Abstract: Objective　 To evaluate the effect of full-mouth tooth extraction on the oral microflora, and to find the reason and analyze the impact of implants. Method: 75 patients who were treated in Department of Stomatology in our hospital from March 2013 to February 2016 were included in this study. All patients, who had 4 teeth left (each had over-5mm periodontal pocket), with moderate to advanced periodontitis and scheduled for full-mouth tooth extraction, were consecutively selected. 4 weeks and 3 months before and after full-mouth tooth extraction, oral microfloras were collected. At different times, saliva was collected for 2ml; tongue, buccal mucosa and alveolar ridge crest samples were obtained. Aerobic and anaerobic culture techniques were employed for the detection and classification of oral pathogens. Result: No differences were observed in total aerobic and anaerobic bacterial load of the tongue, mucosa and saliva samples during different time points. Before tooth extraction, the number of anaerobe was more than aerobe in periodontal pockets, while after tooth extraction anaerobe obviously decreased (P<0.05) and gram negative bacillus remained constant (P>0.05) on the alveolar ridge. Compared with that in non-smoking ones, the number of gram negative bacillus in smoking patients obviously reduced (P<0.05). Conclusion: After full-mouth tooth extraction, anaerobic species of alveolar ridge crest have reduced, which reduces the risk of peri-implantitis.

Key words: Full-Mouth Tooth Extraction, Edentulous, Bacteria, Periodontitis, Peri-implantitis