http://www.joponline.org/doi/pdf/10.1902/jop.2010.100508
Neutrophils and other phagocytic cells kill bacteria using a process called respiratory burst where the immune cell produces superoxide and hydrogen peroxide. These chemicals effectively kill bacteria as well as healthy cells and extracellular connective tissue (both mineralized and unmineralized).
The investigators of this study theorize that refractory periodontitis patients may have a unique neutrophil phenotype. If so, then it might be possible to test patients at time of diagnosis of periodontal disease and predict a subgroup that will require more aggressive treatment and long term supportive management.