Mechanical and surface properties of additive manufactured zirconia under the different building directions

Abstract

The clinical application of dental prostheses manufactured using dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems is now common, owing to the advances in digitalization in the field of dentistry [1]. A CAD/CAM system includes the processes of designing a dental prosthesis using CAD software, converting the scanned data into machining data using CAM software, and using either subtractive manufacturing (SM) or additive manufacturing (AM) technologies to fabricate the dental prosthesis. The former method is employed to fabricate dental prostheses that involve the milling of block-or disk-shaped materials using milling tools [2]. However, SM technologies generate a significant amount of waste materials and tools, and their production of parts with complex geometries is limited, owing to the milling tool size [3]. Previous studies on SM technologies have reported that they are highly reliable, as evidenced by their widespread use in the field of prosthetic dentistry [4][5][6][7]. In particular, zirconia ceramics can only be used to fabricate dental prostheses with a CAD/CAM system, and SM technologies are considered state-of-the-art for fabricating all-ceramic restorations containing zirconia ceramics [8,9]. Zirconia ceramics exhibit exceptional mechanical properties (such as strength, hardness, fracture toughness, wear resistance, corrosion resistance, and biocompatibility) and offer ease of machining through SM technologies in the pre-sintering stage [10][11][12]. However, manufacturing objects with complex geometries is challenging, owing to the limitations associated with milling tools, such as their size and applied angle [13]. In contrast, AM technologies enable the build-up of pieces by adding the material layer-by-layer, unlike SM technologies, which are based on a computerized three-dimensional (3D) printing model. Furthermore, AM technologies can be used to create dental restorations with near-net-shaped dental prostheses that feature intricate details (i.e., grooves, crannies, and valleys), which cannot be fabricated using SM technologies [14,15].The American Society of Testing and Materials has classified J Prosthodont Res. 2022; **(**):

3D Printed Materials for Permanent Restorations in Indirect Restorative and Prosthetic Dentistry: A Critical Review of the Literature

“…In addition to 3D printed resin composites, ceramics and zirconia have also been tested [ 28 , 34 , 35 , 36 , 38 , 47 , 53 , 54 , 55 , 58 ].…”

“…Accordingly, crowns fabricated with both techniques could withstand 5 years of clinical service in the oral cavity. Miura et al investigated the mechanical properties of additively manufactured zirconia in two different studies [ 53 , 54 ]. They found that flexural strength is correlated with the printing angle.…”

“…Also, zirconia seems to have lower flexural strength when 3D printed than milled, but this property was shown to be highly dependent on the building direction. When printed with an angle of 90°, the flexural strength reached the highest values, followed by the 45° and 0° printing angles [ 53 ]. Additionally, flexural strength was higher when building and loading directions were parallel compared to that of specimens in which they were perpendicular [ 53 ].…”

“…When printed with an angle of 90°, the flexural strength reached the highest values, followed by the 45° and 0° printing angles [ 53 ]. Additionally, flexural strength was higher when building and loading directions were parallel compared to that of specimens in which they were perpendicular [ 53 ]. Even though the flexural strength of 3D printed zirconia was lower than milled zirconia, it still reached values of 800 MPa or higher in the 45° and 90° directions [ 53 ], being suitable for fixed dental prostheses with four or more units [ 69 ].…”

Dental material research in prosthodontics—Towards developing better and efficient biomimetic materials

“…The future prospects for prosthetic research in dental materials science are exciting and hold the potential to significantly improve the lives of individuals with dental prostheses. By developing more durable and biocompatible materials using 3D printing technology, artificial intelligence, and advanced regenerative medicine, researchers are poised to make great strides in this field [9,10]. By investing in dental materials science research, we can improve the quality of life of patients.…”