Dental Model Resin is a highly accurate material specifically formulated for creating crown and bridge dental models. When printing these types of dental models, follow the recommended workflow to ensure precise and accurate results. Begin by scanning the patient’s dentition with an intraoral or desktop scanner; design the model and dies in dental CAD software; then print and finish each model using software, hardware, and materials supplied by Formlabs.
Made by Formlabs
- Form 2 3D printer
- Dental Model Resin
- PreForm software (free)
Made by third parties
- Dental design software (CAD)
- Imaging and scanning systems (intraoral or desktop optical scanner)
- Post-cure chamber (recommended: Form Cure or NextDent LC-3DPrint box)
Phase 1: Scan
In order to plan the treatment and design the model, use an intraoral scanner to scan the patient’s dentition directly or a desktop optical scanner on a PVS impression.
Phase 2: Design
Use a dental CAD software package to process and design the model before printing. Choose a software that has open .STL export and that aids in designing the types of models that you prefer. The exact design steps vary for each software package, so contact the software provider for details on generating a model from patient scans.
The basic steps to consider for 3D printing dental models on the Form 2:
- Import the scan. Begin by importing the digital scans into the software program.
Trim the scan data. Use line marking or area selection tools to remove erroneous scan data and select only the portion of the dentition that will be printed.
Section the scan and mark margin lines. Use the software’s selection tools to select each tooth that will be converted to a die. Carefully edit the margin line for the most accurate marking. Check the insertion direction for each die.
Generate dies. Most modeling software generates dies automatically, based on user settings. Use manual configuration options to input or adjust design parameters; alternatively, import preset parameters from a saved file.
As an alternative to printing models with removable dies, generate an unsectioned model to print whole, and generate a separate die for printing individually. To do so, generate an unsectioned model .STL, as well as separate .STL’s for each die being printed.
Generate the model. Automatically create the model with either hollow or solid model settings. Final sculpting is optional; if desired, use a plane-cut tool to cut a chamfer in one end of the model. A chamfered surface makes it easier to remove models from the build platform.
- Export. Create a digital model of the surgical guide in an .STL or .OBJ file format.
Phase 3: Print
Maintaining Resin for Accurate Printing
Print accuracy is dictated by proper printer maintenance and use of the appropriate design and print settings. An in-depth study of 32 printed dies found margins and contact points to be accurate within +- 50 microns of the digital model over 80 percent of the die surfaces when printed on 50 micron print settings. Global accuracy across a full arch guide was found to be +- 100 microns over 90 percent of the surfaces. Accuracy is calculated by scanning printed models in a desktop optical scanner.
To ensure the highest accuracy and precision with printed models, maintain a dedicated resin tank for printing with Dental Model. Due to the highly sensitive beige color and unique print settings, introducing small quantities of other resins subjects Dental Model resin to color changes and less accurate printing.
TIP:Non-mixed Dental Model Resin will lead to color variability in the printed part. Before beginning a print with Dental Model Resin, always agitate resin in the cartridge by rotating the cartridge several times. Simply flip the cartridge by hand to ensure any settled resin is thoroughly mixed. For resin in the resin tank, the wiper will immediately restore consistency of the formulation.
After many prints, the silicone layer in the resin tank will reach the end of its life. An “expired” resin tank will adversely affect print precision; dies will not fit consistently. For the best printing results, replace the resin tank with each cartridge of Dental Model Resin. Resin tanks may still be usable for printing after one liter, as long as the print results are acceptable.
Print the Model(s) on the Form 2
PreForm Software supports .STL and .OBJ files, which you can export from most 3D CAD or animation packages. To load a model, drag and drop it into PreForm, or select “Open” from the File menu.
- Use the Material menu to select “Model,” which will define the appropriate print settings when uploading the .form to the Form 2.
- For the best quality and efficient printing, select the 0.05 mm layer height when printing with Dental Model Resin. The 0.05 mm layer height achieves a clinically relevant level of accuracy and is twice as fast as 0.025 mm print settings.
- Orientation: Print parts directly on the build platform to decrease print time and save resin. Both hollow and solid models can be printed directly on the build platform. To snap the flat bases to the build platform, use the “Select Base…” feature under the Orientation menu.
