Periodontitis and rheumatoid arthritis (RA) are chronic destructive inflammatory diseases with significant worldwide prevalence. They are characterized by inflammatory lesions adjacent to bone destruction involving connective tissue and bone. Dickkopf-1 (DKK-1) is a major regulator of bone mass; however, their involvement in local bone resorption is largely unknown. The aim of this study was to assess the utility of DKK-1 levels in gingival crevicular fluid (GCF) and serum as a potential predictor of bone loss in periodontal disease and/or