Microbial diversity of peri-implant biofilms on implant fixed bar and telescopic double crown attachments.

One of the principal problems in oral implantation is inflammation of peri-implant hard and soft tissues caused by bacterial biofilms. The purpose of the present study was to evaluate the microbial diversity of peri-implant biofilms on 2 different implant-anchored attachment types in vivo. Samples of peri-implant sulcus fluid were collected from 8 patients with implant-supported bar attachments and 8 patients with implant-anchored telescopic double crown attachments. Samples of sulcus fluid of the adjacent teeth were also collected from the partially edentulous patients with implant fixed telescopic double crowns. The mixed amplicons of 16S rRNA fragments of different bacterial origins were separated by use of single-strand conformation polymorphism analysis to identify the predominant bacterial genera. With 3.5 ± 2.1 different predominant bacterial genera in the sulcus fluid surrounding implant-supported bar attachments and 6.3 ± 3.1 different predominant genera in the sulcular fluid of implant-anchored double crown attachments, the differences were not statistically significant (P = .11). The microbial diversity in the sulcus fluid surrounding the remaining dentition was similar to that of the implant fixed telescopic attachments (6.3 ± 2.1). Aside from host response and other individual factors, the microbial diversity of peri-implant biofilms seems to be impaired by cofactors such as the possibility of cleaning the implant-supported supraconstructions and the different plaque-retaining sites. Nevertheless, these differences do not lead to statistically significant differences in the microbial diversity of peri-implant plaques.

Metagenomic analysis of the peri-implant and periodontal microflora in patients with clinical signs of gingivitis or mucositis.

The long-term success of osseointegrated oral implants is endangered by inflammation of peri-implant hard and soft tissues caused by bacterial biofilms that may have been initiated by bacterial transmission from the adjacent dentition. The present study aimed to compare the bacterial communities at inflamed implant and tooth sites by broad-range PCR techniques to evaluate the etiological processes of peri-implant and periodontal diseases and potential future therapeutic strategies. Eighteen samples of peri-implant and periodontal microflora were collected from nine partially edentulous patients with implant-retained crowns or bridges revealing clinical signs of gingivitis or mucositis. The clinical parameters plaque index (PI), probing depth (PD), and bleeding on probing were recorded. Amplified fragments of bacterial 16S rRNA genes were separated by use of single-strand conformation polymorphism analysis, and sequences were determined to identify the predominant bacterial genera. The clinical parameters PI and PD were significantly different at implants (PI = 0.4 ± 0.7, PD = 3.1 ± 0.6 mm) compared with teeth (PI = 1.8 ± 0.8, PD = 2.5 ± 0.2 mm). A total of 20 different genera were found at the inflamed tooth and implant sites. The microbial diversity of the microflora surrounding the remaining dentition (12.0 ± 3.8) was significantly higher (p = 0.01) than the diversity of the peri-implant microflora at implant-retained crowns or bridges (6.3 ± 2.3). Within the limitations of the present study, the microbial diversity of the investigated implants and teeth with clinical signs of mucositis or gingivitis exhibits substantial differences, demonstrating that transmission of the complete bacterial microflora from teeth to implants could be excluded. Furthermore, broad-range molecular biological detection methods specify bacterial genera and species in the peri-implant and periodontal microflora which were not in the focus of research interests so far.