PurposeThe aim of this study was to evaluate the competency of undergraduate students in following the principles of access cavity preparation and the radiographic quality of root canal filling in maxillary molar teeth in either online or face‐to‐face education courses during the novel coronavirus disease 2019 (COVID‐19) pandemic.MethodsA total of 178 extracted maxillary molar teeth that underwent endodontic dental treatment by undergraduate students who completed the endodontic preclinical practice course online or face‐to‐face during the COVID‐19 pandemic were retrospectively analyzed. A visual access cavity examination determined the form, width of the cavity, deroofing of the pulp chamber, and the presence of a perforation. Root canal fillings were examined radiographically on periapical radiographs for length, homogeneity, taper, and the presence of iatrogenic defects. Statistical analysis was performed using the chi‐square test.ResultsThe incidence of incorrect form, wide cavities, and perforation was statistically higher in the online group than in the face‐to‐face group (p < 0.05). It was determined that root filling length and homogeneity were more successful in the face‐to‐face group (p < 0.05). When evaluated for iatrogenic errors, the presence of broken instruments was found to be significantly higher in the online group (p < 0.05). There was no significant difference between the groups in other iatrogenic errors and the taper of the root canal filling (p > 0.05).ConclusionThe students who underwent face‐to‐face education were more successful in accessing cavity preparation and root canal fillings than the students who undertook online education.