title: Effect of home bleaching on the mechanical properties of resin luting cements using Hertzian indentation test.
abstract: OBJECTIVE
  The aim of the present study was to determine the effects of immersion time and 10% carbamide peroxide treatment using a Hertzian indentation test after placing resin-based cements into 37°C distilled water, with and without 10% carbamide peroxide.
  
  
  METHODS
  Disc-shaped specimens (10-mm diameter × 1-mm thick), were prepared from five resin-based cements; seT PP, Maxcem Elite, RelyX Unicem, Panavia F, and G-Cem. The specimens of each material were randomly divided into three groups of six. The study groups were bleached with 10% carbamide peroxide on one surface for 21 days for 2 h per day. Two control groups were kept in distilled water for either 24 h or 21 days. A load was applied to the center of the disc using a hard, steel ball. The load at the first crack was recorded.
  
  
  RESULTS
  Significant differences were observed between the cements. seT PP showed the highest strength, and G-Cem the lowest. Differences between the treatment and control groups were statistically significant for all cements, except Panavia F.
  
  
  CONCLUSIONS
  The effect of 10% carbamide peroxide treatment reduces cement strength, which could be important for patients undergoing bleaching who have crowns.
authors.affiliation: Department of Dental Materials and Biomaterial Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Rafat
authors.initials: R
authors.lastname: Bagheri
authors.affiliation: Department of Dental Materials and Biomaterial Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mahroo
authors.initials: M
authors.lastname: Vojdani
authors.affiliation: Department of Prosthodontics and Biomaterial Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Mogharabi
authors.affiliation: Department of Oral Diagnosis and Polyclinics, Faculty of Dentistry, University of Hong Kong, Prince Philip Dental Hospital, Hong Kong, China.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Burrow
mesh_terms: D000077463:Carbamide Peroxide; D003799:Dental Stress Analysis / Q000295:instrumentation; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D010545:Peroxides / Q000737:chemistry*; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: C528107:G-Cem resin cement; C515955:Maxcem; C438843:Panavia-Fluoro; D010545:Peroxides; C483701:Rely X Unicem; D019279:Resin Cements; D058205:Tooth Bleaching Agents; D014867:Water; D000077463:Carbamide Peroxide; D014508:Urea
keywords: Hertzian indentation; bleaching agent; resin cement