Histopathological observations of human periimplantitis lesions

Objective: The aim of the present study was to analyze some characteristics of advanced and progressive periimplantitis lesions in man. Material and methods: Soft tissue biopsies were obtained from 12 implants in six patients. The implants had been in function between 4 and 21 years and were, with one exception, located in the maxilla. The radiographic examination performed prior to biopsy revealed that all sites exhibited advanced bone loss. Further, clinical signs of severe inflammation, such as suppuration, swelling and/or fistula formation were detected in the majority of sites and seven of the 12 implants were found to be mobile at biopsy. Each biopsy was following fixation embedded in epoxy resin and sections were prepared for histometric and morphometric analysis. Results and conclusion: It was demonstrated (i) that all soft tissue units harbored large inflammatory cell infiltrates (ICT) that extended to a position apical of a pocket epithelium and (ii) that about 60% of the lesions were occupied by inflammatory cells, among which plasma cells dominated. Numerous amounts of PMN cells occurred not only in the pocket epithelium and adjacent connective tissue areas, but were also present in peri-vascular compartments in more central areas of the ICT.