3D Printing of Medical Devices with Silicon Nitride

Using silicon nitride for 3D printing of medical devices, SINTX is able to create novel implant designs with enticing biocompatible characteristics that result in the long-term success of implantable medical devices.

3D Printing Technology in Medicine

Three-dimensional (3D) printing refers to several manufacturing technologies that generate a physical model from digital information. Every year, 3D printing (also called additive manufacturing or additive layer manufacturing) offers numerous applications in the healthcare field, helping to save and improve lives in ways never imagined up to now.

This technology allows medical device manufacturers, such as SINTX, a high degree of intricacy and customization. With 3D printing, implantable medical devices can be created to match very complex structures within a patient’s anatomy.

SINTX’s Outlook as a Medical Implant Manufacturer

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), we are now able to develop novel composite filaments for use in fabricating next-generation medical implants via additive manufacturing. 

Newly acquired polymer processing equipment:

polymer processing equipment used in the 3D printing of medical devices

With this equipment, we intend to utilize our expertise in ceramics and polymer processing with our growing knowledge of 3D printing medical devices to produce complex, novel implant designs of varying silicon nitride compositions. Our medical-grade 3D printer will allow us to fabricate parts with textures and porosities, features that cannot be produced by any other manufacturing method. 

Our development of composite filament will allow us to produce implantable medical devices with enticing 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.

Silicon Nitride – the Ideal Biomaterial for Implantable Medical Devices

SINTX Technologies is focused on the 3D printing of medical devices using medical-grade silicon nitride. 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.

Benefits of using Silicon Nitride as a Medical Implant Material

Enhanced Osteopromotion:

Silicon nitride turns on osteoblasts (bone-forming cells) and suppresses osteoclasts (bone-resorbing cells). A manufacturing change called “nitrogen-annealing” results in a near-200% increase in bone formation by cells exposed to silicon nitride. This finding has excellent implications for speeding up bone healing, bone fusion, and implant integration into the skeleton.

Bacterial Resistance:

Bacterial infection of any biomaterial implant is a serious clinical problem. Silicon nitride offers a potential easy solution; it is inherently resistant to bacteria and biofilm formation. Additionally, a recent study has shown a direct bactericidal effect against an oral pathogen. The antibacterial behavior of silicon nitride is probably multifactorial, and relates to surface chemistry, surface pH, texture, and electrical charge.

Increased Protein Absorption:

The body’s biological response to implantable medical devices is usually to create a protein wall around the device, cutting it off from the rest of the body. Depending on the required function of the device, this protein barrier can cause the device to fail. For example, an artificial valve could not function properly if this were to occur. 

Silicon nitride demonstrates significantly greater protein adsorption in comparison to alternative medical implant materials, such as monolithic PEEK and titanium, thus preventing the buildup of a protein barrier in the first place. 

Compatible With All Imaging Modalities:

Silicon nitride implants are radiolucent with clearly visible boundaries and produce no artifacts or scattering under CT and no distortion under MRI. This enables an exact view of the implant for precise intraoperative placement and postoperative fusion assessment.

Silicon Nitride Based Polymers 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) 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.

PEEK & PEKK Monomers:

PEEK and PEKK Monomers

Medical Applications of 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 health care 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.

In Conclusion

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. 

When you combine this ideal biomaterial with the flexibility that 3D printing of medical devices allows, medical device manufacturers, such as SINTX, can create high-performance medical implantable devices with a high degree of intricacy and customization resulting in high rates of implant acceptance and long-term success.

OEM Partnerships with SINTX

Since its inception, SINTX Technologies has been focused on medical-grade silicon nitride. 

With years of research and expertise, we’re experts in silicon nitride application development. Our unrivaled in-house manufacturing capabilities allow for intricate designs and shapes that can be rapidly developed, prototyped, and tested across a wide variety of medical applications.

We invite you to Contact SINTX Technologies to see how silicon nitride might be beneficial to your patients, practice, or medical device manufacturing facility. Get started on your custom 3D printed medical devices

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