Interview published in June 2022 and produced in collaboration with Lithoz. Roles, applications and industrial figures reflect that period.
On the heels of a dossier that highlights “the current manufacturing landscape of Ceramic 3D printing and the business model that drives industrial applications” (March/April edition of 3D ADEPT Mag – pp 6-12), it feels right to focus on a vertical industry where there is still a long way to go for industry professionals to fully exploit the potential of ceramic 3D printing: the healthcare and medical industries.
Ceramics are used in many medical applications, but medical AM market figures do not automatically isolate ceramic AM. This feature examines its possibilities from Lithoz’s perspective without presenting an exhaustive market measurement.
Healthcare uses of ceramics include certain prostheses, dental restorations and medical equipment components, including imaging equipment. These examples concern ceramics generally; they do not establish that every device is already manufactured by 3D printing.
Laboratories also use ceramic and glass equipment for analysis and technical components. Selection depends on the properties required and the operating conditions.
Beyond geometric possibilities, material limitations, the complete process and device-specific requirements must be examined. This feature discusses these criteria with Daniel Bomze, Lithoz’s Director Medical Solutions at the time of the interview.
Use of AM in the healthcare industry: ceramic 3D printing vs other AM processes?
Most applications that are successfully completed via AM are usually described and highlighted through the lens of conventional manufacturing processes as the primary angle of comparison. Over time, with the advancements of AM technologies and their ability to meet the production requirements of several industries, we increasingly see the advantages of certain AM technologies more highlighted for certain applications. This can be seen in the healthcare industry as well, where we have seen applications made possible with various types of metal AM processes or polymer 3D printing.
“Usually, when we talk about ceramic 3D printing applications, the comparison is easily made with conventional manufacturing processes such as injection moulding and milling”, Dr. Daniel Bomze, Director Medical Solutions at Lithoz lays emphasis on, from the outset.
“However, when we look at the broad range of AM processes that can address the production requirements of various industries, ceramics are likely to compete with metals such as Titanium, cobalt chrome which is used in orthopedic and dental applications, and high-performance polymers like PEEK which can be 3D printed in different ways and resorbable materials. The choice of an additive manufacturing material will therefore depend on where we want to provide a solution. In resorbable applications for instance, metals will not be the ideal choice in terms of materials, while in the polymeric side of the business, there are already materials that are already resorbable”, he continues.
This comparison needs qualification: bioresorbable metallic alloys, including magnesium-based systems, are also the subject of biomedical research. Selection cannot therefore be reduced to a blanket contrast between ceramics and metals.
Lithoz develops ceramic manufacturing machines, software and materials. Its LCM process (Lithography-based Ceramic Manufacturing) uses light to cure a photosensitive binder containing ceramic particles, layer by layer. After cleaning, the green part must be debound and sintered using a material-specific cycle. Lithoz’s technical brochure describes this chain: printing alone does not produce the final ceramic part.
Lithoz presents applications in medical, aerospace and energy sectors. An application or material in its portfolio is not blanket authorisation for medical use. The FDA explains that evaluation concerns the finished device and its intended use, rather than unrestricted approval of a material.
Key factors to consider when exploring technical ceramics in medical 3D printing applications
Oxide ceramics, such as alumina and zirconia, can be distinguished from non-oxides such as certain nitrides. Bioceramic describes a biological use or interaction; it is not a chemical family wholly separate from the first two.
Alumina and zirconia are among the technical ceramics used in AM and studied for medical or dental applications. Properties, cost and processing behaviour depend on composition and manufacturing conditions; a universal maximum of 15% silica does not define oxide ceramics.
Bioceramics are a class of advanced ceramics that increasingly raise the interest of healthcare professionals due to their ability to be used within the body. They are often employed in medical and dental applications, mainly as implants and replacements. Not only for their biocompatibility, but also for their ability to help the body repair itself. Promising applications of bioceramics are therefore seen in reconstructive surgery. According to Bomze, one of their biggest advantage is their unlimited availability. For reconstructive surgeries where bone graft is needed, it may happen that the surgeon requires a large area of extraction to achieve better results. In that case, the bone tissue might require a separate procedure, which means double surgery, and increased risks of complications for both the patient and the surgeon. Whereas artificial bones created using bioceramics may lead to patient-specific 3D printed solutions while “removing the need for further surgeries.” Although they might lead to more brittleness as they do not have the elasticity of bone tissues, Bomze outlines that “with artificial bones, the chemical composition is exactly the same than the mineral fraction of the bone.” Lastly, their utilization also reduces “the surgery time in the operating room and a better patient experience.”
Bomze is describing the potential of certain bone substitutes, notably calcium phosphates. These statements do not apply to all bioceramics. Similarity to bone’s mineral fraction does not mean reproducing complete living bone or guaranteeing that no further surgery will be needed.
Non-oxides, including silicon nitride and aluminium nitride, offer other combinations of properties. Cost, environmental resistance and manufacturing difficulties depend on the material and process; they cannot uniformly be ranked as more costly or harder to print than all oxides.
Interestingly, Lithoz has built up extensive expertise in the development of materials for these three categories. For the Director Medical Solutions at Lithoz, the first criteria that should be assessed when exploring technical ceramics in medical 3D printing, is the properties of the selected material for a given application.
“Ceramics have outstanding properties and in some cases, they can be the only option for specific applications and requirements. However, as all materials, they cannot be the solution for all issues. What’s really important here is to understand first the customer requirements and to select the materials that best meet these requirements. In industrial applications for instance, aluminum nitride may be the ideal ceramic to go with, but you won’t probably use it to create a crown – dental part – because it’s more brittle than zirconia.
And if you do not look at the materials side first when you explore ceramic 3D printing, then I would recommend to assess other details. Almost all technologies’ providers are looking to print the part that looks at first glance to the geometry that the customer requests – This part is often called ‘green part’. However, it’s only after sintering that you will be able to tell if you can rely on the part’s properties, or if the machine you invested in, can produce green parts, you will never be able to manufacture ceramic parts because there will be cracks, and other issues related to size and dimensions.
Therefore, before investing in a production technology, it’s important to understand all the consequences that may result from every type of production and the details that are often least highlighted.”
The key point is to verify properties and dimensions after debinding and sintering, not only the printed geometry. Some ceramics withstand specific thermal or chemical conditions well, but these capabilities are not universal and brittleness must be considered.
“The original fact of ceramics’ brittleness, in my opinion, can be directly addressed by developing new types of ceramics. At Lithoz, we have developed a solid area of expertise in the development of new types of printable ceramic materials which led our customers to develop various forms of 3D objects. Also Lithoz works very closely with ceramic powder manufacturers to offer newly developed ceramic materials for additive manufacturing on the market. Furthermore, with the advancements we made in multi-material 3D printing, we came to realize that combining different kinds of materials enable to address most of the disadvantages raised by technical ceramics.
Let’s take the example of two kinds of ceramics: bioresorbable materials – osseoconductive materials that facilitate bone regeneration – and zirconia oxide, a high-performance ceramic. The combination of these materials allows to fulfill the requirements of a critical size-effect in load-bearing body implants.
In certain applications for instance, you might want to combine zirconia with some types of metals in order to have the elastic properties of a metal with for example, some wear resistance properties of ceramics. Ceramics could be used as a cover to protect the part and metals as a electrical conductive element. At the end, the part created, benefits from the combination of each material selected.
Another solution that is worth mentioning might be to go with non-sintered ceramics. If you use for example, a highly-filled resorbable polymer material with a certain ceramic, you would not come up with a pure ceramic in the end, but rather a composite material that could address the brittleness of ceramics.
At Lithoz, we have also tried the combination of glass fiber and carbon fiber which works well. However, it might come with some limitations and our R&D team is currently working on them” Bomze explains.
These combinations describe development directions and possibilities discussed in 2022; they are not general clinical validation of the corresponding implants.
Lithoz’s representative also raised our attention on the fact that limitations of technical ceramics may also depend on the manufacturing technology you use to process them.
“For every manufacturing process used for medical devices, you need to adapt your processes. At first glance, this might sound like extra work but if it allows you to benefit from the design freedom of AM, then you should do it properly. In this case for instance, it’s crucial to understand the design rules in ceramic AM to know exactly all the advantages that may result from a given application versus the disadvantages. I believe that understanding these design rules are essential to get out the most of the technology”, he adds
Focus on applications: digital dentistry
In the 2022 interview, Lithoz highlights ceramic dental implant development with Dr Jens Tartsch, ESCI’s founder and president, and Swiss technical ceramics specialist Metoxit.
The company highlights LCM’s ability to manufacture multiple complex geometries in one build. It cites zirconia, ATZ and ZTA for dental application development. Series manufacturing capability does not itself establish clinical qualification of every device.
“Zirconia (3 mol% yttria partially-stabilized) offers excellent strength without having to make major compromises on aesthetics. Another newly emerged material in this context is silicon nitride. It provides an exceptional combination of biocompatibility, antibacterial and high-mechanical performances. Another advantage of using silicon nitride for implants is the good nano-roughness of the surface, which strongly facilitates bone attachment. By processing this material with the LCM technology, the micro-roughness can be varied by using different layer heights and helping to produce an implant on which bone cells can anchor and grow on. Materials such as ATZ (alumina toughened zirconia) and ZTA (zirconia toughened alumina) are also suitable for dental applications. Unlike metals, there is no debate around ion release or corrosion and they have long-term stability both in soft and in hard tissue”, the company points out.
These properties are presented by the supplier. They must be verified for the final material, surface and device in the intended application; one formulation’s biocompatibility or performance does not automatically extend to others.
The original feature mentions 95% material utilisation without sufficiently defining its calculation basis or protocol. This is not a conforming-part yield. The following table preserves the productivity figures reported at the time, with their interpretation limits.
| Reported metric | 1 CeraFab System S65 | 4 CeraFab System S65 |
|---|---|---|
| Implants per build | 153 | 612 |
| Reported build duration | 5.6 h | 5.6 h |
| Reported time per implant (see note) | 3 min | 0.5 min |
| Reported implants over 24 h | 656 | 2,624 |
Reading note: the stated nominal dimensions are 103 × 64 × 320 mm. A ratio of 5.6 hours to 153 parts is approximately 2.2 minutes per part, not the reported 3 minutes; for 612 parts it is approximately 0.55 minutes. The original protocol does not resolve this discrepancy. The 24-hour figures assume continuous operation and do not describe the complete time for debinding, sintering, inspection or clinical preparation.
Beyond implants, Lithoz also explores dental restorations. Bruxism, mentioned in the original text, concerns tooth clenching or grinding; it is not a category of printed restoration.
The company describes thin tabletop restorations among the possibilities. Accuracy and indications must be evaluated for the particular process and case, rather than assuming universal superiority over conventional methods.
“The process starts with a scan of the tooth, from which a digital model is created. This model is then accurately and efficiently 3D printed, minimizing material consumption compared to milling or heat pressing. Once debinded and sintered, the restoration is ready to be fitted, avoiding the removal of the healthy tooth material and therefore fulfilling the principles of minimal invasive treatment and maximum patient satisfaction”, a Lithoz report reads.
And right now…?
The interview highlights the importance of connecting material selection, design and control of thermal processing. Collaboration with researchers and device manufacturers can help evaluate these possibilities.
Moving from a demonstrator to a patient device nevertheless requires appropriate validation, traceability and the applicable regulatory steps. Printing a geometry or multiplying production trials does not itself establish clinical safety and effectiveness.
This content has been created in collaboration with Lithoz.
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