4Socransky SS, Haffajee AD, Goodson JM, et al. New concepts of destructive periodontal disease. J Clin Periodontol, 1984,11:21-32.
5Baelum V, Chen X, Manji F, et al. Profiles of destructive periodontal disease in different populations. J Periodontal Res,1996,31:17-26.
6Albandar JM. Global risk factors and risk indicators for periodontal diseases. Periodontol 2000, 2002,29:177-206.
7Cao CF, Ouyang XY, Yang S, et al. A longitudinal survey on periodontal disease in Chinese villagers - preliminary report. Chin J Dent Res,1998, 1:7-16.
8Albandar JM, Brunelle JA, Kingman A. Destructive periodontal disease in adults 30 years of age and older in the United States, 1988-1994. J Periodontol, 1999,70: 13-29.
9Grbic JT ,Lamster IB. Risk indicators for future clinical attachment loss in adult periodontitis. Tooth and site variables. J Periodontol,1992,63:262-269.
10Le H, Anerud A, Boysen H, et al. The natural history of periodontal disease in man. The rate of periodontal destruction before 40 years of age. J Periodontol, 1978, 49:607-620.