Effectiveness of biphasic calcium phosphate block bone substitutes processed using a modified extrusion method in rabbit calvarial defects

Abstract

PurposeThis study evaluated the mechanical and structural properties of biphasic calcium phosphate (BCP) blocks processed using a modified extrusion method, and assessed their in vivo effectiveness using a rabbit calvarial defect model.MethodsBCP blocks with three distinct ratios of hydroxyapatite (HA):tricalcium phosphate (TCP) were produced using a modified extrusion method:HA8 (8%:92%), HA48 (48%:52%), and HA80 (80%:20%). The blocks were examined using scanning electron microscopy, X-ray diffractometry, and a universal test machine. Four circular defects 8 mm in diameter were made in 12 rabbits. One defect in each animal served as a control, and the other three defects received the BCP blocks. The rabbits were sacrificed at either two weeks (n=6) or eight weeks (n=6) postoperatively.ResultsThe pore size, porosity, and compressive strength of the three types of bone block were 140-170 µm, >70%, and 4-9 MPa, respectively. Histologic and histomorphometric observations revealed that the augmented space was well maintained, but limited bone formation was observed around the defect base and defect margins. No significant differences were found in the amount of new bone formation, graft material resorption, or bone infiltration among the three types of BCP block at either of the postoperative healing points.ConclusionsBlock bone substitutes with three distinct compositions (i.e., HA:TCP ratios) processed by a modified extrusion method exhibited limited osteoconductive potency, but excellent space-maintaining capability. Further investigations are required to improve the processing method.Graphical Abstract

Late-term healing in an augmented sinus with different ratios of biphasic calcium phosphate: a pilot study using a rabbit sinus model

“…In contrast to the results of the volumetric analysis, comparable amounts of residual material were observed in the histologic sections of the TCP30 and TCP70 groups. Previous histologic studies of rabbit calvaria using BCPs with varying HA:β-TCP ratios found similar resorption rates among the BCPs [ 28 29 ]. This may reflect a limitation of histologic investigations.…”

Performance of two bone substitutes of novel cotton-like β-TCP/PDLGA and granular β-TCP on bone regeneration in the femoral bone defect of the Beagle dogs

“…In this study, we examined new bone formation under the condition of up to 80% porosity at the filled bone defect. β-TCP with 71–80% porosity ( Chiba et al, 2016 ), block bone substitutes with three distinct ratios of hydroxyapatite: TCP with porosity >70% ( Lim et al, 2015 ), and the scaffolds made of chitosan/hydroxyapatite/β-TCP (ratio of 50:30:20) with 70–80% porosity ( Shavandi et al, 2016 ) were previously examined. An α-TCP scaffold coated with hybrid carbonate apatite/poly-epsilon-caprolactone (CO3Ap/PCL) maintained a fully interconnected structure with a porosity of 80–86% and achieved an improved compressive strength mimicking that of cancellous bone ( Bang et al, 2015 ).…”

Biomimetic characteristics of mussel adhesive protein-loaded collagen membrane in guided bone regeneration of rabbit calvarial defects

“…In another experiment, biphasic calcium phosphate block bone substitutes were implanted in rabbit calvarial defects without a barrier membrane. After healing, in the upper part of the block, bone infiltration was minimal and bone regeneration over the block was not visible [ 33 ].…”