1. Dental Research Center and Department of Endodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
2. Dental Materials Research Center and Department of Pediatric Dentistry, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran.
3. Department of Endodontics, Gorgan University of Medical Sciences School of Dentistry, Gorgan, Iran.