1. Department of Stomatology, The 940th Hospital of Joint Logistics Support Force of People’s Liberation Army, Lanzhou, Gansu, China
2. Department of Stomatology, Quzhou Hospital Affiliated to Wenzhou Medical University (Quzhou people’s Hospital), Quzhou, Zhejiang, China
3. Department of Periodontics, Faculty of Dentistry, Thamar University, Dhamar, Yemen