Print on supports when dies have pin diameters less than 3.0 mm. Supports require sanding or editing support marks; poorly placed or poorly cleaned supports can affect the fit of dies and models. When printing with supports, orient arches at an angle; ensure that supports only touch the base pins on the die and supports do not touch the inside of the arches’ die sockets.
Once all models are properly configured in PreForm, save the .form file and then choose a job name and upload the print to the Form 2.
Phase 4: Prepare
Wash and Dry the Printed Models
Remove models from the build platform, and rinse in isopropyl alcohol (IPA, 90% or higher, 99% recommended) for 10-20 minutes to clean and remove liquid resin before post-curing. To automate the washing process, Form Wash agitates the alcohol bath and removes parts from the bath after a set time. After cleaning, rinse parts in clean IPA. Inspect the models closely to ensure all uncured resin has been removed, then air dry the models for 30-45 minutes before post-curing.
When removing flat parts from the build platform, consider using the flush cutters included in the finish kit to release the model at its corner edge. Use the part removal tool to release parts with chamfered bottom surfaces and the scraper to detach dies from the build platform.
For optimal mechanical properties, accuracy, and precision, expose washed and dried models to 405 nm light at 60°C for 60 minutes.
If applicable, remove any support structures, then use a file or rotating handpiece to sand or grind support touchpoints. In addition, remove any small skirt-like features that print on the base of the part with a file or a rotating handpiece. A large skirt may block the insertion of the die.
Design settings for removable dies
Dental Model Resin is uniquely designed to print directly on the build platform. For the easiest printing and best results, ensure each die and model has a flat bottom surface. Printing on the Form 2 requires using stand-off pins, so that the bottom-most layer is not the stop-surface. The secondary bottom surface ensures an accurate fit, and the bottom of each die’s “shoulder” should rest in the model.
Follow the recommended die and model design settings to ensure that removable dies fit tightly and consistently in crown and bridge models. Manually input and alter settings, or download a preset file. In 3Shape, these presets are saved as .dme files.
Manually altering die and model design settings
When deciding on or altering die and model settings, consider the following parameters:
Printing on the Form 2 requires using pins. Due to the Form 2’s printing sequence, Z-axis accuracy is most reliable after the first 1.0-1.5 mm of printing. Using a pin allows a secondary surface above these initial layers to serve as the stop surface, after which dies will be accurate in the Z-axis.
Within the dental CAD software, configure the following parameters:
- Die-to-model gaps must be large enough for dies to be consistently insertable but small enough that they still fit well. Increasing the die-to-model gap will lead to a looser die fit; decreasing too far will cause dies to insert inconsistently.
- Friction bar overlap settings ensure that friction bars are large enough for dies to fit tightly while maintaining the minimum die-to-model gap necessary for repeated insertion. Increasing friction bar overlaps will increase the tightness of each die’s fit.
- Friction adjustments for size and friction adjustment for angle allow for different friction bar overlaps to be defined for small vs. large dies, as well as more highly angled dies. Select negative friction adjustments for size to create higher friction bar overlaps for small dies vs. large dies. Select positive friction adjustments for angle to create higher friction bar overlaps for highly angled dies.
For further information on these manual-configurable parameters, please contact your 3Shape reseller or 3Shape for support.
3Shape Presets - Beta
Formlabs has tested 3Shape Model Builder to recommend settings for models with removable dies. Beta presets are publicly available for testing and feedback. Please provide feedback to inform improvements for new 3Shape preset releases. The .dme preset files and recommendations will be updated as tests continue.
The current .dme file has three material settings in it. Test models with each setting to find the best fit for each use.
|Formlabs Dental Model - Looser||Looser presets -- these presets will cause dies to fit slightly more loosely than "Medium" or "Tighter" presets. Lowest friction bar overlaps.|
|Formlabs Dental Model - Medium||Medium presets -- fits slightly more tightly than "Looser" presets, but slightly more loosely than "Tighter" presets. Higher friction bar overlaps.|
|Formlabs Dental Model - Tighter||Tighter presets -- first slightly more tightly than "Medium" or "Looser" presets. Highest friction bar overlaps.|