Caracterização de resinas restauradoras impressas em 3D: influência do tipo de solvente, pós-cura UV e tecnologias de impressão

Abstract

With the rapid advancement of 3D printing technology in dentistry, dental restorations have benefited from new materials and processes. However, due to the novelty of the technology and the complexity of the factors involved, such as materials, printers, solvent washing, and UV post-processing times, there is still limited knowledge about the full performance of these approaches. This thesis investigated the mechanical, thermal, and surface properties of resins used in 3D printing for dental restorations, assessing how different factors influence the performance of these materials. Initially, three provisional resins (Resilab 3D Temp, Printax Temp, and Prizma Bioprov) were analyzed, printed using SLA/LCD technology. The washing of specimens was performed with isopropyl alcohol or ethanol, and the post-curing times tested were 5, 10, and 30 min. The response variables studied included fracture toughness (KIC, MPa√m), Knoop microhardness (kgf/mm²), roughness (Ra, µm), gloss (gloss units), and degree of C=C conversion (%DC). The results of this stage revealed that Resilab showed higher microhardness with isopropyl alcohol and 30 min of UV post-curing, while Printax excelled in microhardness with absolute ethanol. KIC, roughness, and gloss were significantly influenced by both the type of solvent used in pre-washing and the post-curing time, highlighting important variations among the different resins studied. In a second stage, the focus was on comparing the properties between a provisional resin (Prizma 3D Bioprov) and a permanent resin (Prizma Bio Crown), printed using two distinct technologies (DLP and LCD) and subjected to post-curing times of 5 or 30 min. In this phase, it was observed that the permanent resin generally presented a higher DC compared to the provisional material, with this degree being higher after 30 min of post-curing, especially when the printing was done with DLP technology. Thermal analysis, conducted via differential scanning calorimetry, revealed a prominent exothermic peak between 160 and 170°C in the specimens post cured for 5 min, which became less intense after 30 min of post-curing, suggesting a more complete and effective curing process with prolonged time. As a general conclusion of this thesis, the results demonstrate that the choice of resin type and the precise adjustment of post-processing parameters, such as the solvent used in washing and post-curing time, are essential for optimizing the mechanical, thermal, and esthetic properties of 3D-printed dental restorations. The proper combination of these factors can enhance the durability and clinical efficacy of printed restorations.