Background <p>Clinical training outcomes are essential indicators of the quality and effectiveness of undergraduate and postgraduate dental education. Post-core restorations in endodontically treated teeth represent technically demanding procedures that require adequate clinical judgment and manual skills. However, limited evidence exists regarding how operator education level influences the distribution of adverse clinical outcomes in such procedures within dental education settings. This retrospective study aimed to evaluate and compare adverse outcomes of prefabricated metal post-core restorations performed by undergraduate and postgraduate dental students.</p> Methods <p>This retrospective study included 160 endodontically treated teeth restored with prefabricated metal post-core systems in a university dental clinic. All cases had a minimum radiographic follow-up of approximately five years (52–60 months). Adverse outcomes, including tooth extraction, post/root/crown fractures, and periapical lesions, were recorded descriptively. Radiographic evaluations were performed independently by two blinded examiners, and inter-examiner reliability was assessed using Cohen’s kappa. Outcomes were analyzed according to operator education level, tooth region, tooth location, and patient demographics. Categorical variables were compared using the chi-square test. Statistical significance was set at <i>p</i> &lt; 0.05. Univariable and multivariable logistic regression analyses were performed to assess independent associations.</p> Results <p>Adverse outcomes were observed in 24.4% of restorations, while 75.6% showed no adverse outcomes. No statistically significant associations were found between adverse outcomes and gender, tooth region, or tooth location (<i>p</i> &gt; 0.05). In univariable analysis, operator education level was associated with adverse outcomes (<i>p</i> &lt; 0.05); however, this association was not significant after adjustment for potential confounding variables. Tooth extraction was the most frequently observed adverse outcome.</p> Conclusions <p>Within the limitations of this retrospective study, operator education level was not independently associated with adverse outcomes after adjustment for confounding variables. The findings should be interpreted descriptively and do not support causal inferences regarding operator competence. These results highlight the importance of considering confounding factors in dental education research and may inform future studies and curriculum development.</p>