Brushite and Self‐Healing Flexible Polymer‐Modified Brushite Bone Adhesives for Fibular Osteotomy Repair

Abstract

The study aim was to compare in vitro properties of two experimental bone adhesives (brushite cement and polymer-modified brushite composite) and then assess their in vivo suitability for fixation of a fibular osteotomy using a lapine model. The composite was produced by replacement of the aqueous phase of the brushite cement (800 Â 10 À3 M citric acid) by polypropylene glycol-co-lactide dimethacrylate. FTIR showed this modification enabled pre-mixing and better control of set through light activated polymer crosslinking instead of the acid-base brushite reaction. Raman confirmed the brushite component [equimolar monocalcium phosphate (MCPM) and b-tricalcium phosphate (b-TCP)] of the composite could react upon water-sorption to enable long-term "bulk composite selfhealing." SEM demonstrated precipitation of brushite crystals in cell culture medium on the composite surface ("surface self-healing") and improved cell attachment. The composite was considerably more flexible than the cement (33% strain before yield compared to 4.6% before sharp brittle fracture). This flexibility was used to explain the more complete union of the fibula osteotomy and high callus index observed with composite use. The presence of cartilage at the osteotomy site in one fibula treated with brushite cement, however, indicated the absence of complete bone healing in this case. Raman mapping also confirmed the composite enabled more rapid mineralization of the fracture site compared with the cement. Both materials provided immediate fixation in vivo. More surprisingly both brushite and adhesive composite showed complete degradation by 5 weeks in vivo enabling complete union particularly with the adhesive composite within this time.

Setting kinetics and mechanical properties of flax fibre reinforced glass ionomer restorative materials

“…FTIR spectra between 500 and 4,000 cm − 1 were then obtained using Timebase software with a resolution of 4 cm − 1 every 12 seconds for 30 minutes. The reaction extent ( ) versus time was calculated from the absorbance change ( ) and the maximum absorbance change ( ) at 1565 cm − 1 using the following equation [ 20 ] :…”

Quantifying effects of interactions between polyacrylic acid and chlorhexidine in dicalcium phosphate – forming cements

“…ChronOs inject®, PD VitalOs®) for bone lling due to their injectability, biocompatibility degradability and transformation into brushite and then hydroxyapatite in vivo. 25,31,32 Additionally, although PAA has been commercially applied more in dental applications it has also been employed previously in bone repair. 33 A further potential application for the new materials is bone fracture stabilisation.…”

“…Production of more exible cement, by total replacement of the aqueous phase of the brushite cement with a polymer, solved this issue. 32 Furthermore, the study suggested that formation of polyacidic groups (as in polyacrylic acid) could enable "self-repair" of the cement-bone interface as the bone remodels. 32…”

“…32 Furthermore, the study suggested that formation of polyacidic groups (as in polyacrylic acid) could enable "self-repair" of the cement-bone interface as the bone remodels. 32…”