The combined use of bioresorbable membranes and xenografts or autografts in the treatment of bone defects around implants - A study in beagle dogs

The aim of the present investigation was to test the effect of a bioresorbable membrane supported by xenografts or autografts in regenerating bone into peri-implant defects. In 3 dogs, the mandibular premolars P-2, P-3, P-4 and M-1 were extracted bilaterally. After 4 months of healing, 3 standardized bone defects were prepared on each side of the mandible and 1 implant per defect was placed. The 6 sites in each dog were distributed into 4 different treatment groups: 2 sites received a Bio-Gide(R) membrane alone (BG); 2 sites received a Bio-Gide(R) membrane supported by Bio-Oss(R) (BG+BO); 1 site received the Bio-Gide(R) membrane supported by autogenic bone harvested from the prepared defects (BG+Aut); 1 site received neither membrane nor bone graft and served as control (C). The soft tissue flaps were adapted and sutured for primary healing. No adverse events occurred during the experimental period. After 16 weeks, the dogs were sacrificed and histomorphometric examinations on non-decalcified ground sections were carried out. The vertical bone growth amounted to 45% (SD+/-13%) of the defect height in the BG group, to 78% (SD+/-29%) in the BG+BO group, to 69% (SD+/-9%) in the BG+Aut group, and to 22% (SD+/-10%) in C group. The horizontal bone growth measured 78% (SD+/-16%) in the BG group, 81% (SD+/-21%) in the BG+BO group, 82% (SD+/-12%) in the BG+Aut group, and 46% (SD+/-21%) in the C group. The vertical height of bone growth in contact with the implant measured 17% (SD+/-12%) in the BG group, 20% (SD+/-12%) in the BG+BO group, 17% (SD+/-7%) in the BG+Aut group, and 12% (SD+/-8%) in the C group. The surface fraction of the graft in direct bone contact measured 89% (SD+/-9%) in the BG+BO group and 93% (SD+/-3%) in the BG+Aut group. It is concluded thar the bioresorbable membrane tested enhances bone regeneration, in particular in conjunction with the use of a supporting graft material. In addition, deproteinized bovine bone mineral and autogenic bone grafts appeared to be equally well integrated into regenerating bone. Finally, no additional effects in the bone growth was observed with the autogenous bone in comparison with the hydroxyapatite.