Flexural strength and Vickers hardness of milled and 3D-printed resins for provisional dental restorations

Abstract

Various forms of temporary resins are offered on the market; however, the properties of temporary resins obtained by milling and 3D printing have not been fully examined. This study aimed to compare the flexural strength and Vickers hardness of milled and 3D-printed resins. Methods: Three resins were tested: Evolux PMMA (milled resin), Cosmos Temp (3D-printed resin), and Structur 2 SC (bis-acrylic resin, group control). Specimens were prepared with rectangular shapes (n = 12) for flexural strength measurements and disc shapes (n = 9) for Vickers hardness tests. Flexural strength tests were performed at a crosshead speed of 0.75 mm/min, and the Vickers hardness was measured under a load of 20 N for 10 s. The obtained data were subjected to the Kruskal–Wallis test. Results: A significant difference (p < 0.05) in flexural strength was observed among the three sample groups: Evolux PMMA (111.76 MPa), Structur 2 SC (87.34 MPa), and Cosmos Temp (56.83 MPa). No significant difference (p < 0.05) was observed between the Vickers hardness values of Structur 2 SC (33.37 VHN) and Evolux PMMA (29.11 VHN); however, both materials were statistically superior to Cosmos Temp (10.90 VHN). Conclusion: While the mechanical properties of the milled resin were superior or similar to those of the bisacrylic resin, the 3D-printed resin was statistically inferior to both the milled and bis-acrylic resins.

The flexural strength of 3D-printed provisional restorations fabricated with different resins: a systematic review and meta-analysis

“… Ultraviolet polymerization Digitally produced intermediate materials outperformed traditionally polymerized materials in terms of mechanical characteristics NA [ 31 ] 3-point flexural bend test SLA = 48.9 SLS = 77.3 Acrylic resin = 69.2 Bis-acryl resin = 75 Polymerized with light SLS resin demonstrated positive outcomes, showcasing higher maximum flexural strength Orientation angles and new types of resins were missing. [ 30 ] Universal testing machine Graphy = 329.3 NextDent = 177.8 NA 3D-printed resin crowns might present a viable alternative for fabricating fixed prostheses for primary teeth Study design [ 38 ] 3-point flexural bend test 3DCS = 143 3DOS = 141 CHP = 76 CAP = 88 Polymerization The tested 3D-printed interim resins outperformed the traditional resins A limited number of materials were investigated and tested [ 32 ] 3-point flexural bend test Cosmos Temp = 56.83 Evolux PMMA = 111.76 Structur 2 SC = 87.34 post-polymerized with 3000 flashes of ultraviolet light Although the mechanical qualities of the milled resin were more significant or comparable to those of the bisacrylic resin, the 3D-printed resin was statistically inferior to both the milled and bisacrylic resins Orientation angles were not considered [ 33 ] 3-point flexural bend test 3D printed = 81.33 Acrylic resin = 72.90 Nanofilled composite resin = 34.97 CAD/CAM PMMA resin = 94.63 Bis-acryl composite resin = 91.57. NA Except for 3D-printed resin, thermocycling lowered the flexural strength of most temporary materials NA [ 35 ] 3-point flexural bend test Before accelerated aging (pre-aging), the flexural strength of the A2 group (151 ± 7) was greater (p < 0.05) than that of the other groups.…”

“…Most studies were conducted in South Korea [ 1 , 29 , 30 ] and Brazil [ 31 – 33 ], followed by Saudi Arabia [ 34 , 35 ], China [ 36 ], Turkey [ 37 ], Romania [ 38 ], India [ 39 ], and Germany [ 40 ]. Most studies have employed Digital Light Processing (DLP) [ 30 , 33 , 35 , 38 , 40 ], stereolithography (SLA) [ 32 ], Both DLP and SLA [ 1 , 29 , 34 ], Fused Deposition Modeling (FDM) [ 1 ], and mono-liquid Crystal Display (LCD) [ 36 ], with a variety of printed materials, such as acrylic, composite resin, and methacrylate oligomer-based materials. The layer thickness was 50 μm in most studies [ 30 , 34 , 35 , 40 ], and the wavelength/light intensity varied across studies, with a maximum of 405 nm/13.14 mW/cm 2[ 34 ].…”

“…The flexural strengths of 3DCS, 3DOS, CHP, and CAP were 143, 141, 76, and 88, respectively [ 38 ], and they underwent polymerization. When post-polymerization was conducted with 3000 flashes of ultraviolet light, the cosmos temperature was 56.83, Evolux PMMA was 111.76, and Structur 2 SC was 87.34 [ 32 ]. Moreover, the flexural strength results before accelerated aging (pre-aging) showed that the A2 group had a significantly greater strength of 151 ± 7 MPa ( p < 0.05) than the other groups following the polishing and aging procedures [ 35 ].…”

“…Similarly, the milled resin exhibited mechanical properties in flexure strength that were superior or comparable to those of the bisacrylic resin. In contrast, 3D-printed resins demonstrate statistically inferior properties compared to milled and bisacrylic resins [ 32 ]. In contrast, one study indicated that printed samples exhibited higher mean bending strengths (141 ± 17 and 143 ± 15 MPa) than traditional samples (88 ± 10 and 76 ± 7 MPa).…”