Thursday, July 18, 2024
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Dental Suction: Why Dentists Use a Suction

A reader named Jeanny recently emailed me the following questions:

Why is it necessary to suction after local anesthetic?
Why is it necessary to suction when doing a filling?
Can blood be involved in both of the above procedures?

I’ll answer the first two questions later on in this article.  In response to the last question, blood can be involved when giving anesthetic and doing fillings, but many times it is not.

First, let’s talk about the two main types of suctions that dentists routinely use.

The Two Main Types of Dental Suctions

Dental SuctionThere are two main types of dental suctions that dentists use: the saliva ejector and the high volume suction.

The saliva ejector does exactly what its name implies; it sucks saliva out of the mouth.  This is the suction pictured at the upper right of this article.  Many times dentists will have the patient close down on this suction so that it can suction away any remaining saliva in the patient’s mouth.

The other main type of dental suction that we use is the high volume suction.  This suction is so strong that the dental assistant simply holds it close to where the dentist is working and it will suck away any nearby debris, much like a strong vacuum cleaner can suck away crumbs without actually touching them.

You can see the high volume dental suction pictured below – try to pardon the lack of glove use by that dentist!

Dental Suction - High Volume

Why Dentists Use a Dental Suction

Now that the introductions are over, let’s talk about some of the different reasons why dentists will use a suction.

For Patient Comfort

Keeping the patient comfortable is a high priority.  In response to Jeanny’s question, we suction after giving anesthetic because the anesthetic has a bitter taste, and most patients prefer to rinse out with water and use the saliva ejector.  Also, if the anesthetic sits in the back of your mouth for too long, it may start to slightly numb the back of your mouth and could give the patient a gagging sensation.

We will also use the suction to make sure that you don’t get too much water in your mouth while we are working.

To Clean Away Any Excess Dental Materials

When a dental hygienist cleans and polishes your teeth, you can get a lot of cleaning paste in your mouth.  We use the suction to help clean all of that away.  Also, when dentists are do amalgam fillings, pieces of the soft amalgam can sometimes fall away from the tooth surface.  We use the suction to help whisk them away.

To Keep The Tooth Dry

During some procedures, such as white fillings, it is important that the tooth stay clean and dry.  The suction helps keep the tooth dry by sucking away any saliva, blood, and water that may have accumulated around the tooth.  If the cavity went below the gum-line, then it’s pretty likely that the gums will bleed during the filling.

To Help the Dentist See

As I mentioned in a previous article about the dental drill, the drill that dentists use to do fillings sprays out a lot of water to keep the tooth cool and clean.  Unfortunately, that water can quickly build up in the mouth and get on the dental mirror.  In order to ensure that the dentist can see the tooth while working on it, it’s necessary to use the high volume suction to suck away all of that debris.

Those are the four main reasons that I came up with as to why dentists use the dental suction.  In conclusion, let’s take a look at a question that I asked my dental hygienist as a child.

Where Does The Stuff Go After It’s Sucked Away?

I remember sitting in the dental chair in Dr. Arnold’s office as a child wondering what happens to all of the stuff that gets sucked down the suction.  Maybe I was hoping that the tooth fairy would somehow be able to save the bad part of my baby tooth that the dentist removed and put it back together once my tooth fell out.  After gathering up the courage to ask, I think I was slightly disappointed by the answer.

After your saliva, tooth debris, etc. gets sucked away, it travels through the suction line to a vacuum separator that will separate out any solids.  After that, your spit makes a journey down the pipes and into the sewer system.

It is now recommended that dentists install amalgam separators in their suction lines to separate out any dental amalgam and keep it from getting into the public sewer systems.


Do you have any questions about why dentists use suction?  Leave a comment below and I’ll try to get back to you.  Thanks for reading!



  1. Hey! This is a great article that you posted. It is really an informative and useful one that there will be many other people or patients out there that would understand why dentists used some kind of suctions. Thanks again! And we’ll be pleased to read more great posts of you.

    • Never mind where the stuff that is sucked up goes How clean is the suction tip and hose I hope they don’t clean these things I hope they use a new one for every patient????

