بررسي آزمايشگاهي سايش سه نوع كامپازيت رزين

In Vitro Evaluation of the Wear of Three Composite Resins

BACKGROUND AND OBJECTIVE Wear resistance of composites is important for preservation of masticatory ability and vertical height. The aim of this study was to compare wear resistance of two laboratory type composites and one direct composite. METHODS: In this in vitro study 5 samples from each type of composites (SR Adoro, GC gradia, Clearfll ST) was prepared in incremental technique. Exposure time was 40 seconds and thickness of layers was 1 mm. Wearing load was 6kg and applied via pressable chromium cobalt bar (1.98 mm2 tip) at 5000, 20000, 80000, 120000 cycles. Pre and post wearing samples weight was measured by an electronical weight balance with 0.0001 gr accuracy. The data was compared. FINDINGS There was significant decrease in weight of all type of composites from initial weight to 120000 cycles (p<0.001). (GC gradia 4.42±1.26mg, SR Adoro 6.5±0.89mg, Clearfil ST 4.52±2.14mg). Although after applying all wearing cycles the average decrease of weight was smaller in GC gradia rather than Clearfil St that smaller than SR Adoro, however there was no significant difference. CONCLUSION: GC gradia and Clearfll ST showed less wear than SR Adoro. There was significant wear in all types of composites in wearing cycles.