*3.2.7 Telopeptide (ICTP)*

A 2015 study found that the concentrations of ICTP were higher in the group with periodontitis and lower in the group with healthy patients; this study suggests that the level of ICTP in saliva increases as the patient presents with gingivitis and periodontitis, since the periodontitis samples had the maximum concentration of salivary ICTP. The authors suggest that more studies with a larger sample size be conducted to establish a correlation between the concentrations of ICTP and the individual clinical parameters [72].

### **3.3 Biomarkers determined in crevicular fluid**

In the oral cavity, we find three fluids: the gingival crevicular fluid, the serum, and the total saliva. The gingival crevicular fluid is an exudate, and at present the quantification of its constituents is a current method to identify specific biomarkers with a reasonable sensitivity [73].

The gingival crevicular fluid is an exudate secreted by the gums that can be found in the crevices located at the point where the gumline meets the teeth. The concentrations of this fluid are usually low but may increase when an inflammatory process occurs in the oral cavity [74].

It is considered that due to the noninvasive and simple nature of its collection, the analysis crevicular fluid can be beneficial in determining the periodontal status [75].

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

Regarding the cytokines that have been evaluated, we can say that they are very similar to those that were evaluated in the saliva; besides that the results are also similar since it has been found that IL-β is the most important cytokine since diverse studies confirm high levels in periodontal disease compared to healthy [48, 76, 77].

In the same way it happens with IL-2 and IL-6, where several studies conclude that both interleukins are important as biomarkers to identify patients with periodontal disease [48, 76, 78].

**27**

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

*3.3.2 Metalloproteinases*

disease [77].

*3.3.4 miRNAs*

*3.3.5 Oxidative stress*

*3.3.6 Telopeptide*

*3.3.3 Alkaline phosphatase*

when mediated in crevicular fluid [80].

between the healthy group and patients with periodontitis.

the periodontal disease can be revealed [82].

*3.3.7 Other markers of periodontal disease*

marker of bone turnover in patients with periodontitis.

crevicular fluid than healthy subjects (p < 0.001) [54].

where both biomarkers were elevated in sick patients [48].

Regarding MCP-1, the levels of this biomarker were significantly higher in

Regarding IFN-γ and TNF-α, both biomarkers were significantly higher in patients with aggressive periodontitis; this correlates with the findings in saliva

With respect to metalloproteinases, studies of biomarkers in crevicular fluid have shown that MMP-7 could be useful as a potential new biomarker for periodontitis [79]. Similar to that determined in saliva, MMP-8 is increased in patients with periodontitis and provides a good sensitive measure to establish differences between patients and healthy individuals [77]. It is also useful as a complemen-

that has proved useful is MMP-9. This metalloproteinase correlates with clinical measures and results in good sensitivity to predict the progression of periodontal

A study was conducted to determine the usefulness of alkaline phosphatase as a biomarker, and this study showed a correlation with the clinical characteristics

According to Mico et al. [81], epigenetic regulation by miRNAs has not yet been studied in periodontal disease using crevicular fluid. They analyzed the possible use as biomarkers of six miRNAs: miR-671, miR-122, miR-1306, miR-27a, miR-223, and miR-1226. Of the six miRNAs analyzed, only miR-1226 can be used as a promising biomarker for periodontal disease since it had statistically significant differences

As previously mentioned, 8-OhdG is a marker of DNA damage and is considered a biomarker to detect oxidative stress [24], that is why it is not surprising that its usefulness as a biomarker of periodontitis was explored. This study was conducted in crevicular fluid, and it could be determined that evaluating this biomarker in crevicular fluid is more effective than in saliva and that it can be useful as a biomarker for determining periodontitis since according to the authors, the severity of

Telopeptide has also been evaluated as a biomarker in periodontitis in the study

Chondroitin sulfate is a biomarker that, due to its results in patients with chronic periodontitis, suggests that it is important in the diagnosis to evaluate the severity

by Aruna [83], which suggests that this biomarker could be useful as a specific

tary tool in the periodontal diagnosis [67]. Another metalloproteinase

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

Regarding MCP-1, the levels of this biomarker were significantly higher in crevicular fluid than healthy subjects (p < 0.001) [54].

Regarding IFN-γ and TNF-α, both biomarkers were significantly higher in patients with aggressive periodontitis; this correlates with the findings in saliva where both biomarkers were elevated in sick patients [48].
