Abstract: PURPOSE: The purpose of this study was to evaluate closure of the fixation screw pores of implant denture by using 4 different light-cured composite resins (LCRs), and to observe the effects of organosilane and thermocycling on microleakage. METHODS: A total of 80 hollow semi-cylinders were fabricated with titanic alloy, with the upper half of the specimens was porcelain, and the internal surfaces were sandblasted and etched. All specimens were divided into 2 groups: treated and not treated with organosilane. After bonding with 4 kinds of LCRs, the testing samples were assigned into 2 subgroups for different thermocycles. Then the degree of microleakage were measured by glucose oxidase-peroxidase(GOD-POD) methods. The results were statistically analyzed with one-way ANOVA by using SAS 11.10 software. RESULTS: Statistical analysis revealed that the microleakage associated with LCRs were significantly different, and the microleakage associated with organosilane or thermocycles were also significantly different (P<0.01). Interactive analysis showed that there was interaction between the organosilane disposal (factor B) and thermocycling disposal (factor C) (P<0.01), whereas no interaction was found between the other factors (P>0.05). CONCLUSIONS: The results suggest that the type of bonding materials would affect the degree of microleakage, and the microleakage can be reduced if the specimens are treated with organosilane. The tolerance of specimens under thermocycling are very poor.

Key words: Implant denture, Fixation screw pores, Microleakage, Glucose oxidase-peroxidase, Organosilane