  2. Reference why do dentists use suction…..I have a disability that is related to a severe allergy to chemicals….from years as a farmer…my crown had fallen out and went to a dentist to have it replaced…his main practice was ‘dental implants’ he suggested that the three crowns I had should come out….was so traumatised believed that as he was the expert he knew something that I didn’t and went along unfortunately with his ‘advice’…..I explained my severe anaphylactic reactions to anesthetic with adrenaline….he used an anesthetic without….he did not use any suction….in desperation I asked to spit his wife pushed a suction at my spittle…I asked for this three times…and then in frustration he told me to swallow it…….that happened throughout the extractions…..because of my years of allergic reactions had already informed him that I had a permanent swollen tongue… I have a permanently swollen throat and can only talk for short bursts of say a few minutes before gagging…..he also had a denture made which cost me $1000 …… is an absolute disaster…..pushing one of my front teeth back behind the other…… has worn sores on the gum (three weeks ago) and is so far back in the mouth that it is causing major problems……when I went for a second fitting he told me that he couldn’t do anything else and to go home put it in hot water and mould it myself…… desperation after this visit I went to a professional dental technician who was horrified that a dentist would have sent a patient out with a denture so badly made but to expect them to repair it themselves having charged the patient $1,000 was a professional disgrace…so angry was he that he called the dentist and told him that he was horrified and extremely angry to see a patient in such dreadful distress…..the dentist then said it wasn’t his fault as the patient had a disability with chemicals……my understanding as to why he took my good crowns out… his partner is a dental surgeon and they have an ongoing business of dental implants……..immediately after the extractions he had arranged for me to meet his dental surgeon..I said no as I was now so ill as a result of the extractions etc., he was extremely cross and said that he had too much to do between now November and Christmas……then four days later he said that I was not dental implant material having taken out the crowns……..

  3. Hi there, I recently when to the dentist and I live in the U.K, to get my teeth cleaned. For some reason I kept on gagging every 20 seconds. It got that bad that the dentist kind of got frustrated and I felt as if I’m an inconvenience to her. As a result i postponed the dental cleaning and i said I will come another day. i have to mention it was in the morning and I wasn’t properly hydrated. I don’t know why but I just couldn’t keep my mouth open for more than 20 seconds. Also that suction thing made it worse, can i ask her not to use it next time? And maybe use it occasionally just clear up the debris?

    • Hi Adj – We use the suction to mainly help you during cleanings. I would discuss your concerns with your hygienist so they are aware. If you weren’t properly hydrated, your throat may have been dry which contributed to the irritation that made you want to cough. Usually when this happens, we offer some spring water to our patients and give them a break. This normally resolves the situation. I hope that helps! Good luck at your next cleaning.

  4. My dentist also uses a high-volume suction as a ‘distraction’ during injections, sucking on the cheek on the opposite side.

  5. I recently went to the dentist for a root canal. While the dentist was performing the procedure, the suction was placed under the dental dam and attached to the skin on the underside of my tongue. This has created far more pain than the root canal itself! It has left me with a lump and horrible pain. I have tried to numb the area with orajel, but it seems that no matter how much I try, it just wont numb, therefore I am unable to find any relief. I am asking for any advise you may be able to offer, as the pain is quite bad. I did mention it to the dentist and showed her after the procedure, and all she had to say was “it will heal”.
    I appreciate any information you may have to offer!

  6. I visited my dentist yesterday to have a composite replaced that had cracked off of a tooth (#30). During this process, the saliva ejector attached itself to the underside of my tongue. When the dental technician pulled it away, it felt as though some of the tissue had actually been sucked inside the little tube, as she had to use considerable force to remove it, and she apologized immediately. Can’t the intake be turned off to relieve the suction prior to removing it? It’s a very sensitive area for that sort of pulling. It was made worse when the dental technician again guided the saliva ejector to the exact same location, only to have it once again attach to what it now a hyper sensitive area of flesh. Upon completion of my procedure, I told the technician that I had experienced considerable pain with the suction device, and she said that they had to keep the area dry. How can it have kept anything dry when it was so firmly adhered to the underside of my tongue? To make matters worse, the dentist hit the same immediate area of my tongue twice with the drill when he was shaping my composite. Ouch! When I arrived at home, I was a little nervous to look to see why my tongue was so painful, and I was surprised to see that the vein along the right underside of my tongue is bright red and enlarged, and there is a white raised, pea-sized area right on that vein that is quite painful. I’ve had the composite on this tooth repaired probably twice a year for the last 8 or 10 years and have never once had an experience even similar to this. I’ve asked about getting this tooth crowned but my dentist says that it’s better to just keep repairing it. I never use any novocain for this procedure as the pain I experience is only brief (and manageable) and immediately subsides once the drill is lifted from my tooth. I’ll add that the pain from the suction was such that I barely noticed the drill yesterday. Today, any movement of my tongue is painful, so talking, eating and drinking are not easy, and go figure, my job requires talking. Is there something that I can use to help with my pain? Orajel hasn’t been effective at all, but it does burn considerably. Thank you in advance for your assistance.

  7. Good information in the various articles. I have a follow up question on the risk of backflow from a saliva ejector. I have seen some information about the risk of backflow from forming a seal around the tip. Most of the time when I have had my teeth cleaned they have had me close my mouth around the tip. Is there a difference between forming a seal and just closing ones mouth for potential backflow? What is the likelihood of someone else’s blood being in any backflow?

