What is 3D Printing?
3-Dimensional (3D) printing is a process that creates a three-dimensional object by building successive layers of raw material. Each new layer is attached to the previous one until the object is complete. Objects are produced from a digital 3D file, such as a computer-aided design (CAD) drawing or a Magnetic Resonance Image (MRI) (1). 3D printing is a type of additive manufacturing and was first invented in the 1984 by Charles Hull, an engineer and physicist (1,3). He invented the first 3D printed object, which was a tiny cup for eye wash (3). In health care, there is great interest in 3D printing as a tool that can help clinicians, health care administrators, and device manufacturers to visualize and plan complex interventions; create patient-specific devices and build devices of complex internal and external shape and structure from biocompatible materials (2).
How is 3D Printing done?
The first step of 3D printing is obtaining a digital model, which can be based on CT‐scan, laser scan data, or could be designed using a computer (CAD). Once a 3D model is created, it is sliced into printable layers. Slicing software takes scans of each layer of a model and instructs the printer on how to move in order to recreate that layer and “fill” a model. This fill gives a 3D printed object internal lattices and columns that help shape and strengthen the object. The last step is printing. During the printing step, the 3D printer adds hundreds or thousands of 2D prints on top of one another to make a three-dimensional object (4,5).
What are the common production techniques for 3D Printing?
The choice of 3D printing technology can depend on many factors including how the final product will be used (5). Some of the frequently preferred techniques are powder bed fusion (selective laser melting [SLM], selective laser sintering [SLS]), material extrusion, stereolithography (SLA). The differences between the techniques are in the method of processing the layers and the material used (4). The most common technology used for 3D printing medical devices is powder bed fusion. Powder bed fusion works well with a variety of materials used in medical devices, such as titanium and nylon (6).
The powder bed fusion process builds a three-dimensional product from very fine metal or plastic powder, which is poured onto a platform and levelled carefully. A laser or electron beam then moves across the powder layer and melts the material it touches. Melted material fuses to the layer below it and to the powder around it to create a solid. Once a layer is completed, the platform moves down and one more layer of carefully levelled powder is placed on top (6).
Clinical Applications of 3D Printing
3D printing health care applications are generally categorized into the following applications: anatomical models (e.g., for surgical preparation, planning, or to aid diagnosis), surgical guides, tools and instruments, implants and therapeutic devices, prosthetics, tissues and organs, dental applications.
Surgical applications: 3D printing has improved the imaging system in surgical planning by ensuring a better visualisation of the patient's anatomical structure. During surgery, a surgical template helps to precisely guide the surgical procedure, estimate appropriate angles and have a prior opinion of the direction and size of the bone or tissue. Therefore, this technology is used today as a guide that provides correct planning and supervision during surgery to provide accurate imaging inside the body. In addition, this application can be adopted as an easy and fast method in the diagnosis and treatment of the disease (4).
Medical devices: 3D printer technology is being utilised in the production of many devices used in the medicine. 3D printers are used to manufacture a variety of medical devices, including those with complex geometry. Some devices are printed from a standard design to make multiple identical copies of the same device. Other devices, called patient-specific devices, are created from a specific patient’s imaging data (6).
Examples of medical devices produced by 3D printing include hearing aids suitable for patient’s ear anatomy, patient-specific prostheses such as knee joints, tibia bone, femur bone, fibula bone implants, dental implants and cranial implants. Cranial implants, for example, may be required due to damage from an accident or injury. These implants protect the brain from further damage, improve the cranial appearance and provide psychological support to the patient. With successful surgical imaging, anatomical information of the patient is obtained, a digital model is created, and complications and errors that may occur in the placement of the implants are prevented. In addition, implants produced specifically for the patient's anatomy increase the chance of success (4).
Bioprinting: Bioprinting is an evolving technology with various applications in making three-dimensional functional artificial tissue structures and organs to replace injured or diseased tissues or organs (2,4). It is a type of 3D-printing technique, that combines living cells (e.g., stem cells) and supportive biomaterials (e.g., scaffolds on which cells can grow) into so-called bioinks. These bioinks are printed into prespecified computer-generated designs with the goal of eventually maturing into specific tissues (2). Some of the methods used for 3D bioprinting of cells are photolithography, magnetic 3D bioprinting, stereolithography and direct cell extrusion (4). While in vivo work in regenerative medicine is still in the very early stages of research — with full organ transplant seen as the long-term goal — a number of companies around the world are actively working to improve bioprinting by expanding the types of materials and optimizing technological approaches (2).
Bioprinting is being explored for tissue modelling, toxicology testing, prosthetics and dental applications, engineered tissues and transplantations of full or partial organs as part of regenerative medicine (2).
3D printing of medications: The potential benefits of using 3D printing techniques for producing medications include the ability to personalize a medication dose, combine the delivery of medications, and avoid the use of bulking agents or fillers that a person may be intolerant to (such as lactose). One example is Spritam (levetiracetam; a treatment for epilepsy), approved by the Food and Drug Administration (FDA) in 2015. This product is produced using a 3D printing technique called ZipDose that combines power and liquid printing to produce high-dose, quick-dissolving pills (2).
Clinical education and training: 3D printed anatomical models can also be used to educate, train clinicians; and help patients understand their condition, understand complex anatomy and procedures, and improve shared understanding when seeking informed consent (2).
