1. 1 Department of Dentistry, Faculty of Medical Sciences, Civilization University, Sana'a, Yemen.
2. 2 Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden.
3. 3 Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden.
4. 4 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Thamar University, Thamar, Yemen.