When natural teeth and implants coexists in the same oral cavity,it is thought that peri-implantitis may occur owing to periopathic bacterial transmission from periodontal pockets of natural teeth to peri-implant sulci.
In this study,we assessed the validity of bacteriological examination to evaluate implants in a maintenance period. We collected subgingival plaque from 108 implants and 39 natural teeth of partially edentulous patients searched from the detection rate of representative 6 periopathic bacteria by means of PCR, and performed quantitative analysis of Porphyromonas gingivalis, which was isolated from subgingival plaque by means of Real-Time PCR.
In addition, we investigated the possibility of bacteria transmission from natural teeth to implants in the same oral cavities, by arbitrarily primed PCR (AP-PCR). As for clinical parameters, probing depth (PD) and bleeding on probing (BOP) were detected in all teeth tested. The validity of all results of bacterial examination was determined by comparison with clinical parameters.
The results from the direct detection of 6 periopathic bacteria by the PCR method in the subgingival plaque of peri-implant sulci and natural tooth pockets, revealed that both groups had the same bacterial pattern, especially for Bacteroides foysythus and P. gingivalis, showing high frequencies.
The mean numbers of 6 periopathic bacteria in pockets deeper than 3 mm, for both groups, were significantly higher than those in shallower pockets.
The investigation of P. gingivalis transmission from natural teeth to implants by the AP-PCR method was not informative because of the low sensitivity of cultivation. On the other hand, quantitative analysis by Real-Time PCR method showed a high positive correlation in the number of P. gingivalis between natural teeth and implants in the same oral cavities.
Moreover, a tendency was shown:the incidence of P. gingivalis in the subgingival plaque of implants was higher than that of natural teeth. However, a difference in the mean number of P. gingivalis between over and under 3 mm pockets, in both groups, was not shown. The mean numbers of P. gingivalis and 6 periopathic bacteria showed significantly high positive correlation in the same oral cavities.
These results indicated that the bacterial examination using PCR and quantitative PCR method is useful for evaluating dental implant in a maintenance period.
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