Examples of few 3D Printed products
Products available in the global market include shoulder implants, hip implants and Cranio-Maxillofacial implants manufactured by a company called Materialise. The company also provides 3D printed anatomical models and personalized surgical guides (7). In 2020, FDA approved a 3D printed Class II Intervertebral body fusion device developed by Emerging Implant Technologies GmbH (EIT; acquired by Johnson and Johnson Medical) that can be used in a number of injuries/defects from the middle to the top of the spine (8). A company named Ossiform, produces 3D printed bioceramic cell culture systems for cell- and bacteria studies, tissue engineering, disease modelling and drug screening. It is also in the process of developing a particle 3D (P3D) Bone a patient specific implant (PSI) that remodels into real living bone. Made from pure, 3D printed ß-tricalcium phosphate, it is a more natural implant in terms of both material, shape, porosity and structure that will enable a full restoration of the functionality and appearance of the patient's bones (9).
Emergence of 3D Printing in Canada
In Canada, medical devices produced using 3D printing are subject to the Medical Devices Regulations (9). The Health Canada Guidance Document: Supporting Evidence for Implantable Medical Devices Manufactured by 3D Printing provides guidance to manufacturers regarding specific evidence required to support pre-market license applications for Class III and Class IV implantable medical devices and is supplementary to existing evidence requirements for all Class III and Class IV devices (10). However, it does not provide guidance on standalone software, custom-made devices, anatomical models or products made through bioprinting, which incorporate viable living cells.
As of April 10, 2019, Health Canada has approved twenty 3D printed implantable devices for orthopaedic and dental applications, such as cranial repair or tooth replacement (11). Health Canada, in December 2021, approved its first Canadian-made 3D printed medical implant, named as Specifit 3D mandibular plate, developed by the 3D Anatomical Construction Laboratory (LARA 3D) in Quebec City. The 3D printed device is a customizable mandibular (lower jaw) plate for use in facial reconstruction surgery, predominantly for patients with oral cancer. It can also be used in conjunction with surgical guides for cutting and drilling operations. The implant can be 3D printed according to the anatomy of the patient, which will help improve surgery success rates, as well as reduce both surgery and recovery times (12).
The 3D printing technology represents a big opportunity to help pharmaceutical and medical companies create more specific drugs, enable a rapid production of medical implants, and changing the way that doctors and surgeons plan procedures. The use of this technology in the pharmaceutical sector and bioprinting applications is not widespread yet and continues to be tested and developed, but when developed in the near future, it will bring revolutionary innovations to the medical field and help prolong and improve the quality of life (4). However, it must be accompanied by updated legislations and regulations in order to guarantee its correct use (2).
Author: Pratibha Duggal, ICON Plc.
References:
- Food and Drug Administration (FDA). 3D Printing of Medical Devices [Accessed 20 May 2022] Available from: https://www.fda.gov/medical-devices/products-and-medical-procedures/3d-printing-medical-devices?source=govdelivery&utm_medium=email&utm_source=govdelivery
- CADTH ISSUES IN EMERGING HEALTH TECHNOLOGIES. An Overview of Clinical Applications of 3-D Printing and Bioprinting. Issue 175, April 2019
- 3D Printing in Drug Development & Emerging Health Care. Presentation by Akm Khairuzzaman, Senior Reviewer, Division of Biopharmaceutics, ONDP, CDER, FDA. [Accessed 31 May 2022] Available from: www.fda.gov/media/125479/download
- Bozkurt Y, Karayel E. 3D printing technology; methods, biomedical applications, future opportunities and trends. Journal of Materials Research and Technology. 2021 Sep 1;14:1430-50.
- What is 3D printing? 3D Printing.com [Accessed 10 Jun 2022] Available from: https://3dprinting.com/what-is-3d-printing/
- Food and Drug Administration. Medical Applications of 3D Printing [Accessed 03 Jun 2022] Available at: https://www.fda.gov/medical-devices/3d-printing-medical-devices/medical-applications-3d-printing#:~:text=3D%20printers%20are%20used%20to,copies%20of%20the%20same%20device.
- Materialise. Products and Services. Personalized implants [Accessed 06 Jun 2022] Available from:https://www.materialise.com/en/products-and-services
- Food and Drug Administration. Approval Letter, July 2020. K201605 [Accessed 06 Jun 2022] Available from: https://www.accessdata.fda.gov/cdrh_docs/pdf20/K201605.pdf
- Ossiform. We Print Bone. P3D Bone and P3D Scaffolds [Accessed on 06 Jun 2022] Available from: https://ossiform.com/p3d-bone.aspx
- Health Canada Guidance Document: Supporting Evidence for Implantable Medical Devices Manufactured by 3D Printing [Accessed 06 Jun 2022] Available from: https://www.canada.ca/en/health-canada/services/drugs-health-products/medical-devices/application-information/guidance-documents/3d-licensing-requirements/document.html
- Health Canada News Release. Increasing access to 3D Printed Implantable Medical Devices for patients. April 2019 [Accessed on 06 Jun 2022] Available from: https://www.canada.ca/en/health-canada/news/2019/04/increasing-access-to-3d-printed-implantable-medical-devices-for-patients.html
- Investissement Quebec, CRIQ. Health Canada Approves the First Medical Implant 3D-Printed by a Canadian Manufacturer. Dec 2021 [Accessed 06 Jun 2022] Available from: https://www.criq.qc.ca/en/headlines/icalrepeat.detail/2021/12/02/429/-/health-canada-approves-the-first-medical-implant-3d-printed-by-a-canadian-manufacturer.html