title: Effect of intrinsic nanoparticle pigmentation on the color stability of denture base acrylic resins.
abstract: BACKGROUND
  Intrinsic pigmentation is widely used to improve the esthetic features of denture base acrylic resins. However, acrylic resin may discolor over time.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effect of intrinsic nanoparticle pigmentation on the color stability of acrylic resins.
  
  
  METHODS
  The acrylic resins, Onda Cryl, QC 20, Classico, and Lucitone, were evaluated. Twenty-one disk-shaped specimens (3 × 30 mm) were fabricated from each acrylic resin. Seven were colored with 3% Poli-Cor intrinsic pigment used to color denture base, 7 were colored with 7% pigment, and 7 were not pigmented. In addition, 7 specimens were fabricated containing only pigment. The specimens were thermally cycled 2000 times between 5°C and 55°C with a 30-second dwell time at each temperature. The specimen colors were measured with a spectrophotometer and evaluated with the CIE L*a*b* system before (B) and after thermal cycling (T). The pigment morphology was analyzed by using a scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS) techniques. The results were analyzed with 2-way nested ANOVA and Tukey HSD tests (α=.05).
  
  
  RESULTS
  Classico acrylic resin with and without pigment underwent the least color change, followed in order by Lucitone, Onda Cryl, and QC-20. The presence of pigments reduced the color change of the acrylic resins significantly (P<.05) for the specimens containing 7% pigment (0.32 ±0.18 ΔE). Titanium was the sole metallic component present in the pigment, probably in the oxide form (TiO2).
  
  
  CONCLUSIONS
  Nanoparticle pigments enhanced the color stability of denture base acrylic resins.
authors.affiliation: Department of Dental Materials and Prosthodontics, State University of São Paulo-UNESP, Faculty of Dentistry of Araçatuba.
authors.forename: Marcelo Coelho
authors.initials: MC
authors.lastname: Goiato
authors.forename: Bruna Carolina Rossatti
authors.initials: BC
authors.lastname: Zuccolotti
authors.forename: Daniela Micheline
authors.initials: DM
authors.lastname: dos Santos
authors.forename: Mário Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003116:Color; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases; D006801:Humans; D020366:Methylmethacrylate / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry*; D017797:Prosthesis Coloring; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; C488492:QC 20 (denture base resin); C539103:onda cryl; C009495:titanium dioxide; D020366:Methylmethacrylate; C040291:Lucitone; D014025:Titanium