1. Department of Periodontology, Nihon University School of Dentistry, Tokyo 101-8310, Japan
2. Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, Tokyo 101-8310, Japan
3. Department of Periodontology, Tokyo Dental College, Tokyo 101-0061, Japan
4. Oral Health Science Center, Tokyo Dental College, Tokyo 101-0061, Japan
5. Department of Prosthodontics, New York University College of Dentistry, New York, NY 10010, USA