title: In vitro color stability of double-layer veneers after accelerated aging.
abstract: BACKGROUND
  Porcelain laminates made from thin alumina shells veneered with feldspathic porcelain could be a promising alternative to conventional veneers. Long-term shade stability is critical for esthetics.
  
  
  OBJECTIVE
  This study compared changes in CIE L*a*b* color coordinates of simulated veneers made from aluminum oxide core material veneered with feldspathic porcelain after 300 hours of accelerated photothermal aging (weathering).
  
  
  METHODS
  Fifteen aluminum oxide disks (Procera) were divided into 3 groups. Each of the 5 disks was veneered with All-Ceram porcelain of the Vita shades A1 and B4, respectively. Five disks remained unfinished as controls. The disks were bonded to composite substrates simulating stained teeth. The color of the specimens was measured with a colorimeter. All specimens were subjected to 300 hours of accelerated aging under light exposure and thermocycling. Color measurements were repeated, and the data were statistically evaluated with multiple paired t tests.
  
  
  RESULTS
  Color changes in the test groups involved an increase in lightness and a decrease in chroma. The calculated total color differences were not statistically significant compared with a level of 3 DeltaE units.
  
  
  CONCLUSIONS
  This simulation of double-layer veneers appears to demonstrate acceptable color stability for this type of restoration. Clinical research is necessary to substantiate these in vitro findings.
authors.affiliation: School of Dentistry, University of Michigan, Ann Arbor, Mich 48109, USA.
authors.forename: G
authors.initials: G
authors.lastname: Heydecke
authors.forename: F
authors.initials: F
authors.lastname: Zhang
authors.forename: M E
authors.initials: ME
authors.lastname: Razzoog
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D003116:Color; D003124:Colorimetry / Q000295:instrumentation; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D004955:Esthetics, Dental; D006801:Humans; D008027:Light; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D013223:Statistics as Topic; D013816:Thermodynamics; D013997:Time Factors; D014025:Titanium / Q000737:chemistry
chemical_list: C105314:AllCeram; D000538:Aluminum Silicates; D003188:Composite Resins; D016876:Metal Ceramic Alloys; D017680:Potassium Compounds; C077451:Procera; D003776:Dental Porcelain; C016447:feldspar; D014025:Titanium; D000537:Aluminum Oxide