A high-quality impression is the foundation of a successful case. Whether for a submission or a revision, accurate impressions are vital to ensuring that treatment is effective and time-wasting delays are avoided. Here are some of the main bad impressions issues we receive and how to correct them.
NOTE: We only accept any silicone-based impression material, including PVS, VPS, and polyether materials.
- Issue #1: Double impression in 2-step material
- Issue #2: Material not fully set
- Issue #3: Posterior distortion
- More Helpful Tips
Issue #1: Double impression in 2-step material
The most common problem that we find is a double impression, which usually happens during a 2-step impression.
If you prefer the 2-step impression process, that's okay too. Just keep an eye out for double impressions. Remember to cover the putty with a plastic sheet when you take the first impression, and to take your second impression before the first one has fully set. We also have a video and a written tutorial for this type of impression as well.
Issue #2: Material not fully set
Our second-most common issue is material that hasn't fully set before being removed. There are two simple things you can do to prevent this problem:
- Set a timer and make sure to follow the directions for your material exactly.
- Discard the first 1 inch of material that comes out of every new mixing tip.
- We recommend waiting an additional 60-90 seconds longer than instructed before removing the trays from the patient's mouth.
Issue #3: Posterior distortion
The final big issue is distortion of the most distal teeth in the impression. It can be hard to see back there, and sometimes the posterior teeth get shortchanged. There are a couple of ways to avoid this problem:
- Make sure that you're using a correctly-sized tray. It should extend past the last tooth in the arch without touching the gums.
- Before inserting the tray containing light body, add some light body directly to the occlusal and distal portion of the last tooth in the arch, ensuring that the last tooth is completely covered with material.
More Helpful Tips
- Make sure the tray is not too small and fits your patient well. If the teeth are touching the edges of the tray, the tray is too small.
- Use plenty of PVS material. It's better to have too much than too little.
- Remove all engagers prior to taking the impression. We need impressions free of engagers to make accurate molds.
- Fill in undesirable undercuts with wax. This will allow you to remove the impression material cleanly without creating tears or distortions.
- Refrain from moving the material as it sets. We recommend waiting an additional 60-90 seconds longer than instructed before removing the trays from the patient's mouth.
- Don't forget the light body material! Add the light body before the putty or heavy body dries completely.
We hope this helps. Look for these issues before you send your impressions in, and you could save yourself & your patient the hassle of taking new impressions.