Expert view

1. Invest in a 3D printing system that offers a simple A-Z solution.


Most dental 3D printers are based on the liquid resin photopolymerization technology. In this 3D printing protocol, printed models need to be cleaned of the excessive resins and further cured prior to being ready.

A few years ago, early adopters of 3D printing built DIY solutions for these processes. Now, various companies like SprintRay are offering simple and efficient units for wash and cure steps. It is time to opt for the best solution and work on utilizing the technology to improve patients' experience.

After over 7 years of tinkering with various 3D printing systems, I would recommend two platforms.

SprintRay 95S with the wash and Procure2. The S series of SR printers have a heated build plate and a series of sensors that reduces 3D printing failure. SprintrRay also has a slew of resins for most dental appliances - i.e., nightguard and pontics.
Epax or Phrozen printers with Keystone resins would be the alternative. This solution offers an inexpensive entry point compared to the SprintRay platform. I would still purchase the wash and Procure2 even if I like to save on the printer cost. Alternatively, one could opt for inexpensive wash units and early generation of Procure boxes by Sprintray.

2. Switch to an all digital model preparation


Ideally For your retainer or reset retainers, you would like to have a software that offers digital wax up. Additionally, you would like the software - most likely a paid version - to offer the following features:
3D print optimized stl file with customized label.

Automated digital block out
Minor tooth movements if needed
Pontic or eruption domes
Attachments (mixed dentition)
A free alternative option to prepare the models for 3D printing is MeshMixer. All the information you need on how to use MeshMixer to prep your digital scan is here.

Here is also a quick video explaining how to block the interproximal space with MeshMixer.

The last resort is to use any polymer like triad to block out the undercut. Based on the quick video above, you can see how easy it is to block out the interproximal area.

3. Invest in a high quality plastic sheet


How did you decide what plastic to use for your current clear retainers? I have learned that many orthodontists go by their peers' recommendations.

Here are a few questions that you want to answer to help you pick the right plastic.
What would one like to get out of a clear retainer? The first thing is to retain the teeth hence no deformation of the plastic overtime - aka no plastic creep. One approach is to use a thicker and tougher plastic sheet - at the expense of patient comfort - to minimize deformation overtime.

What else do you need from a retainer? resistance to crack, tear, or wear, easy to clean, and looks clear.

How long should a clear retainer last? For a compliant patient that wears the retainers every night, I would give it 6-9 months mostly since the plastic starts losing its shape - i.e., plastic creep.
You want a plastic that is clear, doesn’t wear, tear or crack under 6 months, and reasonably priced.

My favorite plastic for retainers is Zendura A 0.76mm/0.03”. I like Essix Plus, invisacryl ultra, and Taglus tuff at similar thickness. I only use 1mm/0.04” for bruxers.

4. Brand your retainer program


In-office clear retainer program is the best opportunity to brand your services. This is how I brand my clear retainers. Sonnyside up designed our packages.

A box or a string bag to include everything.
A branded pouch to include the retainer
An instruction card with a QR code to your website.Retainer seater if you slightly moving the teeth

5. Bundle your retainer program with a 3D printed nightguard


Interestingly, there is no evidence in dental literature on indications of nightguards vs clear retainers for patients with no TMJ issues or heavy restorations including implant supported ones.

3D printing nightguards is a low hanging fruit that can help you maximize the ROI for your printer. You can outsource the design of the nightguard to a local lab or to the design services of SprintRay if you are using that printer.

Some adult patients get a 3D printed nightguard and a set of retainers at my practice - PORTH. Some insurance policies partially cover 3D nightguards. I use a flat plane design and block for 15 mins to adjust the nightguard.

6. Bond attachments on primary teeth


I moved from acrylic retainers for kids with mixed dentition. This saved me several retainer visits and having the uncomfortable discussion with parents for a $500 USD retainer when they lose it or break it.

I use uLab and create eruption domes on loose primary teeth or over edentulous areas, bond attachments on Es. You can do the same with MeshMixer.

A retainer for patients with mixed dentition is basically a passive aligner for me - Zendura FLX 0.76mm. You can easily make a new one if they lose it and have a reasonable price for it - $40-$50 USD.

I don’t charge for the first few replacements. Discontinue the retainer wear about a year post phase 1 treatment. After one year, you can scan and make a new retainer if you deem necessary.
Go and build a great retainer program.

Rooz Khosravi, DMD, PhD, MSD

Clinical Assistant Professor of Orthodontics at the University of Washington

The European Aligner Society looks forward to welcoming delegates to its 4th Congress in the wonderful city of Turin on 11-13th May 2023.
For more information, please visit EAS website.

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