1Eng. A. B. Research Chair for Growth Factors and Bone Regeneration, King Saud University, Riyadh, Saudi Arabia
2Department of Periodontics and Community Dentistry, King Saud University, Riyadh, Saudi Arabia
3Division of Endodontics, King Abdulaziz Medical City, National Guard Hospital, Riyadh, Saudi Arabia
4Division of Endodontics, Oral & Maxillofacial Surgery and Orthodontics, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA