Abstract
Photopolymer resins are widely used in the production of dental prostheses, but their mechanical properties require improvement. We evaluated the effects of different zirconia filler contents and printing directions on the mechanical properties of photopolymer resin. Three-dimensional (3D) printing was used to fabricate specimens using composite photopolymers with 0 (control), 3, 5, and 10 wt.% zirconia filler. Two printing directions for fabricating rectangular specimens (25 mm × 2 mm × 2 mm) and disk-shaped specimens (φ10 mm × 2 mm) were used, 0° and 90°. Three-point bending tests were performed to determine the flexural strengths and moduli of the specimens. The Vickers hardness test was performed to determine the hardness of the specimens. Tukey’s multiple comparison tests were performed on the average values of the flexural strengths, elastic moduli, and Vickers hardness after one-way ANOVA (α = 0.05). The flexural strengths and elastic moduli at 0° from high to low were in the order of 0, 3, 10, and 5 wt.%, and those at 90° were in the order of 3, 0, 10, and 5 wt.% (p < 0.05). For 5 and 10 wt.%, no significant differences were observed in mechanical properties at 0° and 90° (p < 0.05). The Vickers hardness values at 0° and 90° from low to high were in the order of 0, 3, 5, and 10 wt.% (p < 0.05). Within the limits of this study, the optimal zirconia filler content in the photopolymer resin for 3D printing was 0 wt.% at 0° and 3 wt.% at 90°.
Highlights
In recent years, computer-aided design and manufacturing (CAD/CAM) technologies have been used in some medical and dental treatments, and the digitization of prosthesis production has been progressing [1–4]
This study aimed to evaluate the effects of different zirconia filler contents and printing directions (0◦ and 90◦) on the mechanical properties for 3D printing of the photopolymer resin
This study demonstrated that the flexural characteristics obtained using 3 wt.% zirconia filler content with the 90◦ printing direction met the ISO10477 requirements [25]; these values are approximately 5–28% higher than the flexural strengths and moduli of the control and other test groups
Summary
Computer-aided design and manufacturing (CAD/CAM) technologies have been used in some medical and dental treatments, and the digitization of prosthesis production has been progressing [1–4]. Several dental laboratories and clinics have introduced stereolithography (SLA) and digital light processing (DLP) 3D printers using photopolymer resins. PMMA is the most commonly used material in dental prostheses owing to its excellent dimensional stability in the oral environment, low odor, low irritation, low cost, light weight, favorable esthetics, and ease of fabrication and repair. Several challenges, such as fracture due to water absorption, decrease in flexural and impact strengths, porosity, and polymerization shrinkage, limit the use of PMMA [5–7]. Contemporary studies have focused on reinforcement methods, such as the insertion of reinforcing wires and frameworks and the addition of fibers and micro- or nanosized fillers [8,9]
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