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Aim of the study: To evaluate differences in the cellular expression of DNA damage/repair and reactive oxygen/nitrogen species between human periodontitis and peri‐implantitis lesions. Material and methods: 40 patients presenting with generalized severe periodontitis and 40 patients with severe peri‐implantitis were included. Soft tissue biopsies were collected from diseased sites in conjunction with surgical therapy and prepared for histological analysis. Four regions of interest were identified: the pocket epithelium (PE), the infiltrated connective tissue (ICT), which was divided into one inner area facing the PE (ICT‐1) and one outer area (ICT‐2). A non‐infiltrated connective tissue area (NCT) lateral of the ICT was also selected. Results: It was demonstrated that the ICT of peri‐implantitis specimens was considerably larger and contained significantly larger area proportions and densities of CD68‐, MPO‐ and iNOS‐positive cells than that of periodontitis samples. Cellular densities were overall higher in the inner ICT zone lateral of the PE (ICT‐1) than in the outer ICT compartment (ICT‐2). While the NCT area lateral of the ICT comprised significantly larger proportions and densities of y‐H2AX‐, iNOS‐, NOX2‐, MPO‐ and PAD4/MPO‐positive cells in peri‐implantitis than in periodontitis sites, a reverse difference was noted for the area proportion and density of 8‐OHdG‐positive cells in the PE. Conclusions: It is suggested that peri‐implantitis lesions are associated with an enhanced and upregulated host response and contain larger numbers of neutrophils, macrophages and iNOS‐positive cells than periodontitis lesions. [ABSTRACT FROM AUTHOR]

Aim To evaluate the effect of surgical treatment of experimental peri-implantitis at implants with different surface characteristics using different anti-infective procedures. Material and methods Four implants with different surface characteristics (A: TiOblast, B: OsseoSpeed, C: AT-I, D: TiUnite) were installed in a randomized order in each side of the mandible in 6 labrador dogs 3 months after tooth extraction. Experimental peri-implantitis was induced 3 months later. Surgical treatment of peri-implantitis was performed. The implants were cleaned with gauze soaked in either saline (control) or chlorhexidine (test). Clinical and radiographical examinations were performed and microbiological samples were taken during a 6-month period after surgery. Biopsies were obtained and prepared for histological analysis. Results Clinical signs of soft tissue inflammation were reduced after surgical therapy in most test and control sites. While the analysis of bone level alterations in radiographs together with histological and microbiological assessments of resolution of peri-implantitis lesions failed to demonstrate statistically significant differences between test and control procedures, the evaluations disclosed significant differences between implant D and implants A, B and C on treatment outcome. Conclusion It is suggested that (i) the local use of chlorhexidine has minor influence on treatment outcome, (ii) resolution of peri-implantitis following surgical treatment without the adjunctive use of local and systemic antimicrobial agents is possible and (iii) the results are influenced by implant surface characteristics. [ABSTRACT FROM AUTHOR]

Aim To analyze the tissue reactions following ligature removal in experimental periodontitis and peri-implantitis in dogs. Material and methods Four implants with similar geometry and with two different surface characteristics (turned/TiUnite Nobel BioCare AB, Göteborg) were placed pair-wise in a randomized order in the right side of the mandible 3 months after tooth extraction in 5 dogs. Experimental peri-implantitis and periodontitis were initiated 3 months later by ligature placement around implants and mandibular premolars and plaque formation. The ligatures were removed after 10 weeks, and block biopsies were obtained and prepared for histological analysis 6 months later. Results It was demonstrated that the amount of bone loss that occurred during the period following ligature removal was significantly larger at implants with a modified surface than at implants with a turned surface and at teeth. The histological analysis revealed that peri-implantitis sites exhibited inflammatory cell infiltrates that were larger, extended closer to the bone crest and contained larger proportions of neutrophil granulocytes and osteoclasts than in periodontitis. Conclusion It is suggested that lesions produced in experimental periodontitis, and peri-implantitis are different and that implant surface characteristics influence the inflammatory process in experimental peri-implantitis and the magnitude of the resulting tissue destruction. [ABSTRACT FROM AUTHOR]