Survival of root canal-treated teeth adjacent to an implant: a retrospective case-control study

: To evaluate the survival of root canal treated (RCT) teeth adjacent to an implant compared with that of RCT teeth of the same patient non-adjacent to an implant. : RCT tooth of each patient adjacent to an implant were included in the test group. The control group consisted of another RCT tooth of the same patient; the control RCT tooth was not adjacent to an implant and selected to be of the same type of the RCT tooth in the test group. 72 teeth of 36 patients with at least 4-year follow-up were included. In addition to survival, other clinical and demographic parameters investigated were age, sex, tooth type and position, presence of a crown, presence of retreatment, presence of a post-core, presence of adjacent edentulous area, presence of implant-supported fixed prosthetic restoration on the antagonist tooth and periapical health status. Pearson Chi-Square and Fisher Exact tests were used to compare the test and the control groups with categorical variables (α=0.05). Survival curves were obtained by the Kaplan-Meier method, and the Log-rank test was performed to compare the survival probabilities (α=0.05). : No significant difference in survival rates was observed between the test and the control groups (p=0.72). Similarly, no significant relationship was found between the investigated clinical variables and the survival rates of RCT teeth (p>0.05). Survival times differed depending on the presence of an adjacent edentulous area (p<0.001) and the periapical health status (p=0.026). : RCT teeth with unhealed periapical tissues had a shorter cumulative survival time. Similarly, those adjacent to an edentulous area had shorter cumulative and complication-free survival times. This is the first study to determine the survival outcome of a RCT tooth adjacent to an implant compared to a non-adjacent one in the same patient. Being adjacent to an implant did not have a detrimental effect on the survival time and rate of RCT teeth.