In order to print the dental model, the patient’s impression must first be captured digitally. This can be accomplished with intraoral impression scanners, desktop impression/model scanners, or via CBCT impression/model scanners.
Design and Treatment Planning
It is always recommended to clean the excess gum and cheek portions of the intraoral scans for best results:
Scan Integrity Considerations
Intraoral scan should not have problematic areas that can lead to errors in the printed appliance or patient discomfort
Occlusion is unclear or scan has bubbles:
Scan has scraps:
Scan is coincident and contains distortion:
Scan is incomplete and missing data/sections:
Out of Office Occlusal Guard Design
SprintRay Cloud Design helps and provides aligner/retainer model design, where you can upload patient’s scan files and your prescription. Once you receive the STL file of the designed models from SprintRay Cloud Design, printing can proceed
This is done in a dental model CAD software. SprintRay Software allows you to choose a dental model software that best meets your clinical needs. Our software accepts any design file formatted in STL, which means you can use whichever software you are most comfortable with: 3Shape Model Builder, Exocad, BlueSkyBio, etc.
As a general recommendation, we recommend the following design parameters for best success;
- 13 mm
- 19 mm
Printing - Special Considerations
Almost all orthodontic models will be created with flat bases, so therefore should be placed flat horizontally on the build platform with the occlusal surface facing upwards. Aligner cases with multiple models can be printed vertically, but will require supports on the bottom portions of the arches.
In most cases, 100µm Layer Thickness should be selected for recommended print times and accuracy.
Issues to be aware of:
- Model angulation - teeth should be perpendicular as possible to the platform to allow the appliance to lift straight up and off of the printed model
- Model Height - models should not be taller than 20mm, as this will cause the plastic to stretch too thin and result in inaccuracy/distortion
- Bad or Dirty Scans - models that need to be trimmed in a design software, or are missing critical data. Missing data could also be a damaged plaster model that has been scanned as well
- Deep Undercuts/Interproximals - deep gingiva margins, or large undercuts near the interproximals will results in appliance deformation during removal, and must be properly blocked out with wax before thermoforming
RayWare Cloud takes the effort out of preparing your files for print, by automatically nesting them in the most optimal position for printing. If using SprintRay Cloud Design Services, you can send your prepared print job directly from the Treatment page by using the Direct Print feature.
If importing an STL file of a raw scan, a model you have received, or designed in house, start by selecting the Dental Model print job type. Then select if the Dental Model Type is either an Aligner or Other.
If Aligner is selected, you will have the option of of automatically orienting the models Vertically, and generating an standing base of easy to remove supports from the bottom portions of the model
If Other is selected for the model type, this will automatically place the models flat on the platform with the selected resin and layer thickness.
If printing a raw or trimmed intraoral scan, you will need to enable the Auto Mesh Repair option to have RayWare Cloud automatically add a solid base to the scan and make it printable
Example of a raw scan imported, fixed, and automatically placed by RayWare Cloud
Example of Vertical aligner model with support base automatically generated
Place models with flat bases directly on the build platform.
Select a model and use the Base tool to select a surface on the model you wish to be flat against the platform
You should see a darkened portion of the model on the platform when viewed from below, which indicates the model is flat
Indirect Bonding Trays
Indirect bonding trays should also be placed flat on the platform. Due to the flexible nature of IDB materials, printed models should always have a flat base, with no supports:
Models should always be post processed per the recommendation in the resin Instructions For Use (IFU).
- For SprintRay Die & Model and IDB resins, Isopropyl Alcohol with a purity of 91% or higher is required for the washing process, per the FDA.
- If cleaning more than 2 or 3 models in the Pro Wash/Dry, longer wash and dry times may be necessary for best results.
- Always ensure models are completely clean before post curing in the Pro Cure units, and always select the correct profile for the resin being used.
Models for Aligners/Retainers:
After post processing the models for retainers or aligners, the models have appliances created using a thermoform method, also known as a suckdown.
Before creating the suckdown, the models are prepared using a method known as wax blockout. This is where wax or a UV filling material is applied to the model to reduce the undercuts and overhangs of the tooth anatomy and allow the appliance to be removed from the model without distortion. This process can be done digitally in the model design software by extruding tooth surfaces for smooth transitions, or done manually by hand by adding melted wax or UV curable filling material:
After any necessary wax blockout is performed, a non-stick separating medium is coated on the models, then they are placed on the thermoforming machine for appliance creation via thermoform.
The plastic is allowed to cool, then trimmed away from the model into an arch shape, then washed and placed in the patients mouth to either retain teeth, or slightly move them until the next aligner is needed.
Start by trimming the excess away from the model
Next, cut along the midline of the model
Then, trim away the distal portions of the heels of the arches
Finally, use a tool to gently pry the appliance away from the model
Note: removal of the plastic thermoform from the printed model is one of the leading causes of appliance distortion! The plastic should always be allowed to cool to room temperature, plastic should be as trimmed as possible, and care should be taken not to deform the appliance during removal from the printed model.
If any minor distortion of the appliance occurs (i.e. the posterior portions of the appliance do not fully seat on the teeth), then the appliance can be made slightly pliable with warm water or a steamer for delivery to the patient:
Indirect Bonding Trays (IDB):
Once the Indirect Bonding Tray is printed and successfully post processed, the bracketry for the traditional style braces is placed in the model for each corresponding tooth position:
Once the brackets are placed, the tray is cleaned and prepped for placement in the patients mouth: