Soft tissues around long-term platform switching implant restorations : a histological human evaluation. Preliminary results

Background Switching platform restorations seems to reduce the peri-implant bone resorption and to preserve the peri-implant soft tissues. Aim The aim of the present human study was to compare histologically the peri-implant soft tissue in switching and traditional platform implants 4 years after restoration. Materials and Methods Forty-eight months after implant restoration, 37 peri-implant soft tissue samples from 14 patients were harvested from traditionally restored implants (control group) and from three different platforms mismatching 0.25-0.85 mm (test groups). At the harvesting time, all sites were clinically healthy. Samples were processed to evaluate the inflammatory infiltrate area [inflamed connective tissue (ICT)], the microvascular density (MVD) and the collagen content (AA%). Results At the analyses, no significant differences were found between groups in terms of ICT, MVD and AA% (p > 0.05). In all groups, most samples with a well-preserved junctional epithelium showed a small and localized inflammatory infiltrated associated with not-well-oriented collagen fibres and an increased MVD. Conclusions Forty-eight months after restoration, switching and traditional platform implants had similar histological peri-implant soft tissue features, despite different bone level changes detected radiographically and published in a previous parent study. The present study seems to confirm platform switching as a safe prosthetic concept leading to better maintenance of peri-implant bone levels. However, further histological studies are required to longitudinally confirm the present data.