Osteoconductive Effects of Vinyl Styrene Microbeads in Rat Calvarial Defects

Purpose The aim of the present study was to evaluate the use of the nonresorbable vinyl styrene microbeads (VSM) alloplast as a delivery vehicle for platelet-derived growth factor (PDGF-BB) in rat calvarial critical size defects. Materials and Methods Seventy-three Long-Evans male rats were divided into 4 groups; a negative control, vinyl styrene microbeads (VSM), PDGF-BB, and VSM plus PDGF-BB. Critical size calvarial defects were carried out and isolated with membranes sandwiching the defects with their fillers. Animals were sacrificed after 2, 4, and 16 weeks classifying each group into 3 subgroups. Calvarial specimens were radiographed for evaluation of regenerated bone volume and densitometry histogram analysis. Specimens were divided mid-sagittally and stained with hematoxylin and eosin (H&E) and trichrome stain for qualitative and histomorphometric analysis using an image analysis software. Results The VSM groups showed statistically higher defect fills than the VSM-free groups at all sacrifice times except for the VSM/PDGF group that showed this difference after 2 weeks in relation to the PDGF group and the negative control after 4 and 16 weeks. For the radiographic analysis, the VSM/PDGF group showed the lowest bone volume compared with the other groups except when it was compared with the 4 weeks VSM group. In contrast, the PDGF showed the highest bone volumes at all sacrifice times that were only significant when compared with the 4 weeks VSM group and the 4 and 16 weeks VSM/PDGF group. Conclusions VSM enhances bone defect fill whereas the VSM/PDGF-BB is not able to improve bone regeneration capacity when compared with VSM alone.