This paper reviews the past, present, and future of the hydroxyapatite (HAp)-based biomaterials from the point of view of preparation of hard tissue replacement implants. Properties of the hard tissues are also described. The mechanical reliability of the pure HAp ceramics is low, therefore it cannot be used as artificial teeth or bones. For these reasons, various HAp-based composites have been fabricated, but only the HAp-coated titanium alloys have found wide application. Among the others, the microstructurally controlled HAp ceramics such as fibers/whiskers-reinforced HAp, fibrous HAp-reinforced polymers, or biomimetically fabricated HAp/collagen composites seem to be the most suitable ceramic materials for the future hard tissue replacement implants.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400042527

Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants

Recent Developments in Ring Opening Polymerization of Lactones for Biomedical Applications

Bone tissue engineering is a rapidly developing area. Engineering bone typically uses an artificial extracellular matrix (scaffold), osteoblasts or cells that can become osteoblasts, and regulating factors that promote cell attachment, differentiation, and mineralized bone formation. Among them, highly porous scaffolds play a critical role in cell seeding, proliferation, and new 3D-tissue formation. A variety of biodegradable polymer materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past decade. This article reviews the polymer materials, scaffold design, and fabrication methods for bone tissue engineering. Advantages and limitations of these materials and methods are analyzed. Various architectural parameters of scaffolds important for bone tissue engineering (e.g. porosity, pore size, interconnectivity, and pore-wall microstructures) are discussed. Surface modification of scaffolds is also discussed based on the significant effect of surface chemistry on cells adhesion and function.

Polymeric scaffolds for bone tissue engineering.

Synthesis methods for nanosized hydroxyapatite with diverse structures.

Recent development and application products of bulk glassy alloys

New artificial bone materials were prepared using calcium phosphates, hydroxyapatite and β-tricalicum phosphate, and copoly-L-lactide, CPLA. Calcium phosphate powder and CPLA were mixed at 453 K for 10 min with various mixing ratios. Scanning electron microscope observations indicated that the composites of β-tricalicum phosphate and CPLA were homogeneously dispersed and highly adhesive. Young’s modulus of the composites was the same as bone, and bending strength was over half that of bone. The improvement of Young’s modulus compared to the original two materials was due to a composite effect. The composites are expected to be usable as artificial bone materials.

Preparation and mechanical properties of calcium phosphate/copoly-L-lactide composites.

A method is described for preparing dense, polycrystallineβ-tricalcium phosphate. The compressive and flexural strengths of the polycrystalline bodies sintered at a temperature of 1150° C for 1 h were found to be 459 and 138 MPa, respectively. Observation of the fracture surfaces by scanning electron microscopy indicates a predomination of transgranular failures. The polycrystalline tricalcium phosphate is non-toxic in a cell culture system.

Dense polycrystalline β-tricalcium phosphate for prosthetic applications

Preparation and Structure Refinement of Monoclinic Hydroxyapatite

A transcutaneously implantable element in which at least a portion thereof in contact with the cutaneous tissue of a living body is composed of a ceramic material comprising, as the main raw material, at least one member selected from the group consisting of hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate, and which comprises (a) an electrically conductive member for electrically connecting the interior and exterior of the living body to each other or (b) a through hole for mechanically connecting the interior and exterior of the living body to each other. This transcutaneously element can be semipermanently and safely used in a living body without causing any desirable bacterial infection, bleeding, and background noise.

Masaru Akao

Papers

Preparation and mechanical properties of calcium phosphate/copoly-L-lactide composites.

Dense polycrystalline β-tricalcium phosphate for prosthetic applications

Preparation and Structure Refinement of Monoclinic Hydroxyapatite

Transcutaneously implantable element

Hydrothermal growth of carbonate-containing hydroxyapatite single crystals