CUDec Clinical Update Naval Dental School National Naval Dental Center Bethesda, Maryland Vol. Oral bacteria may be classified in different ways.
Indigenous bacteria are compatible with the host and normally are found in high numbers.
Exogenous bacteria come from outside the normal flora and are capable of causing disease. Transient bacteria are present only for a short time. Opportunistic bacteria are indigenous bacteria that quickly multiply to cause an infection if the equilibrium is disrupted between other bacteria or the host response. The Specific Plaque Theory, more popular today, suggests that periodontal disease results from either specific exogenous bacteria or groups of bacterial species. Because periodontal disease has a bacterial etiology, we can assume that a microbial test of the periodontal flora could identify the cause of the disease and an appropriate therapeutic intervention.