You probably brush your teeth several times each day. If you listen to your dentist, you probably floss daily, too. Is there anything else you need to make sure your teeth are as healthy as they can be?

As a matter of fact, there is! It’s called fluoride. It’s probably already in your toothpaste. It may be in the water that comes out of your tap at home, too.

Fluoride comes from fluorine, which is a very common element in the Earth’s crust. Fluoride exists naturally in many sources of water. Long ago, scientists discovered that fluoride can help prevent — and sometimes even reverse — tooth decay.

Wonder Friends already know that bacteria in your mouth break down sugar left on your teeth after you eat. As the sugar breaks down, it turns into acid that can damage the outer coating of your teeth — called enamel — and make holes called cavities.

If you don’t brush your teeth regularly, bacteria can build up to form a clear film on your teeth called plaque. Brushing your teeth regularly helps to remove plaque and prevent it from forming.

Fluoride also helps to fight against tooth decay. When it comes into contact with your teeth, fluoride prevents the acid produced by bacteria from dissolving the enamel on your teeth. It can also help your teeth to repair themselves by rebuilding enamel.

So how do you get the fluoride your teeth need to stay healthy? Most toothpaste has fluoride added, so you get fluoride if you brush your teeth regularly. Since fluoride occurs naturally in water, your local water supply might also provide a regular source of fluoride.

In some areas, though, not enough fluoride is present in the water supply. If this is the case in your area, your local water supplier may add fluoride to your water supply to make sure your teeth are protected. If your water supply is not fluoridated, you can purchase mouth rinses with fluoride at most stores.

Some people oppose adding fluoride to water supplies. They believe that it isn’t effective in preventing tooth decay. They also think it may be hazardous to your health if you ingest too much fluoride.

Research has shown, though, that fluoride does help prevent and even reverse tooth decay. There is also evidence that fluoride is safe when recommended levels of 0.7 to 1.2 parts per million are observed. Dentists also point to the dramatic reduction in tooth decay in the last 30 years during the time when water fluoridation has become popular.

So how can you make sure you’re getting enough fluoride? Ask your dentist! Dentists can check the health of your teeth and recommend additional fluoride supplements if you live in an area with water that doesn’t contain enough fluoride.

44 Join the Discussion

1 Star2 Stars3 Stars4 Stars5 Stars  (18 votes, avg. 3.11 out of 5)
    • Alright, we love your enthusiasm, Joaquin! Thanks for sharing your comment with us– we hope you had fun learning something new! :)

  1. Dear Wonderopolis,

    Today we learned how to keep our teeth clean, and we learned that fluoride is in the earth’s crust.We wonder how do you choose what will become the wonder of the day?

    Mrs. Reasor’s Fourth Grade Class

    • WOW, we’re so happy that the SUPER students in Mrs. Reasor’s class are here today! We Wonder if you enjoyed seeing how big a whale’s teeth are compared to our human teeth! PRETTY COOL! :)

      We love your question about our Wonders of the Day®, too! We have a LOT of Wonder Friends who spend all day using their imaginations, reading, and WONDERing! We love when our Wonder Friends nominate Wonders on our site, too! We can’t wait to see you tomorrow! Thanks for joining us today! :)

  2. I loved the information about flouride, but I was very disappointed to see that Wonderopolis chose to show this video of a whale in captivity. This whale appears happy and content, when in reality it is very distraught and needs to be returned to the wild. I would really appreciate it if in the future you would choose videos that promote animals in the wild and NOT in captivity. Perhaps watching THE COVE would help people at Wonderopolis see the heartbreak and horrific nature of the whale and dolphin drive hunts.
    Thank you for your time. My students and I really love your website! We check it every morning.

    • Hi there Kristin R! Thank you for sharing your comment with us today– we are so happy that we are a part of your classroom activities on a daily basis! We love WONDERing with your students! :)

      We appreciate your comment about today’s fluoride video and we value your thoughts about the dolphin in the film. Thank you for bringing the topic of sea life in captivity to mind for us and all our Wonder Friends. We love the ability to share our thoughts, feelings and opinions at Wonderopolis! :)

  3. We all brush our teeth to keep them clean and healthy. We will check to see if our toothpaste has fluoride.

    We thing tomorrow’s wonder will be about idioms or children who are like their parents.