  8. While having a difficult tooth extraction the assistant did not want to remove water and saliva from my throat,
    therefore I was gagging and coffed, the dentist got upset with me for coffing. The assistant claimed she did not want to create a vacuum void which would cause bleeding. I had to finally keep raising my hand from time to time, sit up and remove the fluid myself so the dentist could continue work. It was crazy, does anybody else coff while having your throat filled with water and saliva at the dentist?

  9. Today I had a dental cleaning. I had a good amount of tarter that had to be removed. All during the procedure, my mouth kept filling up (with saliva, blood, water and tarter debris, etc) without being suctioned out. There was a tube in my mouth, but it didn’t seem to be doing anything. I mentioned to the hygienist that I was swallowing mouthsful of “stuff” but she seemed unconcerned. I should have stopped her at some point to check the suction tube, but I didn’t, so for a half an hour or so, I was constantly swallowing everything filling my mouth.

    Should I be worried, healthwise that I didn’t have anything suctioned out and that I kept swallowing everything? Right now I keep thinking about it and need to know if this is something I should be concerned about.

    Also, I don’t know if it’s connected to the swallowing issue or not, but since I left the dental office a couple of hours ago, the left side of my throat and back of my tongue are very sore and the neck gland on the left side feels a little swollen. I don’t know if that may just be from the intensive cleaning itself or something more.

    • I had this very same thing happen to me today and I would love to know myself, as my stomache feels very sick after they worked on some of my cavities and I can’t keep anything down that I eat.

  10. Comment
    an orthodontist used a dental suction on me and now it’s been 2 months of unhealing throat infection. my singing is so much affected even after trying different medications. am supposed to go back to the same doctor and am so paranoid about it. if the suction caused the infection is there a way the doctor can skip using it?

  11. I actually work in th dental field. I run a laboratory that makes dentures, crowns, bridges, etc. I recently had a root canal down and found that the DA kept resting the low power vaccum against the tissue underneath my tongue! This has resulted in two raised bumps underneath my tongue, one clear as glass and the other is bright red! How long until these go away? They are quite annoying and I feel are the direct result of poor placement of the vacuum itself.

  12. I have been working as a DA for year. Moved and started at a office where the dentist doesn’t let me use the HVE suction tip while assisting. I use the saliva ejector throughout the dental procedure instead. I can see the droplets from the mouth go literally everywhere. Since i have started there (two months ago) i have been so sick. Could something simple as which to use could affect my health?

  13. Hi Tom I hope you see this. I’m an engineering student and I will be working on the development of a dentistry tool that emits water into the mouth and cleans with ultrasonic bubbles. In order for this to work the radius of the stream has to be larger than the equipment dentists use and so the water flow rate will be higher too. Would you be able to tell me what’s the highest flow rate that a patient could take without causing discomfort? Would you be able to point me towards maybe a paper or a journal with some kind of info about this?
    Best regards

  14. What do they do with the solid bits and dental material? The filter or container has to fill up eventually, right?

  15. Was just reading my kid the berenstain bears go to the dentist book (copyright ’81) and it mentioned the suctioner. I was just surprised, I remember it from when i was a kid too, how long has the suction machine been in use? When did it begin?

  16. Went to get teeth cleaned , hygienist used the large suction thing under my tongue. He pulled it away it felt funny. I went home and under my tongue looks like a huge hicki. So will it go away and is it dangerous? ?

  17. Hello, I was at the dentist the other day and was told to never close my lips around the suction straws. My office says there are all sorts of warnings by the CDC. I Googled it and learned more than 20% of the time reverse backflow occurs. YUK!
    Why isnt this more well known? It seems this should be mandatory to never close or something should be done to stop it. Sorry, but the mere thought is too much for this girl!

  18. Can a suction cut a chils on the chin? I took my daughter to get cavaties filled today and she was under local anesthesia so she was knocked out and when i was able to see her, she had broken open skin (like cuts) under her chin. They are sayinf the suxtion could have cut her chin? Please let me know what you think? I just sont understand how it would happen. Thank you.

  19. hey I need braces but I’m worried about the suction pipe. does it go to the back of your throat or just sit under your tongue?

  20. doctor i visited a dentist that did not use suction and he did the filing no rinse suction i got sick on the stomach and after the surgery ask could i please be allowed to spit out a mouth full of blood and bacteria

  21. l had a composite filling recently on the upper front tooth. The dentist was filing away afterwards while the dental assistand was using a bit of suction but was also squirting in some liquid in my mouth, some of which l swallowed as she wasn`t suctioning it out. l now feel a bit sick and very tired. l don`t know what the liqid was, do you think it was water, or mouthwash ?

  22. this is very handy info as ive just haD a wisdom tooth removed at the bottom a suction was used quite a lot and i wondered what it was tough recovery but im getting there.

  23. just had a wisdom tooth romoved very uncomfotable and recovery was agony mainly because i didn’t take enough pain medication.this article is quite handy as suction was used more or less right through my wisdom tooth extraction fortunately today im feeling a lot better.

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