The Effective Evaluation Of Various Cement To Cast Crown And Various Core

The luting material in this study include zinc estroyed teeth is very common in clinic. The cast metal restoration continues to be commonly used to restore teeth severely damaged by caries or trauma and to strengthen endodontically treated teeth. The important factor related to the success of cast restoration is the degree of bond strength between the cement and core material. The retention of cast crown depends on of various core materials and various luting agents. This study is to find the most effective luting agent for various core by tensile strength testing.phosphate cement, polycarboxylate cement, grass-ionomer cement and resin composite luting cement. The objective cores which cement to cast crown are made of silver amalgam, composite resin and melt-point castable alloy. Each cemented sample was thermally cycled 500 times between 5 and 55℃ for 60 second in water bath at each temperature tosimulate oral condition.The experiment result indicate: There were statistically significant difference in silver amalgam core group, the retention of zinc phosphate cement is best in this group. There were statistically significant difference in composite resin core group, the retention of zinc phosphate cement is also best in this group, then it's grass-ionomer cement. There were no statistically significant difference in melt-point castable alloy core group. Two samples of silver amalgam core group were broken in tensile testing, while four samples of composite resin core group were broken. The fracture force of silver amalgam core is larger than composite resin core.Based on these findings, the conclusion are:1. The retention of zinc phosphate cement is best in silver amalgam core group, so zinc phosphate cement is the best choice for silver amalgam core to cast crown.2. The surface composite resin core is easily contaminated. Therefore the retention of composite resin core is weak.3. Among these four luting media, the retention of silver amalgam core and melt-point castable alloy core are better than resin core.4. The mechanical property of silver amalgam is better than composite resin.