title: Effect of light-activated bleaching on the microleakage of Class V tooth-colored restorations.
abstract: OBJECTIVE
  In-office bleaching procedures utilizing highly concentrated 30%-35% hydrogen peroxide solutions or hydrogen peroxide releasing agents are used for tooth whitening. Some recommend that, to enhance the whitening process, light-activation of the bleaching agent should be performed. The current study evaluated the effect of plasma arc bleaching on the microleakage of Class V restorations restored with resin composite, compomer and resin-modified glass ionomer (RMGI).
  
  
  METHODS
  The buccal surfaces of 72 freshly extracted premolars were prepared with Class V cavities (4 x 2.5 x 1.5 mm) extended 1 mm apical to the CEJ. The prepared teethwere randomly divided into six groups. The cavities were restored with Single Bond and Z100 resin composite (Groups 1 and 2), Prompt L-Pop and F2000 compomer (Groups 3 and 4) and Vitremer RMGI (Groups 5 and 6), respectively. They were then thermocycled for 500 cycles. The samples from Groups 1, 3 and 5 were incubated at 37 degrees C and 100% humidity. Groups 2, 4 and 6 were bleached using in-office bleaching gel and the plasma arc bleaching unit, then incubated. All samples were sealed with nail varnish and immersed in 2% basic fuschin for 24 hours. The restorations were sectioned longitudinally and microleakage was evaluated using a scale ranging from 0 to 3. The data were analyzed using the Kruskal-Wallis test (alpha = 0.05).
  
  
  RESULTS
  No statistically significant differences between study groups were observed in both the enamel and dentinal margins (p > 0.05).
  
  
  CONCLUSIONS
  Plasma arc bleaching did not significantly affect the microleakage of existing tooth-colored restorations restored with Z100 resin composite, F2000 compomer and Vitremer RMGI.
authors.affiliation: Department of Operative Dentistry & Torabinejad Dental Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. khoroushi@dnt.mui.ac.ir
authors.forename: Maryam
authors.initials: M
authors.lastname: Khoroushi
authors.forename: Saleh Reisian
authors.initials: SR
authors.lastname: Fardashtaki
mesh_terms: D001641:Bicuspid; D020770:Compomers / Q000528:radiation effects; D003188:Composite Resins / Q000528:radiation effects; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000209:etiology*; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D005899:Glass Ionomer Cements / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide; D008027:Light / Q000009:adverse effects*; D016877:Oxidants; D055668:Photochemical Processes; D014073:Tooth Bleaching / Q000009:adverse effects / Q000379:methods
chemical_list: D020770:Compomers; D003188:Composite Resins; D005899:Glass Ionomer Cements; D016877:Oxidants; D006861:Hydrogen Peroxide