Physicomechanical Properties and Morphological Characterization of Several Universal Resin Composites After Different Aging Procedures

Objectives: To evaluate flexural strength, elastic modulus, microhardness, and microstructure of several universal resin composites before and after artificial aging. In addition, filler characterization, water sorption, solubility, and degree of conversion were analyzed. Methods: Five universal composites, Essentia Universal (EU), Filtek Universal (FU), G-ænial A'Chord (GA), Omnichroma (OM), and Tetric Prime (TP) were compared to a conventional composite, Filtek Supreme XTE (FS) used as a control. Flexural strength, elastic modulus, microhardness, and microstructure were analyzed at baseline and after three aging procedures: (1) Immersion in artificial saliva at 37°C for 2 weeks; (2) the same immersion followed by 10,000 thermocycles (5°C–55°C); and (3) the previous procedure with an additional 48-h storage in 75% ethanol at 37°C. SEM characterization of filler particles, water sorption, solubility, and degree of conversion were also assessed. Results: FU showed the highest flexural strength and elastic modulus. Thermocycling reduced the flexural strength and elastic modulus of all composites except the elastic modulus of FU. FS was the hardest composite and EU the softest. FU, OM, and TP exhibited lower water sorption than FS. EU, GA, and OM exhibited lower solubility than FS. A similar degree of conversion was found for all universal composites. Conclusion: Differences in mechanical behavior depended on the resin composite tested and the aging treatment.