The immune system may be triggered by contact with microbes through the ulceration of epithelium of the periodontal pocket.
No periodontal therapy can selectively eliminate specific bacteria from deep pockets. Mechanical therapy may disturb the subgingival ecosystem as a whole. The role of antibiotic therapy in the Tx of periodontitis concluded that no additional benefit could be measured over and above mechanical Tx in the long term.
The site has to exist before adapted microbes are able to colonize.
The conventional view of a gingival etiology for the initiation of angular alveolar lesion is inconsistent. Chronic dental diseases need to be incorporated into a chronic disease model in which the host defenses and their interaction with environmental agents determine the physiopathologic outcomes in the tissues.
Modified from Clarke NG, Hirsch RS. Personal Risk Factors for Generalized Periodontitis . J Clin Periodontol 1995, 22(2): 136-142