A method for treating a sinus cavity is provided. The method includes the steps of inserting a plasma applicator into a sinus cavity defined in a bone mass, positioning the plasma applicator adjacent a tissue formation, generating a selectively reactive plasma effluent at the plasma applicator and directing the selectively reactive plasma effluent at the tissue formation. The selective nature of the reactive plasma enables treatment of specific targets inside the sinus while minimizing the effect on other tissues. Such treatment includes, but not limited to, sterilization of bacterial colonies, vaporization of unwanted tissues or foreign masses, stimulation of tissues by enriching the content of reactive oxygen and nitrous oxide pathways, and combinations thereof.