Available online 20 December 2025

The digital transition in dentistry necessitates reexamining traditional preparation standards, particularly finish-line quality for 3D-printed restorations. This study investigated how finish-line characteristics affect the marginal adaptation of selective laser melting (SLM) fabricated copings.

Forty typodont maxillary central incisors prepared for porcelain-fused-to-metal crowns were scanned. Margin width, margin curvature, and finish-line curvature were measured at four axial surfaces. Finish lines were graded on a 1–4 scale based on distinctness and continuity. The maximum marginal gap at each surface of every SLM-printed coping on its respective abutment was recorded and categorized as excellent (120 μm). Friedman and Wilcoxon signed-rank tests assessed marginal gaps; repeatedmeasures ANOVA and McNemar–Bowker tests evaluated categorical outcomes. Generalized estimating equations (GEE) estimated odds ratios for poor adaptation (α=0.05).

Marginal gaps on mesial (79.75±42.39 μm) and distal (86.48±32.49 μm) surfaces were significantly larger than labial (25.35±39.76 μm) and palatal (39.83±52.17 μm) surfaces (P0.05).

Finish-line distinctness and axial surface location were the important determinants of SLM coping adaptation. Even in digital workflows, meticulous tooth preparation remains essential, while evaluation rubrics may recalibrate the weighting of finish-line continuity and smoothness.

Coping

Finish-line quality

Marginal adaptation

Metal 3D printing

Porcelain-fused-to-metal (PFM)

Selective laser melting (SLM)

© 2025 Association for Dental Sciences of the Republic of China. Publishing services by Elsevier B.Vé