Invisible braces (including transparent aligners and clear retainers) have
the advantages of being aesthetically pleasing, comfortable, easy to maintain,
easy to clean, having a short treatment cycle, and being convenient to put on
and take off. They are quickly becoming the preferred alternative to traditional
wire braces. In short, invisible braces are made by processing plastic sheets
through thermoforming on custom 3D-printed dental models.
1. Intraoral Scanning
Before manufacturing transparent dental aligners, the first step is to obtain
the patient's oral data. Usually, a 3D intraoral scanner is used to scan the
patient's mouth, or a desktop 3D scanner is used to scan physical models or
plaster models to obtain 3D digital model data in STL format.
2. Design
Import the scanned digital model files into appropriate orthodontic or dental
computer-aided design (CAD) software (such as 3Shape, Exocad). The design
software includes two main categories: making transparent aligners and making
clear retainers.
Invisible Aligners
Dentists perform tooth separation, tooth arrangement, animation, and staging
based on the scanned data, communicate with clients to confirm the treatment
plan and schedule, and sometimes use CBCT data for assistance during the
planning stage.
After the treatment plan is finalized, the dental model data for each stage
is output.
Clear Retainers
Retainers are used in the post-treatment phase. To make retainers, only the
scanned dental model data after treatment is needed. Simple operations such as
trimming and filling undercuts are performed in the design software, and
finally, the dental model data is output.
Optional Designs for Dental Model Data
– Hollow Models
To save costs, dental models are usually designed to be hollow, with a wall
thickness generally ensuring no less than 3mm.
– Through Holes
Hollow models have cavities, which may lead to printing failures. It is
recommended to add through holes at the bottom.
– Honeycomb Filling
To reduce the decrease in overall strength of the hollowed model, honeycomb
structures can be used to fill the hollowed areas.
– Reinforcing Crossbars
To avoid shrinkage and deformation of arch-shaped dental models, crossbars
are added at the opening.
– Fixture Positioning
To match automatic invisible brace cutting machines, positioning holes need
to be added at the bottom of the dental model, with specific shapes referring to
the cutting machine.
– QR Codes
Adding QR codes to the dental model, which can be read by industrial cameras,
enables quick and accurate access to relevant information about the dental
model, realizing automatic identification of dental model information.
– Text Markings
Adding concave or convex text markings on the dental model facilitates later
sorting work and greatly improves work efficiency.
3. 3D Printing
(1) Load the model in the slicing software. Thermoformed dental models are
generally printed directly on trays without supports. Then, select the resin and
parameters to complete slicing.
(2) Upload the sliced data to the printer and complete the printing.
4. Post-Processing of Dental Models
(1) Remove the dental model from the tray.
(2) Place the model in a cleaning machine filled with isopropyl alcohol (IPA,
≥96%) for cleaning. To ensure thorough cleaning, it is usually cleaned
twice.
(3) Take the model out of the IPA and air-dry it in a well-ventilated area at
room temperature or dry it with an air gun.
(4) Put the cleaned and dried model into a curing oven and set appropriate
parameters for post-curing.
5. Thermoforming
Using the printed model, process the sheets into invisible braces with dental
thermoforming equipment.
6. Laser Marking
Use laser marking on the sheets for easy classification, packaging, and
traceability.
7. Trimming
– Manual cutting
– Automatic trimming
8. Polishing
Cutting or trimming with scissors or dental handpieces can result in sharp
and rough edges. Use grinders and polishers to trim and polish the edges.
9. Quality Inspection
Quality inspection is a particularly important step in the manufacturing
process. The finished products need to be thoroughly inspected to ensure they
are clean and free of defects.
10. Packaging
Classify according to the client and their treatment cycle, and pack the
invisible braces into custom boxes.
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