3D printing is a relatively new manufacturing process, used to create small batches of highly personalized items. The technology is also capable of creating products using biological material, which can be biocompatible with human patients. For this reason, 3D printing is used extensively in the medical field. In dentistry, this technology is typically used to replace damaged or lost teeth. Researchers at KU Leuven University, however, are now looking beyond replacement and towards regeneration and regrowth of damaged teeth, using 3D printing to restore the tooth’s root.
Researchers are looking at ways to restore teeth from the root via 3D printing. Image Credit: MarinaGrigorivna/Shutterstock.com
3D Printing: Benefits and Disadvantages
As opposed to subtractive manufacturing in which material is taken away to create the final product, such as carving an item from a large block of wood, 3D printing is a form of additive manufacturing, where the material is gradually added until the product is complete.
A 3D printer consists of a nozzle and extruder which can move freely across the x, y, and z plane. The printer operates by recreating an inputted Computer-Aided Design (CAD) model. The material filament travels through the extruder into the nozzle, which then builds the product on a print bed. The printer will complete this manufacturing process layer by layer, building upon itself in small increments.
The most obvious benefit of additive manufacturing is the reduction of waste. The waste that is produced is also very easy to recycle. 3D printing also means a product can be created straight from a CAD drawing. There is no need for molds or stamps such in subtractive manufacturing and it also means there are no switchover costs from changing tools such as drill bits.
There are still some disadvantages to additive manufacturing methods. Though 3D printing is cheaper for complex structures or small batches of products, it is slow and expensive in comparison to subtractive methods if manufacturing in bulk. 3D-printed products also have a rough surface as the material layers made from additive manufacturing leave ridges across the entire body. Because of this, subtractive manufacturing methods may be needed to give a 3D-printed product a smooth surface finish.
3D Printing in Dentistry
As 3D printing is more suited to creating small batches of unique and complex structures, this method is increasingly used in the regenerative medicine industry and is capable of rapidly manufacturing highly personalized pieces, made specifically for each individual patient, while still being relatively cost-effective.
Another benefit of 3D printing in a medical setting is its ability to create biocompatible components. 3D bioprinting is a method of manufacturing using bioink, a material made using biological material. Bioprinting is being explored for its applications in bone fracture treatment as well as fully 3D-printed human organs. Most importantly, the technology is also being used for the cell regrowth of human teeth.
The focus on tissue restoration regrowth rather than replacement, known as regenerative dentistry, gained traction after new observations and innovations of 3D bioprinting were discovered by researchers at KU Leuven University. They observed compromised dentin-pulp complexes and their effect on tooth growth.
Research has shown that teeth affected by developmental problems or trauma can compromise dental pulp. This pulp houses most of the tooth’s nerves and is responsible for the tooth’s formation of dentin, the less brittle material that supports the enamel of the tooth. In damaged teeth, pulp necrosis may occur and severely hinder tooth growth. In these circumstances, the cell tissue of the tooth, or even the entire tooth, may be lost.
Researchers have begun to experiment with the restoration of compromised dentin-pulp complexes, using 3D-printed chitosan scaffolding. If completed correctly, this will help the inflamed root to promote dentin production, regrowing the previously damaged tooth.
Chitosan refers to the biomaterial used to create the tooth root scaffolding. This material is derived from the exoskeletons of creatures, primarily crustaceans, and from fungi. This material is preferred as it is biocompatible and has antimicrobial properties. The fungi-derived chitosan is also less likely to cause an allergic reaction.
Molds to create these chitosan scaffolds were created in CAD, 3D-printed, and completed using a freeze-drying manufacturing method. These molds can be customized depending on the geometry of the patient’s mouth, or to better accommodate the specific teeth that need repair.
The scaffolds that have been fitted are now currently in observation. If the experiment proves successful, the compromised pulp will not reject the scaffolding, and the immune system will act accordingly. The stem cell growth will also be monitored.
Other Applications for 3D Printing in Dentistry
Another good example of 3D printing’s potential in this industry is in Nasoalveolar Molding (NAM) plates. NAM plates are plastic plates used to “reshape the gums, lip and nostrils with a plastic plate before cleft lip and palate surgery”. The plates are used predominantly in young children. They prevent the cleft palette from worsening, meaning less invasive surgeries will be needed in the future.
As the shape and dimensions of the cleft palette will be different for every child, these NAM plates should be highly customizable. Additionally, the speed of the NAM plate creation process should be as fast as possible; the sooner the child has the plate fitted, the less severe the developing cleft palette can become. The dimensions will also change as the child ages, meaning the fitting must be fast as the plate will become obsolete and need replacement after a set period of time. Both of these requirements- fast rate of manufacture and highly customizable- are both accommodated by 3D printing.
Scientists at the Technical University of Munich (TUM), noticing the potential for this manufacturing method, studied how 3D printing improves the current process of NAM plate manufacture and fitting. Their new process, a “semi-automated workflow” called RapidNAM, scans the mouth of the child with an “automatic detection of the alveolar ridge”. This process can 3D-print “a series of molding plates within minutes”. (Lord, B. 2018). The user is still able to intervene and customize the CAD manually.
References and Further Reading
Everett, H. (2021). Researchers move closer to regenerative dentistry with 3D printing. [online] 3D Printing Industry. Available at: https://3dprintingindustry.com/news/researchers-move-closer-to-regenerative-dentistry-with-3d-printing-189903/ (Accessed 5 June 2021).
K., Y., (2021). Imagine that your teeth regrow from the root, a research team from KU Leuven could make it that happen, using 3D printing. [online] 3D ADEPT MEDIA. Available at: https://3dadept.com/imagine-that-your-teeth-regrow-from-the-root-a-research-team-from-ku-leuven-could-make-it-that-happen-using-3d-printing (Accessed 3 June 2021).
Seattle Children’s Hospital (n.d). Nasoalveolar Molding (NAM). [online] Available at: https://www.seattlechildrens.org/clinics/craniofacial/services/nam/ (Accessed 5 June 2021).
Ford, S. and Despeisse, M. (2016). Additive manufacturing and sustainability: an exploratory study of the advantages and challenges. Journal of Cleaner Production, 137, pp.1573-1587. https://doi.org/10.1016/j.jclepro.2016.04.150
Lord, B. (2018). TUM researchers apply 3D printing to treat cleft lips and palates - 3D Printing Industry. [online] 3D Printing Industry. Available at: https://3dprintingindustry.com/news/tum-researchers-apply-3d-printing-to-treat-cleft-lips-and-palates-138269/ (Accessed 3 June 2021).
Everett, H (2021). Researchers Take Step Closer to 3D Printed Organs with New Cell Laden Bioink.[online] 3D Printing Industry. Available at: https://3dprintingindustry.com/news/researchers-take-step-closer-to-3d-printed-organs-with-new-cell-laden-bioink-186728/ (Accessed 9 June 2021).
Sloan, A., (2014). Stem cell biology and tissue engineering in dental sciences. Cardiff: Elsevier Academic Press.
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