Effect of chemical composition of Ni‐Cr dental casting alloys on the bonding characterization between porcelain and metal

Abstract

The purpose of this study was to investigate the influence of chemical composition of Ni-Cr dental casting alloys on the bonding behaviour between porcelain and metal. A three-point bending test was used to measure the fracture load of alloy after porcelain firing. A scanning electron microscope, accompanied by an energy dispersion spectrometer, was used to analyse the morphology and chemical composition of the fracture surface. An X-ray photoelectron spectrometer and glow discharge spectrometer were used to identify the structure and cross-sectional chemical composition, respectively, of oxide layers on Ni-Cr alloys after heat treatment at 990 degrees C for 5 min. Results showed that the oxide layers formed on all Ni-Cr alloys contained mainly Cr2O3, NiO, and trace MoO3. The Ni-Cr alloy with a higher Cr content had a thicker oxide layer, as well as a weaker bonding behaviour of porcelain/metal interface. The presence of Al (as Al2O3) and Be (as BeO) on the oxide layer suppressed the growth of the oxide layer, leading to a better porcelain/metal bonding behaviour. However, the presence of a small amount of Ti (as TiO2) on the oxide layer did not have any influence on the bonding behaviour. The fracture propagated along the interface between the opaque porcelain and metal, and exhibited an adhesive type of fracture morphology.

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys

“…Ni-Cr alloys are alternatives to gold alloys because they have good mechanical properties, such as high hardness, low density and high tensile strength (3,14). In addition, the low cost and easy manipulation of Ni-Cr alloys have made them widely used in the fabrication of metal-ceramic restorations (14), which combine the resistance of the metal substructure with esthetic properties of the ceramic (7,15,16).…”

“…In addition, the low cost and easy manipulation of Ni-Cr alloys have made them widely used in the fabrication of metal-ceramic restorations (14), which combine the resistance of the metal substructure with esthetic properties of the ceramic (7,15,16).…”

Influence of alloy microstructure on the microshear bond strength of basic alloys to a resin luting cement

“…There are great variations in the composition of basic alloys within the same classification (Co-Cr and Ni-Cr), leading to the formation of different oxides on their surfaces (2), which might alter the bond quality in some aspects (8). it is known that alterations in the composition of an alloy lead to the formation of single microstructures (9) and the generated oxides are fundamental factors in determining resistance to corrosion, biocompatibility, and bonding both to polymer and ceramic materials.…”

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

“…Elas devem manter-se unidas permanentemente ao(s) remanescente(s) dentário(s) na substituição de um ou mais elementos ausentes [2]. Dentre as opções comercialmente disponíveis, as ligas de fundição à base de níquel-cromo são as mais utilizadas na confecção de próteses metalocerâmicas [3][4][5][6][7]. Uma vantagem mecânica das ligas de níquel-cromo sobre as ligas áuricas é o módulo de elasticidade, aproximadamente duas vezes superior, traduzido em menor espessura metálica necessária ao suporte da porcelana [8] e, portanto, maior preservação do remanescente dentário no preparo do elemento suporte.…”

“…O sucesso do sistema metalocerâmico depende especialmente da estabilidade da união [10,11], que ocorre por microrretenção mecânica, ligações tipo van der Waals e, especialmente, pela interação química da camada superficial de óxidos metálicos com a porcelana [2,5,11,14,15]. Os óxidos da superfície metálica são indispensáveis à aderência [7,16,17]. A formação de uma camada muito fina de óxidos é freqüentemente associada ao aumento dos riscos de insucesso na união metalocerâmica [11,18].…”