Microbial changes after full-mouth tooth extraction, followed by 2-stage implant placement

Background Recent studies showed that qPCR could detect bacteria related to periodontitis and peri-implantitis in a low concentration after full-mouth tooth extraction. This study monitored the microbiota from tooth extraction, over 9 months of full edentulism, up to 1 year after abutment connection. Material and methods Ten patients with severe periodontitis were recruited. Six months after tooth extraction, implants were inserted. Three to 6 months later, they were connected to abutments. Plaque samples were collected from the tongue dorsum, saliva, and subgingival area (teeth/implants) before extraction up to 1 year after abutment connection, and analysed via culture, qPCR, and checkerboard technology. Results A reduction in the total amount of aerobic and anaerobic CFU/ml was observed. The concentration of Porphyromonas gingivalis and Tannerella forsythia (qPCR and checkerboard) in the saliva and, to a lower extent, on the tongue dorsum reduced. For Prevotella intermedia, changes were negligible and no changes could be detected for Aggregatibacter actinomycetemcomitans. The pristine subgingival niches were quickly colonized by key pathogens. Their final concentration remained low, while the detection frequencies remained very high over time. Conclusion Complete edentulation results in a significant reduction of bacteria related to periodontitis and peri-implantitis, with the exception of A. actinomycetemcomitans, which might indicate that key pathogens can survive without pockets.