Consensus reports from European Workshops on periodontology have stated that peri-implant mucositis and peri-implantitis are infectious diseases. Peri-implant mucositis describes an inflammatory lesion that resides in the mucosa, whereas peri-implantitis also affects the supporting bone.1 In addition, peri-implantitis is characterized by crestal bone loss in conjunction with bleeding on probing, with or without concomitant deepening of peri-implant pockets. Pus is a common finding in peri-implantitis sites.2
Results from clinical and experimental studies have revealed that peri-implant mucositis and gingivitis have many features in common. Gingivitis and peri-implant mucositis lesions form in gingival and peri-implant connective tissues in response to plaque formation on teeth or implants. The lesions are similar in terms of location, size and composition.3 If left untreated, gingivitis and peri-implant mucositis lesions may become destructive and progress into periodontitis and peri-implantitis lesions, respectively.
More neutrophil granulocytes and osteoclasts in peri-implantitis lesions
Although there are obvious similarities regarding clinical characteristics and the etiology of peri-implantitis and periodontitis, the lesions of the two diseases exhibit important histopathological differences. Results from experimental studies and analysis of human biopsy material have demonstrated that peri-implantitis lesions are poorly encapsulated. They are larger and extend closer to the bone crest than periodontitis lesions. In addition, peri-implantitis lesions contain larger proportions of neutrophil granulocytes and osteoclasts than periodontitis lesions.4-7