Our experiment also suggested that IL-6 may be the most important factor for the development of chronic periodontitis-induced chemoresistance by showing that the serum level of only IL-6 was significantly impacted by P. gingivalis administration and/or paclitaxel treatment and that ibuprofen reduced paclitaxel resistance and the differences in the serum IL-6 levels among groups. This evidence concerns the gene IL6 and chronic periodontitis.