title: The effect of water storage and light exposure on the color and translucency of a hybrid and a microfilled composite.
abstract: BACKGROUND
  Internal discoloration may occur with the intraoral use of resin-based restoration materials. Water storage and light exposure influence the color properties of microfilled and hybrid composites.
  
  
  OBJECTIVE
  The purpose of this study was to determine color and translucency changes in a hybrid and a microfilled composite after light exposure with and without water storage.
  
  
  METHODS
  A hybrid (Tetric) and a microfilled composite (Silux Plus) were subjected to artificial daylight with and without water storage. Tristimulus Yxy values were determined colorimetrically against a black or a white background. Differences from baseline were calculated as Delta E*(ab) for up to 1 month. After 1 month, Delta L*, Delta a*, Delta b*, and the contrast ratio Delta C were calculated. Data were analyzed with 2-way analysis of variance (P<.05).
  
  
  RESULTS
  The Delta E(ab)* increased over time for wet and dry stored specimens of both materials. Wet storage for 1 month resulted in significantly higher Delta E(ab)* and Delta C but lower Delta b* than dry storage. The Delta a* was significantly higher for Tetric compared with Silux Plus. Both materials showed negative Delta L* values under both storage conditions without significant differences between materials or storage conditions.
  
  
  CONCLUSIONS
  The results of this in vitro study suggest that resin-based restoration materials undergo measurable changes due to daylight exposure. Increased changes occurred under the influence of water storage.
authors.affiliation: Department of Conservative and Preventive Dentistry and Periodontology, University Clinic for Dentistry, Georg-August University, Göttingen, Germany. bucalla@med.uni-goettingen.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Buchalla
authors.forename: Thomas
authors.initials: T
authors.lastname: Attin
authors.forename: Ralf-Dieter
authors.initials: RD
authors.lastname: Hilgers
authors.forename: Elmar
authors.initials: E
authors.lastname: Hellwig
mesh_terms: D000704:Analysis of Variance; D003116:Color; D003124:Colorimetry; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D003793:Dental Restoration, Permanent; D006801:Humans; D007259:Infrared Rays; D008027:Light; D008422:Materials Testing; D013499:Surface Properties; D013997:Time Factors; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C090969:Tetric; D014867:Water; C074741:Silux Plus