Effect of Photodynamic Therapy on Soft Tissue Healing After Tooth Extraction at Sites of Periodontal Infection

Inclusion Criteria: * Age range from 18 to 65 years old; * Patients with extensive periodontitis of the whole mouth; * There was a deep periodontal pocket with PD≥5mm and at least one adjacent tooth at the extraction site; * Periodontitis was controlled, and the extraction site and adjacent teeth were not in the acute inflammation or infection stage; * The extraction site has a hopeless prognosis or no preservation value, and it is the first and second molars or maxillary wisdom teeth that erupt in a positive position Exclusion Criteria: * pregnant and lactating women; * patients with systemic diseases that may affect the ability of postoperative healing (such as patients with radiotherapy and chemotherapy, history of hematological diseases, and uncontrolled disease) Diabetes mellitus, etc.); * long-term use of drugs known to affect bone metabolism or mucosal healing such as bisphosphonates and non-steroidal anti-inflammatory drugs; * smoking \> 10 cigarettes per day; * root breakage or gingival tear occurred during tooth extraction.