Physical characteristics of porcelain fired with different heating souces. Part 1 Bond strength.

Abstract

Abstract:Recently, a vacuum furnace for porcelain firing using high density and direct near infra-red rays was developed.A comparative study between the high density and direct near infra-red rays furnace and conventional porcelain firing furnace was made as follows using facial veneer type of porcelain fused cast crowns utilizing three types of alloys (Ni-Cr alloys, palladium alloys and gold alloys):repeated dynamic loading tests were made on crowns and shear bond strength tests using cylindrical rod specimens.Result of repeated dynamic loading tests: 1) Higher bond strength was obtained by firing in the direct near infra-red rays furnace than in conventional furnace.2) The bond strength of the gold alloys was the highest, and followed by that of palladium and Ni-Cr alloys.Results of shear bond strength tests: 1) Higher bond strength was obtained by firing in the direct near infra-red rays furnace.2) The bond strength of the gold alloys was the highest, and followed by that of Ni-Cr and palladium alloys. Result of SEM picture 1) Differences between firing methods were barely discernible in the opaque porcelain layers.2) Better bond strength of feldspar and quarts was observed in the deep part of the body of porcelain layers with direct near infra-red rays.