Opportunistic pathogens (E. faecalis and P. aeruginosa) at internal and external implant portions in peri-implant disease: a cross-sectional study

Background: Studies regarding peri-implantitis have been so far focused on decontamination procedures, without considering that implant-abutment junction faces the same bacterial challenges. As a matter of fact, microorganisms of partially edentulous patients can be transferred to the peri-implant sulcus and therefore increase the risk of disease. Opportunistic pathogens resistant even in extreme hostile conditions such as P. aeruginosa and E. faecalis, found in different sites of the oral cavity and in root canal following treatment failure, could have the ability to colonize the internal implant portions, a fact still not demonstrated in vivo. Aim/Hypothesis: To verify whether different dental implant parts can be contaminated by opportunistic pathogens in a periimplant patient population. Material and methods: A cross-sectional study was performed following the principles outlined in the Declaration of Helsinki of patients previously treated with dental implants. Patients were recruited between September 2012 and July 2013 at the University of Valencia (Spain). Samples for microbiological analysis were obtained from 3 types of sites in the following order: (1) the peri-implant sulcus (PIS) of each implant, (2) the gingival sulcus (GS) of the neighboring teeth (3) and the connection’s inner portion and the abutment surface of each implant. Prior to subgingival plaque sampling, supragingival plaque was eliminated from implants and teeth using a curette or cotton roll, without penetrating the gingival sulcus. Cotton rolls were used for relative isolation and the sampling sites were dried with an air pistol. The paper tips were inserted in the peri-implant or periodontal sulci for 30 seconds. To obtain samples from the inner part of the connections, prostheses and abutments were carefully removed, trying to avoid contamination. Oral, tongue and pharynx swabs were also collected. Quantitative real-time PCR was carried out for total bacterial counts of Enterococcus faecalis and Pseudomonas aeruginosa. Statistical analyses (2-way ANOVA with the General Linear Model) was used to detect any difference between groups. Results: One hundred and eighty sites were investigated. Fifty-two implants in 38 patients showed signs of peri-implant disease. No bacteria was found in the gingival sulci of neighboring teeth group (38 sites). E. faecalis was detected in the peri-implant sulcular fluid (3 of 52 sites; 1.77 9 105 cells) and (3 of 52 sites; 3.87 9 104 cells). On the other hand, P. aeruginosa counts were identified only on swabs (1 of 38 sites) and represent the highest bacterial numbers (3.5 9 106 cells). Statistical analyses (2-way ANOVA with the General Linear Model) demonstrated no significant difference for location, species, and the interaction between location 9 species (P > 0.05). Conclusion and clinical implications: It has been demonstrated in this study that antibiotic-resistant nosocomial bacteria can contaminate the inner parts of implants connection. This conclusion should lead to further studies investigating not only the extraand intra-oral cleaning procedures but also prosthesis removal and peri-implant sulcus decontamination at each follow-up especially in patients prone to peri-implantitis.