by Robert N. Pickron, DDS
How to take a good Invisalign impression every time
|Robert N. Pickron, DDS
Taking a good Invisalign impression on the first try is important for several reasons. First, you minimize the cost of time and materials; second, you impress the patient with the fact that you know what you are doing.
The most difficult areas in which to get a good impression are the upper, buccal to the last molars, and the lower, lingual to the last molars. This is because you cannot get the light-bodied material to flow unless you have support behind it; the cheeks and tongue are the problems.
How We Do It
1) We first take a good alginate impression, making sure that it captures the soft tissue at least 3 mm beyond the margins of all of the teeth. If you cannot take a good alginate, you will have a problem with PVS for sure. Retaking an alginate is cheap and takes little time.
2) Pour up the alginate impression and trim the model for an Essix retainer, blocking out any extreme undercuts, bridges, etc.
3) With a pencil, draw a line 2 mm gingival to the margins of the teeth.
4) Suck down 1 mm Essix material over the model.
5) Cut away the excess stint material back to the 2 mm line.
6) Using a plastic tray and heavy-bodied material, create a custom tray over the model.
7) When the material has set up, remove the custom tray and use a BardParker blade to remove the excess heavy-bodied material close to the 2 mm line. This will make the tray easier to place and remove from the mouth. Now you have your custom tray.
8) Mark the midline with a Magic Marker.
9) When the patient returns, try the tray in for fit and comfort and then load the tray with soft-bodied material only in the channel of the teeth. If this is done right, there will be little excess flow into the throat and onto the tongue, minimizing gagging and excess costs.
We usually do the alginate impression with the records when the patient signs up and makes their first payment, and then have him or her back for the final PVS impression later in the day or week.
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Taking an impression this way is an extra step, but you will get a good impression the first time without gagging the patient, and your patient will be convinced that you know what you are doing.
Robert N. Pickron, DDS, is in private practice in Atlanta. He can be reached at