What are the primary functions of secretory IgA (sIgA) in the oral cavity?

Secretory IgA (sIgA) provides both antibacterial and antiviral defense. It works primarily by immune exclusion — binding to pathogens and preventing their adherence to mucosal surfaces. For bacteria: inhibits streptococcal adhesion (anti-S. mutans IgA). For viruses: neutralizes viral particles before mucosal entry. sIgA is NOT efficient at complement activation (unlike IgG and IgM) — it works through blocking adherence, not killing.