    • GREAT JOB, Wonder Friends in Ms. Bayko’s class! We can’t wait to see if your toothpaste has fluoride in it… and your water, too! We can’t wait to Wonder with you tomorrow… it’s going to be a crunchy kind of day tomorrow! :)

  4. Mrs. Wall shared that she used to have to rinse with fluoride during class in elementary school!

    Fortunately, our class brushes and mouth-washes regularly! Only about 50 % of our class flosses on a regular basis.

    We think tomorrow’s wonder will be about family trees or carving.

    • WOW, what a cool new piece of information about Mrs. Wall! We are glad all our Wonder Friends in her 4th grade class are WONDERing about keeping our teeth nice and healthy! We are so proud to hear that all our Wonder Friends are EXCELLENT brushers and flossers– it’s so important to keep your smiles healthy!

      We love your guesses for tomorrow’s Wonder… we can’t wait to figure out what that crunchy Wonder will be! :)

  5. Dear Wonderopolis,

    We enjoyed learning more about fluoride and where it can be found.

    We think tomorrow’s wonder will be about buildings and building new things.

    Thank you for the great wonders,

    Mrs. Tillman’s 4th graders.

    • WOHOO, we are excited to see all the WONDERful 4th graders in Mrs. Tillman’s class today! We are jumping for joy knowing that you have been WONDERing about fluoride with us today!

      We like your SUPER guesses for tomorrow’s WOnder! We can’t wait to discover what it will be! Have a WONDERful day, Wonder Friends! :)

  6. We learned that fluoride is good for our teeth preventing tooth decay. We also learned that our town has a lot of fluoride in our city water. We are going to check when we get home how much fluoride our toothpaste has.

    We think tomorrow is about idioms.

  7. Hello Wonderopolis!

    Our predictions for tomorrow’s Wonder of the day are:

    Liam- All About Dads
    Dalton-Good Dads and family relationships
    Spencer-How people are like other people
    Riley-a wood chip off an old block
    Ellie- carpentry
    Kalven- a new chip
    Averee-Kids are just like their dads
    Dallas- How chips are made
    Emmalyn-mold on a wood chip
    Cylan- erosion
    Erica-how kids have their parents’ traits
    Sydney-how to build houses
    Brayden- relationship between dad/son
    Luke-football with your dad
    Clyde- talents from parents

    Whew…we have a lot of different predictions! Who is right?

    • WOW, check out all these SUPER WONDERful guesses from the students on Team Caisse Reading! YIPPEE! We are so proud of all the WONDERing you have been doing! We hope you liked today’s Wonder about keeping your teeth healthy! :)

      We can’t wait to find out what that crunching sound is… we’ve heard it all day at Wonderopolis! We’ll find out tomorrow…. :)

  8. Dear Wonderopolis,
    We’ve never seen an orca whale get their teeth brushed before! That was cool. All of my students are careful to brush their teeth every morning and night!

    We think tomorrow’s wonder will be about potato chips!

    • COOL, we’re glad we could see something new together! We’re so happy that the WONDERful students in Ms. Moreland’s 3rd grade class have joined us today! We are also very happy to hear that you are keeping up the great work of brushing your teeth at least twice a day!

      We can’t wait to find out what that crunchy Wonder will be tomorrow… :)

    • We’re glad you’re here, Lance! We think it’s cool to learn about how our teeth stay nice and healthy– and it’s lots of fun to know that other creatures, like whales, need fluoride to keep their teeth healthy, too! :)

    • Hey there Carlee, what a SUPER comment to read! Thanks for telling us you enjoy Wonderopolis– we enjoy great Wonder Friends like you! :)

    • We’re SUPER happy to hear you’ll be brushing more often, Joshua! You’ve got to keep that smile nice and healthy– make sure you’re brushing your teeth at least twice a day! We bet your next dentist visit will be SUPER, just like you! :)

