INTRODUCTION: A computer-assisted tobacco decision support tool increased dental practitioners' (dentists and dental hygienists) advice to quit smoking and referral to a quitline during a group randomized trial. The purpose of this study is to document the extent to which use persisted after the trial. METHODS: Electronic dental record (EDR) data from 2010 to 2013 were analyzed in 2014 for use of computer-assisted tobacco intervention tool advice scripts and referral to a quitline during four periods: during the trial and post-trial when only intervention clinic dental practitioners had access to the tool, and during full deployment, both before and after an EDR modification. RESULTS: Intervention clinic dental practitioners (18.5 dentist full-time equivalents [FTEs] and 27.8 dental hygienist FTEs practicing in seven clinics) referred 19.0% of 1,368 smokers to a quitline during the trial and referred 15.4% of 4,011 smokers post-trial. After full tool deployment but pre-EDR change, these dental practitioners referred 15.6% of 2,214 intervention clinic smokers, whereas 18.3 dentist FTEs and 29.7 dental hygienist FTEs practicing in eight clinics referred 8.5% of 2,113 smokers. Post-EDR change, dental practitioners referred 12.2% of 2,214 intervention clinic smokers and 8.1% of 2,399 control clinic smokers to a quitline. In the last three quarters of observation, clinic script use ranged from 15.4% to 65.8% and referral to a quitline ranged from 2.0% to 18.7% of visits. CONCLUSIONS: Although EDR design affected rates of referral, dental practitioners persisted in using a computer-assisted tobacco intervention tool to refer smokers to a quitline.