Three-dimensional evaluation of marginal and internal fit of 3D-printed interim restorations fabricated on different finish line designs

Purpose: To evaluate the influence of fabrication method and finish line design on marginal and internal fit of full-coverage interim restorations. Methods: Four typodont models of maxillary central-incisor were prepared for full-coverage restorations. Four groups were defined; knife-edge (KE), chamfer (C), rounded-shoulder (RS), rounded-shoulder with bevel (RSB). All preparations were digitally scanned. A total of 80 restorations were fabricated; 20 per group (SLA/3D-printed n = 10, milled n = 10). All restorations were positioned on the master die and scanned using micro-computed tomography. The mean gaps were measured digitally (ImageJ). The results were compared using MANOVA (α =.05). Results: Internal and marginal gaps were significantly influenced by fabrication method (P =.000) and finish-line design (P =.000). 3D-Printed restorations showed statistically significant lower mean gap compared to milled restorations at all points (P =.000). The mean internal gap for 3D-printed restorations were 66, 149, 130, 95 μm and for milled restorations were 89, 177, 185, 154 μm for KE, C, RS, RSB respectively. The mean absolute marginal discrepancy in 3D-printed restorations were (30, 41, 30, 28 μm) and in milled restorations were (56, 54, 52, 38 μm) for KE, C, RS, RSB respectively. Conclusions: The fabrication methods showed more of an influence on the fit compared to the effect of the finish-line design in both milled and printed restorations. SLA-printed interim restorations exhibit lower marginal and internal gap than milled restorations. Nonetheless, for both techniques, all values were within the reported values for CAD/CAM restorations. Significance: 3D-printing can offer an alternative fabrication method comparable to those of milled restorations.