Postloading behavior of regenerated tissues in GBR-treated implant sites

The objective of this study was to assess, using reentry procedures, the capacity of regenerated tissues in implant-associated defects to respond to occlusal loading. Two groups of patients treated with membrane-augmented osseointegrated implants were included in the study. In group A (7 patients), a total of 9 implant-associated defects, including 6 dehiscences and 3 immediate extraction sites, were prospectively followed up 6 months following prosthesis connection. In group B (3 patients), 4 dehiscence defects were retrospectively evaluated 5 years after prosthetic loading. All defects in both groups had an uneventful healing period beyond the 6 months following implant insertion and showed complete fill with bone-like hard tissues at abutment connection surgery. A second surgical reentry was carried out to evaluate the quantitative changes in the regenerated tissues at the membrane-treated sites; it was carried out 6 months following prosthesis connection in group A, and 5 years postloading in group B. At the second reentry procedure, the mean percentage of defect fill at the dehiscence sites was 82% +/- 12.8% in group A and 83% +/- 7.3% in group B. In the 3 immediate extraction sites in group A, the most apical bone-implant contact around the implant was consistently located at about 1 mm, relative to the coronal aspect of the implant shoulder, as evidenced both radiographically and during the second reentry. The trends noted in this investigation suggest that tissues regenerated in successfully treated implant-associated defects can be maintained in the short-term and long-term periods following prosthetic loading.