Evaluation of Salivary and Serum Levels of TNF-α, IL-17A, and YKL-40 in Individuals With Psoriasis

Unstimulated whole saliva samples will be collected in the morning, at least one day after periodontal examination. Participants will be instructed to refrain from eating, drinking, brushing, or chewing gum for at least one hour before collection. The samples will be centrifuged at 1500 rpm for 10 minutes, and the supernatants will be stored at -80°C until analysis. TNF-α levels will be measured using ELISA.

Unstimulated whole saliva samples will be collected in the morning, at least one day after periodontal examination. Participants will be asked to avoid eating, drinking, brushing their teeth, or chewing gum for at least one hour prior to sampling. The samples will be centrifuged at 1500 rpm for 10 minutes, and the supernatants will be stored at -80°C until analysis. IL-17A levels will be determined using ELISA.

Unstimulated whole saliva samples will be obtained from participants in the morning, at least one day after the periodontal clinical assessment. They will be instructed not to eat, drink, chew gum, or brush their teeth for at least one hour before collection. Samples will be centrifuged at 1500 rpm for 10 minutes, and the clear supernatants will be stored at -80°C until the time of analysis. YKL-40 levels will be measured using ELISA.

A total of 8 mL of venous blood will be collected from the antecubital fossa of seated participants. Samples will be transferred into BD Vacutainer® SST™ II Advance serum separator tubes containing acrylic gel and will be allowed to clot for 30 minutes at room temperature. The samples will then be centrifuged at 1500 rpm for 10 minutes at 18-25°C. The resulting serum will be transferred into Eppendorf tubes using a Pasteur pipette and will be stored at -80°C until analysis. TNF-α levels will be measured using ELISA.

A total of 8 mL of venous blood will be obtained from the antecubital fossa of participants in a seated position. After collection, the blood will be placed into BD Vacutainer® SST™ II Advance tubes with acrylic gel and will rest for 30 minutes to allow clotting. The samples will be centrifuged at 1500 rpm for 10 minutes at 18-25°C. The serum will be extracted using a Pasteur pipette and stored in Eppendorf tubes at -80°C until analysis. IL-17A levels will be analyzed using ELISA.

Venous blood (8 mL) will be drawn from the antecubital fossa of seated participants. The samples will be placed in BD Vacutainer® SST™ II Advance tubes containing acrylic gel and will be left to clot for 30 minutes at room temperature. Following this, the samples will be centrifuged at 1500 rpm for 10 minutes at 18-25°C. The supernatant serum will be separated with a Pasteur pipette and transferred into Eppendorf tubes. All samples will be stored at -80°C until analysis. YKL-40 levels will be measured using ELISA.

Clinical periodontal parameters will be recorded from participants who meet the inclusion criteria. The following indices will be measured from all teeth present in the oral cavity: Plaque Index (PI; Silness \& Löe, 1964), Probing Pocket Depth (PPD), Clinical Attachment Level (CAL), and Bleeding on Probing (BOP). Radiographic evaluations will also be performed. All measurements will be conducted by the same calibrated clinician (HD) using a Williams periodontal probe (Hu-Friedy, Chicago, IL, USA).