Are peri-implantitis lesions different from periodontitis lesions?

P>Aim To compare histopathological characteristics of peri-implantitis and periodontitis lesions. Methods A search was conducted on publications up to July 2010. Studies carried out on human biopsy material and animal experiments were considered. Results While comprehensive information exists regarding histopathological characteristics of human periodontitis lesions, few studies evaluated peri-implantitis lesions in human biopsy material. Experimental peri-implantitis lesions were evaluated in 10 studies and three of the studies included comparisons to experimental periodontitis. Human biopsy material: the apical extension of the inflammatory cell infiltrate (ICT) was more pronounced in peri-implantitis than in periodontitis and was in most cases located apical of the pocket epithelium. Plasma cells and lymphocytes dominated among cells in both types of lesions, whereas neutrophil granulocytes and macrophages occurred in larger proportions in peri-implantitis. Experimental studies: placement of ligatures together with plaque formation resulted in loss of supporting tissues and large ICTs around implants and teeth. Following ligature removal, a "self-limiting" process occurred in the tissues around teeth with a connective tissue capsule that separated the ICT from bone, while in peri-implant tissues the ICT extended to the bone crest. Conclusion Despite similarities regarding clinical features and aetiology of peri-implantitis and periodontitis, critical histopathological differences exist between the two lesions.