Abstract Objectives The aim of this study was to determine the technical quality of root canal fillings and the presence of iatrogenic errors in the cases treated by undergraduate dental students using radiographic images. Materials and Methods This study included 480 root-filled teeth, which were evaluated using intraoral periapical radiographic images. The technical quality of obturation was assessed by observing the length, density, and taperness of the root filling. Ledges, apical transportation, fractured instruments, zipping, and root perforation were recorded as iatrogenic errors. Teeth were classified as acceptable if the technical parameters were adequate and there were no iatrogenic errors. Statistical Analysis Data were statistically analyzed using Pearson's chi-squared test. Results The quality of root filling was acceptable in 183 of the 480 teeth. The rate of acceptable quality was higher for the teeth treated by 4th-year students (41.9%) than for those treated by 5th-year students (27.4%; p = 0.004). Length and taperness were adequate in more of the patients treated by the 4th-year students (p<0.05). There was a significant difference in the incidence of ledge formation and apical transportation in relation to the student's level (p<0.05). Conclusions The technical quality of root fillings performed without iatrogenic errors by undergraduate dental students was declared acceptable in 38.1% of the assessed teeth. There was a noticeable difference in the quality of root canal treatment between the 4th- and 5th-year students. Clinical Relevance The findings demonstrate that periodic assessment of the technical quality of root filling performed by undergraduate dental students provides feedback on curriculum standards.