title: Color and luminescence stability of selected dental materials in vitro.
abstract: OBJECTIVE
  To study luminescence, reflectance, and color stability of dental composites and ceramics.
  
  
  METHODS
  IPS e.max, IPS Classic, Gradia, and Sinfony materials were tested, both unpolished (as-cast) and polished specimens. Coffee, tea, red wine, and distilled water (control) were used as staining drinks. Disk-shaped specimens were soaked in the staining drinks for up to 5 days. Color was measured by a colorimeter. Fluorescence was recorded using a spectrofluorometer, in the front-face geometry. Time-resolved fluorescence spectra were recorded using a laser nanosecond spectrofluorometer.
  
  
  RESULTS
  The exposure of the examined dental materials to staining drinks caused changes in color of the composites and ceramics, with the polished specimens exhibiting significantly lower color changes as compared to unpolished specimens. Composites exhibited lower color stability as compared to ceramic materials. Water also caused perceptible color changes in most materials. The materials tested demonstrated significantly different initial luminescence intensities. Upon exposure to staining drinks, luminescence became weaker by up to 40%, dependent on the drink and the material. Time-resolved luminescence spectra exhibited some red shift of the emission band at longer times, with the lifetimes in the range of tens of nanoseconds.
  
  
  CONCLUSIONS
  Unpolished specimens with a more developed surface have lower color stability. Specimens stored in water develop some changes in their visual appearance. The presently proposed methods are effective in evaluating the luminescence of dental materials. Luminescence needs to be tested in addition to color, as the two characteristics are uncorrelated. It is important to further improve the color and luminescence stability of dental materials.
authors.affiliation: Department of Gerodontology, University of Medical Sciences, Poznań, Poland Faculty of Commodity Science, The Poznań University of Economics, Poznań, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Gawriołek
authors.forename: Ewa
authors.initials: E
authors.lastname: Sikorska
authors.forename: Luis F V
authors.initials: LF
authors.lastname: Ferreira
authors.forename: Alexandra I
authors.initials: AI
authors.lastname: Costa
authors.forename: Igor
authors.initials: I
authors.lastname: Khmelinskii
authors.forename: Alina
authors.initials: A
authors.lastname: Krawczyk
authors.forename: Marek
authors.initials: M
authors.lastname: Sikorski
authors.forename: Prof Ryszard
authors.initials: PR
authors.lastname: Koczorowski
mesh_terms: D003069:Coffee; D003116:Color; D003124:Colorimetry; D003188:Composite Resins; D003775:Dental Polishing; D003776:Dental Porcelain; D049449:Luminescence; D008422:Materials Testing; D013053:Spectrophotometry; D013662:Tea; D013997:Time Factors; D014920:Wine
chemical_list: D003069:Coffee; D003188:Composite Resins; D013662:Tea; D003776:Dental Porcelain