Dental LT Clear Resin is a long term biocompatible material formulated for manufacturing dental splints and retainers. When printing these appliances, follow the recommended workflow to ensure precise and accurate results.
Begin by scanning the patient’s dentition with an intraoral scanner or by scanning the impression with a desktop optical scanner. Design the splint in dental CAD software. Then print and finish each splint using software, hardware, and materials supplied by Formlabs and third parties.
As a rigid material, Dental LT Clear is most appropriate for printing hard-only splints. If soft or hard-soft splints are desired, the best method is to print the model and thermoform.
Made by Formlabs
- Form 2 3D Printer
- Dental LT Clear Resin
- PreForm software (free)
- Finish Kit or Form Wash
- Form Cure
Made by third parties
- Dental design software (CAD)
- Intraoral or desktop optical scanner
- Alternative post-cure chamber
- Ultrasonic bath
Phase 1: Scan
In order to 3D print a splint, use a scanner to collect anatomical data of the patient’s dentition. Either scan the patient directly with an intraoral scanner, or use a desktop optical scanner to scan a polyvinyl siloxane (PVS) impression or stone model.
Phase 2: Design
Use a dental CAD software package to process and design the splint before printing. Choose software that offers open STL file export. The exact design steps vary for each software package, so contact the software provider for details on generating a splint from patient scans.
Design splints following the guidelines below to ensure that the parts have sufficient strength and durability:
|Minimum side wall thickness||1.0 mm|
|Minimum bottom/occlusal surface thickness||1.5 mm|
|Offset (aka. “Block Out Undercuts Offset”)||≥ 0.1 mm|
Additional block out settings, such as block out angle and retention, should be determined clinically by the doctor or the dental technician.
The basic steps to consider for 3D printing splints on the Form 2:
- Import and trim the scan. Begin by importing the digital scans - both the preparation and the antagonist - into the software program from the intraoral or desktop optical scanner.
Use line marking or area selection tools to remove erroneous scan data, and select only the portion of the dentition that will be printed.
Define insertion and undercuts. Choose the insertion direction, then block out undercuts. Ensure that the model is blocked out adequately where needed, depending on the specifics of the case. Block out undercuts to directly impact the retention of the splint.
- Mark the margins and generate the splint. To design the splint, use spline tools to mark the margin of the splint along the perimeter of the arch. Generate an initial splint design, using a minimum thickness of 1.0 mm and an offset of 0.1 mm. Adjust the design manually using standard sculpting tools if necessary.
- Generate a splint bar. Some splint design software offer the option to generate a bar and combine it with the splint design. When generating a splint bar, ensure that the total initial thickness of the bar and shell are at an initial minimum of 3.0 mm, to allow space for antagonist adaptation.
When using splint design software that does not allow for the generation of a bar, ensure that the bottom surfaces of the splint are at least 1.5 mm thick
Adapt the splint design. Remove material on the underside of the splint to adapt the design to the antagonist. Use static occlusion or dynamic occlusion with a virtual articulator, depending on the CAD software being used.
Make final adjustments. Inspect the model to ensure that the part is not thinner than 1.5 mm at any point in the occlusion or thinner than 1.0 mm in the side wall. Adjust the design manually using standard sculpting tools if necessary. Finalize the design by double-checking the occlusion and articulation of the model and splint.
- Export. Create a digital model of the surgical guide in STL or OBJ file format.
Phase 3: Print
PreForm Software supports STL and OBJ files, which you can export from most dental CAD software packages. To load a model, drag and drop it into PreForm, or select “Open” from the File menu.
- Use the Material menu to select “LT Clear,” which defines the appropriate print settings when uploading the FORM file to the Form 2. Dental LT Clear prints using the 100 micron layer thickness, which has been tested to print quickly and deliver the necessary print accuracy and quality. With Dental LT Clear Resin, the base layers and initial layers of support pillars print with 300 micron layers to reduce the total print time.
- Orientation: Use the manipulator and orientation tools to configure parts with the intaglio surfaces facing away from the build platform. Ensure that parts are oriented at an angle of 30° or less, measured relative to the build platform. Orienting parts upright or at angles more than 30° will compromise precision and lead to poorly fitting parts. The direction and angle settings ensure that parts will print reliably and that supports will not be generated on intaglio surfaces. When angling the model in PreForm, rotate the anterior portion upward and away from the build platform so that the posterior ends remain closer to the build platform.
CAUTIONPrinting at greater than 30° angles will result in poorly fitting splints. As the angle of inclination of the part increases above 30 degrees, interproximal surfaces will print less accurately and cause a poor fit of the part.
- Generate supports using PreForm’s auto-generation feature. Inspect the part to ensure there are no support touchpoints on intaglio surfaces. Use the manual support editing feature to add or remove supports, if needed.
- Once all models are properly configured in PreForm, save the FORM file and then choose a job name and upload and print on the Form 2.
