We read the article by Zhang et al describing the authors’ efforts to treat patients with periodontitis. The authors concluded that combined orthodontic-periodontic treatment has a favorable effect on periodontitis and could also decrease the levels of inflammatory cytokines.

We were very interested in the study, since more and more patients with periodontitis seek orthodontic treatment to improve their esthetics and health. As we know, periodontitis etiology includes abnormality of the immune reaction. Some patients are more vulnerable to dental plaque bacteria, which might be related to their immune system. Had the subjects been evaluated for their initial levels of inflammatory cytokines? Was the severity of periodontitis considered?

Limited orthodontics was reported to be effective in the correction of infrabony defects caused by periodontitis. Did the subjects have the infrabony defects evaluated before combined orthodontic-periodontic treatment? If so, what kinds of infrabony defects were recovered most effectively? Did the bone graft have some favorable effect?

In the second paragraph of “Materials and methods,” the article said that “The combined treatment group included all patients with pathologic tooth migration” and “The basic treatment group contained all patients without pathologic tooth migration.” However, how could this be, since “These 117 patients were randomly assigned”? We appreciate the authors’ efforts to share the experience with the readers.