Estimation of main effects (fee versus no fee; education versus no education) required 150 practitioners, each contributing outcome data on 25 children for 80% power at a 5% significance level to detect a 15% difference from a 22% baseline control group level. To obtain 150 dentists, the authors recruited and took a random sample of 374 of 908 eligible dentists.Key Exposure/Study Factor
Two interventions were used. First a fee was set at the level of the fee payable through the normal National Health Service (NHS) system for a restorative fissure sealant application, which may involve removal of enamel caries before sealant placement without the insertion of filling composite. Second, an education intervention of a 1-day workshop was provided and run by experts from The Cochrane Oral Health Group, The Centre for Evidence-based Dentistry, and The Dental Health Service Research Unit. A 2 × 2 factorial design cluster randomized-controlled trial (RCT) compared interventions delivered at the dentist level. Randomization was to 1 of 4 arms: (1) a fee for applying sealant (fee arm), (2) a 1-day educational workshop on evidence-based practice (education arm), (3) both interventions (both arms), or (4) no intervention (control arm).Main Outcome Measure
A random sample of 25 per dentist was taken, and data collection forms were sent to each dentist for completion from practice records 12 months post-intervention. The primary analysis estimated the 2 main effects at the dentist level through analysis of covariance (ANCOVA) on the intention-to-treat principle, weighted by number of children seen per dentist.Main Results
Cluster-level analysis shows a significant increase in sealant treatment in the fee arms compared with the other arms (adjusted risk difference, 9.8%; CI 1.8%-17.8%). The increase in sealant treatments in the education arms was not statistically significant (4.1%, CI −3.9%-12.2%).Conclusions
According to the authors, 33% of children with erupted second permanent molars seen by “fee arm” dentists had received sealant treatment, representing, after adjustment for baseline differences, 10% more than among children in the other arms. The difference is statistically significant, and, in the context of the high level of caries among Scotland's children, clinically significant. The fee intervention was also the most cost-effective.