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.