Periodontitis; is an inflammatory disease of tissues characterized by bone destruction around the teeth. Vitamin D plays an important role in several inflammatory diseases by promoting the expression of inflammatory cytokines such as interleukin IL-1, IL-6, and IL-1β, which are directly related to periodontal attachment loss and bone demineralization. These facts suggest that vitamin D may be associated with periodontal disease. Many studies have been conducted on the relationships between serum 25-hydroxyvitamin D (25(OH)D) levels, periodontal disease, and tooth loss. However, as far as we know, there is no study on the relationship between periodontitis and free and bioavailable 25 (OH) vitamin D. In our study, over the age of 35; two groups will be formed, consisting of 40 healthy and 40 periodontitis individuals. Serum total 25 (OH) D level and vitamin D binding protein level will be analyzed by ELISA method, and bioavailable 25 (OH) D level will be calculated using total 25 (OH) D and vitamin D binding protein levels. The aim of this study; To evaluate the total, free and bioavailable 25 (OH) vitamin D levels of patients with periodontitis by comparing them with healthy controls, and to investigate whether bioavailable 25 (OH) D plays a role in the pathogenesis of periodontitis or can be a simple marker of disease activity in the light of these findings.

Inclusion Criteria:

• Without systemic disease,
• Had a least 14 teeth

Exclusion Criteria:

• Individuals with a history of systemic or topical oral antimicrobial therapy use in the last 3 months,
• Individuals with an allergy to any ingredient used in the study,
• Smokers,
• Pregnant or breastfeeding women,
• Using vitamin D,
• Individuals diagnosed with obesity

Forty patients with stage 3 periodontitis and 40 healthy volunteers were included in this case-control study at Atatürk University, Department of Dentistry, Department of Periodontology.