microbiological testing in peri-implant diseases - a comparison between PCR and Real-time PCR

With the increasing number of dental implants, peri-implant diseases are coming to the fore. By the introduction of commercial microbiological testing in periodontal di-seases the expectation of a diagnostic benefit was present. The aim of this study was to evaluate the presence of periodontopathogens in subgingival peri-implant sites using the conventional polymerase chain reaction (PCR) and the real-time po-lymerase chain reaction (Real-time PCR). The hypothesis should be established that the PCR meets all requirements to get qualitative and quantitative microbiological results in peri-implant diseases for use in diagnostic purposes. In addition, the utilization of microbiological tests should be clarified. The subgingival peri-implant microflora of 45 subjects was classified into three groups (15 subjects each): healthy, mucositis and peri-implantitis. These 45 subjects were determined by the presence of the following five periodontopathogens Aa, Pg, Td, Tf and Fn by PCR and Real-time PCR. The PCR was a semiquantitative com-mercially available test (Micro-IDent, Hain Lifescience, Nehren, Germany) based on DNA-strip technology. The detection of the microbiota by Real-time PCR was based on the application of the fluorescent dye SYBRgreen-system. The utilized primers were chosen by literature research and specific pre-experiments conducted. There was no significant correlation between bacterium and disease pattern: Aa (PCR p= 0,56; Real-time PCR p= 0,32), Pg (PCR p= 0,20; Real-time PCR p= 0,16), Td (PCR p= 0,31; Real-time PCR p= 0,92), Tf (PCR p= 0,71; Real-time PCR p= 0,97), Fn (PCR p= 0,41; Real-time PCR p= 0,87). The direct comparison of the re-sults of the two methods showed the following exact accordances: Aa 86,66 %, Pg 33,33 %, Td 51,11 %, Tf 55,56 % und Fn 28,89 %. The bacterial loads by Real-time PCR tended to be higher than by the detection with PCR. Only with Pg there was a slight significant correlation between both methods (Aa p= 0,42; Pg p= 0,04; Td p= 0,59; Tf p= 0,78; Fn p= 0,61). Both methods produced similar results. High and very high bacterial loads were de-tected in all three groups. No significant correlation between bacterium and disease pattern was found. For this very reason there is no benefit in using microbiological tests for diagnostic in peri-implant diseases. More important is the clinical diagnostic. Are microbiological tests be carried out, the hypothesis can be established that the conventional semiquantitative PCR is enough to analyze the periodontopathogenetic bacterial species.2015-05-1