Evaluation of a porcine matrix with and without platelet-derived growth factor for bone graft coverage in pigs

The aim of this investigation was to compare three different techniques for soft tissue closure over intraoral particulated bone grafts in a pig model: primary closure and nonprimary closure utilizing a porcine collagen matrix (Mucograft), with or without the addition of platelet-derived growth factor (PDGF). An additional aim was to determine whether the addition of PDGF to the collagen matrix would prevent the need for primary closure or later soft tissue grafting.

Twenty-four bilateral mandibular alveolar defects were created in 12 minipigs. These defects were reconstructed with a mixture of autogenous bone and bovine bone and secured with a titanium mesh. The animals were randomly assigned to group A (Mucograft+PDGF), group B (Mucograft alone), or group C (primary closure and no Mucograft). In groups A and B the collagen matrix was placed directly over the mesh, and the soft tissue was closed passively. Exposure of the titanium mesh, height of new bone, and the percentage of keratinized mucosa covering the bone graft were analyzed.

Average new bone formation in group A was 7.0 mm, whereas groups B and C had less regenerated bone (4.7 mm and 2.5 mm, respectively). Group A had the thickest keratinized mucosa (1.6 mm), versus 0.9 mm for group B and 0.4 mm for group C. Group A had an average of 95% regenerated keratinized tissue, whereas group B had 41% and group B had 22%.

The addition of PDGF to the collagen matrix appeared to accelerate soft tissue healing and promote bone formation. Mucograft provided an adequate alternative to autogenous soft tissue grafts or primary closure to cover bone grafts intraorally while eliminating adverse effects, namely disruption of the adjacent soft tissue architecture, loss of vestibular height, and the need for further surgery.