1. Division of Orthodontics and Dentofacial Orthopedics; Department of Oral Growth and Development; School of Dentistry; Health Sciences University of Hokkaido; Hokkaido Japan
2. Division of Cariology and Endodontology; Department of Oral Rehabilitation; Health Sciences University of Hokkaido; Hokkaido Japan
3. Division of Restorative Science and Prosthodontics; College of Dentistry; The Ohio State University; Columbus Ohio USA
4. Department of Endodontics; College of Dentistry; University of Illinois; Chicago Illinois USA