Mechanical characterisation of porous glass reinforced hydroxyapatite ceramics: Bonelike®

Abstract

In the present study, mechanical properties of porous glass reinforced hydroxyapatite bioceramics were assessed by microhardness, bending and compression tests and fracture toughness determination. Porous discs were produced by a dry method using wax spheres as pore formers. Green bodies were sintered and the final microstructure of the composites consists of hydroxyapatite, alpha and beta tricalcium phosphate (alpha and <FONT FACE=Symbol>b</font>-Ca3(PO4)2)due to the reaction between the glassy phase and the hydroxyapatite matrix. The results of the mechanical tests showed that the glassy phase yielded higher fracture toughness and bending strength when comparing with literature data for single hydroxyapatite. There is a compromise between mechanical properties and the porosity level for bioceramics: for example, according to Weibull statistics for composites with 65% porosity the maximum bending stress level is 0.2 MPa for 100% survival probability whereas this stress level increases to 2.5 MPa for composites with 40%. However, only the 65% porosity composite samples seem to have the complete adequate morphology for bone ingrowth

Porous hydroxyapatite scaffolds fabricated from nano-sized powder via honeycomb extrusion

“…The compressive data reported is comparable to that of dense HA-BG hybrids [455,496]. Previous work has also sought to combine HA with phosphate-based glass, and the compressive strength and porosity thereof are comparable to that obtained herein [497,498]. Similarly, BG has been combined with other bioceramics, such as β-TCP and calcium sulphate, which have attained compressive strengths below that obtained in this study [290,499,500].…”

“…Bonelike®, which has been stated as a promising material with enhanced bioactivity compared to HA-only material [149,502], and is suitable for direct clinical use, consists of HA with 4 wt% bioactive glass. Though the porosity values are comparable to that of the samples examined in the present study, the compressive strengths and macro-pore sizes are, respectively, 2 MPa and 100 µm [498]. Hence, the hybrid scaffolds fabricated herein, comprised of a higher glass content, remarkably greater compressive strength and larger pore sizes, would be more desirable for BGS.…”

Porous hydroxyapatite‐bioactive glass hybrid scaffolds fabricated via ceramic honeycomb extrusion

“…This was confirmed when Bonelike ® was implanted in the tibia of 13 patients during osteotomy surgery, with the aim of treating the medial compartment osteoarthritis of the knee . Although the porosity values are similar, hitherto the compressive strengths reported for Bonelike ® are 2 MPa with pore sizes of approximately 100 μm . Therefore, comprised of a higher glass composition and remarkably greater compressive strengths, it can be concluded that honeycomb extruded hybrid scaffolds used for similar clinical applications will result in superior biological and mechanical performances.…”

Investigation of Fracturing and Adhesion Behavior of Hydroxapatite Coating Formed by Aminoacetic Acid-Sodium Aminoacetate Buffer Systems

“…The average maximum indentation depths obtained at the end of the measurement are shown in Table 5, while the Vickers hardness and elasticity modulus values are given in Table 6. When the data in Table 5 are examined, it can be observed that the average indentation depths (ht) at maximum load increase continuously with the increase in holding period (24,48 , 72 and 96 h).…”

“…The fracture toughness values obtained are shown in Table 8. In the literature, when the calculated fracture toughness values of the HA coating surfaces were examined, the fracture toughness values of hydroxyapatite coating surfaces made by Zhang [24], between 0.23 and 1.20 MPa m 1/2 [25], between 0.49 and 0.67 MPa m 1/2 [26], between 0.99 and 1.27 MPa m 1/2 value [27] and 0.74 MPa m 1/2 , respectively [28]. Çaglayan found the fracture toughness values of coatings obtained in the Alanine-Alanine sodium salt buffer medium as 1.57 MPa m 1/2 , 1.73 MPa m 1/2 , 2.29 MPa m 1/2 and 2.31 MPa m 1 for 24, 48, 72 and 96 h, respectively [22].…”