This study aimed to evaluate the biomechanical properties in vitro and the bone regeneration of whitlockite (WH) compared with hydroxyapatite (HA) or β-tricalcium phosphate (β-TCP)-based material. We investigated the morphology and phase composition of the bone grafts using a scanning electron microscope and X-ray diffractometer patterns and tested the compressive strength. Four circular defects of 8 mm in diameter were created on the calvaria of twelve rabbits. One defect was left empty, and each of the other defects was filled with WH, HA, and β-TCP. At 4 and 8 weeks, the specimens were harvested to evaluate for the new bone formation and the remaining bone grafts. Regarding the biomechanical properties, the three grafts had a similar micropore size, and WH showed nanopores. The compressive strength of WH was higher than HA and β-TCP without statistical significance. The radiological and histomorphometric analyses demonstrated that the new bone formation was similar among the groups. The remaining bone graft of the WH group was greater than that of the HA and β-TCP groups at 4 weeks (p < 0.05), and the total bone area of the WH, HA, and β-TCP groups was greater than that of the other (p < 0.01). WH has excellent volumetric stability and osteoconductivity compared with HA and β-TCP.

Bone graft substitutes are extensively investigated for addressing critical-size bone defects; however, their efficacy is limited by inadequate bone regeneration and subpar handling properties. Herein, we compared the bone regenerative capacity of CaO–SiO₂–P₂O₅–B₂O₃-based bioactive glass (BGS-7) macrobeads with that of β-tricalcium phosphate (β-TCP) beads and evaluated their performance when incorporated into hydrogels to improve their handling properties. BGS-7 macrobeads were fabricated via alginate crosslinking and heat treatment, and their physicochemical properties and microstructures were characterized. In a rabbit calvarial defect model, BGS-7 macrobeads, heat-treated at 600 and 800 °C, exhibited superior bone bridging and degradation than size-matched β-TCP macrobeads. To further evaluate their regenerative potential, critical-size defects (6 mm diameter × 10 mm depth) were created in the rabbit femoral condyle. To enhance clinical applicability, BGS-7 beads were incorporated into cellulose-based hydrogels and implanted into the defects. Radiographic and histomorphometric analyses demonstrated that bone formation and stable fixation achieved with hydrogel formulations containing BGS-7 microbeads and Laponite were more pronounced than those with BGS-7 beads alone. The findings suggest that BGS-7 macrobeads, particularly when combined with microbead- and Laponite-containing hydrogels, represent a promising bone graft substitute with improved regenerative and handling properties compared with using BGS-7 beads alone.