Influência da angulação e espessura da camada de impressão na resistência à flexão, estabilidade dimensional e rugosidade de uma resina impressa

Abstract

Objective: To evaluate the influence of printing layer angulation and thickness on the three-point flexural strength (), dimensional stability and roughness of a printed provisional resin. Methodology: From the modeling of a bar (26 x 2.2 x 2.2mm) in Meshmixer software (Autodesk) and obtaining an STL file, it was exported to the SLA 3D printer software (Forms2/Formlabs), where 225 bars of the same dimensions were printed with Cosmos Temp resin, Yller (n=15) according to the factors “print layer thickness” (25μm;50μm;100μm) and “angulation” (0°; 30°; 45°; 60° e 90°). After printing, the samples were cleaned with isopropyl alcohol and sent to post-processing in an ultraviolet oven (Anycubic Wash and Cure Plus, Anycubic) for 15 minutes. The bars were submitted to the  test in a universal testing machine (100KgF,1mm/min) and the data (MPa) analyzed with 2-way ANOVA, Tukey (5%) and Weibull analysis. Roughness and dimensional stability analyzes were also performed, whose data were analyzed by 2- way ANOVA and Tukey (5%), in addition to the SEM of the surfaces. Results: For the flexural strength, 2-way ANOVA revealed that the factor "Print layer thickness" (p<0.0001) was statistically significant, while the factor "Angulation" (p=0.8074) did not show statistical significance. The 30°/25μm (51.2±4.6AMPa), 60°/25μm (49.1±4.3ABMPa), 0°/25μm (48.6±6.6ABMPa), 90°/50μm (46.8±4.1ABCMPa) and 90°/25μm (46.2±4.9ABCMPa) showed  values statistically higher than the 0°/100μm (39.4±5.4DEFMPa), 60°/100μm (37, 7±4.2DEFMPa), 90°/100μm (37.1±4.1EFMPa) and 30°/100μm (34.8±4.5FMPa), which were similar to each other. For dimensional stability, the 0°/50μm (1746.9±61.80Aμm) and 0°/100μm (1704.7±84.30Aμm) groups showed greater dimensional changes, while the 90°/25μm group (401.1±48.61Gμm) showed the smallest changes. For surface roughness, ANOVA revealed that the 30°/100μm (0.90±0.10Aμm), 45°/100μm (0.79±0.07ABμm) and 60°/100μm (0.88±0.08Aμm) groups were similar to each other and presented the highest values, while the 90°/100μm (0.23±0.08F ) configuration showed the lowest values. Conclusion: The lower the printing layer thickness, the greater the flexural strength, regardless of the chosen angle. Additionally, the thinner the printing layer, the greater the dimensional change, while objects printed vertically (90°) have greater dimensional stability. For surface roughness, the greater the layer thickness, the greater the roughness.