Comportamento tribocorrosivo de sistemas metalocerâmicos odontológicos de Ni-Cr/Porcelana e Ni-Cr/Ti/Porcelana

Abstract

Partial fixed prosthodontic restoration is used to rehabilitate both the form and function of partial or total compromised teeth and must remain permanently joined to the remaining teeth. The most useful material in prosthodontics is feldspar porcelain, commercialized as aluminosilicate powders. Dental porcelains depict limited mechanical strength to rehabilitate extensive spaces. The association of porcelain with Ni-Cr metallic infrastructures allows the metallic component to compensate for the brittle nature of porcelain, thus preserving the thermal insulation, aesthetics and, most important, reducing the possibility of cracking during mastication efforts. Cohesive flaws caused by low mechanical strength connect the metallic substructure to the oral environment, characterized by the presence of an electrolytic solution (saliva), aggressive temperature and pH cycles as well as mechanical demand. As a result, ions are released and can promote allergic or inflammatory responses, in addition to clinical degradation of the prosthodontic system. Therefore, the aim of this study was to evaluate the presence of an intermediate titanium layer on the behavior of Ni-Cr/porcelain systems. Plasma deposition of titanium films were also carried out to create barrier layers capable of isolating the metallic substrate from the hazardous effects of the oral environment. Tribocorrosion tests were performed to simulate the oral environment and corresponding wear, making it possible to early detect crack formation and growth on metal-ceramic systems and estimate the adherence between the metal and ceramic components. Plain samples consisting of dental feldspar porcelain deposited onto metallic substrates coated or not with titanium were fired and characterized. The results showed that the deposition of titanium films improved the adherence of the system compared to conventional metal-ceramic systems, thus holding crack growth towards the metallic component.