3D printed composite materials for craniofacial implants: current concepts, challenges and future directions

Abstract

Millions of craniofacial surgeries are performed annually worldwide for craniofacial bones’ replacement and augmentation. This represents a significant economic burden as well as aesthetic expectations. Autografts and allografts are the first choice for treatment of craniofacial defects; however, their limited availability and difficulty to shape have led to investigation for alternative strategies. Biomaterial-based approaches have been used for implantation as they have ample supply but their processing through conventional technologies present several drawbacks; the major one relates to the poor versatility towards the production of patient-specific implants. Additive manufacturing has gained considerable attention during the last decade, as it allows the manufacturing of implants according to patient need. Biomaterial implants can be additively manufactured but have one or more limitations of stress shielding, radiopacity, high strength to weight ratio and limited bone integration. Over the last few decades, composites are investigated to surmount the limitations with traditional implants and also improve their bone integration. This review provides an overview of the most recent polymeric composite-based biomaterials that have been used in combination with 3D printing technology for the development of patient-specific craniofacial implants. Starting with the conventional treatments, biomaterials available for the craniofacial implants, the additive manufacturing rationale are discussed. Also, the main challenges still associated with 3D printing of polymer-based composites are critically reviewed and the future perspective presented.

Quantitative Assessment of Point-of-Care 3D-Printed Patient-Specific Polyetheretherketone (PEEK) Cranial Implants

“…With advances in computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies, cranial reconstructions have witnessed tremendous progress [5][6][7][8][9][10]. In particular, additive manufacturing (AM) or three-dimensional (3D) printing have become ways of aptly reconstructing the patient's affected surgical anatomy with patient-matched implants [11][12][13][14]. Patient-specific implants (PSIs), in general, are driven by the imperative need of surgeons to treat complicated reconstructive cases that demand a unique patientspecific approach [15][16][17].…”

Additively manufactured metallic biomaterials

“…Although autografts and allografts have been the first choices for the treatment of craniofacial defects, they have some disadvantages such as limited resources and fitting with the shape of the defected tissue. The precise design of the craniofacial substitutions and mimicking the shape of the defected tissue is critical due to the essential role of the craniofacial bones in eating, vision, airway, audition, speech, brain function, facial symmetry, and social stigmatization [ 319 ].…”

“…The Ti alloys are the most common metallic substitutions used in craniofacial surgeries, among which Ti–6Al–5V is well-known as a biocompatible metal widely used in AM cranium fixation components ( e.g. , screws, plates, and meshes) [ 319 ]. Fig.…”

Effects of Pentagonal Pore Sizes in the Zinc Hydroxyapatite Parietal-Temporal Implant

“…However, it also has a disadvantage which is titanium implant can cause stress shielding at the boneimplant contact because it has a higher modulus of elasticity compared to the bone [9]. Furthermore, the metallic implant may cause corrosion as well as cytotoxic reactions inside the host body due to the release of metal ions [10]. PEEK is also commonly used, which is a semicrystalline thermoplastic polymer with excellent thermal, chemical, and mechanical properties.…”

“…Still, it is not without its weakness. PMMA implant has poor adhesion to the soft tissues that surround them [10]. Additionally, PMMA has a smooth texture that inhibits tissue regeneration [12].…”