**Abstract**

Inflammation is a physiological response of the innate immune system against several endogenous or exogenous stimuli. Inflammation begins with an acute pattern; however, it can become chronic by activating the adaptive immune response through cellular and noncellular mechanisms. The main etiologic factor of periodontal disease is bacteria which substantially harbor the human oral cavity. The most common periodontal diseases are gingivitis and periodontitis, whose main characteristic is inflammation. The knowledge of how immune mechanisms and inflammatory responses are regulated is fundamental to understanding the pathogenesis of periodontal disease. The purpose of this chapter is to show the current panorama of the immunological mechanisms involved in the pathogenesis of periodontal disease.

**Keywords:** periodontal tissues, biofilm, inflammatory response, innate and adaptive immunity, periodontitis
