline): 810 N (controls follow‐up): not reported N (interventions baseline): 806 N (interventions follow‐up): not reported Recruitment: schools, first grade Gender Intervention: 53.6% male, 46.4% female Control: 51.5% male, 48.5% female
Interventions	Intervention: 3‐year oral health promotion programme 30‐minute oral health education instruction delivered by school teachers, biweekly for 3 years. Instruction consisted of tooth structure and function, cause and development of dental caries and gingivitis and toothbrushing methods and caries‐reducing effects of fluoride Oral health education booklet for use by children Annual poster presentation Oral examination by dentist in the classroom once per year Control: received none of the intervention Duration of intervention: 3 years
Outcomes	Net caries increments of children (DMFT/DMFS) and OH15 status, including changes in plaque index
Implementation related factors	Theoretical basis: health promoting schools Resources for implementation: training, training packages, teacher and clinical staff time Who delivered the intervention: teachers and clinicians PROGRESS categories assessed at baseline: gender, SES, education PROGRESS categories analysed at outcome: not reported Outcomes related to harms/unintended effects: not reported Intervention included strategies to address diversity or disadvantage: not reported Economic evaluation: not reported
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Unit of randomisation was the school, and all children in the first grade participated. Fifteen schools were randomly assigned to intervention group (n = 7) or control group (n = 8). Randomisation was performed via a block randomisation method by a researcher not involved with the study
Allocation concealment (selection bias)	Low risk	All dentists were blind to group allocation of children throughout the study
Incomplete outcome data (attrition bias) All outcomes	Low risk	Participant attrition rate by the end of the study period was 18% for the intervention group and 14% for the control group. Loss of children from the study was caused by their transfer to other schools. To assess attrition effects, distributions of children both with and without a follow‐up exam were compared with regard to gender, age, oral health behaviour, socioeconomic status and baseline caries variables. No significant difference was observed between the 2 groups
Selective reporting (reporting bias)	Unclear risk	Unclear
Other bias	Unclear risk	Unclear, but this study was funded by a commercial company, which could have resulted in other potential sources of bias
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Teachers and local dentists in the intervention group were trained in the OHP programme and were aware of their school’s test status
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All dentists were blinded to group allocation of children throughout the study