3D printing: Current applications and perspectives – by Dr Carlo Mangano

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2021 is Planmeca’s 50th anniversary. As part of the milestone year, we are publishing a series of articles written by our own specialists and by dental experts from around the world. In this article, Dr Carlo Mangano, President of Digital Dentistry Society (DDS), takes us through the fundamentals of 3D printing, what dentists can expect of digital dental technology in the future and his advice to anyone thinking of making the digital leap.

Digital technologies are rapidly spreading in dentistry. Tools, such as intraoral and laboratory scanners, cone beam computed tomography (CBCT), computer-aided design and computer-aided manufacturing (CAD/CAM) software, as well as innovative manufacturing procedures, such as 3D printing and laser sintering, are changing the way we treat our patients. Therapies are increasingly personalised, and the tools available allow more predictable results with levels of diagnostic precision and manufacturing accuracy that were previously unthinkable.

The applications for 3D printing have also increased significantly in the dental world. This is because 3D printing allows obtaining customised products easily and efficiently, saving on production and simplifying the processing of patient image data, with continuous improvement of the materials used.

The exciting possibilities of 3D printing

3D printing has opened up many new and interesting possibilities particularly in oral surgery, prosthetics and orthodontics. Thanks to the technology, it is now possible to fabricate hollow and extremely complex objects impossible to produce through conventional methods. The constraints of traditional tools, such as cutters and moulds, do not apply to 3D printing. This allows producing complex objects quickly and freely while saving a considerable amount of material.

The whole process of dental additive manufacturing can be divided into four main stages:

  1. Generating a digital 3D model using software that is able to process intraoral, facial or computed tomography scans.
  2. Slicing the 3D model into many two-dimensional layers.
  3. 3D printing the final product layer by layer.
  4. Post-processing of the printed object.

This basic workflow applies to a range of different printing technologies as well as materials, such as polymers, metals and ceramics.

Speed, accuracy and resolution

The two main 3D printing technologies used in dentistry today are stereolithography (SLA) and digital light processing (DLP). In SLA, a laser beam in the ultraviolet spectrum is used to cure photoactive resin, while DLP utilises a light projector to cure the resin. The two methods therefore differ in the light source used: laser (SLA) against structured light (DLP)*.

In dentistry, speed is important, especially for e.g. large dental labs, which regularly produce large amounts of dental applications. The DLP technique, such as the LCD variant (where the LCD screen projects an entire image directly onto the resin basin) is faster than SLA, because DLP printers can produce one whole layer at once, while the laser in SLA printers has to move around to complete the layer. It is easy to see how DLP printers are faster, because the projector has larger dimensions than the laser spot and can therefore ‘polymerise’ more resin in less time.

However, speed doesn’t automatically mean accuracy. In fact, 3D printers could be likened to an orchestra, because it is never a single element that determines the accuracy of the object we are going to print. There is a multitude of important factors to consider: the physics of light and its propagation, the chemistry of the resin used and its polymerisation, the electronics of the panels (DLP and LCD) or the laser (SLA), the lenses and mirrors, the mechanics of advancement and/or rotation of the system, and of course the software – the heart of the printer and the ‘harmoniser’ of the process.

One thing that is often used as a selling point is resolution, which is frequently confused with accuracy. The concept of resolution on the (vertical) Z axis can be simplified to the minimum possible advancement in Z; unfortunately, the coincidence of this minimum advancement with the minimum thickness of the layer is only ideal, and not yet demonstrated (in fact, the material variable must be considered). Meanwhile, the concept of resolution on the (horizontal) XY axis is valid only for LCD printers.

In fact, for SLA and DLP printers, one should rather talk about the minimum size of the light source – i.e. the laser spot in SLA printers and the micro-mirrors in DLP printers. Ideally, the minimum size of the light source should correspond to the minimum printable size. However, even then, there remains the variable that is the material. Therefore, the resolution alone does not guarantee the accuracy of the printed object because of the many other variables, from the machine components to the materials used all the way up to the post-curing procedure. Accuracy and resolution are two different concepts that together determine the quality of the print jobs.

Since the emergence of 3D printing, manufacturers have further simplified the printing process by making 3D printers more accessible and improving the quality of the dedicated software. Printing is not difficult: once you understand how to position the models (the STL files exported from CAD software) on the build platform and how to adequately support them (to avoid their detachment from the build platform during printing), the game is done.

Dentistry in the next five years

The impact of 3D printing on digital dentistry continues to be very strong: surgical guides, indirect bonding trays, aligner bases and study models can now all be 3D printed using different materials. The race to be able to print zirconia restorations and complete prostheses has already started. The possibilities are many, and they will grow together with the development of new materials. It is not difficult to predict that soon every dental office and dental lab will be equipped with at least one 3D printer. Thanks to all this, 3D printing is pushing dentistry towards the definitive digital transformation.

In the next five years, we will also see an influx of new tools and software as manufacturers and companies continue to invest in research and development. Digital technologies will bring epochal changes to the world of dentistry, altering not only patient expectations of dental care, but also the way dental professionals think about and implement therapies. They will be able to use increasingly better performing tools, easier software and, above all, new materials with high aesthetic value that are more compatible with the patient’s health. There will also be predictable clinical protocols, higher quality and lower costs.

Advice to new digital dentists

No clinician should underestimate the key role of digital technologies, ignore them or think that they can work without them. Giving up or waiting too long to adopt digital technologies in their daily practice would be a great mistake. The development of new technologies happens very quickly – the computational power of computers alone increases around 50% every year. As a result, clinicians should dedicate time to understanding how to use digital technologies to their advantage and, if necessary, attend training courses as well.

The initial investment can be considerable both in terms of time and money; therefore, it is important to make the most of it. In order get off to a good start, two machines are key in daily practice: a cone beam computed tomography (CBCT) unit and an intraoral scanner (IOS). CBCT is certainly a device that increases your diagnostic capacity and simplifies therapeutic planning. Meanwhile, IOS technology is now more accurate, efficient and intuitive than ever. IOSs simplify and improve communication with the patient – but, above all, allow access to the full digital workflow, with advantages both in terms of time and costs.

The clinician needs to address the new challenge by increasing their knowledge and asking precious suggestions from colleagues, who have already started their digital journey a long time ago. Furthermore, they should attend training courses that will help them make correct choices that are not just based on information from the market. Digital Dentistry Society (DDS) organises events and certified training courses, which are practical and follow a unified format at an international level. Official courses are held by DDS’ certified speakers, all internationally recognised clinical experts and researchers.

The quality of the available training will determine the speed with which clinicians will change their way of thinking and working to adapt to a fascinating new digital world of IOSs, CBCTs, CAD/CAM software, milling machines and 3D printers. Waiting too long to adopt or integrate these technologies into the daily workflow could be a dire mistake, especially for young dentists.

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