Background. Vitamin D has both direct effects on bone metabolism and an antimicrobial effect on periodontopathogens. It also inhibits inflammatory mediators that contribute to periodontal destruction. The purpose of this study was to evaluate the association between serum 1.25-hydroxyvitamin D (1.25(OH)2D3) and 25(OH)D levels and periodontal inflammation.

Methods. This study included 28 subjects with chronic gingivitis, 29 subjects with chronic periodontitis and 25 periodontally healthy subjects. Blood samples were collected from the participants to determine serum levels of 25(OH)D, 1.25(OH)2D3, tumour necrosis factor α (TNF-α), C-reactive protein (CRP) and interleukin 6 (IL-6). Clinical parameters were recorded. Results were statistically analysed with a Shapiro-Wilk's test, Mann-Whitney U test, Kruskal-Wallis H test, Wilcoxon test and post-hoc multiple comparison test.

The subjects included in the study were selected from among patients who applied to our clinic, for routine periodontal examinations. Individuals who had been using immunosuppressive drugs and antibiotics for the past three months, smokers, individuals who had periodontal treatment within the past six months, and individuals with additional or supplementary vitamin D and systemic diseases were excluded from the study. In addition, since the region's level of sunlight exposure may have an effect on the level of vitamin D, participants were required to live in the region for the last five years.

A total of 82 subjects, including 25 as a periodontally healthy control group, 28 with chronic gingivitis and 29 with chronic periodontitis, were included in the study. Clinical criteria for chronic periodontitis are the formation of plaque and calculus and ≥ 5 milimeter (mm) pocket depth or attachment loss in more than 30% of the teeth. Diagnosis criteria for chronic gingivitis are the formation of plaque and/or calculus in the mouth, bleeding, and no loss of pocket or attachment. The diagnosis criteria for periodontally healthy individuals are having clinically healthy periodontal tissues or minimal periodontal inflammation, with no loss of pocket or attachment.

Inclusion Criteria:

• live in the region for the last five years.

Exclusion Criteria:

• individuals who had been using immunosuppressive drugs and antibiotics for the past three months, smokers, individuals who had periodontal treatment within the past six months, and individuals with additional or supplementary vitamin D and systemic diseases.

live in the region for the last five years.