Why Dentists Need to Take Impressions of Your Teeth

Why Dentists Need to Take Impressions of Your Teeth

Reasons Dentists Take Impressions of Your Teeth
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As I’ve been assisting the third and fourth-year dental students in the clinic over the past couple of years, I’ve had the opportunity of taking quite a few impressions on many different patients.

Taking an Alginate Dental Impression - Photo Courtesy of SuperWebDeveloperI think the whole impression and plaster pouring ordeal is kind of interesting.  However, many students and patients don’t seem to love it. The whole process is a bit messy.  Inevitably, the patient needs help removing the impression material that got stuck on his or her face.  Also, it leaves a bad taste in their mouths. Oddly enough, it doesn’t appear as though the man to the left is having the time of his life while his impression is being taken. So why do we take those dental impressions anyways?

Why Dentists Need to Take Impressions of Your Mouth

A dentist might need an impression of your teeth for many reasons.  A few of the more common reasons are:

  1. To make a removable partial denture or a complete denture
  2. To make a conventional dental crown – the newer Cerec in-office crowns can take digital impressions, without the need for the messy impression material.
  3. To make bridges or fixed partial dentures.
  4. To analyze the relationship of your jaws.  This can be useful for orthodontic treatment as well as an evaluation for oral surgery.
  5. To make a custom mouthguard for protection while playing sports or to wear at night to prevent teeth grinding.
  6. To make custom teeth whitening trays.
  7. To make oral appliances such as space maintainers.
  8. To know how your teeth look in case you chip or damage one or more so that they can be properly restored to their ideal shape and size.
Dental Cast
When the dentist takes a good impression, it is easy to visualize the crown and bridgework that will go into the mouth to make sure everything will fit perfectly.

These are just a few of the reasons that I could think of.  There may be many more.  If your dentist wants to take an impression of your teeth, then he or she likely has a good reason.  It is always a good idea to communicate with your dentist to find out the reasons behind their actions, whether they include taking dental impressions or not. If you have an experience with a dental impression that you’d like to share, or if you have any questions or comments, please leave them below in the comments section.


    • Hi Chris – They shouldn’t be painful. The step by step process is normally:

      1 – We try an empty tray in your mouth to make sure it is the right size.
      2 – We fill the tray with the impression material.
      3 – We insert the tray in and have you close your lips around it so the material goes up around your teeth where we need it to go.
      4 – We wait for it to set up, and then remove the impression tray from your mouth.

      I hope that helps, let me know if you have any other questions.

      • Hi thanks for that. My friend has had impressions and he said it was really painful. Why would that be? Also will it make me sick because of my gag reflexes?

        • Hi Chris – The pain may be from a tray that doesn’t fit properly. It’s a good idea to have your dentist try the tray in your mouth first without any impression material to make sure that it’s not pushing up against the gums/lips/cheek. I’m guessing the reason that it hurt was because part of the hard tray was pressing into something that it shouldn’t have.

          It can be challenging to take impressions on people with gag reflexes. I think the worst case scenario would be that you would have to remove the impression tray before it had completely set up. If that’s the case, have the dentist/dental assistant try putting in less impression material the next time around.

          I hope that helps – Let me know if you have any other questions.

          • Hi me again! I am going for impressions on Wednesday but my gag reflexes are really bad! I have had impressions once before and I had to be held dOwn for them as I took it out before it harder and didn’t want to have it done again! Is there anything I can do to help Or anything another dentist could do?

            • Hi Chris – We generally recommend breathing through the nose. We also have some anesthetic spray that we can use. This page on Dental Fear Central offers a lot of tips on how to reduce gagging.

              I hope that helps, Dee – Thanks for your comment! Let me know if you have any other questions.

