How to Take One-step Impressions

For information regarding taking a one-step impression, refer to the following:

• Definition and Uses
• Parts Needed
• Taking a one-step impression

Definition and Uses

One-step impressions are when the heavy/medium and light body is loaded into the impression tray at the same time for the impression. 

Impressions are taken when submitting a case and whether you take one-step or two-step impressions is entirely up to you as the doctor and what is your preference.

Parts Needed

The following are a list of parts needed for a one-step impression:

• Two impression trays
• Tray adhesive
• Heavy body impression material
• Light body impression material
• Impression gun
• Timer
• Scissors (for cutting end of heavy and light body tips)

Taking a one-step impression

The following is a video and step by step instructions on how to take one-step impressions.

Download a printable guide to taking one-step impressions here. 

To take a one-step impression, perform the following steps:

1. Ensure that you have the right size tray for the patient's mouth. The tray should extend beyond the last tooth in the arch without touching the gums.

2. When you’re sure you have the right size trays for your patient’s mouth, apply adhesive to the trays. This will help prevent the impression material from becoming unseated from the tray upon removal from the mouth.

3. Place the mixing tip into the heavy body material and load it into the impression gun. Discard the first inch of material on every new mixing tip. Set your timer for the working time of your material, then squirt the heavy body into the tray. Fill the tray from one side to the other. Don't lift the tip out of the material, or you'll get air bubbles in the impression.

4. Unload the heavy body impression material from the impression gun and load the light body. Be sure you're using the small tip, because the mixture will flow quickly.

NOTE: Fill the tray from side to side, completely covering the heavy body material. Do not over-fill the tray.

5. Beginning with the distal side of the last tooth in the mouth and working mesially, cover the arch with the light body material. Stop when you reach the central incisors.

6. Go to the other side of the mouth and, again, starting with the distal side of the last tooth and working mesially, cover the rest of the teeth in the arch.

7. Press the tray into the teeth, but not too hard - you don't want the teeth to push all the way through the impression material and touch the tray. Set your timer for the intra-oral set time of your light body material, and keep pressure on the tray until the impression has set.

8. When you're checking your impression for quality, make sure that:

•    All teeth are clearly registered
•    There are no voids or tears
•    At least 5mm of gum tissue is visible
•    No teeth are hitting the tray