Abstract:

Objective To evaluate the effect of Green Or^TM on the crown retention using standardized tooth preparation. Methods Forty recently extracted molars were prepared by lathe. Total oclussal convergence（TOC）angle of half of the molars were 10°and the others were 20°. The cast crowns were made and the samples within each degree were randomly divided into two groups. In the experimental group，Green Or^TM was applied to the samples before the cast crown cemented with glass ionomer. In the control group，the samples were only cemented with glass ionomer. The samples were stored in 37 ℃ artificial saliva for 24 h before tensile testing on an instron testing machine at a crosshead speed of 1 mm/min until failure. The surface of the specimen was observed by means of an optical and a scanning electron microscope. Results When TOC angle was 10°，the retention power of the testing force was （443.59±74.20）N of the experimental group and （509.07±69.05）N of the control group respectively. There was no statistically significant difference between the two groups （P=0.056）. When TOC angle was 20°，the retention power of the testing force was （291.57±49.27）N of the experimental group and （390.82 ±91.44）N of the control group respectively. There was statistically significant difference between two groups （P=0.009）. Conclusion When TOC angle was 10°，there was no effect on the retention power of cast crown luted with glass ionomer after using Green Or^TM desensitizer. When TOC angle was 20°，Green Or^TM desensitizer
decreased casting retention stress when used with glass ionomer.

Key words: Green Or^TM')">Green Or^TM, crown, tooth preparation, retention