**Preface to "Oral Inflammations and Systemic Diseases"**

Oral infections occur frequently in humans and often lead to chronic inflammations affecting the teeth (i.e., as caries), the gingival tissues surrounding the teeth (i.e., as gingivitis and endodontic lesions), and the tooth-supporting structures (i.e., as periodontitis). It has been proposed that these inflammations are not restricted to specific sites in the oral cavity and may have a negative impact on the general health of the affected patients by increasing their risk of several widespread diseases, such as diabetes, coronary heart disease, peripheral arterial disease, ischemic stroke, and small vessel disease in the brain. At least four basic pathogenic mechanisms involving oral inflammation in the pathogenesis of widespread diseases have been proposed: (1) low level bacteremia by which oral bacteria enter the blood stream and invade the body; (2) systemic inflammation induced by inflammatory mediators released from the sites of the oral inflammation into the blood stream; (3) autoimmunity to host proteins caused by the host immune response to specific components of oral pathogens; and (4) pathogenic effects resulting from specific bacterial toxins produced by oral pathogenic bacteria.

This Special Issue focuses on several aspects of the interaction between oral infections and widespread systemic diseases. We collected contributions in the form of reviews and original papers written by highly reputed experts in this field.

> **Udo Seedorf, Ghazal Aarabi** *Special Issue Editors*
