Andrews 1999

Methods	Country: USA Recruitment: Hygiene patients in private dental practices Cluster randomized trial
Participants	633 ST users >= 15 years of age
Interventions	1. Intervention: Determine tobacco use, identify oral disease, strong advice to quit, set quit date within 2w, motivation video, written material, call patient within 2w. 2. Usual care
Outcomes	12m 'sustained' abstinence from ST and all tobacco: subjects must have reported 7‐day PP ST and all tobacco abstinence at both 3m and 12m. Abstinence verification: None
Notes	Data for smokers in the same trial reported in Severson 1998 ICC calculated < 0.0009. Intervention group more likely to have previously been advised by a dental care provider to quit use of ST and were less likely to be single. Study reports only those using smokeless tobacco.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Cluster randomized: Practices were blocked (by average number of hygiene visits per week and years dentists had been in practice). Method not described
Allocation concealment (selection bias)	Low risk	At hygiene visit all patients completed health survey; those responding 'Yes' to current use of tobacco were enrolled.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow‐up was 26% (102/394) in intervention and 26% (62/239) in the control group.