Research On Subgingival Flora Of Peri-implantitis

[Purpose] This experiment was to study the subgingival microflora in peri-implantitis and to compare differences in marginal bone resorption and composition of subgingival flora between immediate and delayed implant in Beagle dog model.[Methods] In this study, four inbred Beagle dogs were chose to be the experimental animal. After the forth premolars were extracted from both side of Beagle dogs' mandibular, Bego implants were placed into the tooth socket using both immediate and delayed implant methods separately. The animal models were built by this way. The peri-implantitis were induced by silk ligature in all the right side implants. In the process, implant clinical parameters were detected and analyzed. Then the subgingival bacteria around the normal and inflammatory implants were cultured respectively, CFU (Colony-forming unit) count was used to analysis the composition of subgingival microflora. The PCR (Polymerase Chain Reaction) technology was used to identify the target bacteria.[Result] In the experiment, the animal model was successful established, and we found that:whether immediate implant or delayed implant, the dental implants in the mandible of Beagle dogs are firmly stable and formed an effective osseointergration. The soft tissue inflammation and bone absorption all around the implants is obvious after the induction of peri-implantitis. There are no statistically significant differences in bone resorption and other clinical parameters between immediate implant and delayed implant. When peri-implantitis happened G- anaerobic black-pigment bacteria and G- anaerobic bacillus increased, G+ facultative cocci and G+ facultative streptococcus reduced (P≤0.05), facultative staphylococci, actinomyces, G-anaerobic cocci and G+ anaerobic bacillus are essentially the same (P≤0.05). The colonial morphology will performed different when the subgingival bacteria cultured in separate or mixed. Whether immediate or delayed implant, there are no significant differences in the composition of subgingival microflora.[Conclusions] Regardless of immediate implant or delayed implant, there is little difference in the clinical parameters or the composition of the subgingival microflora. We can not yet conclude which implant method is better, in clinic, doctors should choose implant methods according to the clinical situation and strictly control the indications. By inference, some oral streptococci and facultative G+ cocci are the main colonization bacteria all around the healthy implant subginginval flora and some anaerobic black-pigment bacteria, anaerobic G" bacillus may be the pathogens in subgingival microenvironment. Compared with the implants in peri-implantitis, there are more types of bacteria around the healthy implant, each bacterium in the composition of the flora is relatively balanced, but when peri-implantitis happened, the kinds of subginginval flora reduced and there are several bacteria have significant increase in the composition of the flora. As a whole system, in the subgingival microflora, each colony has its own special features and there is interdependence or mutual competition between the various colonies. If the interaction between a varieties of subgingival bacteria could be clear, doctors could use the beneficial subgingival bacteria attract the harmful bacteria, then the inflammation subgingival flora would reversed to the healthy state, a new method to cure peri-implantitis will be started.