Alginate impression

Below is the video that shows you how to take good impression. I do it slightly differently. Instead of seating the tray on the posterior teeth first, I seat the tray on the anterior first and then I gently push the tray on the posterior teeth….and I stop pushing on the tray when I see a small amount of excess alginate material start to flow out toward the patient’s throat. This helps make it more comfortable for the patients, especially the ones who have a strong gag reflex. I know most schools teach you to seat the tray on the posterior teeth first, which is the correct way. Try my technique to see if you like it. I train my staff to do it this way and they love it.

A common mistake is the failure to capture the depth of anterior vestibule and frenum. So make sure you retract the lip before you seat the tray. To accomplish this, I usually put a small amount of alginate material on the anterior teeth (the same way that the doctor in the video did on the occlusal surfaces of his posterior teeth) before I seat the tray. Another mistake is having alginate material that is too runny. So make sure you have the correct water powder ratio by using a scoop and measuring cup. Later on, when you have more experience, you won’t need the measuring cup. You can make the material set quicker by using slightly warm water.

Nicole M said:

Hi I'm a dental student, I would like to know some tips to make my alginate impressions more accurate, tips such as mixing, timing, and how to place the impression please!

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Dental assistant here! When mixing alginate it should be more on the “firmer” (consistency should be like a cake batter. it’s smooth and thick but not watery) side than runny. When it’s runny it tends to flow all over the place, and sometimes not good. I usually mix my alginate until it is smooth, I use cold water so it sets slower.

(Another tip, runny alginate impressions work better if the patient is edentulous—-I will sometimes mix like this for maxillary impressions)

Before taking impressions I always try in my trays. I typically like to use a slightly larger tray on patient’s, because I’m bound to capture more of their mouth. I also make sure patient’s place their lips over the tray while seating it in their mouth. When I take impressions I make sure to jiggle their lips over the tray so I catch the vestibule, and trays should be seated from back to front so that material flows toward the front of the mouth—and not back down the patient’s throat.

The thicker you mix your alginate, the faster it will set. If it is watery, it will take a bit longer. If you use warm water the alginate will also set faster.

I also have patient’s move their mandible from side to side.