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How can chemistry help you take care of your teeth?

Format
Carolina Vendetti, Chris Langley & Let's Talk Science
Readability
7.49

How does this align with my curriculum?

What are your teeth made up of? What chemistry is at work in your mouth? Why do some people get cavities even if they brush regularly?

Do you brush your teeth every morning? How about before you go to bed? Maybe you’re like me, and you brush your teeth after every meal!

For many of us, brushing our teeth is a forgettable, everyday activity. But did you know that your mouth is the site of some very cool chemistry? And that it’s home to the hardest substance in your body? Let’s learn about the structure of teeth and the chemical processes going on in your mouth. And then, let’s look at the science behind why it’s so important to brush your teeth.

What are the layers of a tooth?

Each of your teeth has several layers that protect the pulp deep inside the tooth. The pulp is made of living connective tissue that contains blood vessels and nerves. The blood vessels in the pulp supply the other layers of the tooth with minerals. The nerves send messages to the brain about temperature, pressure, and injuries to the tooth.

The layers that protect the pulp are the cementum, dentin and enamel. The cementum connects the tooth to the bones in your jaw. Surrounding the pulp is the dentin. The dentin forms the foundation for the outer enamel layer. Dentin is yellow and rates a 3 on the Mohs scale of hardness

The outermost layer is the enamel. It’s the hardest substance in the human body! Enamel is mainly made up of a crystalline form of calcium phosphate (Ca10(PO4)6(OH)2). It is even harder than bone and rates a 5 on the Mohs scale.

Parts of a tooth
Parts of a tooth (Let’s Talk Science using an image by KDS4444 [CC BY-SA 4.0] via Wikimedia Commons).

Did You Know?

The enamel on your teeth is made up of 95% minerals. The rest is water and other organic materials.

How do cavities form?

Do you ever wonder why people get cavities, even when they brush their teeth twice a day? Your teeth are pretty hard, but the enamel can be weakened by bacteria and the pressure that comes with chewing. Weakening the enamel can lead to tooth decay, including cavities.

Did You Know?

In Canada, 59% of 12-19 year olds have or have had at least one cavity

We all have some bacteria in our mouths. These bacteria convert foods, such as sugars and starches, into acids. The most common bacteria are Streptococcus mutans and lactobacilli, which are responsible for producing lactic acid CH3CHCO2H or C3H6O3

Skeletal formula, molecular formula and space filling model of lactic acid
Skeletal formula, molecular formula and space filling model of lactic acid (Let’s Talk Science using images by Jynto and NEUROtiker via Wikimedia Commons)

 

Together, bacteria, acid, food debris, and saliva combine to form a sticky substance called plaque. Plaque sticks to surfaces, especially just above your gums, in the indentations on your back molars, and on the edges of any fillings you might have. The lactic acid produced by the bacteria in the plaque can slowly dissolve the enamel of your teeth, creating holes. These holes are better known as a dental caries or cavities

Once a cavity forms in your enamel, it can quickly move through the other layers of your tooth. When a cavity reaches your dental nerves, it can cause a lot of pain! 

Did You Know?

If plaque is not regularly removed from your teeth, it can harden into tarter. Tarter can only be removed by a dental professional.

When there is enough acid in the mouth that the pH level drops below 5.5, then the acid begins to dissolve the calcium phosphate through a process called demineralization. The balanced chemical equation for this chemical reaction is

Demineralization of calcium phosphate
Balanced chemical equation of the demineralization of calcium phosphate (© 2019 Let’s Talk Science).

 

Chemical reaction - Text Version

Calcium phosphate and hydrogen ions undergo a reversible reaction with calcium ions, phosphoric acid and water.

 

The products of the reaction are calcium ions, phosphoric acid and water. All of these exist in chemical equilibrium with the crystalline calcium phosphate. When acid levels in the mouth are high, the chemical reaction is forced to the right (forward reaction) which means that more calcium is dissolved.

Eventually, if enough of the enamel is demineralized, the soft, yellow dentin underneath is revealed. This is what dentists see when you go in for check-ups. 

How can you prevent cavities?

So why is everyone always telling you to brush your teeth? In part, it’s because of plaque. By brushing and flossing your teeth regularly and really well, you can remove the plaque and stop it from building-up on your teeth. You should also use a toothpaste that contains fluoride

Did You Know?

