The Influences of Periodontal Status and Periodontal Pathogen Quantity on Salivary 8‐Hydroxydeoxyguanosine and Interleukin‐17 Levels

Background: Periodontitis is a biofilm‐initiated disease that is characterized by elevated inflammatory status. 8‐Hydroxydeoxyguanosine (8‐OHdG) and interleukin (IL)‐17 are highly associated with inflammation and bone resorption and therefore are regarded as potential biomarkers for periodontitis. In this study, the associations between salivary 8‐OHdG and IL‐17 levels and clinical and microbial parameters before and after non‐surgical treatment are investigated. Methods: Forty‐five patients with chronic periodontitis (CP) and 47 periodontally healthy volunteers were recruited for the study. Clinical parameters, including the probing depth (PD), clinical attachment level (CAL), sulcular bleeding index, and simplified oral hygiene index (OHI‐S), were examined for each participant. Microbial parameters including the quantities of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola in the subgingival plaque and saliva were determined by real‐time polymerase chain reaction at baseline and 1 and 3 months after the non‐surgical treatment. Salivary 8‐OHdG and IL‐17 levels were detected by enzyme‐linked immunosorbent assays. Results: Compared with healthy volunteers, CP group patients had significantly higher salivary 8‐OHdG and IL‐17 levels at baseline. Baseline salivary 8‐OHdG and IL‐17 levels were positively correlated with all clinical parameters as well as the quantities of T. forsythia and T. denticola. After non‐surgical treatment, baseline levels of salivary 8‐OHdG and IL‐17 were reduced significantly at both the 1‐ and 3‐month follow‐ups. The hierarchical linear model revealed that variations in the PD, CAL, and OHI‐S had significant positive effects on variation in the salivary 8‐OHdG level. However, variations in the PD; quantity of T. forsythia in the subgingival plaque; and quantities of P. gingivalis, T. forsythia, and T. denticola in saliva were associated significantly with variation in the salivary IL‐17 levels. Conclusions: There was a strong association between salivary 8‐OHdG and IL‐17 levels and periodontitis. Variation in the salivary 8‐OHdG level was correlated with variations in the clinical parameters, whereas variation in the IL‐17 level was correlated with variation in the microbial parameters.