1. Department of Periodontology, School of DentistryKyung Hee University Private Practice in Periodontics and Implant Dentistry Seoul South Korea
2. Department of Periodontology, Division of DentistryHanyang University College of Medicine Seoul South Korea
3. Division of Periodontics, Section of Oral, Diagnostic and Rehabilitation SciencesCollege of Dental Medicine New York New York