**3. Biomarkers for the diagnosis of periodontitis**

#### **3.1 Importance of the different biomarkers used for the diagnosis of periodontitis**

Because there are certain molecules, like trace elements, proteins (cytokines), and proteolytic enzymes, these have been considered as possible biomarkers of periodontal disease, we will try to discuss the relevance of these groups below.

#### *3.1.1 Proteins (cytokines) involved in the inflammatory process of periodontitis*

Inflammation has evolved as a protective response to an injury, is a primordial response that eliminates or neutralizes foreign organisms or materials, in general; the innate inflammatory response starts in minutes and, if all is well, resolves in a matter of hours. In contrast, chronic inflammation persists for weeks, months, or even years [9]. The inflammatory response that occurs in periodontal disease is mediated mainly by B and T lymphocytes, neutrophils, and monocytes/macrophages. These are activated to produce inflammatory mediators, including cytokines and chemokines [10]. Several pro-inflammatory cytokines including interleukins like IL-1, IL-6, IL-12, IL-17, IL-18, and IL-21; tumor necrosis factor alpha (TNFα); and interferon (IFN-γ) have been demonstrated to be involved in the pathogenesis of periodontitis [2].

**21**

*3.1.6 pH*

*3.1.7 Oxidative stress*

*Use of Biomarkers for the Diagnosis of Periodontitis DOI: http://dx.doi.org/10.5772/intechopen.85394*

There is significant evidence showing that collagenases, along with other matrix metalloproteinases, play an important role in periodontal tissue destruction. The main group of enzymes responsible for the collagen and other protein degradation in extracellular matrix (ECM) is matrix metalloproteinases (MMPs) [11]. Several works have shown that matrix metalloproteinases are upregulated in periodontal inflammation; transcription of matrix metalloproteinase genes is very low in healthy periodontal tissue. In periodontal disease, secretion of specific matrix metalloproteinases is stimulated or downregulated by various cytokines [12].

The importance of calcium in the development of periodontal disease has been recognized since the 1980s [13]. In addition to this, a relationship has been found between people who suffer from periodontitis and who also have osteoporosis [14].

Alkaline phosphatase (ALP) is an intracellular enzyme. It is considered that when this enzyme increases in saliva, it can be determined that there is inflammation and destruction of healthy tissues [15]. It is worth mentioning that other enzymes representative of tissue degradation are aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline

Phosphorus is an essential element and plays an important role in multiple biological processes, due to the fact that maintaining physiological phosphate balance is of crucial biological importance for bone health [17]. Approximately 85% of phosphorus is in the bone, primarily compounded with calcium (Ca2+), the most abundant mineral in hydroxyapatite (HAP) crystals deposited on the collagen matrix [18]. The importance of phosphate in periodontal disease has been observed in X-linked hypophosphatemia (XLH); this disease is a rare skeletal genetic illness in which increased phosphate in the kidney produces hypophosphatemia and prevents normal mineralization of the bone and bone dentine. In a study of 2017, it was observed that the frequency and severity of periodontitis increased in adults with XLH and that the severity varied according to the treatment of hypophosphatemia. Patients who benefited from early and continuous phosphate supplementation during childhood had less loss of periodontal attachment than patients with late or

Although the pH of the oral cavity is between 5 and 9, it is also known to vary widely depending on several factors. There are studies that report that there is a statistically significant correlation between pH and periodontal pocket formation [20].

Periodontitis is an inflammatory disease of the supporting tissues of the teeth, it is defined as a complex infectious disease that results from the interaction of the

phosphatase (ALP), and acid phosphatase (ACP) [16].

*3.1.2 Metalloproteinases*

*3.1.3 Calcium*

*3.1.5 Phosphate*

incomplete supplementation [19].

*3.1.4 Alkaline phosphate*
