Tags Posts tagged with "Amalgam"


Dental Suction Dentists Suctioning

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!

Dental Fillings Fix Chipped Teeth
©Steven Frame/Shutterstock.com

Many people wonder why their dentist tells them that they need a filling.  Although having a cavity is the #1 reason we do fillings, there are also many other reasons that people get fillings.

Why You Need a Filling

1 – Cavities

Cavities remain the number one reason that dentists give patients fillings.  Even so, not all cavities need fillings.  Sometimes very small cavities can be “watched.”  When this happens, the dentist monitors the cavity and if it appears to be repairing itself, you won’t need to get a filling.

I’d like to add a word of caution: Only leave a cavity unfilled if your dentist has recommended that your cavity should be watched.  Putting off necessary dental work can complicate your dental health and increase your costs.

If you do have small cavities that your dentist is keeping an eye on, check out these 12 weapons of plaque destruction to see how you can help your cavity heal.

2 – Tooth Fracture

Many times, fractured teeth can be repaired with white composite filling material.  You can take a look at a tooth that I repaired with a white composite filling before I started working with real patients in dental school.

Prevent your teeth from fracturing by wearing a mouth guard during these 16 activities.

3 – A Slow Loss of Tooth Structure

When you fracture your tooth, you lose a lot of tooth structure quickly.  There are other ways that you can lose tooth structure more slowly, such as abrasion, abfraction, erosion, and attrition.  You can learn about those in the article about the four ways you wear away tooth structure.

The best way to prevent this type of tooth loss is by avoiding acidic drinks and acidic candy, not grinding your teeth, and not using your teeth as tools.

4 – Tooth Discoloration

Do I Need a Filling?Another reason that dentists do fillings is to cover up discolored teeth.  Teeth can be discolored for a variety of reasons, such as staining from antibiotics and dental fluorosis.

5 – Replacing Old Fillings

Old fillings may need to be replaced.  Over time, white fillings can discolor and the bond between the filling and the tooth can break down.  Silver fillings may also fracture after many years of service.  One of the first fillings I did in dental school (unbeknownst to my patient!) was the replacement of a silver amalgam filling that had fractured.

Questions About Fillings?

Do you have any questions about why dentists do fillings or why you need a filling?  Go ahead and leave a comment in the comments section below.  Thanks for reading!

Dental Pain Toothache

Go to the Dentist Before You Get a Toothache!This morning I saw a patient who had been in extreme pain for the last couple of weeks.  What started as a small cavity grew into a large cavity that eventually made its way to the tooth’s pulp.  We were able to take her out of pain by starting a root canal today.

If we end up fixing her tooth, rather than extracting it, it will cost her around $1200.  Even then, with the condition of the tooth, it may only last her 5-10 more years.

A bridge to replace that tooth would cost her $1350.  An implant to replace that tooth would cost her $2100.  And those are dental school prices.  It would probably be about twice that in a private practice. You can find the average dental fees in your area here.

Had she come in a couple of years ago, we could have easily removed the decayed portion of the tooth and put in a filling.  With the prices at my dental school, that would have cost her only $84 and would have most likely lasted her at least 20 years (she has several amalgam fillings that are still going strong after more than 15 years.)

Find out how long a silver filling lasts.

The Moral of the Story

What I’m trying to get across is that if your dentist recommends getting a filling in a tooth, get it (As long as you trust your dentist!)

If you put it off simply because the tooth doesn’t bother you, there’s a good chance both you and your wallet will be experiencing some pain in the future.

Tooth Sensitive After Dental Filling

Many people experience sensitivity after getting a dental filling.  As I’ve mentioned, sometimes this sensitivity can be attributed to a high filling.

A tooth can also be sensitive after a filling due to other reasons.  Here are a few reasons why your tooth might be sensitive after a filling and what you can do about it.

Why Your Tooth Is Sensitive After a Filling

Tooth Sensitive After FillingWhen you sit down in the dental chair to get a filling, one of the first things that the dentist will do is to give you an anesthetic injection to make it so you can’t feel the pain of the upcoming dental procedure.

When your dentist goes in and removes the decay from your tooth, it is very painful and can traumatize the tooth.  Luckily, due to the anesthetic, you usually don’t feel the pain caused by this process of repairing your tooth.  This is the main cause of tooth sensitivity after a filling — your body is simply telling you that the tooth was traumatized.

The bigger your cavity (and resulting filling), the more likely it is that you will experience sensitivity after the filling is done.

Other than trauma, there are a few other reasons why you might experience a sensitive tooth after a filling:

  • If you have a high filling
  • If you have a large metal filling – it can conduct cold more quickly to the nerve of the tooth.  Also, if your dentist didn’t use a material to seal the tiny tubes that travel from the filling to the nerve, it can cause increased sensitivity.
  • If you have a large white filling – if it is placed too quickly, it can cause stress on the surrounding tooth structure

What to Do When Your Tooth Is Sensitive After a Filling

In most cases, you don’t need to do anything — your dental pulp will gradually insulate itself from the filling, which should cause the sensitivity to go away.  This process can take anywhere from one to several weeks.

If your sensitivity does not resolve and feels like it’s getting worse, then you should see your dentist.  It could be that you have a high filling, or that the filling needs to be redone.


In summary, know that having a sensitive tooth after a filling is completely normal.  Sensitivity that gets worse is not normal.  Worsening sensitivity is a sign that something is wrong and you should see your dentist to determine the problem so that a solution can be found.

Do you have any questions, comments, or concerns about tooth sensitivity after a filling?  Go ahead and leave them in the comments section below.  Thanks for reading!

Contents of Silver Amalgam Fillings
©Steve Heap/Shutterstock.com

Have you ever wondered what an amalgam filling looks like inside?

Dental Amalgam CapsuleMany people question how a metal can be soft enough to be shaped into a tooth yet hard enough to endure the force of chewing and other abuse that occurs during its ten or more years in your mouth.

Other people are curious about the amount of mercury contained in an amalgam filling…so let’s get some answers!

I opened up an amalgam capsule (pictured to the left) and took a picture of what I found inside:

Amalgam Filling Contents

Aside from the capsule body, I found three main components:

1 – Mercury Disc – Amalgam fillings are made up of about 50% mercury, and 50% metal powder.  The mercury is sealed away in a plastic disc so that it doesn’t evaporate and contaminate the environment.  The mercury disc breaks open when the amalgam capsule gets mixed.

2 – Metal Powder – The metal powder is made up of varying metals.  In the Dispersalloy brand of dental amalgam (a widely used brand), the metal powder contains about:

  • 69% Silver
  • 18% Tin
  • 12% Copper and
  • 1% Zinc

3 – Pestle – The pestle is simply a plastic rod.  When the amalgam is mixed and vibrated quickly back and forth, the pestle breaks open the sealed mercury disc and helps to thoroughly mix the mercury with the metal powder to form a soft metallic mixture.  While the amalgam is still soft, the dentist uses it to fill your cavities.  The amalgam begins to harden after a few minutes and eventually hardens into a filling that can withstand lots of force.


As you can see, the formulation of amalgam is pretty simple: mercury and metal powder.  Fortunately, modern amalgam capsules come pre-measured so that dentists don’t have to worry about mixing up mercury with other metals by hand.

Do you have any questions about the contents of amalgam fillings?  I’d love to hear your thoughts int he comments section below.  Thanks for reading!