Objective This study aimed to investigate the correlation between the systemic immune-inflammatory index (SII) and the diagnosis of periodontitis grading. Methods According to the inclusion and exclusion criteria, patients who attended Changsha Stomatological Hospital from January to October 2023 were screened and divided into the perio-dontitis group (131 patients) and the periodontal health group (132 patients). The differences in SII, neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and lymphocyte to monocyte ratio (LMR) were analyzed between the two groups. We used Logistic regression analysis and receiver operating characteristic curve to analyze the factors related to the prevalence and diagnostic value of periodontitis. Spearman correlation analysis was conducted to determine the correlation between blood cell indicators and pe-riodontitis grading. Results SII, NLR, and PLR were significantly higher and LMR was significantly lower in the periodontitis group compared with the periodontal health group (P<0.05). SII, NLR, PLR, and LMR all had a predictive value for periodontitis, with SII having the greatest Youden index and a better value than NLR, PLR, and LMR. Logistic regression analysis showed that SII and NLR were significantly correlated with periodontitis. We observed a significant difference in SII, NLR, PLR, and LMR among the grades in the periodontitis group (P<0.05). Periodontitis grading was positively correlated with SII, NLR, and PLR but negatively correlated with LMR. Conclusion We found a correlation between SII and periodontitis grading, which may be of clinical value in the assessment of disease progression rate.
