title: Discoloration of PMMA, composite, and PEEK.
abstract: BACKGROUND
  To assess the discoloration and stain removal potential of different cleaning methods relevant to individual/professional prophylaxis and laboratory cleaning on polyetheretherketone (PEEK), poly(methyl methacrylate) (PMMA)-based, and composite (COMP) materials after storage in different media for 7 days.
  
  
  METHODS
  One thousand three hundred twenty specimens of PEEK, PMMA, and COMP (N = 440 of each group) were prepared and stored in four different media for 7 days to cause stain. Samples were divided into three cleaning groups (n = 10): (i) individual prophylaxis, (ii) laboratory protocols, and (iii) professional prophylaxis. Color was determined by a portable spectrophotometer and calculated between different time points (∆E). The data was statistically evaluated using univariate analyses, Kruskal-Wallis H and Mann-Whitney U tests (p < 0.05).
  
  
  RESULTS
  The significantly (p < 0.001) lowest discoloration was found when specimens were stored in distilled water and chlorhexidine (CHX), followed by red wine. Curry solution caused the highest discoloration. PEEK showed the significantly (p < 0.001) lowest color changes, while COMP showed the highest changes. Ultrasonic bath and Air Flow Plus (AFP) were the significantly (p < 0.001) most effective methods to remove staining. The least cleaning effect was found using a soft toothbrush (ST), a medium-hard toothbrush (MT), and SunSparkle (SS) cleaning system.
  
  
  CONCLUSIONS
  PEEK seems more stable against discolorations than other denture resin materials. Regarding the cleaning potential, individual prophylaxis can be conducted with toothbrushes. For professional prophylaxis, air-abrasion devices using gentle powders are effective. Laboratory protocols should include gentle cleaning methods like ultrasonic bath.
  
  
  CONCLUSIONS
  Clinicians and dental technicians should inform their patients about the discoloration potential of certain foods/beverages and recommend the most efficient cleaning, but preventive methods.
authors.affiliation: Department of Prosthodontics, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Sina
authors.initials: S
authors.lastname: Heimer
authors.affiliation: Clinic of Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Schmidlin
authors.affiliation: Department of Prosthodontics, Ludwig-Maximilians-University, Munich, Germany. bogna.stawarczyk@med.uni-muenchen.de.
authors.forename: Bogna
authors.initials: B
authors.lastname: Stawarczyk
mesh_terms: D001577:Benzophenones; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008422:Materials Testing; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D017797:Prosthesis Coloring; D013053:Spectrophotometry; D013499:Surface Properties; D014075:Tooth Discoloration; D014099:Toothbrushing
chemical_list: D001577:Benzophenones; D003188:Composite Resins; D003764:Dental Materials; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D019904:Polymethyl Methacrylate
keywords: Cleaning; Discoloration; Polyetheretherketone; Surface free energy; Surface roughness