Many people assume that dental 3D printing ends when the printer stops running. However, when the build platform rises, the printed part is still covered in uncured liquid resin, and the material properties are far from acceptable. What follows is the 3D printing post-processing stage.
Post-processing is crucial to the quality of dental parts, involving steps such as cleaning, drying, curing, removing supports, polishing, and final inspection. Read on for more details.
Freshly printed resin parts still contain uncured material on their surface and inside. These residues not only make the surface sticky and prone to contamination. More importantly, they come into direct contact with oral tissues and may cause allergic reactions or cytotoxic effects.
3D printing post-processing aims to address them:
Biocompatibility: Thorough washing and curing remove or convert all uncured material. This ensures the restoration meets safety standards for long-term intraoral use.
Mechanical strength: Insufficient post-curing prevents the material from achieving its designed hardness, flexural strength, and wear resistance. This leads to fractures under functional loads.
Restoration accuracy: Residual resin shrinkage or uneven post-curing directly causes poor marginal fit of crowns and dimensional distortion of models. This ultimately results in poor clinical seating.
Surface quality and aesthetics: Layer lines, residual support marks, and a sticky surface compromise the gloss and texture of the restoration. These defects increase staining and plaque accumulation.
Proper cleaning and 3D print finishing techniques create a smooth surface texture.
How to do after dental 3D printing? There are six standard post-processing steps. (The exact workflow may vary according to the printer, resin, restoration type, and manufacturer's instructions.)
Take the build platform off the printer and place it in a dedicated workstation. Then, use a scraper or similar tool to detach parts from the metal plate. Care is particularly important around thin walls, margins, edges, and other delicate features.
Automated part-release systems can reduce the force and manual handling at this stage. SHINING 3D’s FabWash, for example, includes an automated part-release function to reduce the risk of damaging printed parts.
Washing is essential in the 3D printing post-processing workflow, aiming to dissolve and remove the uncured liquid resin.
Soak the parts in the solution, usually isopropyl alcohol (IPA), water, or a material-specific cleaning agent. This depends on the resin type.
The washing time should be adjusted based on the resin type and part complexity, typically ranging from 5 to 8 minutes. For transparent resin materials, pay special attention to solvent compatibility to prevent whitening or embrittlement.
After washing and complete drying, the next step is post-curing. This step uses a dental light cure unit to expose the part to light at specific wavelengths to complete polymerization and achieve the material properties.
Dental light cure parameters, including wavelength, light intensity, exposure time, temperature, and part orientation, affect the final part hardness and toughness. Follow the resin manufacturer's instructions.
Important reminder: the part must be completely dry before entering the curing chamber. Any residual moisture will absorb or scatter light, significantly reducing curing effectiveness.
After washing and curing, it is time to remove the support structures used for overhanging geometries.
Use flush cutters or other tools to carefully snip off the supports at touch points attached to the model until the surface feels smooth. Be careful not to knock or scratch the dental parts, and avoid leaving any dents, pits, or surface cracks.
Polish cannot be ignored for restorations requiring high gloss, such as:
Crown margins
Fitting surfaces
Occlusal contact areas
Surgical-guide interfaces
Polish the model with a polishing machine, and if desired, apply wax to the model to enhance its color and create a glossy finish. Then use a steam gun to clean the model and remove any excess wax.
Place the finished part from all previous steps under adequate lighting to check:
Scratches and surface defects
Sharp edges
Warping or deformation
Dimensional or fitting issues
Overall surface appearance
To eliminate manual bottlenecks and errors during post-processing 3D prints, many clinics and dental laboratories generally rely on automated post-processing machines:
SHINING 3D FabWash: A smart post-washing system automates part release, washing, and drying in one workflow. It uses a magnetically coupled impeller for cleaning and provides predefined or customizable wash and dry settings. It is compatible with all SHINING 3D dental printers and supports alcohol, IPA, and water solvent.
SHINING 3D FabCure N2: A dental light cure unit provides controlled post-curing with 365-385 nm UV light and an automated nitrogen system. Nitrogen curing reduces oxygen exposure during curing and is designed to produce more uniform, tack-free surfaces. The unit also provides temperature control and supports applications including clear aligners, surgical guides, dentures, crowns, bridges, and permanent restorations.
Contact SHINING 3D DENTAL for more information.
Avoiding these pitfalls for successful post processing 3D prints:
Insufficient or excessive washing: Insufficient washing time leaves residual resin. Excessive washing can soften and swell the resins.
Curing before the restoration is completely dry: Residual alcohol or water on or inside the part leads to uneven curing, surface mottling, or compromised overall mechanical properties.
Using the same washing and curing parameters for all resins: Different resins have different chemical compositions and energy requirements. Using uniform parameters inevitably leads to underperformance in some materials.
Damaging edges or surfaces when removing supports: Using improper tools or excessive force leaves irreversible scratches or pits on the model surface. These defects are magnified in the final restoration.
Contamination of cleaning solvents or equipment: After repeated use, the cleaning solvent dissolves a large amount of resin, and its cleaning power drops sharply.
Leaving prints untreated for a long time after printing: Ambient light partially cures surface resin, while oxygen leaves underlying layers sticky and unwashed.