1. Department of Fixed Prosthodontics; Faculty of Dentistry; Tanta University; Tanta Egypt
2. Department of General Dentistry; Baylor College of Dentistry; Texas A&M Health Science Center; Dallas TX USA
3. Department of Chemistry; College of Science; Texas A&M University; College Station TX USA
4. Department of Public Health Sciences; Baylor College of Dentistry; Texas A&M Health Science Center; Dallas TX USA
5. Department of Dental and Biomedical Materials Science; Nagasaki University Graduate School of Biomedical Science; Nagasaki Japan