title: Spectroscopic analysis of polymer-ceramic dental composites after accelerated aging.
abstract: OBJECTIVE
  The aim of the study was to determine the color and surface chemistry changes of two fiber-reinforced composites and one "advanced composite" as a function of an accelerated aging process by light exposure and water spray.
  
  
  METHODS
  Three composites (Artglass, Targis, and Conquest Sculpture) were assessed for color evaluation in three different shades and with XPS analysis. Four specimens of each shade were analyzed with the UV/VIS/NIR Spectrophotometer in reflectance to determine the baseline color for the CIE L*a*b* system. XPS spectra were obtained from three specimens for each material group. All sample disks were artificially aged in a weathering machine and exposed to water spray and a controlled irradiance xenon arc of 0.55 W/m2/nm measured at 340 nm for a total exposure time of 122 hours. L*a*b* and XPS analyses were repeated after the aging process for all specimens.
  
  
  RESULTS
  Artglass had "just perceptible," changes, with deltaE* between 1.8 and 2.7, while Conquest Sculpture showed, in all shades, "visually perceptible" changes from deltaE* 5 to 9. Targis had just perceptible as well as visually perceptible changes after aging. All materials showed decreased Ba and Si on the aged samples, while carbon increased.
  
  
  CONCLUSIONS
  All materials tested underwent a surface change after the aging process. Artglass and Targis changed minimally into whitish/reddish and yellowish appearances, respectively. An organic-rich surface was produced by a combination of washout of filler particles and rearrangement of polymer molecules through diffusion.
authors.affiliation: Department of Preventive and Restorative Dental Sciences, Division of Biomaterials and Bioengineering, University of California San Francisco, 94143-0758, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Schulze
authors.forename: Joachim
authors.initials: J
authors.lastname: Tinschert
authors.forename: Sally J
authors.initials: SJ
authors.lastname: Marshall
authors.forename: Grayson W
authors.initials: GW
authors.lastname: Marshall
mesh_terms: D001464:Barium / Q000032:analysis; D002244:Carbon / Q000032:analysis; D002516:Ceramics / Q000737:chemistry* / Q000528:radiation effects; D003116:Color; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D004058:Diffusion; D004577:Electron Probe Microanalysis; D005899:Glass Ionomer Cements / Q000737:chemistry / Q000528:radiation effects; D006801:Humans; D008027:Light; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D012823:Silicate Cement / Q000737:chemistry / Q000528:radiation effects; D012825:Silicon / Q000032:analysis; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; C092421:Conquest composite resin; D003764:Dental Materials; D005899:Glass Ionomer Cements; D011108:Polymers; C111282:dental polyglass; D014867:Water; D012823:Silicate Cement; D001464:Barium; D002244:Carbon; D012825:Silicon