title: Discoloration of restorative materials after bleaching application.
abstract: OBJECTIVE
  The esthetic application of bleaching materials has gained popularity, with consequences for teeth and restorative materials. The aim of this investigation was to evaluate the influence of different bleaching agents with varying peroxide concentrations on restorative materials.
  
  
  METHODS
  The color behavior, Vickers hardness, and surface roughness were determined on different restorative materials and bovine enamel. Cylindric samples of two fine hybrid composites, one microfilled composite, one compomer, and one ormocer were bleached for two 2-hour periods with three commercial and three experimental bleaching agents with varying peroxide concentrations. The properties were determined before and after bleaching. As a control, all materials were investigated without bleaching after a 14-day storage.
  
  
  RESULTS
  The restorative materials showed maximum changes in Vickers hardness of 44, maximum changes in surface roughness of between 0.2 and 0.7 microm, and a maximum discoloration of deltaE = 6.8. A statistically significant deterioration of hardness, combined with the highest discoloration, was found for the microfilled composite and the compomer. Different bleaching systems showed varying effects on surface roughness.
  
  
  CONCLUSIONS
  Bleaching resulted in a deterioration of the restorative materials, indicated by a decrease of hardness and an increase in surface roughness. Generally, bovine enamel showed significantly higher discoloration compared to the restorative materials.
authors.affiliation: Department of Prosthetic Dentistry, University Clinics, University of Regensburg, Germany. martin.rosentritt@klinik.uni-r.de
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
authors.forename: Reinhold
authors.initials: R
authors.lastname: Lang
authors.forename: Tobias
authors.initials: T
authors.lastname: Plein
authors.forename: Michael
authors.initials: M
authors.lastname: Behr
authors.forename: Gerhard
authors.initials: G
authors.lastname: Handel
mesh_terms: D000818:Animals; D002417:Cattle; D002516:Ceramics / Q000737:chemistry; D003116:Color; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003743:Dental Enamel / Q000187:drug effects / Q000473:pathology; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D006244:Hardness; D008422:Materials Testing; D063225:Organically Modified Ceramics; D016877:Oxidants / Q000737:chemistry*; D010545:Peroxides / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D013053:Spectrophotometry; D013499:Surface Properties; D013997:Time Factors; D014073:Tooth Bleaching
chemical_list: D020770:Compomers; D003188:Composite Resins; D003764:Dental Materials; D063225:Organically Modified Ceramics; D016877:Oxidants; D010545:Peroxides; D012821:Silanes