RESUMO
The present study aimed to characterize the microstructure of a temporary 3D printing polymer-based composite material (Resilab Temp), evaluating its optical properties and mechanical behavior according to different post-curing times. For the analysis of the surface microstructure and establishment of the best printing pattern, samples in bar format following ISO 4049 (25 × 10 × 3 mm) were designed in CAD software (Rhinoceros 6.0), printed on a W3D printer (Wilcos), and light-cured in Anycubic Photon for different lengths of time (no post-curing, 16 min, 32 min, and 60 min). For the structural characterization, analyses were carried out using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The mechanical behavior of this polymer-based composite material was determined based on flexural strength tests and Knoop microhardness. Color and translucency analysis were performed using a spectrophotometer (VITA Easy Shade Advanced 4.0), which was then evaluated in CIELab, using gray, black, and white backgrounds. All analyses were performed immediately after making the samples and repeated after thermal aging over two thousand cycles (5-55 °C). The results obtained were statistically analyzed with a significance level of 5%. FT-IR analysis showed about a 46% degree of conversion on the surface and 37% in the center of the resin sample. The flexural strength was higher for the groups polymerized for 32 min and 1 h, while the Knoop microhardness did not show a statistical difference between the groups. Color and translucency analysis also did not show statistical differences between groups. According to all of the analyses carried out in this study, for the evaluated material, a post-polymerization time of 1 h should be suggested to improve the mechanical performance of 3D-printed devices.
RESUMO
O objetivo deste trabalho foi avaliar a resistência de união entre uma resina nanohíbrida para impressão 3D com cimento resinoso após diferentes tratamentos de superfície e envelhecimento. Foram fabricados 120 blocos da resina nanohíbrida (Nanolab 3D, Wilcos do Brasil) em tamanhos de 10 x 8 x 2 mm, desenhados no software Rhinoceros 7 e depois impressos (W3D PRINT, Wilcos do Brasil) por método digital de processamento de luz (LCD). Foram produzidos também blocos de mesmo tamanho obtidos a partir de blocos de CAD/CAM de uma resina híbrida (Hybrid, Blue Dent), como grupo controle. Cinco tratamentos de superfície foram realizados nos blocos de resina: nenhum tratamento, condicionamento ácido com ácido fluorídrico, jateamento com Al3O2, imersão em monômero de metilmetacrilato (primer) e um grupo somando o jateamento com imersão em primer. Foram construídos cilindros (< 1 mm2) de cimento resinoso convencional dual sobre as superfícies tratadas com auxílio de matriz de silicone. A resistência de união foi medida usando uma máquina de ensaio universal e um teste de microcisalhamento com fio. Metade das amostras de cada grupo foram testadas sete dias após a cimentação, já a outra metade foi termociclada por 12.000 ciclos térmicos (5-55 ºC, 30 segundos cada) e ensaiadas a seguir. Os modos de falha foram analisados por um estereomicroscópio e imagens representativas foram realizadas com o auxílio do microscópio eletrônico de varredura. Após a análise inferencial com ANOVA 3-fatores foi possível observar que houve diferença estatisticamente significante tanto para os fatores material, tratamento de superfície e envelhecimento isoladamente, como para as interações entre eles. A resina híbrida de impressão mostrou maior resistência de união quando comparada com os blocos CAD/CAM. A ciclagem térmica aumentou a resistência de união das resinas impressas e diminuiu a mesma nos blocos de CAD/CAM. É possível concluir que a aplicação de silano é o melhor tratamento de superfície para as resinas de impressão 3D já que proporcionou bons valores de resistência de união e confiabilidade da interface adesiva. A resistência adesiva a longo prazo da resina híbrida de impressão 3D (Nanolab) é influenciada positivamente pelo envelhecimento (AU)
The objective of this work was to evaluate the bond strength between a nanohybrid resin for 3D printing with resin cement after different surface treatments and aging. 120 blocks of nanohybrid resin (Nanolab 3D, Wilcos do Brasil) were manufactured in sizes of 10 x 8 x 2 mm, designed in the Rhinoceros 7 software and then printed (W3D PRINT, Wilcos do Brasil) by digital light processing method (LCD ). Blocks of the same size obtained from CAD/CAM blocks of a hybrid resin (Hybrid, Blue Dent) were also produced as a control group. Five surface treatments were performed on the resin blocks: no treatment, acid etching with hydrofluoric acid, sandblasting with Al3O2, immersion in methylmethacrylate monomer (primer) and one group adding the sandblasting with immersion in primer. Cylinders (< 1 mm2) of conventional dual resin cement were built on the surfaces treated with the aid of a silicone matrix. Bond strength was measured using a universal testing machine and a wire microshear test. Half of the samples from each group were tested seven days after cementation, while the other half was thermocycled through 12,000 thermal cycles (5-55 ºC, 30 seconds each) and then tested. Failure modes were analyzed using a stereomicroscope and representative images were taken using a scanning electron microscope. After the inferential analysis with 3-way ANOVA, it was possible to observe that there was a statistically significant difference both for the material, surface treatment and aging factors alone, as well as for the interactions between them. The hybrid impression resin showed higher bond strength when compared to the CAD/CAM blocks. Thermal cycling increased the bond strength of printed resins and decreased it in CAD/CAM blocks. It is possible to conclude that silane application is the best surface treatment for 3D printing resins as it provided good bond strength values and reliability of the adhesive interface. The long-term adhesive strength of the 3D printing hybrid resin (Nanolab) is positively influenced by aging. (AU)