In Vivo Evaluation of Scaffolds with a Grid‐Like Microstructure Composed of a Mixture of Silicate (13–93) and Borate (13–93B3) Bioactive Glasses

Abstract

This study was undertaken to create and evaluate scaffolds composed of 13-93 glass and varying volume fractions of 13-93B3 glass (0-100%). The scaffolds were fabricated by a robotic deposition (robocasting) technique to create the same grid-like microstructure. The capacity of the scaffolds to regenerate bone in rat calvarial defects was studied as a function of the volume fraction of 13-93B3 glass in the scaffolds. The compressive strength and elastic modulus of the as-fabricated scaffolds decreased with increasing amount of 13-93B3 glass in the scaffolds. When implanted in rat calvarial defects in vivo, the scaffolds showed a decreasing capacity to regenerate bone with increasing volume fraction of 13-93B3 glass in the scaffolds. The percent new bone in the defects implanted with the 13-93 scaffolds (23 ± 4% at 6 weeks and 28 ± 8% at 12 weeks) was significantly higher than in the defects implanted with the 13-93B3 scaffolds (6 ± 4% at 6 weeks and 9 ± 7% at 12 weeks). While the 13-93 glass was only partially converted to HA after 12 weeks in vivo, the 13-93B3 glass was almost fully converted within 6 weeks. The lower capacity of the 13-93B3 scaffolds to support bone regeneration might be related to the high boron concentration released from the rapidly converting glass.