['Vitamin D is associated with a number of inflammatory diseases and plays a significant role in regulating bone metabolism. Serum calcifediol was demonstrated to be potentially associated with periodontal disease. The purpose of this study was to evaluate whether an association exists between plasma calcifediol concentrations and aggressive periodontitis (AgP) and whether plasma levels of bone-related biomarkers (osteocalcin, alkaline phosphatase, calcium, and phosphorus) regulated by vitamin D are related to AgP.', 'Sixty-six patients with generalized AgP, 52 patients with chronic periodontitis, and 60 healthy controls were included in this study. Periodontal examination consisted of probing depth, attachment loss, and bleeding index measurements. Hematic calcifediol and bone-related biomarker levels were detected using radioimmunity assay kits or a biochemical analyzer.', 'Plasma calcifediol levels in patients with AgP were higher than those of healthy controls (29.28 versus 21.60 nmol/l; P <0.05) and were statistically significantly correlated with bleeding index (r = 0.321; P <0.05). Plasma osteocalcin concentrations in patients with AgP were higher than those of healthy controls (0.90 versus 0.70 ng/ml; P <0.05). Serum inorganic phosphorus values of both periodontitis groups were lower than those of healthy controls (1.06 +/- 0.18 mmol/l and 1.10 +/- 0.15 mmol/l versus 1.26 +/- 0.17 mmol/l; P <0.05).'] Is elevated plasma calcifediol associated with aggressive periodontitis?