3D Printing and Orthodontics

By Dr. Christian Groth

As we move towards the 2015 AAO Annual Session in San Francisco many of us will be making check lists for items to investigate at the exhibition hall and lectures. Anybody who has attended recent meetings has seen that intraoral scanners are a hot topic. Every year new products are being released, or updates to current systems are offered. Intraoral scanning has opened the door for additional technologies within (and outside of) the orthodontic office. Dr. John White wrote a very informative blog post in February talking about the use of intraoral scanning for same day consultations (click here to read it). As more people are offering clear aligner therapy (including general dentists and the mail order aligner system that we all know about) it is time that we differentiate ourselves as orthodontic specialists. One way in which we can do this is to incorporate 3D printing into our daily practices.

3D printing, also known as additive manufacturing, is a process by which a physical object is created from a digital file (check out a video of 3D printed models here). There are several different types of 3D printers available that range in price from a few hundred dollars to almost one hundred thousand dollars. They all have one thing in common: they build models layer-by-layer with a build platform that moves vertically. The smaller the layer thickness the better looking the model will be. The four most popular types of printers are: Fused Deposition Modeling (FDM), Stereolithography (SLA), Digital Light Projector (DLP), and Polyjet Photopolymer (PP). Without getting too technical here is how each basically works. FDM involved heating up a thin strand of plastic resin that comes off of a spool and is deposited in layers as thin as 100 microns. SLA and DLP technologies are similar in that they utilize a vat of liquid, photosensitive resin. When the light hits the resin it is cured and platform moves to enable the next layer to be cured. The different between SLA and DLP is that SLA uses a single laser point to draw an image whereas DLP uses a projected image to cure a whole layer simultaneously, which allows the printing process to move faster (think of this as the difference between drawing a picture and stamping a picture). PP printers are probably the most popular in dentistry and use inkjet technology (yes, just like your desktop printer). Liquid resin is jetted out of nozzles in an extremely accurate fashion and cured by a UV. Layer thickness of SLA, DLP, and PP printers can be as low as 16 microns (for your reference the average piece of paper is 100 microns thick).

While the technologies differ between printers what truly sets them apart is the quality of the parts. Cheap printers are made from cheap parts that can degrade over time and result in inaccurate models. It is truly a case of you get what you pay for. So if you are in the market for a 3D printer to be used in your practice, buy the best one that you can afford.

3D printed models can be used for anything in the orthodontic office.   The most practical use is for retention and relapse treatment. A major downside to stone models is that they are often destroyed during the retainer fabrication process. 3D printed models do not get ruined and can be used as many times as necessary for retainer fabrication. Imagine being able to print a model, make a clear retainer, and mail it off to a patient who is away at college. What a service you have just provided to your patient and they never stepped foot in your office! Pairing 3D printing with one of several software programs available allows us to create sequential setups/models for minor tooth movement. By controlling the process we control the overhead and thus have the ability to pass these savings on to the patient. Another great service that we can offer our patients if they have a lapse in retainer wear.

Whatever your practice is like there is a place for 3D printed models in it. While you will pay a little bit more for the physical model, the longevity, versatility, patient excitement, and ability to virtually eliminate alginate impressions from your practice will pay off in the end!

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