1. Division of Endodontics, Department of Advanced Oral Sciences and Therapeutics University of Maryland, School of Dentistry Baltimore Maryland USA
2. Prince Abdulrahman Advanced Dental Institute Riyadh Kingdom of Saudi Arabia
3. Endodontic division, Department of Preventive and Restorative Dentistry Aracatuba School of Dentistry, São Paulo State University (UNESP) Araçatuba Brazil