Fluoride is often added to drinking water, because it's the easiest way to offer fluoride protection to the greatest number of people. In Ontario, 70% of people live in areas with fluoridated water.

Fluoride does not prevent cavities, but it does slow down the demineralization process. When fluoride ions are present, they can form a tough coating over the enamel. This coating helps protect the enamel as it repairs itself. Yes, your teeth can repair themselves! When the acid levels in your mouth are low and you eat calcium-rich foods, your teeth can remineralize.

Graph showing how plaque pH changes after eating
Graph showing how plaque pH changes after eating (Let’s Talk Science using image from Lesion [CC BY-SA 3.0] via Wikimedia Commons).

 

Graph - Text Version

Before you eat, the pH in your mouth is between seven and seven point five. Within the next ten minutes, the pH in your moth drops just below four point five. The pH at which decay begins is five point five. Up to 40 minutes after eating, teeth are demineralized. pH goes up. After 40 minutes, teeth begin to remineralize. pH is not back to around seven until after 60 minutes.
The curve is known as the Stephan Curve.

 

Whenever possible, brush with a fluoride toothpaste after you eat. If you can’t brush your teeth, rinse your mouth with water. This will help raise the pH of your mouth closer to a neutral 7 and will force the chemical reaction back to the left side. Limiting the amount of sugary foods and drinks you consume also helps. And remember to see your dentist regularly! 
 

Starting Points

Connecting and Relating

  • Do you brush your teeth regularly? Why?
  • Do you like to drink soft drinks or other sugary drinks? Have you considered how these drinks may be affecting your teeth? Have you observed any see-through edges on your teeth?
  • Has your dentist or dental hygienist ever warned you about eating or drinking particular foods or beverages? Have they ever mentioned that your teeth show evidence of acid wear or damage?
     

Connecting and Relating

  • Do you brush your teeth regularly? Why?
  • Do you like to drink soft drinks or other sugary drinks? Have you considered how these drinks may be affecting your teeth? Have you observed any see-through edges on your teeth?
  • Has your dentist or dental hygienist ever warned you about eating or drinking particular foods or beverages? Have they ever mentioned that your teeth show evidence of acid wear or damage?
     

Relating Science and Technology to Society and the Environment

  • Does you community have fluoridated water? Do you think it should be legislated that all municipalities provide fluoridated water? Why or why not? 

Relating Science and Technology to Society and the Environment

  • Does you community have fluoridated water? Do you think it should be legislated that all municipalities provide fluoridated water? Why or why not? 

Exploring Concepts

  • What structures form a tooth? Describe the function of each part.
  • What is plaque? How can plaque affect the health of your teeth?
  • What is happening chemically when your teeth are being demineralized?
  • How does fluoride help reduce the demineralization process that can occur in teeth exposed to acids? 
  • Research different technologies that been developed to help reduce and remedy acid wear on teeth.
  • Examine and compare the roles of dental hygienists and dentists in preventing and remedying the various effects of acids on teeth. 
     

Exploring Concepts

  • What structures form a tooth? Describe the function of each part.
  • What is plaque? How can plaque affect the health of your teeth?
  • What is happening chemically when your teeth are being demineralized?
  • How does fluoride help reduce the demineralization process that can occur in teeth exposed to acids? 
  • Research different technologies that been developed to help reduce and remedy acid wear on teeth.
  • Examine and compare the roles of dental hygienists and dentists in preventing and remedying the various effects of acids on teeth. 
     

Nature of Science/Nature of Technology

  • Design an inquiry to explore how the consumption of soft drinks relates to number of cavities.
  • Design an inquiry to explore how the frequency of brushing and/or flossing teeth relates to the number of cavities a person has. 
     

Nature of Science/Nature of Technology

  • Design an inquiry to explore how the consumption of soft drinks relates to number of cavities.
  • Design an inquiry to explore how the frequency of brushing and/or flossing teeth relates to the number of cavities a person has. 
     

Media Literacy

  • How do toothpaste advertisers influence your choice of toothpaste to protect and/or repair your teeth from plaque build up and acid wear? What other features of toothpaste do advertisers address?

