title: Effects of aging and irradiation time on the properties of a highly translucent resin-based composite.
abstract: This study investigated the effects of aging and irradiation time on the macro- and micro-mechanical properties of a highly translucent nanohybrid composite (IPS Empress Direct, Trans Opal shade, Ivoclar Vivadent). Flexural strength, flexural modulus, indentation modulus, Vickers hardness, and creep were measured after being irradiated with different durations (5, 10, 20, and 40 s) and aged under different conditions (24 h at 37°C in water; 5,000 times of thermocycling between 5°C and 55°C followed by 4-week storage in artificial saliva or alcohol). Rate of cure was also measured for these four irradiation times at composite specimen surface and at 2 mm depth. Effects of aging and irradiation time were statistically analyzed using one-way ANOVA with Tukey's HSD post hoc test (α=0.05), partial eta-squared statistic, and Weibull analysis. Alcohol aging significantly reduced the mechanical properties. Aging in saliva produced a positive effect on micro-mechanical properties. Irradiation time should be at least 20 s to yield favorable mechanical properties.
authors.affiliation: Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Goethestr, 70, 80336 Munich, Germany.
authors.forename: Henrik
authors.initials: H
authors.lastname: Bauer
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Ilie
mesh_terms: D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D000431:Ethanol / Q000737:chemistry; D006244:Hardness; D006801:Humans; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D018583:Pliability; D058105:Polymerization; D012464:Saliva, Artificial / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D012464:Saliva, Artificial; D014867:Water; D000431:Ethanol; D012822:Silicon Dioxide