Affiliations: Department of Operative Dentistry, University of Iowa, Iowa City, IA 52242, USA | Department of Operative Dentistry, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece | POSTECH, Department of Mechanical Engineering, Pohang Institute of Science and Technology, P.O. Box 125, Pohang 790‐784, Korea | Department of Biomedical Engineering, Department of Mechanical Engineering and the Optical Science and Technology Center, University of Iowa, 238 IATL, Iowa City, IA 52242, USA
Note: [] To whom correspondence should be addressed. Current address: Department of Engineering Physics, University of Wisconsin–Madison, 147 Engineering Research Building, 1500 Engineering Drive, Madison, WI 53706‐1687, USA. Tel.: +1 608 265 8697; Fax: +1 608 263 7451; E‐mail: lakes@engr.wisc.edu.
Abstract: Effects of aging on several dental composites were studied using a torsion creep apparatus. A constant torque was applied from 1 second to 3 hours, and recovery was observed from 10 seconds to 2 days, for specimens aged from 3 hours to 8 weeks following polymerization. Specimens aged for shorter times exhibited more creep and less complete recovery than specimens aged for longer times. Modulus and creep results were qualitatively consistent with a composite model for particulate inclusions.
