Healing patterns of critical size bony defects in rats after grafting with bone substitutes soaked in recombinant human bone morphogenetic protein-2: histological and histometric evaluation.

The aim of the study was to evaluate the effect of different bone substitutes soaked in recombinant human bone morphogenetic protein-2 (rhBMP-2) on the healing of critical size defects in calvarial bone. Defects were created in 24 Sprague Dawley rats. The rhBMP-2 was diluted to obtain a final concentration of 0.2mg/ml. Rats were divided into four groups and treated as follows: in the first group the defect was filled with anorganic bovine bone mineral (ABBM) and rhBMP-2, the second group was treated with freeze-dried bone allograft (FDBA) and rhBMP-2, and the third group was treated with autogenous bone (AUTO). In the control group the defects were left untreated. Animals were killed after 8weeks and calcified histological sections prepared. Histometric measurements showed that mean (SD) bone formation was 4.00 (1.69)mm(2) in the ABBM group, 2.56 (1.06)mm(2) in the FDBA group, and 2.30 (0.34)mm(2) in the AUTO group. The difference between the ABBM group and the other 3 groups was significant (p<0.0001) with a mean bone formation of 0.82 (0.25)mm(2) in the control group. There was no significant difference between the FDBA and the AUTO groups (p=0.96). Within the limits of this study we concluded that the addition of rhBMP-2 to bone substitutes was efficacious in regenerating bone in critical size bone defects in calveria in rats.

Healing patterns of critical size bony defects in rat following bone graft.

PURPOSE: The aim of the present study was to evaluate the healing patterns of critical size calvarial bony defects treated with different bone substitutes and to compare them to an autogenous graft and an ungrafted control group. MATERIALS AND METHODS: Thirty-six Sprague-Dawley rats (200-230 g) were used. A periosteal flap was raised and an 8 mm defect was trephined. Rats were divided into six groups and treated as follows: group 1 was treated with a deproteinized bovine xenograft (XO), group 2 was treated with a bovine xenograft and covered with a resorbable membrane (XOCM), defects in group 3 were filled with a decalcified freeze-dried bone allograft (DFDBA), group 4 was treated with a composite bone substitute made of bovine xenograft and collagen (XOC), group 5 was filled with autogenous bone (AUTO), and group 6 was left untreated (control). The animals were euthanized at 2 months. RESULTS: Mean bone formation was 2.97 +/- 1.82 mm2 in group 5 (AUTO) followed by 2.93 +/- 1.93 mm2 in group 3 (DFDBA) and 2.25 +/- 1.94 mm2 in group 4 (XOC). Groups 1, 2, and 6 (XO, XOCM, and control, respectively) were not significantly different (p > 0.05) with a mean bone formation of 1.97 +/- 1.64, 1.87 +/- 1.07, and 1.85 +/- 1.04 mm2, respectively. CONCLUSIONS: This work confirmed the superiority of autogenous bone when it comes to bone grafting. Nevertheless, some bone substitutes can improve bone formation when compared to the control. New bone substitutes with growth factors to improve their abilities to induce bone formation should be experimented.