• Science Project of the Month: Tooth Decay Experiment


    Welcome to our first Science Project of the Month Series! Each month Secular Homeschool will feature a science project that you can do with your homeschoolers. Whether you are “sciency” or not, these will be easy, fun and perfect to do as a family. I will include several fun facts that coincide with the featured project, so for homeschool, we can pull double duty and learn something while we do science. February is Dental Health Month, so naturally, we are doing a dental health experiment for kids.

    February is all about hearts, valentines, and chocolate. It always struck me as hilarious that it is also dental health month. I wonder if dentists voted it in because of the vast amount of candy given and consumed on Valentine’s Day? Dental health is no laughing matter. Our teeth are important for more than just chewing. Talking, smiling, laughing all work better with teeth. Teeth are also connected with the rest of our body and issues within our body can show up in our teeth and vice versa. Pretty amazing how connected the human body is! Check out how different things we drink affect our teeth below using our Tooth Health Science Project of the Month.

    Science Project: Tooth Decay Experiment - Egg Scrub

    Age Level: Preschool-High School
    Items Needed:

    • 1 cup soda/cola/pop (whatever you call it in your neck of the woods!), make sure it’sdark brown such as root beer or a cola
    • 1 cup vinegar
    • 1 cup water

    • 1 cup fruit juice (more acidic such as orange juice or lemonade work better)
    • 4 hard-boiled eggs
    • 1-4 toothbrushes (you can wash and reuse the same toothbrush or have a clean one for each liquid)
    • 4 plastic cups (make sure they are deep enough to hold a whole egg and liquid with the egg 100% submerged)
    • Toothpaste or baking soda
    • Paper towels
    • Egg carton or egg holder


    1. Fill each cup with each liquid. Do not overfill; remember to leave room for water displacement with the egg addition.
    2. Put 1 egg in each cup carefully so you don’t crack the shell. Make sure it is completely submerged and covered by the liquid.
    3. Leave this overnight. Be aware that some liquids (vinegar for example) can start to dissolve the shell the longer they are left in but that is another experiment for another day.
    4. Remember to note which liquids are in which containers, though you can probably use your senses to figure this out.
    5. While you are waiting, hypothesize what will happen with each liquid. Write these down. You can do as a group or have each child make their own hypothesis and then compare.
    6. Next morning, assemble water, toothpaste, and toothbrush(es).
    7. Carefully remove each egg and place it in an egg holder or carton. Observe, discuss, and note what the liquid did to the egg and shells.
    8. Try to remove the liquid and residue using plain water and a toothbrush. Did it work? Why? Why not?
    9. Move onto water, toothpaste and a toothbrush. Did it work? Why? Why not?
    10. Note what each shell looked, felt and smelled like. Discuss why you think this might have happened. Chat about what could happen if this experiment was applied to their teeth. Discuss the importance of brushing teeth, removing plaque, keeping gums and our body healthy by eating and drinking things that are better for our teeth. You can wrap it up with a shopping trip to pick out new toothbrushes and toothpaste. Don’t forget the floss!

    Other Liquid Suggestions

    • Coffee
    • Tea, try several different types
    • Clear soda
    • Dark juice, like grape or prune
    • Energy drink
    • Milk
    • Vegetable juice
    • Alcohol

    Personal Update:
    We had a great time doing this. Both my childcare kids and my own kids enjoyed this experiment. I kept it simple for the little kids and for homeschool we added in red wine and beer to test in, plus the other liquids listed. My counter was covered in cups for about 12 hours. It was a great way to see the importance of brushing teeth and fun to see how the liquids affected the eggs and/or shells. The effects of vinegar and red wine were family favorites.

    Fun Dental Facts

    • The average American spends 38.5 total days brushing their teeth in their lifetime. That is a lot of toothpaste!
    • Tooth enamel is the hardest substance in the human body.
    • Flossing takes care of 40% of the tooth surface.
    • If you are right-handed, you will chew your food on the right side. If you are left-handed, you will chew your foot on the left side. No idea what it means if you are ambidextrous like me. Most of you are testing this theory right now.
    • Tongue prints are like fingerprints, each one is different and unique. Most of you are now looking at your tongue in the mirror and comparing it to family members.
    • Dental floss was first manufactured for sale in 1882.
    • Dental plaque contains more than 300 types of bacteria. Ewwww!
    • More people use blue toothbrushes than red ones. Most of you are in the bathroom looking at the toothbrushes, checking this fact.
    • Dogs have 42 teeth. Cats have 30 teeth. Most of your kids are considering checking out the pet’s teeth right now. Do so carefully. February is pet dental health month too!
    • A single can of soda contains 10-12 teaspoons of sugar. Great way to find out how do sugary drinks affect your teeth
    • The recommended brushing time is 2-3 minutes. Most people do half of that time.
    • Ancient Greeks used talc, alabaster, iron rust, coral powder or pumice as toothpaste.
    • Earliest known dentist by name is Hesi-Re and he lived in Egypt over 5,000 years ago.

    We hope you enjoyed this Science Project of the Month demonstration. If you create this, please share how it went for you in the comments. Add a photo if you can, or better yet, share on our Instagram page tagging @Secular_Homeschool.

    I welcome suggestions for future Science Project of the Month ideas! Drop me an email at [email protected] with your ideas. I love hearing from members.
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