Periodontal diseases are among the major causes of tooth loss. Smoking may play a role as a contributing factor in the development of periodontitis by reducing the immune response. The role of cytokines in the pathogenesis of periodontal disease is clearly indicated in the literature; it has been shown that microorganisms that cause periodontal disease cause cytokine increase in saliva, gingival tissue and gingival crevicular fluid. Among these cytokines, interleukin (IL) -17 is proinflammatory and IL-35 is antiinflammatory and has been associated with periodontal disease.

Periodontal diseases are among the complex inflammatory diseases that are considered among the leading causes of tooth loss, mostly observed with multiple etiological factors. The complexity of periodontal disease is due to the presence of the biofilm and the accompanying host response together.

Smoking, which is considered as one of the risk factors in terms of periodontitis, is one of the most preventable risk factors that affect the periodonium with many different mechanisms. Smoking plays a role in the etiopathogenesis of periodontitis, with its physiological changes in gingival tissue and its effects on host response and is considered to be an established risk factor. Although the effects of smoking on host response and its role in increasing the risk of periodontal disease are still being investigated, its effects on natural and acquired immune response cells have been studied separately. Consequently, components of cigarette suppress the immune system's defense responses; however, it has been reported to exacerbate pathological reactions.

The process of progression from periodontal health to periodontitis is formed by biofilm pathogens and host immune responses activated by these microorganisms. Intercellular communication is crucial during the progression of chronic inflammatory diseases, such as periodontitis. Cytokines, one of these ways of communication, are soluble proteins produced by various types of cells, such as structural and inflammatory cells, responsible for maintaining a complex network of communication between homotypic and heterotypic cell groups.

Interleukin-17 (IL-17) is a pro-inflammatory cytokine mostly stimulated from Th17 cells, stimulating inflammatory processes with many different mechanisms.

IL-35 inhibits the differentiation of Th17 cells and suppresses IL-17 production and therefore plays a protective role in Th17-related diseases.

There are many studies evaluating the effect of non-surgical periodontal treatment on individuals with smokers with periodontitis. However, the obtained results do not allow a clear data to be revealed. To exemplify, when the studies which investigates the evaluation of non-surgical periodontal treatment on IL-17 levels were evaluated, contradictory results were determined. In addition, as a result of our research, no studies evaluating the effects of non-surgical periodontal treatment on IL-35 levels in smokers with periodontitis have not been found.

Inclusion Criteria:

• To be volunteer to participate in the study
• To be over 18
• Being systemically healthy
• Having greater than or equal to 15 teeth out of 3rd molar teeth
• To have localized or generalized periodontitis for the experimental group (clinical attachment loss in at least 6 surrounding areas and presence of greater than or equal to 5 mm periodontal pocket)
• For Smoking group; more than 10 cigarettes a day for more than 5 years
• For non-smokers; have not smoked for at least 3 years.

Exclusion Criteria:

• Have any systemic disease affecting periodontal condition
• To receive periodontal treatment in the last 6 months
• Use any medication that may affect the inflammatory process in the last 3 months
• Use local or systemic antibiotics in the last 3 months
• Pregnancy or lactation for female patients
• Regular use of mouthwash