Histological Evaluation of PDGF for Bone Graft Coverage in Pigs

Objective: The stimulatory effects of platelet-derived growth factor (PDGF) as a chemoattractant and mitogen for mesenchymal cells, along with its ability to promote angiogenesis, have been demonstrated in a variety of preclinical models predicting maxillofacial and soft-tissue applications. Mucograft® is a new porcine collagen matrix membrane proposed as a substitute for autogenous soft tissue grafts for intraoral mucogingival defects. The aim of this study is to compare a porcine collagen matrix (Mucograft®) with and without PDGF for soft tissue closure over intraoral bone grafts in pigs.

Methods: Twelve micro-pigs in 24 weeks old were used. Mandibular posterior teeth were extracted with simultaneous alveoectomy followed by a healing time of 8 weeks. Twenty-four mandibular defects were used at 2nd stage surgery for three treatment groups: A) mucograft + PDGF; B) mucograft alone; C) primary closure (no mucograft). Autogenous bone combined with BioOss was implanted in the mandibular defect. Titanium mesh crib with screws used to contain bone graft into the bony defect. Mucograft with or without PDGF were placed upon mesh crib and sutured to the surrounding mucosa in two experimental groups. Measurements of change in vestibular depth before and after bone graft as well as size of the regenerated soft tissue were taken. Pigs were sacrificed after three months healing. Specimens were harvested for histological evaluation using Exakt-cutting-grinding system.

Results: The size of regenerated soft tissue covering bone graft in mucograft + PDGF group was larger than that in mucograft alone group. The new bone formation in bone graft area was higher in mucograft +PDGF group than that in other two groups.

Conclusion: Mucograft® allowed tension free closure over the bone graft and minimized incidence of graft exposure. The addition of platelet derived growth factor (PDGF) to the mucograft® appeared to accelerate soft tissue healing over intraoral bone grafts.