Background: Performing root canal treatment is complex and requires the development of psychomotor skills adapted to working without the advantage of vision. Students have allocated special importance to preclinical training in helping them acquire these skills. The aim of this prospective study was to investigate the influence of exposure to additional preclinical training on undergraduate students’ confidence level and clinical performance defined by technical quality and quantity of root canal treatment. Methods: Clinical root canal treatment performed by a cohort of fifth-year undergraduate dental students was followed after half of them attended an additional (elective) endodontic preclinical course the year before. Root canal treatment was radiographically evaluated according to root canal filling length, density and presence of procedural errors. Technical quality and quantity of root canal treatment performed by students who had attended the elective course (attendees) and non-attendees, were compared. All students were also invited to participate in a survey to rate their undergraduate endodontic training and confidence levels performing root canal treatment. Statistical analysis of data was performed using Person chi-square test, Fisher Freeman Halton exact test, and T-test. A p-value <0.05 was considered statistically significant. Results: No significant difference between the two groups in overall root canal treatment quality (p=0.619) was found. Although elective attendees performed significantly less procedural errors (p=0.004), non-attendees completed more root canal treatments (p=0.012). Despite, no significant difference in the reported level of confidence between the attendees and the non-attendees, significantly more elective attendees rated their undergraduate endodontic training as adequate (p=0.002).Conclusion: While there was no significant difference in overall technical quality of root canal treatment, nor confidence levels, between both groups, undergraduate students who attended additional preclinical training performed significantly fewer procedural errors. Furthermore, students who attended additional preclinical training were more satisfied with their undergraduate endodontic education.