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, 95μm and for milled restorations were 89, 177, 185, 154μm for KE, C, RS, RSB respectively. The mean absolute marginal discrepancy in 3D-printed restorations were (30, 41, 30, 28μm) and in milled restorations were (56, 54, 52, 38μm) 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. Significance3D-printing can offer an alternative fabrication method comparable to those of milled restorations.
Read the abstract or the full article published on Journal Of Prosthodontic Research –October 2017 https://www.ncbi.nlm.nih.gov/pubmed/29032176