Influence of milling systems and marginal configurations on the fit of yttrium stabilized tetragonal zirconia polycrystals (Y-TZP)’ copings

Abstract

Objective: The aim of this study was to evaluate marginal fit of yttrium tetragonal zirconia polycrystals (Y-TZP)’ copings with different finish line designs fabricated with various digital scanners and milling systems. Methods: Three model plastic teeth were prepared with three finish line designs: Design-1, continuous chamfer; Design-2, chamfer with shallow depression; Design-3, chamfer with deep depression. The “master models” were replicated using elastomeric polyvinyl siloxane impression material and poured in type IV stone generating 90 dies, 30 dies for each design. Dies were scanned and copings were milled utilizing three digital scanners and computer-aided design/computer-aided manufacturing (CAD/CAM) systems: System-1, InEos Red Scan (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); System-2, Cerec® AC Connect with BlueCam (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); and System-3, NobleProcera™ Optical Scanner (NobleBiocare™), procera zirconia coping milled by a Noble Procera™ milling machine (NobleBiocare™). Copings were seated on their respective “master models” and secured with uniform force. Eight measurements per coping were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) connected to a high precision digital video-micrometer (Javelin JV6000, California, USA) at 200 × magnification. Results: The tested systems demonstrated marginal gaps ranging from 12.4 to 26.6 µm. Results for marginal fit of milled copings fabricated using three systems with different finish line designs differed significantly ( p < 0.05). Procera zirconia copings scanned and milled with NobleProcera™ exhibited significantly lower marginal gaps compared to other specimen groups. However, InEos Red Scan/Vitablocks® Mark II/Cerec® inLab showed maximum marginal gaps among the study specimens. Conclusions: CAD-CAM manufactured Y-TZP’ copings exhibited marginal gaps ranging from 12.49 to 26.6 µm. The CAD-CAM fabrication system was a significant factor influencing the marginal misfit of Y-TZP’ copings. Margin design exhibited system dependent influence on the marginal misfit. Marginal misfit observed for all systems were within clinically acceptable parameters.

Comparison of Marginal Integrity and Surface Roughness of Selective Laser Melting, CAD-CAM and Digital Light Processing Manufactured Co-Cr Alloy Copings

“…Precise marginal fit of dental cast restoration is considered as the most critical and technical feature for the long-term successful clinical outcomes. Available evidence advocates an acceptable range of marginal misfit of full veneer crowns to be 100 to 120 µm [3]. However, multiple studies suggest different ranges of acceptable marginal misfit (10 to 160 µm) [4].…”

“…However, multiple studies suggest different ranges of acceptable marginal misfit (10 to 160 µm) [4]. Increased marginal discrepancy accounts for the 10% of prosthetic failures, i.e., exposure of dental cement to the oral environment, bacterial penetration and plaque retention, secondary carious lesions, negative pulp reactions, marginal discoloration, periodontal disturbances, and esthetic and functional compromise [3].…”

“…Primarily, marginal integrity of cast copings are influenced by the surface characteristics, cast adaptation, and luting adhesives used [5]. Similarly, surface micro-roughness 2 of 12 (Ra) also influences the retention of indirect restoration [3]. It has been proposed that different fabrication techniques exhibit different Ra levels for cast indirect restorations.…”

Marginal Misfit of 3D-Printed (Selective Laser Sintered), CAD-CAM and Lost Wax Technique Cobalt Chromium Copings with Shoulder and Chamfer Finish Lines: An In-Vitro Study

“…Conventional casting is a sensitive technique with multiple steps, being time-consuming, operator and material dependent; and therefore is prone to errors [ 8 , 9 , 10 ]. CAD-CAM technology offers increased accuracy and efficiency, reduced time, labor and cost of production and reproducibility; however, wastage of material and finite resolution limits its ability to fulfill misfit goals [ 8 , 11 ]. In addition, evolution in CAD-CAM technology has resulted in a myriad of milling systems, which show misfit outcomes ranging from 16 μm to 100 μm [ 6 ].…”

Marginal and Internal Precision of Zirconia Four-Unit Fixed Partial Denture Frameworks Produced Using Four Milling Systems

“…The demand for convenient, metal-free dentures has increased significantly in recent years. In particular, the excellent translucency of zirconia (ZrO2) in combination with an all-ceramic veneering material makes it suitable for fixed partial dentures (FPDs) [3][4][5]. Zirconia has a flexural strength from 900 to 1200 MPa and resists dispersion of cracks by undergoing a crystalline phase transformation [6][7][8].…”