    • Thanks for sharing your comment today, Rori! We are glad you learned something new about fluoride– it’s cool to find out where it comes from! Keep up the SUPER job of brushing your teeth each and every day! :)

    • Gee whiz, thanks for your comment, Kaytlyn! We are happy you are WONDERing with us at Wonderopolis! It’s so much fun to use our imaginations each and every day! :)

  9. Dear wonderopolis I love to read your wonder of the day you guys are amazing I will get on it as much as I can. I have fluoride. I will try to comment as much I can. ;) ;) ;) ;)

    • Hey there, Sophie, we are so excited to read your comment! We really enjoy WONDERing with our great Wonder Friends, like you! We hope you will come back tomorrow to find out what the next Wonder will be– there is so much WONDERing to do! HOORAY! :)

    • WOHOO, we are glad to hear that, Oneeba! Thanks for sharing today’s Wonder with your little cousin– how fun! Have a SUPER day! :)

    • WOW, how cool that you learned about fluoride, Romey! We’re glad you could learn something new about how to keep your teeth healthy, too! Thanks for having fun and WONDERing with us today, Wonder Friend! :)

  10. I learned some new thing today in this story:

    First that fluoride is in my tooth brush

    and also my tap water which I drink sometimes.

    Last, fluoride comes from fluorine, which is a very common element in the Earth’s crust.

    • Hi there Jules, we enjoyed learning what fluoride is, too! We learned that fluoride is found in most toothpastes– there are usually just bristles and plastic that make up your toothbrush! Great job, Wonder Friend! :)

  11. I have a friend who adamantly states that fluoride damages IQ and has no benefit when ingested only marginally beneficial when topically applied. Can you guys please give me a link to the studies that show how fluoride is safe and effective for dental cavities. I have scoured the internet trying to locate these and thought it should be easy to find the studies but so far I cannot. If you can’t show me the studies I will have to admit he may be right. Thanks and great website.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>


  • Wonderopolis on Facebook
  • Wonderopolis on Pinterest
  • Print

Have you ever wondered…

  • What is fluoride?
  • Why is fluoride often added to local water supplies?
  • Can you get too much fluoride?

Wonder Gallery

brushing teeth_shutterstock_107382053dreamstime_xl_8969973-customdreamstime_xl_30696751-customVimeo Video

Try It Out

If you want to brush up on your knowledge of fluoride, check out one or more of the following activities with a friend or family member:

  • Your teeth are an important part of your body. Without them, your smile would look much different. You’d also have a hard time eating your favorite foods! Learn a little bit more about the anatomy of your teeth when you check out Picture of the Teeth online. Did you realize that your teeth are made up of so many different parts and layers?
  • Does your water supply have fluoride added to it? Find out! Ask friends and family members about your drinking water supply. If they don’t know the answer, head to city hall and ask someone who works in your local water department. If your drinking water does contain added fluoride, ask someone for a tour of the area where fluoride is added. Ask if you can speak to someone involved in the monitoring of fluoride levels. What questions might you want to ask this person?
  • Now that you know all about how fluoride can help prevent tooth decay, you may be WONDERing what other steps you can take to make sure your teeth stay as healthy as possible. Here are some things you should also be doing:

o   Brush your teeth regularly. Dentists recommend you brush your teeth at least twice each day. For example, after breakfast and right before bed are perfect times to brush your teeth. If you can brush after every meal, that’s even better!

o   Take your time. Spend at least two minutes brushing your teeth. Make sure you get the sides and backs of your teeth.

o   Floss your teeth, too. Flossing helps remove food and plaque that hide in places your toothbrush can’t reach.

o   Get regular check-ups from a dentist at least twice each year. Seeing your dentist regularly will help you find and fix problems early.

Still Wondering

In National Geographic Education’s Big Cats, Big Teeth activity, children compare the shape and size of human, lion and gazelle teeth and jaws.

Test Your Knowledge

Wonder What’s Next?

Tomorrow’s rhythmic Wonder of the Day may have you saying, “Boom ba da boom!”

Upload a Photo or Paste the URL of a YouTube or SchoolTube Video.