1. Dental and Oral Medical Center, Kurume University, School of Medicine, Kurume, Fukuoka 830‑0011, Japan
2. Department of Diagnostic Pathology, Kurume University Hospital, Kurume, Fukuoka 830‑0011, Japan
3. Department of Dentistry and Oral Surgery, Oita Saiseikai Hita Hospital, Hita, Oita 877‑1292, Japan