**Abstract**

Periodontal disease is the most common oral condition of human population; if periodontitis is not treated in its initial stages, it can cause the loss of teeth. The diagnosis of periodontitis is based on clinical measurements. However, currently with the advancement of technology, other diagnostic and monitoring options are being search. In fact, different types of biomarkers have been evaluated where different biological fluids have been used as a source of the sample. We will try to summarize existing biomarkers of different periodontitis stages and make a comparison of the periodontal biomarkers evaluated so far and their usefulness in diagnosis and monitoring of periodontitis.

**Keywords:** biomarkers, periodontitis, dentobacterial plaque, gingivitis

## **1. Introduction**

Health in general is fundamental in humans, oral health plays an important role, and any alteration in it can influence the general welfare of individuals. Diseases of the oral cavity are very important due to its high incidence and prevalence according to the World Health Organization [1].

Regarding the epidemiology of the disease, we can say that from 5 to 15% of the population of the United States suffers from severe periodontitis [2]. Data from the Department of Health of Mexico mention that approximately 8.8% of the Mexican population has chronic periodontitis. This is more common among subjects 35 years of age and older, where it is estimated that the frequency is 22% [3].

Periodontitis is a chronic inflammatory disease that compromises the integrity of the tissues that support the teeth, which include the gingiva, periodontal ligament, dental cement, and alveolar bone, and are collectively known as the periodontium [4, 5].

This disease is caused by specific microorganisms or groups of specific microorganisms, which in the end produce a greater formation of probing depth, recession, or both. When these conditions remain, they cause the tissue to be destroyed and the tooth to be lost. This disturbs the mastication, phonation, and esthetics of the patient, which affect the quality of life [4].

The traditional treatment for periodontitis decreases the microbial presence by means of the mechanical interruption and the elimination of the bacterial layers that form in the surfaces of the teeth and adjacent soft tissues [2].

In the pathology of periodontitis, the clinical, radiographic, and histological characteristics of the gingival groove and pouch epithelium, the underlying connective tissue and the types of resident and infiltrating blood cells in the initial, early, established periodontal injury are known [6].

Currently, the diagnosis requires rapidity, sensitivity, and specificity since determining the stage in which the patient is located is fundamental for a good treatment; for this reason molecules are currently being sought that vary when the person is healthy and when the person has the disease. However, despite all the researches that exist regarding chronic inflammation, the diagnosis of periodontitis is based on clinical measurements; these not only show low sensitivity and specificity as diagnostic tests but are also subjective and laborious. The objective of this chapter is to try to describe what a biomarker is, the types of biomarkers evaluated in periodontitis, the sources to obtain these biomarkers, and their usefulness.
