RESUMEN
AIM: To determine and explain the principal sources of stress among preclinical and clinical dental undergraduate students with a particular focus on the stressors linked to endodontics. METHODOLOGY: A mixed-methods study, with an explanatory sequential design, was employed. Volunteer students of second, third and fourth years were asked to complete both the Dental Environment Stress (DES) questionnaire and a bespoke questionnaire for endodontic-related stress assessment, which had 21 questions in common with the DES. The results were analysed by Kruskal-Wallis and Marginal Homogeneity tests. In the second part of the study, a qualitative phase was conducted through focus group interviews of students from each academic year included in the study. Interviews were analysed by inductive content analysis. RESULTS: The DES questionnaire determined that for all years the most stressful domains were 'performance pressure', 'workload' and 'clinical training'. According to the endodontic stress questionnaire, the most stressful domains were 'self-efficacy beliefs', 'endodontic clinical training' and 'faculty and administration' in early years, while they were 'endodontic patient treatment', 'performance pressure in endodontics' and 'clinical training' in later years. Comparing questions common to both questionnaires revealed that the stress score was lower for the endodontic stress questionnaire than in the DES questionnaire for 17 questions, being significantly lower for 13 questions (p < 0.05) and significantly higher for no question. The qualitative study showed that students' dental and endodontic-related stress was linked to different domains: patient, clinical procedure, organization, staff, academic education, evaluation and COVID-19-related issues. Qualitative aspects highlighted the important role that patients and COVID-19 have played in student stress. However, they suggested a possible explanation for the lower endodontic stress observed in this dental university hospital, which was based on: the nature of the teaching in endodontics, the consensus between endodontic supervisors, the use of a logical, progressive procedure and the considerable experience that students gain over the years. CONCLUSION: Students considered endodontics stressful; however, education can play a central role in reducing stress, particularly during the early parts of the undergraduate course.