Peng 2004

Methods	Study design: quasi‐experimental, controlled before‐and‐after study Conducted in: Hongshan District of Wuhan City, Hubei Province, China Unit of randomisation: school Unit of analysis: individual Setting: primary school Funded by: "This study was supported by the Hubei Committee for Oral Health, PR China and the WHO Collaborating Centre for Community Oral Health Programs and Research, University of Copenhagen, Denmark" Duration of the study: 2 years
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Age at baseline: 6.5 ± 0.4 years Total N at baseline: 1143 N (controls baseline): group C, 370 N (controls follow‐up): not specified. Total dropout rate, 19.9% N (interventions baseline): group G, 363; group E, 410 N (interventions follow‐up): not specified (total dropout rate, 19.9%) Recruitment: All children in grade 1 were recruited Gender Group G = 54.8% male Group E = 52% male Group C = 53% male
Interventions	Intervention: oral health education and sugar‐free chewing gum programme. Two intervention groups: group G and group E Group E: WHO HPS approach (school teachers involved, classroom activities: 2‐day training workshop, OHE package for teachers, OH instruction given monthly to children along with supervised toothbrushing, parent engagement sessions around OH instructions); implementation monitored by senior dental advisor every 3 months through school visits Group G: all OHE in group E plus sugar‐free gum (4 times/d, sessions supervised by teachers and parents); gum supplied by school to parents Control: 1 control group C: no specific intervention. Head teachers were aware of intervention programme. Children received toothpaste at the end of the trial Duration of intervention: 2 years
Outcomes	DMFS12/DMFT Bleeding scores
Implementation related factors	Theoretical basis: health promoting schools Resources for implementation: teacher time, sugar‐free chewing gum, training package Who delivered the intervention: teachers and a senior public health dentist PROGRESS categories assessed at baseline: gender 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)	Unclear risk	Method of sequence generation not described ‐ study states only: “nine primary schools were chosen at random from the district and all children from grade 1 were recruited”
Allocation concealment (selection bias)	Unclear risk	Unclear
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropout rate was about 15% overall (14% group E; 13% G and 17% C groups) No reasons for dropouts were provided. Study authors considered that dropout rates would not have any serious effect on outcome evaluation
Selective reporting (reporting bias)	Low risk	Published report presents all expected outcomes of interest to the review
Other bias	Unclear risk	Group G had higher caries level at baseline compared with groups C and E, although this difference was non‐significant
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Examiners were blinded. Details of the intervention were explained to parents of the children and teachers. It may not have been possible to blind participants owing to the nature of the study design
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded