title: Effect of intracoronal bleaching agents on ultrastructure and mineral content of dentin.
abstract: OBJECTIVE
  The purpose of this in vitro study was to evaluate the ultrastructural changes of dentin induced after exposure to different intracoronal tooth bleaching agents.
  
  
  METHODS
  Dental discs of 1 mm thickness were prepared from coronal dentin of sixty-four human maxillary premolars. Experimental specimens were divided into four subgroups: 45% carbamide peroxide, 35% hydrogen peroxide, sodium perborate + 30% hydrogen peroxide, sodium perborate + water. The specimens were then evaluated under scanning electron microscope to determine diameter of dentinal tubules and chemical analysis.
  
  
  RESULTS
  There was significant difference between dentinal tubule diameter of all test and control groups with the exception of sodium perborate + water. Chemical analysis revealed that there was no significant difference between experimental subgroups regarding calcium and sulfur wt%.
  
  
  CONCLUSIONS
  All bleaching agents increased dentinal tubule diameter and promote alterations in mineral content of dentin with the exception of Sodium perborate mixed with water.
authors.affiliation: Department of Operative Dentistry, Mashhad Dental School and Dental Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Maleknejad
authors.forename: Hamideh
authors.initials: H
authors.lastname: Ameri
authors.forename: Iman
authors.initials: I
authors.lastname: Kianfar