How it Works: PolyJet 3D Printing with TrueDent™
As an application engineer at Stratasys, I’m fascinated by the technology behind our dental 3D printing solutions. In particular, TrueDent, which offers game-changing abilities for creating monolithic, aesthetic, accurate dentures at scale. In this blog, I’ll offer a high-level explanation on how PolyJet, multi-material jetting works and how TrueDent dentures are created.
The PolyJet Process
PolyJet uses material jetting (inkjet) technology to deposit tiny drops of liquid photopolymer layer-by-layer. Each layer is cured with UV light, bonding it to the layer below. In the case of TrueDent appliances, 5 base color resins (cyan, magenta, yellow, white and clear) are loaded into the J5 DentaJet PolyJet 3D printer and jetted in precise combinations to create specific shade profiles, fabricating monolithic dentures, with the base and teeth printed together in one piece. By contrast, other 3D printing technologies, such as DLP, produce dentures in sections - base and teeth separately - that must be manually assembled. PolyJet’ s ability to print full-color dental prosthetics in a continuous structure results in high fidelity between design and print which leads to a better fit and occlusion in a patient’s mouth.
Unique support material is also jetted at the same time as the TrueDent resin, encapsulating each part completely thus ensuring that the intended geometrical structure is maintained. This support structure is later removed with a water jet, leaving the surface area of the prosthesis unharmed.
PolyJet 3D Printing with TrueDent
TrueDent resin was developed specifically for the J5 DentaJet platform. It offers a digital workflow that not only creates an accurate full color denture but can also reprint the exact replica if needed. Here is an overview of the process, for more detailed information, please refer to the Instructions for Use.
- Digital Denture Design. The dental lab will receive the impression and instructions from the dentists as to the prosthetics that need to be created. Dentists can choose from 10 base shades and 19 teeth shades with varying translucency to find the best match for their patient or capture the required shade profile directly from the intraoral scan. The lab technician will design the denture based on the patient data on dental CAD software and will import the final design into GrabCAD Print as an STL/3MF file.
- Digital Selection of Base and Teeth Shades. In the GrabCAD print software, the operator digitally assigns a shade profile to the teeth and base. Users can even assign different shades to individual teeth in a single denture. After all the cases have been loaded and assigned a shade, the software nests and orients each part automatically on the tray to optimize the print job.
- Unattended Printing. The J5 DentaJet is loaded with two sets of each resin base color or support material to enable a “hot swap” ensuring that resins do not run out mid print. An important point that is often overlooked is that using PolyJet, operators do not handle uncured resin as in other technologies, this ensures a safer working environment.
- Multiple Materials Jetting. Using the five base shades and support material, with each resin connected to one printhead, the individual nozzles drop a single drop at a time of resin to create the predetermined shade including the appearance of capillaries on the base and the internal structure and translucency of the teeth.
- Accurate Layer Control. Once the resin droplets are deposited each layer is leveled.
- UV Curing. Each layer is cured using a UV lamp, which bonds the layers together. After UV curing a single layer, the jetting, blending, and leveling steps are repeated to form another layer, which is then cured.
- Support Structure. The support material in the PolyJet process completely encases the model. This material can be washed off with a water jet, so there is no recontouring necessary and no risk of support bars leaving scarring.
TrueDent with PolyJet allows creating up to 30 dentures, each a different shade combination, simultaneously in a single print run. I encourage you to learn more about our multi-material printing capabilities and how they can transform your business!
