1 Division of Endodontics, Department of Dentistry, Oral Health Institute, Hamad Medical Corporation, Doha, Qatar; College of Dental Medicine, QU Health, Qatar University, Doha, Qatar; Hamad Dental Center, Hamad Medical Corporation, Doha, Qatar.
2 College of Dental Medicine, QU Health, Qatar University, Doha, Qatar.
3 Division of Endodontics, Department of Dentistry, Oral Health Institute, Hamad Medical Corporation, Doha, Qatar; College of Dental Medicine, QU Health, Qatar University, Doha, Qatar.
4 Division of Endodontics, Department of Dentistry, Oral Health Institute, Hamad Medical Corporation, Doha, Qatar; Hamad Dental Center, Hamad Medical Corporation, Doha, Qatar.
5 College of Dental Medicine, QU Health, Qatar University, Doha, Qatar; Hamad Dental Center, Hamad Medical Corporation, Doha, Qatar.
6 H. M. Goldman School of Dental Medicine, Boston University, Boston, MA.
7 College of Dental Medicine, QU Health, Qatar University, Doha, Qatar. Electronic address: fmarino@qu.edu.qa.