The oral cavity plays a vital role in chewing, digestion, breathing, speech, facial expression, and sensory perception. It serves both as a reflection of overall health and as one of the body’s first lines of defense against external threats (such as certain bacteria, for example). Certain systemic diseases can contribute to the onset, progression, or severity of oral diseases. Conversely, certain oral diseases can have systemic consequences and contribute to the onset, progression, or severity of certain systemic diseases.