Advanced MaterialsCeramicsCompositesMaterialsOrthopedic Implants

SINTX 3D prints of medical implants with Flex-SN PEEK

The silicon nitride composite material was processed using a polymer material extrusion 3D printer

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By leveraging the unique properties of silicon nitride and the transformative power of 3D printing, SINTX Technologies created high-performance 3D printed medical implant devices with exceptional biocompatibility, resulting in high rates of acceptance and long-term implant success. The implantable medical devices, created to match very complex structures within a patient’s anatomy, were printed using FleX-SN PEEK, a PEEK-silicon nitride ceramic-polymer composite material.

With SINTX’s recent acquisition of polymer processing equipment (e.g., twin-screw extruder and ancillary equipment, plastic shredder/recycler, injection molder, and medical-grade 3D printer), the Utah-based company was able to develop the novel composite filaments for use in fabricating next-generation medical implants via additive manufacturing with the FleX-SN PEEK material.

With this equipment, SINTX intends to utilize its expertise in ceramics and polymer processing and combine it with growing knowledge of 3D printing medical devices to produce complex, novel implant designs of varying silicon nitride compositions. The medical-grade 3D printer allowed the team to fabricate parts with textures and porosities, features that cannot be produced by any other manufacturing method.

Development of the composite filament allowed SINTX to produce 3D printed medical implants with characteristics like the decreased chance of infection, biocompatibility, favorable mechanical properties, and osteogenic properties to further increase the body’s likelihood of acceptance of the implant.

An ideal material

Silicon nitride is a ceramic material that is known for its high strength and excellent biocompatibility making it the ideal biomaterial material for 3D printed implants which need to be able to withstand the mechanical stresses of the body.

When used to make spinal fusion implants, silicon nitride has the flexibility of a dense, porous architecture that can mimic the cortical cancellous structure of bone. Silicon nitride is biocompatible, bioactive, and has shown bacterial resistance and superb bone affinity.  With >33,000 human spine implantations over 10 years, and less than 25 reported adverse events, silicon nitride has a good safety record. Silicon nitride can be polished to a smooth and wear-resistant surface for articulating applications, such as bearings for hip and knee replacements.

Silicon nitride-based polymer for medical devices

Composite materials have long been used to exploit the characteristics of different materials by combining them. The composites we are making at SINTX consist of our silicon nitride powder in a matrix of PEEK (Polyether ether ketone), which is the FleX-SN PEEK product, or PEKK (Polyether ketone ketone) which belong to the family of PAEK (Polyaryletherketone) polymers.

PAEK polymers are semi-crystalline thermoplastics with high temperature, mechanical, and chemical resistance properties. Utilizing these composite filaments in the 3D printing of medical devices, we are now able to combine silicon nitride’s demonstrated hydrophilicity, radiopacity (favorable imaging via x-ray detection), antipathogenic, and osteogenic properties with the mechanical properties of PEEK and PEKK which are similar to that of human bone for use in medical implants.

Medical 3D printing with silicon nitride

3D printing of medical devices has a variety of applications, particularly in the manufacture of custom 3D printed medical implants for use in spinal dental, and maxillofacial surgery. Using silicon nitride (Si3N4) for these implants can give them antibacterial and osteogenic (promoting bone growth) properties:

Spinal Implants

With over 40,000 human spine implantations over 10 years and a very low percentage of reported adverse events, FleX SN-MC2 “silicon nitride” has an excellent safety record. It is biocompatible, bioactive, and has shown bacterial resistance and superb bone affinity.

Dental Implants

As a dental implant material, FleX SN-MC2 “silicon nitride” has been thoroughly tested to ISO 10993-01 standards and shown to be highly biocompatible. Silicon nitride ceramic is metal-free, like all ceramics, and free of corrosion, galvanism, and electronic disturbances, offering the latest technology in dental implants.

Craniomaxillofacial implants

When used in implants for CMF applications, silicon nitride has the potential to accelerate bone healing, eliminate metal toxicity, and enhance radiographic imaging. Because it’s antipathogenic, silicon nitride can also decrease infection rates and ease the healthcare burden associated with failed implants.

Foot osteotomy & fusion

Silicon nitride has the flexibility of a dense, porous, or combined architecture that can mimic the cortical-cancellous structure of bone. This characteristic combined with numerous other benefits, such as antibacterial resistance, make silicon nitride a strong consideration as an implant material in this application.

Partnering with SINTX

Silicon nitride has a fortuitous combination of strength, toughness, wear resistance, biocompatibility, bioactivity, bone integration, structural stability, corrosion resistance, and ease of imaging; all of which are desired properties in medical implants.

By harnessing the unique properties of medical-grade silicon nitride and the limitless possibilities of 3D printing, SINTX and other medical device manufacturers can produce highly complex, high-performance 3D printed implants that achieve exceptional rates of acceptance and improve patient outcomes.

Since its inception, SINTX Technologies has been focused on medical-grade silicon nitride. With years of research and expertise, the company has acquired extensive expertise in silicon nitride application development. With unrivaled in-house manufacturing capabilities, SINTX can create intricate designs and shapes that can be rapidly developed, prototyped, and tested across a wide variety of medical applications.

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Davide Sher

Since 2002, Davide has built up extensive experience as a technology journalist, market analyst and consultant for the additive manufacturing industry. Born in Milan, Italy, he spent 12 years in the United States, where he completed his studies at SUNY USB. As a journalist covering the tech and videogame industry for over 10 years, he began covering the AM industry in 2013, first as an international journalist and subsequently as a market analyst, focusing on the additive manufacturing industry and relative vertical markets. In 2016 he co-founded London-based VoxelMatters. Today the company publishes the leading news and insights websites and, as well as VoxelMatters Directory, the largest global directory of companies in the additive manufacturing industry.

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