The Effectiveness of Vitamin D Supplementation in Association with Non-Surgical Periodontal Therapy: A Systematic Review

Background: Vitamin D has been increasingly investigated for its pleiotropic immunomodulatory and antimicrobial effects, which may influence periodontal inflammation and healing. This systematic review aimed to evaluate the impact of serum vitamin D levels and vitamin D supplementation as an adjunct to non-surgical periodontal therapy (NSPT) on clinical and microbiological outcomes in patients with periodontitis. Methods: An electronic search was conducted in MEDLINE and other major databases up to September 2025. Randomized controlled trials assessing the relationship between vitamin D status or supplementation and periodontal outcomes following NSPT were included. Data were synthesized qualitatively, focusing on changes in serum 25(OH)D levels and periodontal parameters, including probing pocket depth (PPD), clinical attachment level (CAL), plaque index (PI), and gingival inflammation. Results: Four studies met the inclusion criteria. In patients with sufficient baseline vitamin D levels, supplementation provided limited additional clinical benefits beyond NSPT alone. Conversely, in vitamin D-deficient patients, supplementation regimens capable of restoring serum 25(OH)D levels above 30 ng/mL were consistently associated with greater reductions in PPD, improved CAL, and decreased plaque and bleeding indices. Microbiological analyses also revealed a reduction in red complex periodontal pathogens in supplemented groups. Conclusions: Vitamin D supplementation enhances the clinical effectiveness of NSPT primarily in patients with documented vitamin D deficiency. Its adjunctive benefits appear to be mediated by immunomodulatory and antimicrobial mechanisms that complement mechanical debridement. While current evidence supports targeted supplementation in deficient individuals, long-term randomized trials are required to establish standardized protocols and confirm sustained clinical benefits.