24 - Mechanical Properties of Dental Composites Aged in Different Media

Abstract

Resin based dental composite materials have become the most commonly used restorative material due to their biocompatibility, mechanical properties, and excellent aesthetics. However, exposure to different corrosive constituents of saliva and mechanical loading, limit their service life in the oral cavity The objective of this project was to investigate the effect of long-term ageing of resin based dental composites in different in vitro solutions for different time periods. Mechanical properties: diametral tensile strength (DTS), push-out strength (POS), and stiffness(S) were measured for a micro-hybrid composite (Alelite, Bisco, USA) following ageing in four different environmental conditions (air (A), artificial saliva(AS), esterase enzyme in artificial saliva(Enz +AS), and de-ionized water (DI) for three different aging times (120, 150, and 180 days). The composite (0.25 gr were light cured in an epoxy ring, (6.3 mm diameter x10 mm length) simulating an occlusal restoration. DTS decreased in all the liquid media whereas the opposite trend was found for POS. ANOVA analysis, media versus time, showed a significant difference for DTS and POS, but no difference in S. The absorption of water explains and shrinkage the effect on DT and POS from the air control. Aging in in vitro media effects the mechanical properties of resin based composite restorative materials. Additional studies are being done on the potential leaching of polymers in the different solutions.