The present authors regard researchers seeing marginal bone loss as a periodontitis-like disease to be on the wrong track; the onset of marginal bone loss around oral implants depends in reality on a dis-balanced foreign body response.

The working hypothesis of guided bone regeneration (GBR) is that the membrane physically excludes non-osteogenic tissues from interfering with bone healing. However, the underlying mechanisms are insufficiently explained. This study aimed to investigate the molecular and structural pattern of bone healing in trabecular bone defects, with and without naturally derived resorbable membrane. Defects were created in rat femurs and treated with the membrane or left empty (sham). After 3d, 6d and 28d, the defect sites and membranes were harvested and analyzed with histology, histomorphometry, quantitative-polymerase chain reaction (qPCR), Western blot (WB) and immunohistochemistry (IHC). Histomorphometry demonstrated that the presence of the membrane promoted bone formation in early and late periods. This was in parallel with upregulation of cell recruitment and coupled bone remodeling genes in the defect. Cells recruited into the membrane expressed signals for bone regeneration (BMP-2, FGF-2, TGF-β1 and VEGF). Whereas the native membrane contained FGF-2 but not BMP-2, an accumulation of FGF-2 and BMP-2 proteins and immunoreactive cells were demonstrated by WB and IHC in the in vivo implanted membrane. The results provide cellular and molecular evidence suggesting a novel role for the membrane during GBR, by acting as a bioactive compartment rather than a passive barrier.

The results of this study indicated that a surgical procedure based on pocket elimination and bone re-contouring and plaque control before and following surgery was an effective therapy for treatment of peri-implantitis for the majority of subjects and implants. However, complete disease resolution at the site level seems to depend on the initial bone loss at implants. Implants with no signs of peri-implantitis following treatment tended to remain healthy during the 2-year period, while a tendency for disease progression was observed for the implants that still showed signs of peri-implant disease following treatment.

The results of this study yielded differences in the pocket probing measurements at implants with or without the prosthetic reconstruction in place and that the probing pocket depth following the removal of the prosthesis had a high correlation with the amount of bone loss at implants assessed during surgery.