RESUMO
The aim of this study was to investigate the effect of antagonist material and configuration on combined wear, which was produced by alternating toothbrush wear and simulated occlusal wear on one specimen. Worn volume and maximum worn depth comparisons were done using two antagonist materials (steel and ceramic) and two antagonist configurations (flat and round). For the material factor, worn volume by the ceramic antagonist was greater than that by steel antagonist in the combined wear test. For the configuration factor, the round ceramic antagonist induced a greater volume loss of the resin composite. As for maximum worn depth, both the material and configuration of antagonist were influencing factors in the combined wear test--where the round ceramic antagonist induced a deeper wear of the resin composite. Based on the results of this study, we concluded that a round ceramic antagonist is suitable to be used for evaluating the wear behavior of resin composites.
Assuntos
Resinas Compostas/química , Materiais Dentários/química , Desgaste de Restauração Dentária , Força de Mordida , Cerâmica/química , Desgaste de Restauração Dentária/classificação , Dureza , Humanos , Teste de Materiais , Metacrilatos/química , Polimetil Metacrilato/química , Dióxido de Silício/química , Aço/química , Propriedades de Superfície , Escovação Dentária/instrumentação , Zircônio/químicaRESUMO
The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment. The effect of the additives was evaluated from the color difference (deltaE*) between the as-cast surface and the polished surface of the cast specimen. B and Al were effective to prevent the blackening of a Type 4 gold alloy and the color of the as-cast surface approached that of the polished surface with increasing B and Al content. The prevention of the blackening of the gold alloy can be achieved by restraining the formation of CuO.