1. Dental Materials Research Center, Department of Community Oral Health, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
2. Dental Research Center, Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
3. Department of Occupational Health Engineering, Zanjan University of Medical Sciences, Zanjan, Iran
4. Department of Periodontics, Louisiana State University, New Orleans, LA, USA