Using Dental SG Resin
Dental SG Resin has been engineered to offer dental professionals a desktop solution to improve clinical outcomes in implant surgeries with 3D printed surgical guides. The resin is a Class I biocompatible resin (EN-ISO 10993-1:2009/AC:2010, USP Class VI).
Dental SG can be printed only with the Formlabs Form 2 3D printer. It is designed for dental surgical guides or similar applications, in compliance with industry standards and testing protocols. Dental SG can be steam sterilized using an autoclave, allowing it to be used directly in the operating room.
- Implant treatment planning software
- Imaging and scanning systems
- Form 2 3D Printer
- Formlabs Finish Kit
- Dental SG Resin
- UV post-cure chamber (recommended: NextDent LC-3DPrint box)
Phase 1: Treatment Planning and Surgical Guide Design
Implant Treatment Planning
3D printed surgical guides are designed based on the patient’s anatomy using implant treatment planning software. Cone beam computer tomography (CBCT) captures the patient osteotomy, while intraoral scanners or desktop optical scanners can capture accurate optical scans of the patient’s dentition.
In implant planning software, clinicians plan the implant treatment using the patient’s CBCT data and a template of the desired final prosthetics. Depending on the type of guide being designed, clinical pro-operative design considerations include position, angulation, depth, the specific implant system, and the surgical kit. The patient’s surface dentition can also be incorporated.
Surgical Guide White Paper
Learn how Daniel Whitley DDS and Sompop Bencharit DDS, MS, FACP perform dental implant surgery with Dental SG in this white paper, including in-depth information on implant planning and placement accuracy with the Form 2.
Surgical Guide Design & Export
Once the treatment is planned, generate a surgical guide model to cover a partial or full arch, depending on the clinical preferences. From the fully designed guide, export a digital model of the surgical guide, in .STL or .OBJ file format. Select an implant treatment planning software that allows for open model export.
In designing for printability, Formlabs recommends wall thicknesses of 3 mm or greater for oral surgical guides printed in Dental SG resin. Select the wall thickness from the implant planning software; the correct geometry provides strength and rigidity while the guide is inserted and removed from the mouth.
Phase 2: Print Preparation in PreForm
Import the surgical guide model into PreForm for print preparation. All Dental SG Resin parts are printed at a layer height of 50 microns. The print settings are carefully developed and optimized for speed of printing and accuracy of printed parts.
The basic steps of print preparation are: Orient, Support, Layout, Print.
Preparing for Precision and Success
To print precisely with Dental SG resin, follow two main design requirements:
- Do not include support touchpoints on occlusal surfaces.
- Do not include support touchpoints on guide sleeve holes or surfaces.
Wherever PreForm generates a support touchpoint, there will be local areas of inaccuracy, which require post-processing clean up. Verify the placement of support touchpoints during the Orient and Support print preparation steps.
Avoid placing support touchpoints on occlusal surfaces. The easiest way to prevent improper touchpoint location is to orient the occlusal surface away from the build platform.
Use PreForm to inspect and remove support touchpoints from guide holes and occlusal surfaces. After initially generating supports, inspect the location of support touchpoints. If any support tips are attached to guide sleeve hole surfaces or occlusal surfaces, manually remove these support touchpoints.
Phase 3: Printing on the Form 2
Upload the print to the Form 2. While the model uploads and before beginning the print, shake the Dental SG Resin Cartridge for 5 minutes to ensure complete mixture of the resin’s chemical formulation. Insert the cartridge along with a resin tank and build platform, and start the print.
Use separate accessories for Dental SG Resin. For full compliance and biocompatibility, Dental SG Resin requires a dedicated resin tank, build platform, and finishing kit, which should not be mixed with any other resins.
Resin tank wear and Dental SG resin
Dental SG resin causes the resin tanks to cloud and wear faster than other Formlabs resins. This clouding will eventually have an effect on the accuracy of prints. Use a new resin tank with each new Dental SG resin cartridge. For extremely high accuracy, switch resin tanks more often.
Effect of tank clouding on print accuracy
From studying 84 surgical guide models printed on six Form 2 printers, the deviation between printed models and the intended print was within +/- 100 microns over 93% of the occlusal surface area. Accuracy is calculated by scanning printed models in a desktop optical scanner.
Print accuracy decays over time as resin tanks become increasingly clouded. The same study observed that when printing the same model in an identical location over consecutive builds, the deviation between surgical guide model and intended print is within +/- 100 microns over 80% of the surface area after the fifth print. In order to extend tank lifetime, vary model position in consecutive builds. When tanks have become too clouded, please discard the resin tank and resume printing with a new resin tank.
Phase 4: Post-Processing
After printing, rinse, dry, UV post-cure, and assemble guides with sleeve tubes. Follow the instructions for use to ensure biocompatibility. Parts can also be steam-sterilized in an autoclave.
Parts must first be removed from the build platform and rinsed in two buckets of isopropyl alcohol (IPA, 90% or higher) for 10 minutes each to clean parts and remove liquid resin before post-curing. The first bath may become more dirty or more saturated with resin after repeated part washing. The second bath should be clean, unsaturated IPA, to ensure that all uncured resin is dissolved in the alcohol.
Rinse and leave the printed guide in the first bath for 10 minutes, then transfer the print to the second, clean bath for an additional 10 minutes. Do not leave parts in IPA for greater than 20 minutes, as this may cause micro-cracks and abrasions to form in the printed part.
Expose parts to UV light and heat for biocompatibility and optimal mechanical properties. Visible light and heat cure chambers will not properly post-cure the guide; UV light curing is required. During post-curing, a color change from translucent yellow to translucent orange will occur.
Cure time depends on the light intensity and the internal temperature of the curing device. One acceptable method for post-curing is exposure for 10 minutes to 108 watts each of Blue UV-A (315 – 400 nm) 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).
Formlabs recommends the use of the NextDent LC-3DPrint cure chamber, which complies with the suggested post-cure procedure and has been tested with Formlabs Dental SG resin. For more information, or to purchase this device, please see the product website or contact [email protected].
Remove supports after post-curing to ensure that parts do not warp during post cure. Use flush cutters included in the Formlabs Finish Kit to carefully cut the supports at the point where they attach to your model. Use caution when cutting the supports, as the post-cured material may be brittle. Supports can also be removed using other specialized appliances, such as cutting disks or round cutting instruments such as carbide burs.
Polishing printed guides
For a smoother surface finish, use high grit sandpaper to smooth support marks. For higher levels of part translucency, polish guides using pumice and a rag wheel or other specialized appliances.
Assemble parts with metal guide sleeve tubes prior to autoclave sterilization.
Sterilize printed Dental SG parts in an autoclave after fully rinsing, drying, post-curing, and assembling. A sterilization pouch is optional. The recommended autoclave presets are 134°C for 6 minutes, 121°C for 15 minutes, or 138°C for 3 minutes. Dental SG Resin prints can also be sterilized by gamma ray sterilization.
If disinfection is required, use non-chemical products. If this is not possible, ethanol solution is recommended for disinfection purposes.
Before sterilizing, parts must be properly rinsed in IPA, fully dried, and post-cured according to the instructions for use. Carefully inspect parts for cracks or micro-abrasions prior to autoclaving.