          • Hi Tom
            I’ve had four different impressions done the last one was left in too long my dentist had trouble pulling it out when she did manage to get it out it came out with my 2 back teeth crowns. When I went in for my wax bite fitting where the teeth and positioning were revealed to me I was delighted, the teeth were perfect. natural looking ceramic/enamel just as you would imagine teeth to be. I even took a photo of them in. 2 weeks later I was called in to fit the finished denture and take home. To my horror on the reveal the teeth had been swapped. The teeth on the denture are somewhat similar to a cheap NHS plastic teeth, the positioning was totally different the size and shape were totally different. I took another photo to compare and its clear in the photos they are different teeth. I confronted the technician and she completely stood her ground and said they were not swapped. I noticed on my patient statement there is a quantity of 2 teeth and 1 acrylic. I asked for natural looking teeth and I end up with something that I wouldn’t even pay £100. for. I am thinking the original ones were made then either broken or lost in transit and another set were made on the quick with cheaper material. What do you think. what should I do. I was forced to pay for them by my dentist I part paid as I am not happy with them I refused to pay the full amount. I have since been told by friends that I shouldn’t have paid anything. but they closed ranks so I had to.

  1. It is definitely a scary situation, or at least it was for me. Yesterday I went to have impressions both upper and lower. He started with the top. They were stuck, after janking and janking forever it seemed and nothing he ended up having to give me anesthetic shots (4 or 5) and it felt like my remaining teeth were going to be janked out with the impression. The worst part of all this is that I have to do the bottom in 10 days and now I’m petrified, but have to go cause I can’t leave this as they are. Is this what cave men used?? or maybe Chinese torture. Today I feel as I have just lost a heavyweight match or been in a wreck and I have whiplash. Any suggestions? and don’t tell me to breathe through my nose doesn’t work!!

    • Hey Tom! About a week ago i asked my mom what they do to get the gooey impressions off your teeth
      and she said that it just hardens… But i was wondering, when they take it off does rip out your teeth?
      -Annabel 🙂

      • Yes this can happen, it happened to me. On my last impression taken for my upper denture my dentist ripped out my back crown.

  2. Trust me i am totally with you i am totally scared out of my wits probably more
    scared than get any shots!!!! I am hyperventilating, not kidding!!!
    -Annabel 🙁

  3. My dentist prepped my tooth and forgot to make a tooth impression first. Will this pose a problem with my bite?

  4. Hi ,
    I have a bridge on the upper gum with 5 teeth on it ,
    I,m having trouble with one of my lower teeth and I think the dentist will need to do an impression ,My worry is that the impression may pull the bridge out ,this will be my second impression that I have had over the years ,I have had the bridge in since 2008 ,,what would the dentist do if my bridge came out ?
    sincerely ,Brenda..

  5. Hi
    You have every right to be scared. I recently went to the dentist because I had lost a cap. They took an impression and ripped out 2 caps and a 4 unit bridge. I think he used the wrong impression material. I would love to know more about the procedure and materials used for taking impressions

  6. i went to the dentist and had my impressions done and i still have like 10 teeth in my mouth and when he did them ity felt like my teeth were coming out with it.i didnt know they could do impressions with teeth still in your mouth isnt that gonna be a problem and make them not fit right.

  7. I had a dental impression done last week for lower left for a 3 unit bridge. The material seemed to harden or stick to my lower jaw so much that dentist pulled so hard and out came my 4 unit lower rt.bridge. It was just completed 6 mths ago. the bridge was on 3 root canaled teeth and dentist told me the tooth roots came out with it. She reapplied bridge with some material acting as a splint to keep it in place My face was swollen & discolored. She said it will take about 6 weeks to see if root reattaches itself. have you ever heard of this happening? Or should I opt for implants?

  8. Hiya everyone wanted to know if someone could please give me an answer I’ve had impression done fory denture upper mouth my dentist is leaving my two front teeth in! They are abit yellow & my bottoms will my denture be yellow?? Or will he whiten my other teeth I’m so scared 🙁 please help.

