Degree of polymerization and Cusp deflection caused by polymerization shrinkage in composite resin at 4, 25 and 54 degree centigrade

Abstract

The aim of this study was to investigate degree of polymerization and cusp deflection caused by polymerization shrinkage of a photo-activated composite resin cured at 4C, 25C and 54 C temperatures. Method: For measuring the degree of polymerization, 15 composite samples were placed in plastic sample holders and divided to 3 different groups regarding the temperatures (4, 25, 54C). After reaching the specific temperatures, specimens were exposed to light cure beam for 40 seconds using LED curing unit. Then they were pulverized for further study using FTIR machine. Data were analyzed using Friedman NP (p < 0.05). In order to measure the cusp deflection 45 upper premolar Ivorines were selected and divided to 3 different groups regarding the temperatures (4, 25, 54C). Class II MOD cavities were prepared and packed by composite resin. After reaching the specific temperatures samples were cured for 40 seconds by the use of LED curing unit. Cusp deflection was determined by stereo microscope for each sample. Data were analyzed using One-way ANOVA (p < 0.05). Results: There was no significant difference in Degree of polymerization of composite resin among different temperatures (p=0.16) There was no significant difference in cusp deflection among different temperatures (p=0.51) Conclusion: This study showed that there is no significant difference in degree of polymerization and cusp deflection caused by polymerization shrinkage of composite resin at 4, 25 and 54 C temperatures.