Inclusion and exclusion criteria
PD, bleeding
PERIODONTITIS, BLEEDING, SYSTEMIC DISEASE
Inclusion criteria: (a) Type of studies: human experimental studies (randomized controlled trial (RCT)/non-RCT/observational studies). (b) Subjects: individuals with periodontitis. (c) Intervention or exposure factors: SRP or SRP + vitamin D. (d) Outcome measures: periodontal clinical parameters, including probing depth (PD), clinical attachment level (CAL), gingival index (GI), and bleeding index (BI); vitamin D indicators, including serum/saliva vitamin D levels or serum/saliva levels of 25(OH)D.Exclusion criteria: (a) Animal studies or vitro studies. (b) Review or Meta-analysis. (c) Case reports or conference papers. (d) Duplicate publication. (e) Combined with other systemic diseases. (f) Pregnant and lactating women. (g) Qualitative research. (h) Incomplete data and the original articles could not be found.