Osteoconductive effects of vinyl styrene microbeads in rat calvarial defects

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.

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.

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.

VSM enhances bone defect fill whereas the VSM/PDGF-BB is not able to improve bone regeneration capacity when compared with VSM alone.