A Comparative Study of Additive and Subtractive Manufacturing Techniques for a Zirconia Dental Product: An Analysis of the Manufacturing Accuracy and the Bond Strength of Porcelain to Zirconia

Abstract

This study was aimed at preparing zirconia samples via additive manufacturing (AM) and subtractive manufacturing (SM) and testing the following aspects: (1) the manufacturing accuracy of the zirconia samples and (2) the bond strength of porcelain to zirconia to evaluate the applicability of the zirconia fabricated by AM in dental clinics. We used three milling machines for SM (AR, K5, and UP) and a 3D printer for AM (AO). The manufacturing accuracy of the zirconia specimen in the internal and marginal areas was evaluated by superimposing techniques to calculate the root mean square (RMS) values. The bond strengths of porcelain to zirconia prepared via SM and AM were measured using a universal testing machine. The internal and marginal RMS values of the zirconia prepared by AM (AO) were within the range of those of the zirconia prepared by SM (AR, K5, and UP). Moreover, the bond strength value of the zirconia prepared by AM (35.12 ± 4.09 MPa) was significantly higher than that of the zirconia prepared by SM (30.26 ± 5.20 MPa). Therefore, AM technology has significant potential for applications in dentistry.

Manufacturing and Characterization of Dental Crowns Made of 5-mol% Yttria Stabilized Zirconia by Digital Light Processing

“…Mean RMS values for the internal gap and marginal discrepancy were 22.8 ± 1.6 μm and 44.4 ± 10.8 μm, respectively ( Figure 17 B). These values are comparable to those obtained for zirconia dental crowns manufactured using DLP [ 11 , 12 ]. These findings suggest that our DLP technique can offer reasonably high dimensional accuracy with assistance of tightly controlled processing parameters, including initial dimensions of dental crowns, sequential photopolymerization process, and heat-treatment (debinding and sintering).…”

“…From the viewpoint of resolution and accuracy of 3D printing techniques, digital light processing (DLP) and stereolithography (SLA) have been most extensively investigated for the manufacturing of zirconia dental crowns [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. These techniques can selectively photo-cure thin layers of zirconia suspensions, where zirconia particles are uniformly dispersed in photocurable monomers, using high-resolution UV engines according to pre-designed 2D images layer-by-layer [ 3 , 4 ].…”

“…This approach can precisely replicate intricate 3D geometries of dental crowns designed for individual patients [ 3 , 4 ]. In the DLP process, a build platform can move downward to a predetermined position in a vat containing a zirconia suspension, and thus a uniform layer can be formed between the build platform and vat, which can be then photopolymerized by 2D images of UV light [ 7 , 8 , 12 , 13 , 15 , 16 ]. In addition, recoating systems can be integrated into DLP machines (e.g., lithography-based ceramic manufacturing (LCM)), in order to mechanically spread ceramic suspensions uniformly just above the bottom of a vat [ 5 , 14 ].…”

“…In addition, our group recently developed a new type of top-down DLP process by employing specifically designed feeding and recoating systems, where ceramic suspensions can be extruded through a nozzle at a controlled rate and then uniformly spread onto previously photopolymerized layers by a recoater [ 6 ]. A number of recent works have demonstrated that DLP and SLA techniques could offer outstanding dimensional accuracies comparable to CAD/CAM [ 10 , 11 , 12 , 13 , 14 , 15 , 18 ]. However, 3D-printed zirconia objects often suffer from imperfections, including pores within layers and weak interfaces between layers, causing severe reductions in mechanical properties [ 5 , 6 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ] and optical translucency [ 6 , 22 ].…”

Roughness of the Surface of Zirconia Reinforced Lithium Disilicate Ceramic Treated by Different Procedures

“…The advantage of CAD/CAM fabrication is the simplified manufacturing process. This ensures less risk of deformation of the dental prosthesis, which often occurs with conventional procedures due to their complex and numerous steps [11]. The number of appointments is also reduced and the fabrication time is shorter, resulting in less tooth movement.…”