Media Literacy

  • How do toothpaste advertisers influence your choice of toothpaste to protect and/or repair your teeth from plaque build up and acid wear? What other features of toothpaste do advertisers address?

Teaching Suggestions

  • This article can be used for teaching and learning in Chemistry, Health and Food & Nutrition related to acids & bases, bacteria, chemical equilibrium and wellness. Concepts introduced include pulp, blood vessels, nerves, cementum, dentin, enamel, bacteria, tooth decay, acids, lactic acid, plaque, dental caries, cavities, tarter, demineralization, phosphoric acid, fluoride and remineralize. 
  • Prior to reading this article, teachers could have students do a Vocabulary Preview learning strategy to engage prior knowledge and introduce new terms. Ready-to-use Vocabulary Preview reproducibles are available in [Google doc] and [.pdf] formats. 
  • For a health focus, teachers could have students survey class members to find out key information about the oral hygiene practices, regularity of dental visits and dental hygiene visits, number of cavities, sugar consumption, etc. Survey information collected could be summarized in a graphic organizer or infographic. 
  • For a hands-on health and wellness activity, teachers could provide students with plaque disclosing tablets after they have first brushed their teeth. This allows students to evaluate the effectiveness of their brushing technique. Students could take pictures of their teeth after chewing the tablets to clearly see at the places in their mouth that still have plaque.    
  • For a science demonstration of the effects of demineralization, a clean, dry chicken bone can be put in vinegar for several days. Over time the bone becomes weakened and more flexible as the calcium is demineralized. 
     

Teaching Suggestions

  • This article can be used for teaching and learning in Chemistry, Health and Food & Nutrition related to acids & bases, bacteria, chemical equilibrium and wellness. Concepts introduced include pulp, blood vessels, nerves, cementum, dentin, enamel, bacteria, tooth decay, acids, lactic acid, plaque, dental caries, cavities, tarter, demineralization, phosphoric acid, fluoride and remineralize. 
  • Prior to reading this article, teachers could have students do a Vocabulary Preview learning strategy to engage prior knowledge and introduce new terms. Ready-to-use Vocabulary Preview reproducibles are available in [Google doc] and [.pdf] formats. 
  • For a health focus, teachers could have students survey class members to find out key information about the oral hygiene practices, regularity of dental visits and dental hygiene visits, number of cavities, sugar consumption, etc. Survey information collected could be summarized in a graphic organizer or infographic. 
  • For a hands-on health and wellness activity, teachers could provide students with plaque disclosing tablets after they have first brushed their teeth. This allows students to evaluate the effectiveness of their brushing technique. Students could take pictures of their teeth after chewing the tablets to clearly see at the places in their mouth that still have plaque.    
  • For a science demonstration of the effects of demineralization, a clean, dry chicken bone can be put in vinegar for several days. Over time the bone becomes weakened and more flexible as the calcium is demineralized. 
     

Learn more

Fun Dental History Facts (2006)

A compilation of facts about the history of dental products and dentistry from DeCare International.

The Best and Worst Foods for your Teeth 

Examples of foods that are good and bad for the health of your teeth from the University of Rochester Medical Center.

Removing Plaque and Tartar from Teeth (2019)

Deborah Rose Wilson gives some ways to remove plaque from your teeth, including “home remedies”.

References

Animated-Teeth.com. (2019, April 22). The science and chemistry of tooth decay.

ChemPages. (n.d.). Acids and bases: Salts.

Cotner, P. (2019, April 23). How important is fluoride protection?

Dental Health Foundation of Ireland. (n.d.). Structure & function of teeth.

Greany, T. J. (2018, February 9). Tooth enamel demineralization. ToothIQ.

Limmer, J. (2015). Analytical chemistry. Clayton State University.

Ross, M. H. (2019). Histology: A text and atlas. Wolters Kluwer. 

Western Pennsylvania and Ohio Valley Oral and Maxillofacial Surgery PC. (2017, August 10). How hard are human teeth and enamel?

C. Venditti

Carolina earned a Bachelor's degree in Life Sciences from Queen's University. She then continued her studies into graduate school, where she earned a Master's of Science in Anatomy and Cell Biology. She is currently completing her Doctorate in Biomedical and Molecular Sciences, specializing in reproductive sciences and disorders of pregnancy.

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