Zarod 1992

Methods	Study design: RCT
Participants	Participants: 528 Inclusion criteria: school children aged 4 to 6 years attending primary schools in Wallasey Exclusion criteria: children requiring immediate treatment like pulp treatment, extractions or have received such treatment in recent past. Age at baseline: 4 to 6 years old Gender: not mentioned Number of participants randomised: test group n = 270, control group n = 258 Number of participants evaluated: test group n = 262, control group n = 243
Interventions	Comparison:'screening followed by referral letter versus without follow‐up letter' programme for increasing dental attendance. Secondly, the study compared effectiveness of dental screening in areas of contrasting socioeconomic status. Intervention: baseline screening followed by referral letter to parents via child (n = 270). A second letter was mailed to child's home address if return slip was not returned within a week of the first letter. If response to either was not received within 21 days, personal telephone was made wherever possible. Control: baseline screening without any further communication, (n = 258)
Outcomes	Duration of follow‐up: 4 months after baseline screening Primary outcome: dental attendance in both groups
Notes	Language: English Funded by: not mentioned Costs of follow‐up: not reported Conducted in: UK Unit of randomisation: individual Author contact information: m.a.lennon@sheffield.ac.uk No reply received on queries for risk of bias assessment
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information
Allocation concealment (selection bias)	Unclear risk	No information
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss of follow‐up of 8 children from test group and 15 children from control group was noted in the trial. However, these numbers would not have affected the overall results (based on our intention‐to‐treat analysis).
Selective reporting (reporting bias)	Low risk	All pre‐stated outcomes in the methods were reported.
Other bias	Low risk	No other source of bias