Profiling of Differentially Expressed Genes in Peri-implantitis and Periodontitis in vivo by Microarray Analysis

The purpose of this study was to compare gene expression profiles of peri-implantitis and periodontitis to elucidate potential differences at the molecular level. With the help of microarray analysis, genome-wide gene expression of inflamed peri-implant granulation tissue, inflamed and healthy periodontal tissues (n = 48 patients) were compared and the data were validated by real-time reverse transcription polymerase chain reaction. After highlighting different gene classes, we focused on the extracellular matrix receptor interaction pathway and gene expression of extracellular matrix molecules, their receptors and matrix degrading enzymes. Only genes of non-fibril-forming collagens (types IV, Vi, VII, and XI I) were increased in peri-implantitis compared to periodontitis, whereas the expressions of two fibril-forming collagens (types III and XI) were decreased in peri-implantitis, which suggested that peri-implant tissue remodels faster than periodontal tissue in vivo. Furthermore, cathepsin D and cathepsin S seem to participate in the destruction of peri-implant connective tissue. Despite their clinical similarities, the present investigation demonstrated that peri-implantitis and periodontitis are two different disease entities at least at the messenger ribonucleic acid level. The data provide insight for future studies aimed at dissecting the pathogenesis of peri-implant inflammation.