Immunoglobulin G (IgG) 

This type is almost entirely derived from gingival crevicular fluid, now more commonly called gingival fluid. This is a blood exudate (a protein-rich fluid that has escaped from blood vessels) that emerges from the crevice between the gingiva and the tooth. It contains immunoglobulins such as IgG, which can be produced by plasma in periodontal pockets. An increase in gingival fluid and IgG to a variety of oral microbial agents, including S mutans, has been seen in response to periodontal irritation and inflammation. Yet, IgG to oral microbial agents are also present in the healthy mouth, suggesting that it prevents early stages of plaque development from worsening.18 Compared to SigA, IgG is strong in complement-activating and opsonizing that can lead to antibody-mediated phagocytosis. In the absence of inflammation, the naturally low levels of complement would reduce IgG, and may play a role in modulating oral microflora.