Abstract: Objective: To evaluate the difference of alveolar bone height and density of patients with periodontitis before and after initial periodontal therapy by cone beam computed tomography, and to analyze the influences of age and severity degree to provide clinical basis for further therapy design. Methods: Fifty patients with chronic periodontitis were recruited including15 with mild periodontitis, 18 with moderate type and 17 with severe type. The alveolar bone height and bone density were measured with Simplant software and analyzed by t-test to compare the difference between baseline and 6 months after treatment. Results: All patients' alveolar bone height and density improved after 6 months therapy. For the patients younger than 50 years old, alveolar bone density in patients with mild, moderate periodontitis 6 months after treatment were significantly higher than that before treatment (P<0.05). Alveolar bone height in severe periodontitis after treatment also improved, but showed no significant difference. However, the efficacy of therapy decreased as age increased, as there was no significant difference between before and after treatment. As to different tooth sites, mesial and distal sites of premolar and molar improved much more than other sites, as demonstrated by changes of both alveolar bone height and density (P<0.05). Conclusion: Initial periodontal therapy can effectively improve the alveolar bone height and density of patients with chronic periodontitis. CBCT and Simplant software can help to evaluate changes of alveolar bone throughout the treatment.

Key words: Periodontal initial therapy, Cone beam computed tomography, Alveolar bone