(PR86) **CANCELLED** Outcomes of Endodontically Treated Teeth with Iatrogenic Errors Among  Undergraduate Dental Students at KAUFD: A Retrospective Cohort Study

Background: Root canal treatment (RCT) focuses mainly on the chemomechanical removal of microbes and debris to prevent and treat apical periodontitis. Despite the high success rate of endodontically treated teeth, iatrogenic errors during the treatment can occur and might have adverse effects on the treatment outcomes.

Objective: To assess the outcomes of root canal treated teeth with and without iatrogenic errors (control and mishaps groups) performed by senior undergraduate students at King Abdulaziz University Faculty of Dentistry (KAUFD) with minimum of two years follow up.

Methods: A retrospective cohort study conducted at KAUFD who underwent endodontic treatment during the 2018-19 academic year by senior undergraduate dental students. Matching tooth type was considered for inclusion criteria and eligible patients were recalled and clinical and radiographic examinations were performed.

Results: A total of 170 patients included in the study (n=85 control and n=85 mishaps). The survival rate was 84.6% (mishaps) vs 90.6% (control) and the success rate was 41.7%. (mishaps) vs 63.5% (control). The negative predictors were: perforation (three times more likely to cause failure); instrument separation (two times more likely to cause failure); and underfilling and overfilling (1.5 times more likely to cause failure).

Conclusion: Overall, iatrogenic errors resulted in a 20% reduction in success rates. Significant negative impact factors were perforation, separated files and inadequate obturation length. However, the quality of coronal restoration didn’t affect the outcomes of treated teeth.