1. Epidemiology Unit, Faculty of Medicine; Prince of Songkla University; Hat Yai Thailand
2. Department of Pathology, Faculty of Medicine; Prince of Songkla University; Hat Yai Thailand
3. Department of Biomedical Sciences, Faculty of Medicine; Prince of Songkla University; Hat Yai Thailand
4. Department of Oral Surgery and Oral Medicine, Faculty of Dentistry; Srinakharinwirot University; Bangkok Thailand