The impact of in vitro aging on the mechanical and optical properties of indirect veneering composite resins.

Flexural strength, hardness, surface roughness, discoloration, and abrasion resistance are important properties of veneering composite resins. Recently introduced veneering resins are purported to have enhanced mechanical properties due to their composition, but their long-term durability is not known. The purpose of this study was to test the impact of aging on 3 different veneering composite resins. Indirect composite resins, GC Gradia, VITA VM LC, and Sinfony were prepared for flexural strength (n=165 per group), Martens hardness (n=10), surface roughness (n=10), discoloration measurement (n=30), and abrasion resistance (n=6) testing. After initial flexural strength measurement, the remaining specimens were stored in water or subjected to thermocycling for 1, 7, 28, 90, or 180 days, and hardness and surface roughness (water stored: n=5 and thermocycling: n=5) were tested. The discoloration specimens were divided into 3 groups: coffee, black tea, and red wine; n=10), and age and discoloration were measured. Abrasion resistance was determined after 120,000, 240,000, 640,000, and 1,200,000 mechanical thermocycling loading. One-way ANOVA was used, followed by a post hoc Scheffé test and t test. The longitudinal observations were analyzed by using linear mixed models (α=.05). When considering all 5 of the properties tested, Sinfony demonstrated the best results, followed by GC Gradia and VITA VM LC. The veneering composite resin, Sinfony, showed the most stable properties.