title: Coronal microleakage of three different dental biomaterials as intra-orifice barrier during nonvital bleaching.
abstract: BACKGROUND
  This study was designed to assess the microleakage of glass-ionomer (GI), mineral trioxide aggregate (MTA), and calcium-enriched mixture (CEM) cement as coronal orifice barrier during walking bleaching.
  
  
  METHODS
  In this experimental study, endodontic treatment was done for 70 extracted human incisors without canal calcification, caries, restoration, resorption, or cracks. The teeth were then divided into three experimental using "Simple randomization allocation" (n = 20) and two control groups (n = 5). The three cements were applied as 3-mm intra-orifice barrier in test groups, and bleaching process was then conducted using a mixture of sodium perborate powder and distilled water, for 9 days. For leakage evaluation, bovine serum albumin marker was traced in a dual-chamber technique with Bradford indicator. The Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis.
  
  
  RESULTS
  The mean ± standard deviation leakage of samples from negative control, positive control, GI, MTA, and CEM cement groups were 0.0, 8.9 ± 0.03, 0.47 ± 0.02, 0.48 ± 0.02, and 0.49 ± 0.02 mg/mL, respectively. Statistical analysis showed no significant difference between three experimental groups (P > 0.05).
  
  
  CONCLUSIONS
  It is concluded that GI, MTA, and CEM cements are considered as suitable intra-orifice barrier to provide coronal seal during walking bleaching.
authors.affiliation: Department of Restorative Dentistry, Sari Dental School, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Zarenejad
authors.affiliation: Iranian Center for Endodontic Research, Dental Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Asgary
authors.affiliation: Children and Adolescent Health Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
authors.forename: Nahid
authors.initials: N
authors.lastname: Ramazani
authors.affiliation: Department of Microbiology, Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Haghshenas
authors.affiliation: Department of Immunology, Molecular and Cell Biology Research Center, Mazandaran University of Medical Sciences, Sari, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Rafiei
authors.affiliation: Department of Endodontics, Sari Dental School, Mazanaran University of Medical Sciences, Sari, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Ramazani
keywords: Calcium enriched mixture cement; RMGIC; WMTA; coronal barrier; nonvital bleaching