Although Resilon has been in clinical use as an endodontic obturation material for more than a decade, there is a lack of long-term clinical outcome studies. The purpose of this retrospective case-control study was to compare long-term clinical outcomes in teeth obturated with Resilon/RealSeal SE (RS) and GP/AH Plus (GP).One hundred teeth treated at Texas A&M University College of Dentistry between 2007 and 2012 were included; 50 teeth were obturated with RS and 50 with GP. All cases were initial treatments without preoperative periapical radiolucencies. Success and failure were assessed on the basis of clinical signs and symptoms and/or the presence of periapical radiolucency. Chi-square test and odds ratio were used to determine the association between the obturation material and outcome. Potential prognostic factors were evaluated including age, sex, tooth location, preoperative diagnosis, and one versus multiple visits.The average recall time for RS was 5.8 years and 6.6 years for GP. Fifty-six percent of RS-obturated teeth were classified as successful at recall compared with 88% of GP-obturated teeth. RS had 5.7 times greater odds of failure compared with GP (P < .001). When periapical radiolucencies were present, they tended to be larger and involve multiple roots in the RS group compared with GP group. None of the prognostic factors examined were found to have any significant effect on outcome.Within the limitations of this study, teeth obturated with RS had 5.7 times greater chance of failure compared with teeth obturated with GP.