Mohamed I. Fayad, BDS, MS, PhD, is Assistant Clinical Professor in the College of Dentistry - University of Illinois at Chicago, Chicago, USA. Dr. Fayad graduated from the Faculty of Oral and Dental Medicine, Cairo University, Egypt in 1985 and subsequently gained his Masters and Doctorate in Endodontics from the same university. He completed further postgraduate studies in the Department of Endodontics, College of Dentistry, University of Illinois before joining the Department professionally in 2000. Since that time his private practice has been limited to endodontics. Dr. Fayad is a Diplomate of the American Board of Endodontists. From 2004 to 2006 he was a member of the Research and Scientific Affairs Committee of the American Association of Endodontists and in 2013-2014 he served as President of the Illinois Association of Endodontists. He is also a past president of the Edgar D. Coolidge Endodontic Study Club. Dr. Fayad has given many scientific presentations at national and international meetings and is the author of 16 articles in peer-reviewed journals.Bradford R. Johnson, DDS, MHPE, is Head of the Department of Endodontics, College of Dentistry - University of Illinois at Chicago, Chicago, USA, where he is an Associate Professor and Director of Postdoctoral Endodontics. Dr. Johnson has engaged in clinical practice limited to endodontics since 1991 and is proficient in all phases of nonsurgical and surgical endodontics. He is a Diplomate of the American Board of Endodontics, a Fellow of the American Dental Education Association Leadership Institute, a Fellow of The Odontographic Society of Chicago, and a Fellow of the International College of Dentists. Dr. Johnson is a Director and board member of the American Association of Endodontists (2015-2018), and a past chair of their Evidence-Based Endodontics Committee (2009-11) and Research and Scientific Affairs Committee (2002-3). He has also been President of the Illinois Association of Endodontists (2002-3) and the Edgar D. Coolidge Endodontic Study Club (2007-8). Dr. Johnson has been a member of the Scientific Advisory Panel of the Journal of Endodontics since 2003. He is the author of more than 30 articles in peer-reviewed journals.