Perić M, et al. - Researchers evaluated the relationship between serum vitamin D levels and periodontal disease. In total, they identified 365 studies and analyzed 24 studies. The inclusion criteria were fulfilled by 7 studies. Findings suggested the scarcity of the literature on the effect of serum vitamin D levels on periodontal status and the literature was controversial. Nonetheless, a “perio-protective” role for vitamin D was supported by some data.