1. Department of Periodontics; Chang Gung Memorial Hospital; Taipei Taiwan
2. Chang Gung University; Taoyuan City Taiwan
3. Department of Periodontics and Oral Medicine; School of Dentistry; University of Michigan; Ann Arbor MI USA
4. State Key Laboratory of Oral Diseases; Department of Prosthodontics; National Clinical Research Center for Oral Disease; West China Hospital of Stomatology; Sichuan University; Chengdu China