…larger, more robust [3-D printers]…open up more possibilities….[and] can print multiple units (such as models) at the same time with increased speed.
|3-D-printed denture made from Dentca Denture Base and Dentca Denture Teeth 3-D printable materials.|
|Dentca-Zenith 3-D printer (Dentca; Dentis).|
I have discussed 3-D printers earlier this year, including the compact, affordable desktop unit from Formlabs—the Form 2. However, there are larger, more robust units that are aimed at dental laboratories and large dental offices that open up more possibilities. These larger 3-D printers can print multiple units (such as models) at the same time with increased speed. The costs are plummeting, and a very professional unit can be had for $10 thousand to $12 thousand. There seem to be a number of orthodontists installing these units to help with appliances and even case presentations. The cost per unit is probably less than the manpower involved in pouring a model (as well as not worrying about a bubble in the wrong place).
Some of the larger names to watch are EnvisionTEC, 3D Systems, Stratasys, and Asiga (the latter company is based in Australia and distributed by Whip Mix). There are countless others, old and new, that will show up at dentistry trade shows and in advertising. Right now, these companies are rushing to get printers and printed materials approved by the FDA for final restorations that can be “permanently” placed in the mouth. So far, the materials for crowns are considered “temporaries,” although a few are now called “long-term temporaries” or “provisionals.” We all have to be able to scrutinize these claims and look to our materials experts for guidance.
One of the companies that is very close to getting approval by the FDA for permanent restorations is NextDent, which was recently acquired by 3D Systems. They have an array of materials, such as NextDent C&B for single units and up to 3-unit bridges. Like the other companies, including Formlabs, NextDent has approved materials for nightguards, surgical guides, and more. See the available materials on nextdent.com. Keep in mind that since these are not fixed restorations, the FDA rules are quite different.
EnvisionTEC is also pushing ahead. One of the interesting products it now has is a clear, flexible material that can be coordinated with orthodontic software. The brackets are virtually placed on the teeth onscreen, and that data prints a template (which looks like a clear sports guard) with wells where the brackets can be placed. To bond them, the teeth are all etched simultaneously, the bonding agent is spotted on the teeth, and the light-cured adhesive is put on the brackets that are in the template. Next, seat the template, cure through the clear material, and peel it off. The brackets are now in perfect position. Anyone who has done a Six Month Smiles case is familiar with this whole process, and I wouldn’t be surprised if the company adopts this technology.
There is also now a push to produce a printed full denture. Currently, “digital dentures,” as I discussed in an earlier column, require a standard type of impression (in special trays) that are scanned and put into the digital workflow. At the initial visit, the impressions are taken, as well as other records such as vertical, bite, lip-line, and more. This information is added to the scanned impressions and the case is set up virtually. The dentures now, though, are made from bases that are a milled denture acrylic or milled wax that can be processed conventionally. Standard teeth are then set into these bases. If a try-in is requested, some of the companies can 3-D print one but it will all be one color. The companies in the lead here are AvaDent, Kulzer (Pala), Ivoclar Vivadent, and Dentca.
But what if the whole denture could be printed quick and easy and the file could be kept to replace a lost or damaged denture in less than a day? Well, that day is here: Dentca has just introduced an FDA-approved printed denture. Two materials are used: One is a pink denture base and the other is used to print the teeth. The materials come in different shades for both the base and teeth. An interesting aspect of this printed marriage is that there is no seam present as there is in traditional teeth that are bonded or embedded into a denture base. Thus, there is none of the staining at the interface that we all have had to deal with since the first Vulcanite bases with porcelain teeth were invented.
Not far behind Dentca is EnvisionTEC. The company has announced an FDA-approved denture base and tooth material for its printers that should be available to labs later this year.
Keep in mind that, at this time, the digital process is still done in a laboratory. But as the printers come down in size and cost, I foresee the dental office being able to get the files from the lab and print them on the spot.
Remember that the process is not very fast at this time. One of the printers being marketed to orthodontists prints 7 models in 4 hours. Of course, no one has to stand there once the button is pushed. Many dentists have asked me if we can print temporary crowns; currently, the time it takes is still a factor. We also have to learn a new language. Later this year I will attempt to define stereolithography (SLA) versus digital light processing (DLP). This reminds me of the early days of digital x-ray sensors when we had to choose either CMOS or CCD. Watch this space; I will provide updates both here and online as things change with this rapidly evolving technology.