1. Department of Prosthetic Dentistry I, Faculty of Dentistry, Kyushu University, Fukuoka 812-82, Japan
2. Department of Oral Anatomy I, and 2Oral Pathology, Faculty of Dentistry, Kyushu University, Fukuoka 812-82, Japan
3. Department of Oral Pathology, Faculty of Dentistry, Kyushu University, Fukuoka 812-82, Japan
4. Department of Oral Anatomy I, Faculty of Dentistry, Kyushu University, Fukuoka 812-82, Japan