title: The effect of two remineralizing agents and natural saliva on bleached enamel hardness.
abstract: BACKGROUND
  In order to compensate the adverse consequences of bleaching agents, the use of fluoride-containing remineralizing agents has been suggested by many researchers. The aim of this study was to compare the effect of applying two remineralizing materials on bleached enamel hardness and in comparison to natural saliva.
  
  
  METHODS
  In this experimental study, 30 enamel samples of sound human permanent molars were prepared for this study. Microhardness (MH) of all specimens was measured and 35% hydrogen peroxide was applied 3 times to the specimens. After completion of the bleaching process, MH of samples was measured and then enamel specimens were divided into three groups each of 10, specimens of groups 1 and 2 were subjected to daily application of hydroxyl apatite (Remin Pro) and casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF) (MI Paste Plus) pastes, respectively, for 15 days. In group 3, the specimens were stored in the operators' natural saliva at room temperature in this period of time. Final MH of all groups was measured. The data were analyzed using repeated measures ANOVA (α = 0.05).
  
  
  RESULTS
  The hardness significantly decreased in all groups following bleaching. Application of either Remin Pro, CPP-ACPF or natural saliva increased the hardness significantly. The hardness of the three test groups after 15 days were statistically similar to each other.
  
  
  CONCLUSIONS
  The hardness of enamel increases eventually after exposure to either MI Paste Plus, Remin Pro or natural saliva.
authors.affiliation: Department of Operative Dentistry, Islamic Azad University Dental Branch, Tehran, Iran.
authors.forename: Haleh
authors.initials: H
authors.lastname: Heshmat
authors.affiliation: Department of Operative Dentistry, Islamic Azad University Dental Branch, Tehran, Iran.
authors.forename: Maryam Hoorizad
authors.initials: MH
authors.lastname: Ganjkar
authors.affiliation: Private Practice, Tehran, Iran.
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Miri
authors.affiliation: Dental Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohamad Javad Kharrazi
authors.initials: MJ
authors.lastname: Fard
keywords: Bleaching agents; casein phosphopeptide-amorphous calcium phosphate nanocomplex; enamel; hardness; surface properties; tooth remineralization