Objective <p>This study aimed to compare the marginal and internal fit of endocrowns with cavity depths of 3&#xa0;mm and 5&#xa0;mm, using two printable resins fabricated by additive manufacturing within a digital workflow.</p> Materials and methods <p>Thirty-two human mandibular molars were prepared for endocrowns with cavity depths of 3–5&#xa0;mm and allocated into four groups (<i>n</i> = 8). Two printable resins (Biocrown Diamond and Voxel Print) were evaluated at both preparation depths. The restorations were designed using CAD software and manufactured by DLP-based additive manufacturing. Marginal and internal fit were assessed using micro-computed tomography (micro-CT) from standardized sagittal and coronal sections at predefined anatomical regions. Data were analyzed using two-way repeated-measures ANOVA followed by Tukey’s test (α = 0.05).</p> Results <p>Material and preparation depth influenced the marginal and internal fit of endocrown restorations, with a significant interaction with the anatomical region. The highest discrepancies were observed in the axio-occlusal angle, particularly for the 5-mm preparation groups. Significant differences between materials occurred at the axio-occlusal angle for 3-mm preparations and in the marginal gap for 5-mm preparations. No significant differences were detected in the pulpal regions.</p> Conclusion <p>Endocrowns showed clinically acceptable marginal adaptation at both preparation depths. However, internal adaptation was region-dependent, with greater discrepancies in the axio-occlusal region. Both resins demonstrated acceptable behavior, although localized differences were observed according to preparation depth and anatomical region.</p> Clinical significance <p>Preparation depth and printable resin type may influence the internal adaptation of additively manufactured endocrowns and should be considered during treatment planning.</p>