The aim of this study was to recommend the optimal age for prevention of periodontal disease and to investigate the trend of treatment modality according to different period.

From the chart recordings of the patients who had been treated periodontally from Jan. 1981 to Dec. 1995 in the dept .of periodontics, Chosun University Dental Hospital, those of the periodontally treated patients on more than 4 sixtants were selected for the present study. The distribution of the patients was counted according to the age group and the gender. And they were divided into 3 groups(group 1: 1981-1985, group 2: 1985-1990, group 3: 1991-1995) by 5 year interval according to the treated year. The periodontal treatment modalities were classified into non-surgical therapy, pocket elimination surgery, regenerative periodontal surgery, mucoginigival surgery, clinical crown lengthening, and others.

The results were as follows;

In the distribution of the periodontally treated patients according to the age group, 40's age group was the highest, and 30's, 40's, and 50's age groups occupied more than two thirds(73%).

The sexual distribution of the periodontally treated patients showed that males(53.4%) were a little more than females(46.6%%). Within 20's group female was higher, but within 40's male was higher.

Regardless of the age group and the gender, pocket elimination surgery was the most frequent treatment modality.

In group 1 and 2(1981-1990) the main treatment modality was pocket elimination surgery and non-surgical therapy, but in group 3(1991-1995) it was regenerative periodontal surgery and pocket elimination surgery.

The above results suggest that the prevention of periodontal disease should be initiated from early twenties, and the most frequent treatment modality may be closely related with development of new material and method.