Improvements in Healing with a Bioactive Bone Graft Substitute in a Canine Metaphyseal Defect

INTRODUCTION: Osteoporotic patients, smokers and diabetics are among those who represent higher risks with regard to bone formation. In these clinical situations where bone regeneration can be especially difficult there is a need for an active agent or material which can stimulate osteoblasts in addition to providing a scaffold for growth. Extensive research has been performed on silicon and calcium containing glasses, especially 45S5, because of their potential for osteostimulation [1-3]. Upon implantation bioactivity is initiated by the release of soluble ionic species including Si, Ca and Na into the surrounding aqueous environment [1]. A series of reactions then leads to the deposition of a hydroxycarbonate apatite layer (HCA) on the glass surface which creates an ideal site for osteoblast attachment [1]. In addition, numerous studies have shown that the dissolution products of 45S5 increase osteoblast differentiation and proliferation [1-3]. Various forms of bioactive glass have been in clinical use for over 20 years [1]. The glass itself, however, is not an ideal scaffold due to the lack of porosity and adequate handling characteristics. Vitoss® Foam Bone Graft Substitute (Orthovita, Inc.) (VT) is a composite of β-TCP and bovine Type I collagen. Vitoss Bioactive Foam (BA) is a similar composite with the addition of a proprietary 45S5 bioactive glass. The present study investigates VT and BA in a canine metaphyseal defect to compare the rates of healing.