RESUMO
OBJECTIVES: This in vitro study investigated the effect of selected luting media on the fracture resistance of a flame-sprayed all-ceramic crown. METHODS: Three groups of 10 human upper premolar teeth were prepared for crowning using a standardised technique. Flame sprayed crowns were fabricated and cemented onto the preparations using zinc phosphate (ZPC), glass polyalkenoate (GPC) or composite luting cement (CLC). During crown seating, a pressure perfusion system simulated pulpal fluid outflow equivalent to 300mm of H2O. Compressive fracture resistance was determined for each group using a Universal Testing Machine with a crosshead speed of 1mm min(-1). A group of unrestored teeth acted as a control. RESULTS: The fracture resistance of the groups ranked as follows: ZPC>CLC>>GPC=unrestored teeth. The difference between the fracture resistance of ZPC and CLC groups and the control group was statistically significant. The mode of fracture between the luted crowns and natural crowns was markedly different. CONCLUSIONS: When tested in compression, a new, flame-sprayed all-ceramic crown, when luted in place using ZPC, GPC or CLC, could produce strengths comparable to or greater than natural unrestored teeth. The luting agent used significantly affected the recorded fracture loads.
Assuntos
Cerâmica/química , Coroas , Cimentos Dentários/química , Falha de Restauração Dentária , Análise de Variância , Dente Pré-Molar , Cimentação , Resinas Compostas/química , Força Compressiva , Intervalos de Confiança , Colagem Dentária , Polpa Dentária/fisiologia , Análise do Estresse Dentário/instrumentação , Cimentos de Ionômeros de Vidro/química , Humanos , Teste de Materiais , Pressão , Cimentos de Resina/química , Estatística como Assunto , Estresse Mecânico , Dente/fisiologia , Preparo Prostodôntico do Dente , Cimento de Fosfato de Zinco/químicaRESUMO
Root surface cavities prepared in extracted premolars were restored with a selection of restorative materials. Prior to eosin dye immersion, one group of teeth was kept at constant temperature whilst another group underwent thermal cycling. The teeth were sectioned transversely through the restorations and an assessment of the degree of microleakage was used to compare the sealing ability of the selected materials. Eosin dye was able to discriminate more effectively between the microleakage behaviour of the restorative materials when samples were kept at a constant temperature.
