Effect of object build orientation on optical and mechanical properties and accurary of provisional 3D-printed resins

Author(s)

Eduardo Fernandes de Castro

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2022-07-07

Examining board members

Marcelo Giannini; Américo Bortolazzo Correr; Nelson Renato França Alves da Silva; Luis Felipe Jochims Schneider; Adilson Yoshio Furuse

• Advisor: Marcelo Giannini

Abstract

The purpose of this study was to evaluate the effect of build orientation of 3D-printed provisional resins (3DRs) on gloss (Gs), surface roughness (Sa), maximum profile valley depth (Rv), color difference (?E00), accuracy, flexural modulus (FM), flexural strength (FS), and microhardness (KHN). Samples were obtained in two formats: 2.5-mm thick cylinders (15-mm diam.) and rectangular bars (25x2x2 mm). PMMA CAD/CAM blocks (Vita Temp/Vita) served as a Control and were sectioned (cylinders) or milled (Inlab XL/Sirona) (bars). Different 3D printers (Form 2/Formlabs, P30/Straumann, Hunter/Flashforge, W3D/Wilcos) were used to print dour 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos, respectively) in three orientations (0o, 45o, and 90o). Samples were cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. Ten cylindrical samples for each group were submitted to 10,000 toothbrushing (TB) cycles with half of their surface covered with an adhesive tape. The Gs and Sa at the brushed and not brushed surfaces were evaluated with a glossmeter (Novo-curve) and a laser confocal microscope (OLS5000) (n=10), which also obtained the Rv and 3D images. On another set of cylindrical samples (n=5), the coordinates of luminosity and color were obtained with a spectrophotometer (Easyshade 4.0) at baseline and after 16.7h and 200h of UVB aging (EQUV), to calculate the ?E00 using CIEDE:2000. The dimensions of bar samples were measured and the mean percent errors were calculated to obtain the accuracy (n=20). Samples were stored in distilled water at 37oC and submitted to three-point bending test in a universal testing machine (Instron 4411) after 24h or 1 year (n=10). Ten cylindrical samples were polished prior to evaluation of KHN (FM-ARS 9000) (n=10). Data of Gs, Sa, FM and FS were submitted to three-way-, Rv and KHN to two-way-, and ?E00 to mixed-ANOVA tests, followed by Tukey’s test (?=0.05). For all variables, results from experimental groups were compared to control using Dunnett’s test (?=0.05). Student’s t-test was used to compare the control at different TB cycles (Gs, Sa) or aging periods (?E00, FM and FS) (?=0.05). Build orientation of 3DRs did not influence Gs, Sa, Rv, ?E00, and KHN. The TB wear decreased Gs and increased Sa of all resins. Control presented lower ?E00 than all 3DRs after 200-h UVB-aging. All 3DRs presented higher ?E00 than the clinically acceptable after 200h of UVB-aging. Except for Cosmos-DLP, the 90o-orientation obtained the best overall accuracy for the 3DRs. The overall accuracy of Cosmos-SLA was similar to control and higher than other 3DRs. The FM of all 3DRs was lower than control, for all orientations and aging periods. After 1-year aging the FS of 45o-Cosmos-SLA and all orientations of PriZma was not different from control, while 90o-Cosmos-SLA was higher than control. Nanolab was the only 3DR to present higher KHN than control. The results suggest that 3DRs’ build orientation did not influence some variables studied (Gs, Sa, Rv, ?E00, and KHN), but had some influence in FM and FS. The 90o-orientation obtained the best overall accuracy for most 3DRs and the highest FS for Cosmos-SLA after 1 year of aging (AU)

• FAPESP's process: 20/05610-5 - Characterization of 3D printed provisional resins and evaluation of the effect of printing orientation on accuracy, mechanical and optical properties, accelerated fatigue strength and finite element analyses of these materials
• Grantee: Eduardo Fernandes de Castro
• Support Opportunities: Scholarships in Brazil - Doctorate