title: Evaluation of the effect of a home-bleaching agent on the surface characteristics of indirect esthetic restorative materials: part I--roughness.
abstract: BACKGROUND
  Pressing esthetic demands of good looking make people undergo bleaching procedures. However, the effect of bleaching agents on esthetic restorative materials with different surface preparations has been poorly studied.
  
  
  OBJECTIVE
  The aim of this study was to examine the effect of a homebleaching agent (carbamide peroxide: CP 38%) on the surface roughness of the polished fiber reinforced composite (FRC), overglazed, autoglazed, or polished ceramic samples.
  
  
  METHODS
  Twenty standardized cylindrical specimens were made of each of the following groups: over-glazed, autoglazed, polished porcelain and also FRC. The test specimens exposed to the CP 38%, 15 minutes, twice a day for 2 weeks according to the manufacturer's recommendation. Six samples from each group were selected randomly to form negative controls. Surface roughness measurements (Ra, micrometer) for baseline, test and control specimens were performed by use of a profilometer. Paired t-test, Mann-Whitney test, and Kruskal-Wallis test were used for statistical analyses.
  
  
  RESULTS
  The data showed that bleaching with CP 38% significantly increased the surface roughness of all the test samples (p < 0.05). The type of surface preparation caused significant differences between the susceptibility of porcelain subgroups to bleaching (p < 0.05). The polished porcelain specimens showed the highest changes after bleaching.
  
  
  CONCLUSIONS
  CP 38% significantly increases the surface roughness of the porcelains and FRC. The type of surface condition affects the amenability of the porcelain surface to the bleaching agent. Glazed porcelains were more resistant to roughness than the polished porcelains and also the composite.
  
  
  CONCLUSIONS
  Roughening of porcelain and FRC occur following bleaching procedure. No special surface preparation of indirect esthetic restorative materials can completely preserve these materials from adverse effects of bleaching agents.
authors.affiliation: Associate Professor, Department of Prosthodontics, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Kianoosh
authors.initials: K
authors.lastname: Torabi
authors.affiliation: Assistant Professor, Department of Prosthodontics, Shiraz and Tehran Universities of Medical Sciences, Shiraz/Tehran, Iran.
authors.forename: Sasan
authors.initials: S
authors.lastname: Rasaeipour
authors.affiliation: Assistant Professor, Department of Prosthodontics, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Amir Alireza
authors.initials: AA
authors.lastname: Khaledi
authors.affiliation: Professor, Department of Prosthodontics, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mahroo
authors.initials: M
authors.lastname: Vojdani
authors.affiliation: Assistant Professor, Department of Prosthodontics, Shiraz and Tehran Universities of Medical Sciences, Shiraz/Tehran, Iran, e-mail: s-ghodsi@sina.tums.ac.ir.
authors.forename: Safoura
authors.initials: S
authors.lastname: Ghodsi
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry*; D045662:Dental Etching / Q000379:methods; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D003776:Dental Porcelain / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D004955:Esthetics, Dental; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D010545:Peroxides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D003764:Dental Materials; C095718:Duceram; D010545:Peroxides; D017680:Potassium Compounds; D058205:Tooth Bleaching Agents; D017973:Tungsten Compounds; D014867:Water; C002802:tungsten carbide; D003776:Dental Porcelain; C016447:feldspar; D000077463:Carbamide Peroxide; D014508:Urea; D000537:Aluminum Oxide