To get started, we only recommend that you make in-house “lifetime” retainers if you have the proper armamentarium, including a pressure-vacuum former like a Durfomat or Biostar. A standard vacuum-former doesn’t give enough detail/fit for long-term retention. If you don’t have the proper equipment, it is best to refer your retention out for fabrication to a local lab or Align Technology Vivara. Remember, “Essix-type” retainers last on average 6 months to 2 years so throughout a lifetime the patient will need to replace them often. Be sure you are transparent about how the re-ordering process will work and what the cost is. Also, if the patient gets new dental work, a new retainer may need to be made.

Not all plastic is alike. Material for retention is stiffer and often thicker than aligner or bleaching material. Here are some of our favorites:

  • Essix ACE® Plastic (Clear material with a green Essix® protective film on both sides)
  • Essix C+® Plastic (Cloudy material- NOT perfectly clear) – good for bruxers
  • Essix Plus
  • Zendura Classic
  1. If you are taking impressions, PVS is better than alginate for long-term retention. We don’t recommend using alginate except for temporary retention. A scan is always better, and scans can be stored in the cloud for easy re-ordering.
  2. If you are making it in-house, pour your impression up in stone, not plaster.
  3. The case should be trimmed to a 3/4-inch base. Any thicker, and the plastic won’t adapt ideally. Bubbles should also be removed.
  4. Make sure you get the right size and shape thermoforming plastic to fit your machine. Some are circles, some are squares.
  5. Wheel saws and electric heat knives are helpful for removing the cast from the plastic.
  6. Iris or Mayo scissors can be used to trim further, and wheels can be used to polish

Essix comes in 030, 035, 040.

I recommend 035 or 040 for retention but ultimately it depends on how you’ll be trimming it. If you do 040 and do a straight line trim you may struggle to get it off.
If you do scalloped it will likely be ok.