Fabrication of HA/PLLA Composite Scaffolds for Bone Tissue Engineering Using Additive Manufacturing Technologies

Abstract

This chapter presents an overview of a research work carried out for the rapid manufacture of bioceramics (HA)/biopolymers (PLLA) composite scaffolds by means of Selective Laser Sintering (SLS) technique, to be used for bone tissue implantation aiming to replace and/or repair bone defects due to traumatised, damaged or lost bone. SLS is an Additive Manufacturing Technology (AMT) that selectively sinters powders of engineering materials, from solid or surface models created by a CAD 3D file, by means of a CO2 laser and in a layer-by-layer basis. HA (hydroxyapatite) is a bioceramic used since several years for medical applications although being mainly processed by conventional methods (cast, machined or manually produced). In recent years ceramics and their composites are being used to augment or replace various parts of the body, particularly bone. Their relative inertness to the body fluids, high compressive strength, and aesthetically pleasing appearance led to the use of ceramics in dentistry as dental crowns. Some carbons have found use as implants, especially for bloodinterface applications, such as heart valves. Due to their high specific strength as fibbers and their biocompatibility, ceramics are also being used as reinforcing components of composite implants and for tensile loading applications such as artificial tendons and ligaments. Calcium phosphate based bioceramics have been in use in medicine and dentistry in the last thirty years, in several applications: dental implants, periodontal treatment, alveolar ridge augmentation, orthopaedics, maxillofacial surgery, and otolaryngology. Different phases of calcium phosphate ceramics are used depending upon whether a resorbable or bioactive material is desired. Porous hydroxyapatite has been studied for use in repairing large defects in bone. Implanted HA is slowly resorbed by the body over several years and replaced by bone. HA as the capability to form a direct chemical bond with hard tissues. On implantation of HA particles or porous blocks in bone, new lamellar cancellous bone forms within 4 to 8 weeks. Porous materials are used on bone compatible implants to encourage bony ingrowths. Therefore, pore size is of considerable biological importance. PLLA (Poly-L-lactic acid) is a biodegradable polymer. The interest in biodegradable polymeric biomaterials for biomedical engineering has increased dramatically during the