Arunakul 2012

Methods	Study design: randomised controlled trial Conducted in: Thailand Unit of randomisation: individual Unit of analysis: individual Setting: 3 schools for the deaf/hearing impaired Funded by: "The study was supported by the Faculty of Dentistry, Mahidol University" Duration of the study: 3 months
Participants	Inclusion criteria: not reported Exclusion criteria: not reported Age at baseline: 6 to 10 years N (controls baseline): 20 N (controls follow‐up): 16 N (video presentation baseline): 20 N (video presentation follow‐up): 17 N (illustrated book baseline): 20 N (illustrated book follow‐up): 16 N (video + Illustrated book baseline): 20 N (video + illustrated book follow‐up): 17 Recruitment: Baseline study was conducted at 3 hearing impaired schools (Nonthamburi, Nakhon Pathom and Thungmahamek) in Thailand. After the baseline study, 80 hearing impaired students were randomly divided into 4 groups Gender (M/F) Video presentation = 15/5 Illustrated book = 13/7 Video + illustrated book = 13/7 Control group = 10/10
Interventions	3 intervention groups included Video presentation group: received oral health instruction via video presentation and toothbrushing instructions Illustrated book group: received oral health instruction via illustrated book and toothbrushing instructions Video presentation + illustrated book group: received oral health instruction via video and illustrated book and toothbrushing instructions Control: received no oral health instruction Duration of intervention: not reported, but follow‐up measurements were taken after 3 months
Outcomes	Gingival index Gingival bleeding index
Implementation related factors	Theoretical basis: not reported Resources for implementation: not reported Who delivered the intervention: unclear PROGRESS categories assessed at baseline: disability. Study participants had hearing impairment PROGRESS categories analysed at outcome: disability. Study participants had hearing impairment Outcomes related to harms/unintended effects: not reported Intervention included strategies to address diversity or disadvantage: Study targeted hearing impaired students Economic evaluation: not reported
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Unclear
Allocation concealment (selection bias)	Unclear risk	Unclear
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rate was low (17.5%)
Selective reporting (reporting bias)	Unclear risk	Unclear
Other bias	Unclear risk	Unclear
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Unclear
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear