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Additive Manufacturing Systems for dental and Medicinal purposes

 

Lithoz - your trusted partner in medicine

When it comes to people’s health, it is extremely important to have strong and competent partners. Lithoz possesses expert knowledge in this industry, and has a wide spectrum of products and services available which are specially suited to the manufacture of innovative and patient-specific products for medical applications. We offer customized solutions to doctors, researchers and manufacturers of medical devices throughout the entire process chain of the additive manufacturing of ceramics.

 

All Ceramics – from patient-specific implants to surgical instruments

In contrast to materials already established in the medical field, such as metals or polymers, bioinert or bioresorbable ceramics possess properties which facilitate a multitude of new applications in the medicinal sector. Using the tool-free Lithography-based Ceramic Manufacturing (LCM) technology, it is possible to manufacture highly complex lattice structures, undercuts and channels with dimensions of up to 100 µm. The limitations of conventional manufacturing technology (such as milling or injection molding) are largely eliminated, and the development and production of components for medical devices, surgical instruments, dental prostheses and patient-specific implants is possible. The result is a batch-orientated process for producing individualized components, with the additional possibility of series production.

 

Medical and dental applications of 3D-printed ceramics

FULLY ANATOMICAL CROWNS FOR MINIMALLY INVASIVE RESTORATIONS

Best practice example: crowns with perfect fissures (material: zirconia)

While crowns and bridges can be reliably produced using conventional subtractive manufacturing techniques (such as CAD/CAM), this technique is not ideal for ultra-thin reconstructions. With these so-called minimally invasive occlusal veneers, a therapeutic approach is taken where as little healthy tooth material as possible is removed before the reconstruction is fixed over it. LCM technology enables the production of veneers with minimum wall thicknesses of only 100 µm, and offers unprecedented imaging accuracy when producing anatomically shaped fissure surfaces.

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In conventional subtractive manufacturing techniques, zirconia is processed in the whiting phase (where it is not fully compacted). The material has a low inherent strength and the marginal areas need to be artificially made thicker to prevent the edges from breaking. Both the occlusal and marginal surfaces are essential areas of the restoration, which is why post-processing must be carried out very carefully and by hand. Furthermore, the use of rotating instruments means that tapered fissure geometries cannot be adequately reproduced.

Through the use of LCM technology, veneers made of zirconia can now have wall thicknesses that were previously unachievable. Manual post-processing of the functional surfaces is no longer necessary due to the high geometrical accuracy of the process. Other advantages include perfectly shaped occlusal surfaces and excellent surface quality.

LCM technology can also proves itself during the manufacture of all-ceramic crowns and bridges. Manual veneering may be omitted under certain circumstances, and the clinical problem of the veneer splintering is therefore reduced.

HIGH PERFORMANCE CERAMICS FOR DENTAL IMPLANTS

Best practice example: dental implant for series production (material: zirconia)

This endosseous tooth implant can be used as a basic foundation for replacing a missing tooth. Using LCM technology, it is possible to produce complex shaped implants. Additionally, existing standard designs (see illustration) can also be manufactured in large quantities with high strength and geometric accuracy.

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Tooth implants manufactured using LCM technology exhibit excellent surface quality even without post-processing (“as-fired”) (see Figure).The material used, 3 Mol% partially-stabilized zirconia (3Y-TZP), offers excellent strength without having to make major compromises on aesthetics. Naturally, materials such as ATZ (alumina toughened zirconia) and ZTA (zirconia toughened alumina) are also suitable for dental applications. Bioinert high-performance ceramics facilitate the manufacture of diverse implants for dental applications which require perfect surface quality and high accuracy.

BIODEGRADABLE AND BIONIERT CERAMICS FOR THE JAWBONE

Best practice example: Combination implant for the lower jaw (material: beta-tricalcium phosphate and zirconia)

Critically large bone defects can be the result of severe trauma, such as a comminuted fracture of the jaw or bone resection due to bone tumors. The challenge in treating such large defects is that the bone itself is not able to heal the defect without appropriate measures. A dual approach is presented here, in which a cage made of high-strength zirconia gives support during the healing phase and where the inner volume of the implant is made up of bioresorbable beta-tricalcium phosphate (β-TCP).

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β-TCP exhibits very good osseo-integrative properties. The selection of suitable porous and web geometries can significantly improve bone growth and trabecular bones and similarly complex structures can be emulated. Scaffolds which are lightweight but still mechanically strong allow bone and blood vessels to grow in at the same time. Additionally, the supply of blood vessels accelerates the healing process; nutrients reach the new cells, and metabolic products are removed and excreted more quickly.

Another advantage is the high-precision and reproducible macroporosity in connection with a defined surface quality, which significantly improves the cell adhesion of osteoblasts. This eliminates the need for the otherwise necessary removal of autologous bone (e.g. from the iliac crest), which is frequently associated with severe pain and complications at the extraction site.

The image above shows an application in which the β-TCP can be resorbed into the cells and replaced by newly formed bone. The zirconia cage can be left in place due to its outstanding biocompatibility.

Alongside zirconia, alumina and silicon nitride are also suitable for a multitude of new applications for permanent implants in the human body, due to their outstanding mechanical properties (including high strength and wear resistance) in combination with the design freedom of LCM technology.

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HIGH-PERFORMANCE CERAMICS FOR MEDICAL DEVICES

Best practice example: pneumatic cardiac catheter pump (material: alumina)

This intracardial pump, made from bioinert alumina, supplies the heart with blood after a heart attack or operation. Developed by TU Wien and Medizinuniversität Wien, produced by Lithoz.

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The material used is characterized by high mechanical strength and wear resistance, as well as very low surface roughness
(Ra = 0.4 µm). Because of these characteristics, the likelihood of blood clots forming is reduced. The pump is powered with helium and guarantees blood supply during the healing phase without any electrical input, therefore preventing thermal damage to the surrounding tissue.

Bioinert high-performance ceramics allow for the manufacture of components for medical devices which require perfect surface quality and accuracy. For example, the cell interaction with build components which are in direct contact with blood can be minimized and a thrombus formation (blood clot) can therefore be prevented using these implants.

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BIORESORBABLE PATIENT-SPECIFIC IMPLANTS

Best practice example: cranial implant (material: tricalcium phosphate)

This implant is used for bone replacement of parts of the human cranium (e.g. after a severe trauma or trepanation). The geometry of this model is inspired by the cranium with its two layers of cortical bone on the outer side and the highly porous layer of trabecular bone in between. Size and shape of the pores can be varied independently while the interconnectivity of the pores is ensured. The combination of a resorbable material with defined macro porosity enables an ingrowth of bone cells and subsequent vascularisation.

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Tricalcium phosphate (TCP) and hydroxyapatite (HA) are common materials used in bioresorbable implants due to their similarity to the inorganic fraction of bone tissue. By resorption of the material in the body a regrowth of native tissue and thus an ideal healing effect can be achieved without the need for removal of the implant after the healing process. For the designing process data from computed tomography (CT) or magnetic resonance imaging (MRI) can be used. Thus, a maximum fit of the implant to the operation site can be achieved.

Chen et al. compared bone ingrowth in tricalcium phosphate and titanium scaffolds.

Ghayor et al. analyzed different saffold geometries and pore sizes towards their ability to enhance bone ingrowth in tricalcium phosphate scaffolds.

SCAFFOLDS

Best practice example: open pore cell scaffold  (material: Tricalcium phosphate)

AM is well suited to produce ceramic scaffolds that mimic the complex spongy structure of bone, allows it to be both lightweight and strong. Scaffolds allow the in growth of bone cells and provide pathways for vascularization, which accelerates the healing process by enabling the transport of nutrients and removal of metabolic waste. LCM can produce both precisely defined and highly reproducible macro porosity and textured surfaces on the microporous structures, which together can improve osteoblast adhesion and coverage.

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Lithoz LCM-technology enables the fabrication of optimized scaffold designs. Scaffolds are implants with defined geometry and pore structure, that are placed inside the body to treat substantial bone defects caused by tumor removal procedures. Bioresorbable implants are resorbed by the surrounding cells, and thus gradually replaced by endogenous bone tissue. For the development of highly functional scaffolds the pore design is essential to achieve achieving optimized osteoconductivity.

Bioceramic materials are suitable for medical and dental applications due to their outstanding properties

• High mechanical strength and wear resistance • Low thermal and electrical conductivity • Choice between bioinert or bioresorbable materials
• Components can all be removed
  (except bioresorbable materials)
• No interference from CT or MRI • Anti-allergenic materials
• Non-corrosive • Easy to sterilize

• electrically insulating

 

 

LCM TECHNOLOGY FOR MEDICAL AND DENTAL PURPOSES

LCM technology is your first choice when it comes to manufacturing accurate, crack-free and reproducible components with excellent surface quality. It allows for the production of highly complex and finely porous lattice structures up to a feature size of only 100 μm. Iterations and design adaptations can be carried out quickly and digitally on a CAD file and there is no need for tool storage.  Due to this, the procedure is suitable for the cost-effective manufacture of individual components and also for the series production of different batch sizes (from prototype development to series development).

 

Bioresorbable materials for patient-specific implants (material: hydroxyapatite)

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Ceramic-based materials for medical engineering

Lithoz offers its customers an array of materials which are specially suited to the additive manufacturing of medical and dental products, such as:

  • Hydroxyapatite

 

As Lithoz’s success is based on its innovative capabilities and the continuous development of its products, research and development is one of its core assets. Our open system allows you to process a multitude of customer-specific powders that also can be applied for medical purpose, such as:

  • ATZ/ZTA
  • Biodegradable photopolymers
  • Highly dielectric ceramics
  • Bioactive glass (e.g. bioglass)
  • Cermets (ceramics and metal composites)
  • Preceramic polymers

 

Find more information about our medical materials here.

 


Contact us!

 

Are you interested in learning more about our products and services for medical applications? Get in touch with Dr. Daniel Bomze, our in-house expert for any concern in medical: +43 1 934 66 12 - 219 / dbomze@lithoz.com