ABSTRACT
Abstract The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.
ABSTRACT
Objective: Thermally activated acrylic resins (RAATs) are widely used in dentures as a base material due to their good dimensional stability and biocompatibility. However, their low thermal conductivity is a disadvantage, as it affects acceptance when using dental prostheses. Thus, the objective of this work was to measure the conduction heat in RAATs with and without incorporation of silica and silver nanoparticles (NP) and rigid reline (RR). Material and Methods: For this, samples were made and divided into 10 groups (n = 6). The first five groups were 2-mm-thick samples: G1 (RAAT control), G2 (RAAT + RR control), G3 (RAAT and NP + RR), G4 (RAAT + RR and NP), and G5 (RAAT and RR modified by NP). In the other five groups, 8-mm-thick samples were made: G6 (RAAT control), G7 (RAAT + RR control), G8 (RAAT and NP + RR), G9 (RAAT + RR and NP), and G10 (RAAT and RR modified by NP). The heat that cross the surface of the specimens was quantified using a wireless device. The data were submitted to two-factor ANOVA statistical analysis and Tukey Ìs test with a 5% significance level. Results: After measuring the temperature variation as a function of time, it can be observed that there was a statistically significant difference for thermal conduction between the control groups and those modified with NP. Conclusion: Thus, it was possible to conclude that the NP improved the heat conduction in RAAT and in the RR because the nanoparticles have a higher thermal conductivity. (AU)
Objetivo: As resinas acrílicas termicamente ativadas (RAATs) são amplamente utilizada em próteses dentárias como material de base, pois possuem uma boa estabilidade dimensional e biocompatibilidade. Porém, como desvantagem, possuem baixa condutividade térmica, o que prejudica a aceitação do uso de próteses dentárias. Assim, o objetivo deste trabalho foi medir a condução de calor em RAAT com e sem incorporação de nanopartículas de sílica e prata (NP) e reembasador rígido (RR). Material e Métodos: Para isso, foram confeccionadas amostras que foram divididas em 10 grupos (n=6). Os primeiros cinco grupos eram amostras de 2 mm de espessura: G1 (RAAT controle), G2 (RAAT + RR controle), G3 (RAAT e NP + RR), G4 (RAAT + RR e NP) e G5 (RAAT e RR modificados por NP). E nos outros cinco grupos foram feitas amostras com espessura de 8 mm: G6 (RAAT controle), G7 (RAAT + RR controle), G8 (RAAT e NP + RR), G9 (RAAT + RR e NP) e G10 (RAAT e RR modificados por NP). O calor percorrido pela superfície dos corpos de prova foi quantificado por meio de um dispositivo sem fio. Os dados foram submetidos à análise estatística ANOVA dois fatores e teste de Tukey com 5% de significância. Resultados: Após medir a variação da temperatura em função do tempo, pode-se observar que houve diferença estatisticamente significante para a condução térmica entre os grupos controle e os modificados com NP. Conclusão: Assim, foi possível concluir que a NP melhorou a condução de calor na RAAT e no RR, pois as nanopartículas apresentam maior condutividade térmica. (AU)