  9. Good article.
    I have been going to the dentist having teeth pulled to have dentures made. Today the hygienist was taking an impression of my bridge and when she pulled the material out my bridge came out also. This was a horrible and painful experience. The dentist did fix my teeth. Has this happened to anyone else? I know

  10. How long do they have to place it in the teeth in so scared and I don’t want to go please any advice please I’m really worried

  11. I’m going for dental impressions today for an expander appliance, as well as braces. I got an impression before and I gagged and they had to take it out. The reason why was because they over filled the tray and leaned me back too far so it all ran down my throat. This time I’m getting numbing spray and I’m going to lean forward. Wish me luck 🙂 And to everyone else worried about getting impressions, practice putting a toothbrush or some clean fingers as far back in your throat as you can to see what the impression will feel like if it drips a little bit. Also, ALWAYS breathe through your nose while getting an impression. You almost definitely won’t gag if you do that. Good luck to everyone who is worried 🙂

  12. I had impressions taken just not sure what it was for asked the hygienist she said she didn’t know. But the impressions weren’t bad the bottoms hurt some only because I have sentive teeth. After she had me bite down on a flat sheet of something like wax to do another impression. I didn’t get a chance to ask the dentist any questions after that he worked on one of my teeth. Then I went home.

  13. How many impressions does a dds need, seems like i’m getting one every other year or so and i’m in my 50’s now, its not lioke my mouyh and teeth are going to change much from here on out?

  14. I need a crown, and I just got the temp. However, it’s very badly shaped. The tooth before getting crown was missing a whole wall and edge (the one facing the tongue) and instead of repairing it and then making an impression, the dentist decided to do the crown just like that. With the missing tooth wall/edge. Is that what dentists normally do?
    Do you think I should go back to her and ask her to fix it, or would she charge me for a new crown seeing as she probably already sent the order to the lab?
    Thank you so much.

  15. Hi, I went for my second orthodontic appointment today. I was told that I have to extract two of my upper teeth before putting on braces two weeks after my teeth extraction. My question is, my orthodontist did not take my dental impression. Only photographs. Is this normal? Thank you.

  16. Hello,

    I lost my bottom retainer and although i have a permanent retainer, i didn’t want my teeth to move so rang my othrodenist and booked an appointment for a new retainer to be fixed. I went to get a mould for my bottom teeth two days later and i teeth didn’t appear to have moved much. However the mould was taken very quickly- i feel as though it was not in my mouth for long enough to harden. Since i have received my new retainer i have been wearing it properly yet my teeth have changed shape-they are all in line yet i feel like all have moved forward/backward together as my mouth has changed shape then closed. I am worried the mould was not taken correctly. is this possible? if the mould was not in my mouth for long enough could it have possible impacted the shape of it? Thank you in advance

  17. A collective reply to all:
    I’ve had numerous impressions, the last one was to have dentures made.
    For those who deal with ‘gag reflex’ try the trick that worked for me. A few days/week before you’re going for your impressions and/or dentures, ‘desensitize’ that area by pressing down lightly the back of the tongue a few times a day. Trust me, it actually does work!
    As far as the ‘goo’ sticking on & pulling out your teeth – insist on the dentist coating your natural teeth ahead of time. (its almost like a Vaseline which will allow the impression to slip off without yanking). Again, it made all the difference and honestly, one day at a time really helped.

  18. Re: impression trays.
    I am having impressions for a new top denture but unlike previously, this Dental Clinician has not used the trays; she just put the material in my mouth directly?? Surely this will not give an accurate impression?

  19. I had impressions done 2 days ago and can’t get the taste out of my mouth no matter how many times I brush my teeth or what I use to rinse. Help!

    • I can’t open my mouth wide enough to get an impression. Can I be put to sleep to get it. I am afraid that I will be left toothless because the dentist can’t get an impression.

  20. If you are not happy with any part of your dental procedures then seek out a 2nd or 3rd opinion. Impressions should not cause any pain, discomfort or disrupt previous dental work if you have the right dentist. I was also petrified to get impressions and I had absolutely zero issues, other than the material making a mess, and which the hygienist cleaned up after. Your paying for the work to be done so you should be happy with the results and the dentist.

  21. I just saw a new dentist today. He told me 30% of his diagnostics require him to have a mold of my teeth. He mentioned how it was important to have so he can study my bite. No other reason. I am healthy, not needing anything other than a regular cleaning and regular x-rays done. My jaw/bite is fine. He can see the way I bite visually so now I am feeling dumb as to why I went through with this. Did he scam me? I t cost me $80 because insurance doesn’t cover it.

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