title: Influence of ceramic thickness and curing mode on the polymerization shrinkage kinetics of dual-cured resin cements.
abstract: OBJECTIVE
  The purpose of this study was to assess how ceramic disc thickness and curing mode (light or chemical) affects the polymerization shrinkage of dual-cured resin cements and to evaluate the effect of the ceramic discs on the curing speed of the cements during light exposure.
  
  
  METHODS
  Six commercial resin cements, RelyX ARC, Bistite II, Duolink, Panavia F, Variolink II and Choice were used. Filler weight contents were determined by the ash method. Four ceramic discs with thicknesses of 0.5, 1, 2 and 4mm, respectively, were made. The attenuation of light intensity due to the ceramic discs was measured using a radiometer. The polymerization shrinkage kinetics of the resin cements by chemical or light cure through the different ceramic discs was measured using a bonded-disc method.
  
  
  RESULTS
  There were differences in filler content among brands of resin cement. The polymerization shrinkage without ceramic disc was 2.61-4.59% by chemical cure and 2.93-4.66% by light cure. The polymerization shrinkage of RelyX ARC and Panavia F by chemical cure was statistically lower than by light cure (p<0.05). Polymerization shrinkage and filler weight were inversely related (R=-0.965). Both the transmitted light intensity and polymerization shrinkage decreased with increasing thickness of ceramic discs (p<0.05). The time to reach the maximum shrinkage rate of the resin cements increased with increasing ceramic thickness. The cure speed by light cure was 15-322 times faster than by chemical cure.
  
  
  CONCLUSIONS
  The polymerization shrinkage kinetics of dual-cured resin cements significantly differed between brands under various curing conditions. Clinicians should be aware of the setting characteristics of the cements, so they can choose the optimal materials for different clinical situations.
authors.affiliation: Department of Conservative Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, 28-2 Yeongeon-Dong, Jongro-Ku, Seoul 110-749, South Korea. inboglee@snu.ac.kr
authors.forename: In Bog
authors.initials: IB
authors.lastname: Lee
authors.forename: Woong
authors.initials: W
authors.lastname: An
authors.forename: Juhea
authors.initials: J
authors.lastname: Chang
authors.forename: Chung Moon
authors.initials: CM
authors.lastname: Um
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D006801:Humans; D008027:Light; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; C096475:Bistite Resin Cement; C086628:Choice resin cement; D003188:Composite Resins; C431350:Duo-Link; C075815:IPS-Empress ceramic; C438843:Panavia-Fluoro; D011108:Polymers; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; D003776:Dental Porcelain; C103502:Variolink; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate