Histologic evaluation of demineralized freeze-dried bone allografts in barrier membrane covered periodontal fenestration wounds and ectopic sites in dogs

Abstract

Background/aim: The aim of this study was to investigate healing responses to demineralized freeze-dried bone powder allografts in standardized periodontal fenestration defects, compared with subcutaneous wounds in a dog model.

Methods: Circular periodontal fenestration defects were created buccally at all four canines in 14 mongrel dogs. Each site received one of the following underneath a barrier membrane: (a) ethylene oxide (EO)-sterilized demineralized freeze-dried bone allografts (DFDBA), (b) heat-treated DFDBA, (c) non-sterilized DFDBA and (d) ungrafted control. Twelve of the 14 dogs had three subcutaneous chest wall pouches created and one of the three DFDBA materials placed in each. The animals were necropsied at 4 weeks. Histologic sections were prepared through the center of the fenestration sites in an apico-coronal direction. Quantitative analysis using computer-assisted imaging technique was performed. Subcutaneous implants were evaluated histologically and quantified for associated inflammatory cell infiltrate.

Results: Fenestration defects healed by partial osseous fill and cementum regeneration with formation of a periodontal ligament. The graft particles generally appeared isolated from the site of osteogenesis and covered by cementum-like substance. Graft particles incorporated into newly formed bone at a distance from the root surface was the exception. No statistically significant differences in new bone formation were observed between treatment groups within animals, but significant inter-animal variation was found (p<0.01). Quantities of retained graft particles were limited, and without cellular resorption. A bone augmentation effect was associated with the barrier in the majority of sites. No bone formation was evident at the subcutaneous sites where graft particles displayed distinctly modified surface zones and multinucleated giant cell resorption. Significantly more inflammatory infiltrate was associated with EO-sterilized grafts compared with heat-treated grafts (p=0.05).

Conclusion: Implantation of DFDBA neither enhanced osseous healing in periodontal fenestration defects, nor resulted in ectopic bone induction. DFDBA particles implanted in either periodontal fenestration or subcutaneous wounds evoked distinctly different healing responses.