1 Department of Endodontics, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Faculty of Dentistry, Tanta University, Tanta, Egypt. Electronic address: hatem@unc.edu.
2 Faculty of Medicine and Dentistry, Department of Orthodontics, University of Alberta, Edmonton, Alberta, Canada.
3 Department of Statistics and Operation Research, University of North Carolina, Chapel Hill, North Carolina; Faculty of Commerce, Tanta University, Tanta, Egypt.
4 Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
5 Faculty of Medicine and Dentistry, Department of Orthodontics and Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada.