Serum level of vitamin D in patients with recurrent aphthous stomatitis: A systematic review and meta-analysis of case control studies.

Objectives: Recurrent aphthous stomatitis (RAS) is an ulcerative condition with unknown etiology. The effect of vitamin D in the etiology of RAS is still a matter of controversy. In this study, we aimed at review the available evidence on the role of vitamin D deficiency in RAS etiology.