- Insert a resin tank, resin cartridge, and build platform into the printer. Thoroughly agitate the resin cartridge before insertion, by shaking and rotating it several times.
CAUTION:For full compliance and biocompatibility, Dental LT Clear requires a dedicated resin tank, build platform, and finishing kit, which should only be used with other Formlabs biocompatible resins, such as Dental SG.
Using Standard Resin Tanks vs. Resin Tank LTFor the highest accuracy and precision, Resin Tank LT is recommended for printing with Dental LT Clear. Testing of Dental LT Clear on Resin Tank LT revealed no degradation of accuracy or precision over the lifetime of the tank. If using standard resin tanks, laser exposure will form white, clouded marks on the surface of the resin tank’s silicone layer. This clouding will eventually become extreme enough to affect accuracy. Testing revealed that repeated laser exposure began to affect splint accuracy after 2,000 layers were printed in a given position on the tank. In testing a worst-case scenario of printing an identical splint in the same position in a resin tank multiple times, splints still fit accurately after 25 consecutive prints. To avoid fit issues due to tank clouding, switch to a new standard resin tank after 25 consecutive prints, or with every new cartridge of resin, whichever comes earlier.
Phase 4: Prepare
Post processing 3D printed splints requires several steps that prepare the splints for their intended use. Once parts are removed from the build platform, proceed with rinsing, drying, post-curing, removing supports, and polishing.
Remove parts from the build platform with the part removal tool.
Wash and dry. Rinse parts in isopropyl alcohol (IPA, 96 percent or higher) for two minutes in an ultrasonic bath to dissolve any uncured or excess resin. Transfer parts to a new bath of clean alcohol solution (96 percent) and rinse them for an additional three minutes in an ultrasonic bath.
Do not leave parts in alcohol for more than six minutes, as this may reduce mechanical performance and cause defects in the printed parts. Leave parts to air dry completely, or use a compressed air hose to blow IPA away from parts’ surfaces. Inspect parts closely to ensure all uncured resin has been removed from the parts.
Form Wash and Form Cure + Dental LT ClearValidation testing is underway for using Form Wash and Form Cure in conjunction with Dental LT Clear. Once testing is complete, Form Wash and Form Cure will be the official recommended post-processing units for the resin, and settings recommendations will be available. In the meantime, follow the proper Instructions For Use.
- Post-cure. Expose parts to light and heat to achieve biocompatibility and optimal mechanical properties. Post-cure time depends on the light intensity and the internal temperature of the post-curing device. One acceptable method for post-curing is exposure for 10 minutes to 108 watts each of Blue UV-A (315-400nm) and UV-Blue (400-550 nm) light, in a heated environment at 60 °C (140 °F). One acceptable lighting setup is six (6) 18W/71 lamps (Dulux L Blue) and six (6) 18W/78 lamps (Dulux blue UV-A).
CAUTIONPost-curing beyond the recommended post-cure settings can lead to extreme discoloration of the parts. Parts may become yellow when post-cured at too high a temperature, for too long a duration, or with too high intensity of light. In addition, improper post-curing steps can lead to sub-optimal mechanical and biocompatibility properties.Post-cure only in accordance with official recommendations from Formlabs for the clearest and best possible results.
Remove supports. Use the flush cutters included in the Formlabs Finish Kit to carefully cut the supports at the points where they attach to the printed splint. Use caution when cutting the supports, as the post-cured material may be brittle. Supports can also be removed using other specialized tools, such as cutting disks or round cutting instruments like carbide burs.
CAUTIONRemove supports only after post-curing to prevent parts from warping.
Polish. For a glossy surface finish, polish parts using a rag wheel and pumice at low speeds. After initial rough polishing, switch to a dry cloth polish. Finish with a high-grit acrylic buffing paste, such as Hi-Shine, at high speeds.
Check fit. Print a solid model of the patient’s dentition, and place the splint on the model to check the fit accuracy. Make adjustments to the 3D model or the post-processed parts, if necessary. Use Standard White or Grey Resin for printing orthodontic models. Use Dental Model Resin for higher accuracy.
Phase 5: Clean and Disinfect
Use an ethanol solution to disinfect parts before use.
Dental LT Clear is a Class IIa biocompatible resin that is in conformity with the essential requirements and provisions of the Council Directive 93/42/EEC concerning medical devices as amended by Directive 2007/47/EC, and is in conformity with the following standards:
- EN ISO 1641:2009
- EN-ISO 10993-1:2009/AC:2010
- EN-ISO 10993-3:2009
- EN-ISO 10993-5:2009
- EN 908:2008
- Dental LT Clear EC Declaration of Conformity [en] [de] [fr] [it] [no] [se] [dk] [pl]
- Dental LT Clear Instructions for Use [en] [uk] [de] [fr] [it] [pl]
- Dental LT Clear Safety Data Sheet (SDS) [en] [dk] [se]
- Dental LT Clear Technical Data Sheet [en]