ABSTRACT
@#Periodontitis is a chronic inflammatory disease that is initiated by bacteria. Pathogens and their virulence factors alter normal cellular metabolic activity and deteriorate periodontal microconditions. Owing to the complexity of tooth structure and the limitation of conventional treatment, we may not live up to all patients’ expectations, especially those with grade C and stage Ⅲ or Ⅳ periodontitis. With the advantages of bactericidal effects, high safety, inhibition of bacterial drug resistance and promotion of tissue healing, photodynamic therapy （PDT） seems to be an ideal technology in periodontal treatment. However, it cannot remove subgingival stones and still cannot replace mechanical treatment to preliminarily control periodontal inflammation. Therefore, near-infrared low-energy light combined with traditional photosensitizers is mostly used in clinical periodontal adjuvant treatment. In periodontal maintenance treatment on a regular basis, a single application can also reduce the sensitivity of patients and effectively control plaque, but its effect will be affected by the degree of periodontal inflammation, the concentration and type of photosensitizer, the energy of the light source, etc. With the further development of material science, the performance of photosensitizers to accelerate oxides and target bacteria will be optimized. In the future, parameters of PDT need to be designed in large-scale studies in accord with different stages and grades of periodontitis.