We have evaluated the periodontal conditions of about 300 patients with Juvenile Diabetes (Insulin Dependent Diabetes Mellitus, IDDM. We found that periodontitis starts at the age of 12-13 years and progressively increases to involve about 1/4 of patients 19 years or older. These periodontitis lesions characteristically started at the first molars and incisors and progressively spread to other sites. We have also found a unique constellation of bacterial flora in periodontitis in IDDM which is substantially different from those found in other forms of periodontitis. Thus, we have identified a cohort of about 300 patients with IDDM in whom the development of periodontal complication has been characterized with respect to (1) the age of onset, (2) sites of early lesions, and (3) the estimated frequency with which those lesions may develop. Such a cohort of patients with IDDM would provide an opportunity for a study of the pathogenetic mechanisms for the development of periodontitis. Our aims of this proposal are: (1) Longitudinal and prospective evaluation of periodontal conditions in a cohort of 300 patients with IDDM to document the incidence, prevalance, and progression of periodontal complications associated with IDDM, (2) Isolation and characterization of pathogenic bacteria associated with the periodontal infections in IDDM and (3) Study of the changes in microbial flora and host factors which may play a role in the development of periodontitis, whose manifestation appears to coincide with the onset of puberty in IDDM.