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3D printing in dentistry: fad or fundamental?

In this editorial piece adapted from a talk at the 3D Medical Printing Series conference (29–30 March 2022, Veldhoven, Netherlands), Les Kalman of Western University (London, Canada) and Ghazel Ghasemi of York University (Toronto, Canada) discuss the potential of 3D printing in dentistry – is it a fad or fundamental?

There has been such a surge of 3D printing in dentistry that it looked as though 3D printing was going to become mainstream; however, it appears that 3D printing has plateaued…or has it? The question remains, is 3D printing in dentistry a fad, or is this going to be a fundamental component of the profession? Let’s consider some cases and workflows and see if we can come to a consensus.

If we reflect on digital dentistry and consider the workflow, we can generalize that it is about creating something tangible, such as a prosthesis or device, in a predictable and successful manner from a digital file. The workflow requires obtaining a digital file through scanning, then using digital design to optimize the device, selection of the material of choice and fabrication through subtractive manufacturing, milling and, finally, processing through staining and glazing. This creates the final prosthesis that can then be delivered to the patient.

 

 

 

 

 

 

Digital file converted to a 3D-printed zirconia crown.

An example of a brief clinical case that we published many years ago illustrates how we replaced a failed resin bonded anterior bridge with an in-house, chair-side lithium disilicate immediate provisional using CAD/CAM. The workflow highlights the typical subtractive manufacturing approach.

  

 

 

When we consider 3D printing, we can appreciate that the material selection and fabrication pathway differ.

3D printing offers several benefits, such as efficiency, convenience, customization – including patient-specific prostheses – desirable physical properties and the ability to fabricate very complex micro geometries. 3D printing seems to be a much leaner manufacturing approach and it does seem to present a more sustainable option for the fabrication of medical devices and dental prosthesis.

Plastics

It appears 3D printing with plastics impacted dentistry, especially with guides and aligners. We now also have plastic patient models, implant guides, appliances, simulation replicas, and patient-specific models used for education and communication. The use of different colors and different textures are possible, essentially opening up the fabrication workflow with the only limiting factors being time and cost.

If we consider a brief clinical case, utilizing 3D-printed dentures, the efficiency and workflow can be truly appreciated. In this particular case, we have a patient that required the removal of all the remaining teeth. Once the teeth were removed in the arches were healed, we employed a hybrid approach, where we still required impressions of the arches. It was these impressions that would be sent off to the lab for digitization and the fabrication of the 3D-printed try-in dentures.

The 3D-printed dentures were analogous to the wax rims or complete try-in dentures, which are teeth in wax. These dentures provided the opportunity to assess the aesthetics, phonetics, occlusion, lips support, and vertical dimension, among many other factors. These dentures can be modified in any way, and many iterations of these can be incorporated into the treatment plan.

3D-printed dentures for try-in.

Once all patient details have been optimized, the dentures are then exchanged for the final dentures, which in this case were milled dentures.

Dentures can now be 3D-printed and these novel workflows deviate significantly from the traditional flasking process, which can introduce distortion, complicating the procedure.

Metal

If we move from plastics the metals, we can truly appreciate how additive manufacturing (AM) or 3D printing has altered the medical device space. In fact, now we have the ability to manufacture very complex geometries. This was the case with our novel dental implant abutment, which provides a unique component and process for provisionalization in dental implant therapy.

With this particular investigation, once we developed the novel workflow for the fabrication of a metal additively manufactured novel implant abutment, we then compared it against a conventionally manufactured abutment. The conclusions are that we have a significant savings of cost, a reduction of fabrication time, a reduction of fabrication cost, and an increase in the quality of components, as 100% of the devices that were AM manufactured were able to be used for the investigation.

Workflow development for fabrication of a novel dental.

QR code for workflow publication.

QR code for testing publication.

This particular project exposed us to a novel method for polishing metal dental implant components produced by AM. Polishing becomes complicated due to the size and complexity of the device, as rotary instruments can cause damage. We investigated the application of dry electropolishing technology to improve the surface finish, critical to preventing biofilm accumulation. This process pairs very well with metal AM.

QR code for DET publication.

The application of metal AM was also applied to the fabrication of cobalt chromium restorations without the use of digital design. Our results indicated that this novel workflow presents a predictable alternative pathway for the fabrication of indirect onlays.

QR code for onlay publication.

Further application of metal AM was used for the fabrication of dental implant overdenture bars. Implant overdenture bars are predictable and successful when proper case selection is applied. In one case, we had the opportunity to provide a 12-year clinical follow-up and illustrate the advantages of this treatment modality. The implant bar can help compensate for angled implants and provide the support and retention required for the denture that fits on top of the bar.

QR code for implant publication.

Our research used additive manufacturing for the fabrication of a solid implant bar and applied the design of a lattice-structured implant bar. The workflow has been developed and the advantages, in terms of time, cost and complexity, are clear. It is hoped that the physical data will be very compelling.

QR code for bar publication.

Zirconia

The final material that will consider for 3D printing is zirconia. We are currently involved in an investigation comparing conventionally manufactured zirconia through milling to that of 3D-printed zirconia with anterior crowns and veneers.

The 3D printing of zirconia represents a similar workflow to that of metal, provides very similar advantages, and the results of the study provide strong support for utilizing 3D printing for zirconia prostheses.

Courtesy: Lithoz

Conclusions

If we consider technology and whether something is fundamental or a fad, I always like to bring up similar disruptive technologies. Consider our modern GPS, found in our cars, versus mapping out a trip. I think we can all agree and appreciate that almost everyone uses their GPS to get them from point A to point B, instead of plotting a map. Similarly, the old-school rotary telephone has been replaced by our smartphones, which contain so much critical information about us that some find it difficult to manage without their smartphones. Can you remember the last time you used a rotary phone? Lastly, I was part of the revolution from film cameras to digital cameras – yes, I’m old – which disrupted the industry tremendously and provided significant advantages and a completely different social media landscape. I feel that 3D printing will have the same impact on dentistry as these technological disruptions had.

Based on the examples and workflows, some conclusions and takeaways can be summarized. 3D printing (and additive manufacturing):

  • technology is here, is improving, and gaining popularity globally
  • provides an alternative pathway with a unique workflow
  • fabrication provides appliances with impressive clinical performance
  • physical testing data may implicate preparation guidelines
  • requires a steep learning curve and an understanding of the processes
  • represents another very useful tool in our digital toolbox (especially during the pandemic)
  • is no substitute for applying fundamentals and principles
  • requires the clinician to decide if it will provide your patient with the ideal treatment modality

Is 3D printing in dentistry a fad or a fundamental component? I feel it has become a fundamental part of our workflow. As we look to always improve the patient experience (including accessibility), the clinical practice, treatment predictability and success, and professional sustainability, 3D printing should be considered as an alternative, and potentially preferred, workflow in dentistry.

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