How to Take Perfect Impressions

Set your patient records up for treatment success

Dr. Alex Molayem avatar
Written by Dr. Alex Molayem
Updated over a week ago

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Achieving a beautiful smile with Orthosnap clear aligners starts with perfect impressions. Since the quality of your impression dictates the fit and therefore the capability to move teeth, the quality of impressions matters. A lot. 

Impression redos damage the patient experience, waste chair time, and cost you money. Avoid this frustration by making sure your dental impressions meet the high-quality standards necessary for Orthosnap technicians to fabricate perfectly fitting aligners. 

Here's a video of our impression technique:

Tips on Taking Impressions

Tip #1: Use PVS, VPS, or Polyether Impression Material

Alginate can dry out and distort. Therefore, while plaster models or alginate impressions allow us to evaluate a case, we cannot produce aligners with these molds. Also, use plenty of material. Remember, too much is better than not enough.

Tip #2: Send BOTH Arches!

Even if you are only treating one arch, send both arches and a bite registration. The lab tech needs to know the location of opposing teeth to prevent hyper-occlusion or inter-arch collision. The bite registration allows us to correct the relationship between upper and lower aligners for bite issues.

Tip #3: Use Rigid Impression Material for Bite Registration

Ask the patient to close the teeth where they meet best and keep the bite spread out but heavier on the back teeth.

Tip #4: Use Correctly Sized Trays

When it comes to trays, proper sizing is the most important factor. The tray must extend 4 mm beyond the gingival margin and fit all the teeth. It should also extend beyond the terminal teeth. If the tray is too large or too small, it can cause issues that may require a re-make. Use disposable trays as we will not return trays. If the teeth touch the edges of the tray, it is too small. 

Tip #5: Remove Engagers or Buttons

To make accurate molds, the impressions must be free of engagers. If your patient has engagers on any teeth, be sure to remove them before taking impressions. 

Tip #6: Fill in Undercuts

Use wax to fill in undesirable undercuts. Neglecting this step can cause distortions or tears when removing the impression material. 

Tip #7: Do Not Forget to Use Light Body

Be sure to add the light body material before the heavy body or putty sets. 

Tip #8: Avoid Common Operator Mistakes

  • Not allowing the material to set fully

To ensure the best impressions, make sure the materials fully set. Here’s a tip: Discard the first inch of material from each new mixing tip. Then, be sure to set a timer based on the instructions for your material. As a safeguard, wait an additional 60-90 seconds beyond what the instructions advise before removing the tray.  

  • Double impression

When using a two-step impression method, the most common error is a double impression. To avoid this mistake, consider switching to the simpler and more reliable one-step method. If you prefer the two-step method, we will accept them. Just be sure to cover the putty for the first impression with a plastic sheet and begin the second step before the first one fully sets.  

Inspecting Impressions

Inspecting your impressions to ensure they meet our standards before you send them to our lab can help you avoid costly delays. In fact, it is best to look at them while the patient is still in your office. This way, if you notice any issues, you can remake new ones without having to recall the patient.

The following rules will help you understand what to look for before submitting impressions.

Rule #1: Capturing the Distal Surface of Molars

When making impressions, be sure to capture the distal surface. If the distal surface is not captured, the result is ill-fitting aligners. Avoid this common problem by ensuring over half of each of the terminal molars is visible in the impression.

Rule #2: Accurate, Detailed Occlusal Surfaces

Look for sharp, detailed cusps. Make sure no part of the tray shows through the impression.

Rule #3: Intact Impression Material

If the impression material is thin or damaged, the inaccuracies will compromise aligner fit. Be sure to inspect for warping, damage, bubbles, tears, or separation of heavy and light body material.

Rule #4: Clearly Defined Gingival Margins

Effective tooth movements require adequate retention points. This means the gingival margins must be clear and defined. When taking impressions, be sure to include a minimum of 4 mm of lingual and buccal surfaces outside the gingival margin.

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