title: Color Stability Behavior of Methacrylate-based Resin Composites Polymerized with Light-emitting Diodes and Quartz-Tungsten-Halogen.
abstract: Despite significant developments in improving the optical properties of resin composite materials, their color stability remains a challenge. This study aimed to evaluate the shade stability of light-polymerized, methacrylate-based resin composites with different filler particle composition (microfill, minifill, nanohybrids, and microhybrids) polymerized with quartz-tungsten-halogen (QTH) and light-emitting diodes (LED).
  
  
  METHODS
  Composite discs were fabricated from Tetric EvoCeram, Premise, Artiste, and Beautifil II (nanohybrids); Filtek Supreme Plus and Vit-l-escence (microhybrids); Heliomolar (microfill); and Estelite Sigma Quick (minifill) using a Teflon mold. The specimens were irradiated either with QTH (Elipar 2500; 600 mW/cm(2)) for 40 seconds or with LED (Bluephase G2; 1200 mW/cm(2)) for 20 seconds. Color parameters were measured with a colorimeter before and after polymerization and at 24 hours, one week, one month, and three months. Color change was calculated among the different storage periods.
  
  
  RESULTS
  There was a significant effect of the composite, time, and their interaction (p<0.001) but no effect of the polymerization unit on the color stability. Color changes immediately after polymerization and at 24 hours (4.22 and 3.88 for LED; and 4.08 and 3.82 for QTH) were not significantly different from each other but were both significantly higher than changes after one week (0.96 and 0.78), one month (1.12 and 1.02), and three months (1.27 and 1.11) for LED and QTH, respectively (p<0.001).
  
  
  CONCLUSIONS
  Color changes were observed for all the materials that were dependent on the type of composite but not on the polymerization unit. These color shifts took place primarily immediately after polymerization and after 24 hours and were additive in nature.
authors.forename: C
authors.initials: C
authors.lastname: Sabatini
mesh_terms: D003116:Color; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects / Q000627:therapeutic use*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008689:Methacrylates / Q000737:chemistry / Q000627:therapeutic use*; D058105:Polymerization
chemical_list: D003188:Composite Resins; D008689:Methacrylates