title: Residual stress in composites with the thin-ring-slitting approach.
abstract: During polymerization, dental composites develop residual stresses that may compromise the marginal integrity and properties of the restorative. The objective of this study was to use the thin-walled ring-slitting method to measure and compare residual stresses. The hypotheses to be tested were that composites would generate different levels of residual stress based on their specific formulations and slitting times. Rings made from composites (Z100, Herculite, and Heliomolar) were cut at different times (10 min, 1 and 24 hrs) after being light-cured, and stress was measured. Residual stress was higher at the earlier cutting times, except for Heliomolar (alpha < 0.05). For the 10-minute and one-hour cutting groups, stress followed this order: Z100 > Herculite > Heliomolar. Early slitting was better to capture residual stress, and the thin-walled rings showed higher values than thick-walled rings and were better able to discriminate residual stress in composites.
authors.affiliation: Department of Conservative Dentistry, College of Dentistry, Yonsei University, 146-92 Dogok-dong, Gangnam-gu, Seoul 135-720, Korea. pjw@yumc.yonsei.ac.kr
authors.forename: J W
authors.initials: JW
authors.lastname: Park
authors.forename: J L
authors.initials: JL
authors.lastname: Ferracane
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods*; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D008956:Models, Chemical; D011140:Polyurethanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D015040:Zirconium / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D003764:Dental Materials; C513708:Heliomolar; D011140:Polyurethanes; C083568:Z100 composite resin; D012822:Silicon Dioxide; D015040:Zirconium