Abstract: Objective This study aimed to explore the period of endodontic treatment and the effects of periodontal-endodontic treatment for advanced periodontitis. Methods A total of 180 patients with advanced periodontitis participated in this clinical multicenter study. The respondents were randomly divided into an endodontic combined treatment (experimental) group and a periodontal treatment alone (control) group; each group consisted of 90 teeth. The control group received periodontal therapy only. The experimental group received periodontal therapy and root-canal treatment, and then pulp status was recorded. The cases were followed up at 1, 3, 6, and 12 months after treatment. Results Out of 90 teeth in the test group, 22 teeth had completely necrotic pulps, 45 teeth had partial necrosis (coronal pulp necrosis or root pulp necrosis), and 23 had vital pulp. Differences between clinical parameters in the control and experimental groups were not significant (P>0.05) before treatment but were significant after three months (P<0.05). Conclusion Pulp treatment for teeth with advanced periodontitis and dull pulp vitality can control the development of inflammation and thus benefit the healing of periodontal tissue.

Key words: advanced periodontitis, combined treatment of periodontal-endodontic, pulp vitality, root canal treatment