1. Department of Advanced Prosthodontics, Tokyo Medical and Dental University—TMDU, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
2. Department of Biomaterials Science, Turku Clinical Biomaterials Centre—TCBC, Institute of Dentistry, University of Turku, Itäinen Pitkäkatu 4B, 20520 Turku, Finland
3. Department of Orthodontics, School of Dentistry, University of Texas Health Science Center at Houston, 7500 Cambridge St., Houston, TX 77054, USA