Immunohistochemical characteristics of inflammatory lesions at implants

Objective: The aim of the present investigation was to study some immunohistochemical features of peri-implant mucositis and peri-implantitis lesions. Materials and methods: Two groups of subjects (Groups A and B) were included. Group A consisted of 10 partially edentulous subjects (eight females and two males; 45-72 years of age) who had been restored with implants (Branemark System((R)), Nobel Biocare AB, Goteborg, Sweden). The implants had been in function between 2 and 5 years. In each subject, one implant site demonstrating signs of peri-implant mucositis, i.e. soft tissue inflammation but no bone loss, was selected. The site was anaesthetized and a soft tissue biopsy was collected. In Group B, six subjects were included. They had been restored with implants (Branemark System((R)), Nobel Biocare AB, Goteborg, Sweden) between 5 and 11 years prior to the current study. In each individual greater than or equal to 1 implant site exhibited signs of periimplantitis and was selected for biopsy. All sites of peri-implantitis had (i) a history of continuous marginal bone loss (assessed in radiographs), (ii) clinical symptoms of soft tissue inflammation (bleeding on probing and suppuration) but (iii) no implant mobility. From each selected peri-implantitis site a 4 X 4 mm large soft tissue biopsy was obtained. All specimens were snap frozen and prepared for immunohistochemical analysis regarding the proportions of cells positive for the CD3, CD4, CD8, CD19 and elastase markers. Results: Peri-implantitis lesions were considerably larger and contained significantly greater proportions of B cells (CD19(+)) and elastase-positive cells than mucositis lesions. Peri-implantitis sites, in contrast to sites with mucositis, consistently displayed elastase-positive cells in the central portions of the infiltrate. Conclusion: It is suggested that peri-implantitis lesions exhibit properties that are different from mucositis lesions.