Impact of Nonsurgical Periodontal Therapy on Cathepsin‐K in Saliva and Gingival Crevicular Fluid

ABSTRACT Objective The aim of this study was to investigate the association between Cathepsin K (CatK) levels in gingival crevicular fluid (GCF) and saliva with periodontal health and disease, and to evaluate the effects of non‐surgical periodontal therapy (NSPT) on these biomarkers. Methods GCF and saliva samples were collected from periodontally healthy individuals ( n = 33) and patients diagnosed with periodontitis ( n = 33). The periodontitis group underwent NSPT, and follow‐up samples were collected from the same individuals one month after treatment. CatK concentrations in both GCF and saliva were measured using ELISA. Results At baseline, CatK levels in both GCF and saliva were significantly higher in periodontitis patients than in periodontally healthy controls ( p < 0.001). NSPT resulted in significant reductions in CatK levels in both GCF and saliva ( p < 0.001). Salivary CatK decreased to values comparable to healthy subjects, whereas GCF CatK, although reduced, remained higher than healthy levels. A strong positive correlation between salivary and GCF CatK observed before treatment ( r = 0.88, p < 0.001) disappeared after NSPT. Multiple regression identified cohort and gingival index as the strongest independent predictors of CatK concentrations. Conclusion CatK levels in both GCF and saliva were associated with periodontal status and responded significantly to NSPT. These findings suggest that CatK may have potential as an adjunctive biomarker for monitoring short‐term biochemical changes following NSPT.