Open Wide and Trek Insideskip navigation
Main Getting Started Teacher's Guide Student Activities About NIH and NIDCR Glossary Map Contact
Return to Lesson Plans
     1 | 2    next

PDF Files for PrintingLesson 5-Elaborate: What Keeps Your Mouth Healthy?

AT A GLANCE

Overview

Exee holding a toothbrushLesson 5 asks students to participate in a dramatization through which they act out the oral disease process. Students realize that eating fewer sugary and starchy foods and brushing their teeth regularly with fluoride toothpaste can help reduce plaque and tooth decay. In the dramatization and in a Web site animation, students learn how sealants and fluoride can protect their teeth.

Purpose

In this lesson, students will

Objectives

After completing this activity, students will

BACKGROUND INFORMATION

Tooth decay (dental caries) is a common, chronic, but entirely preventable bacterial disease that affects people throughout their lives. Dental caries in children can lead to significant problems including pain, infection, and missed school days. When it occurs in very young children or toddlers, tooth decay can cause severe harm to the primary teeth and result in problems with eating, growth, and speech. Practicing good oral hygiene and maintaining a healthy diet can help prevent these problems.

The Importance of Fluoride

Did You Know?
Fluoride is added to community water supplies to help people fight tooth decay.

Most bottled water does not contain fluoride at a level recommended for tooth decay protection. If you drink only bottled water, you may be missing the benefits of fluoridated water.

Fluoride is a mineral that is beneficial to teeth. At a low dose over a length of time, fluoride can prevent tooth decay. Fluoride works mainly through direct contact with the surface of the teeth. Fluoride is also important during formation of the tooth enamel before teeth erupt through the gums. boy at a drinking fountain and girl brushing her teethPeople can obtain fluoride in two ways: topically and systemically. Topical fluoride is applied directly to the surface of the teeth. Fluoride toothpaste, fluoride mouth rinses, and fluoride treatments given by a dental professional are examples of topical fluorides. Fluoride taken systemically enters the body by drinking from community water supplies, by taking dietary supplements (such as tablets or drops), and through the food we eat and the beverages we drink. Although systemic fluorides are important, they do not provide the same benefits as topical fluorides in protecting teeth from decay. To get the most benefit from fluorides, daily exposure to small quantities is important. Most adults and children can prevent tooth decay by brushing with a fluoride toothpaste and drinking fluoridated water.

Fluoride protects teeth through three mechanisms.

The following sections provide additional information on how fluoride works with other minerals to protect and strengthen teeth.

Helping Teeth Repair Themselves

Throughout the day, a tug of war is taking place inside our mouth. Whenever we eat or drink, oral bacteria produce acids that begin to eat away the enamel of our teeth. However, as time passes between episodes of eating or drinking, the amount of acid decreases and the weakened tooth enamel may repair itself. Our teeth go through this constant and natural process of demineralization and remineralization. Scientists have learned that the tooth surface can, in the presence of fluoride and other minerals, repair itself if demineralization has not passed a certain point.

tug-of-war between tooth decay and tooth repair
Cartoon created by the Ohio Department of Health—Robert Hill, graphic artist.

Demineralization

Demineralization is the loss of minerals from the tooth enamel caused by the acidic waste products of oral bacteria. Each time we eat foods containing sugars or starches, the pH in our mouth drops because oral bacteria produce acid. This more acidic environment causes small amounts of minerals of the tooth enamel to dissolve. How fast demineralization occurs depends on how acidic the oral environment becomes (how much the pH decreases).1 The more often we eat, especially foods high in sugars, the more frequently the pH in our mouth drops and the less time the oral environment has to correct itself by raising the pH. That is why it is as important, if not more important, to monitor how often we eat as well as what we eat.

pH Scale: 1 - acidic, 7 - neutral, 14 - basic

Demineralization occurs just below the surface of the enamel. The enamel and the dentin located just below the enamel of the tooth are made up of many mineral crystals. These crystals are very soluble in acid. So, when we ingest food, the oral bacteria produce acids, and the acids break down the mineral structure of the tooth surface. If the acids remain on the tooth, it will continue to lose minerals.

We can see evidence of demineralization as white spots, called white spot lesions, on the teeth. When teeth lose minerals, more light goes through the surface of the enamel, causing it to appear chalky white. If demineralization outweighs remineralization, tooth decay continues and a cavity eventually forms.

Remineralization

Remineralization is the process that replaces the minerals in tooth enamel after demineralization. Saliva greatly enhances remineralization as it regularly bathes the teeth with buffering components, such as bicarbonate, phosphate, and peptides, that neutralize the acids produced by the oral bacteria. This buffering action then raises the pH level in the oral environment, creating the opportunity for remineralization to occur.

Saliva is 99 percent water with protein, enzyme, and ion components. Saliva contains calcium, phosphate, and fluoride, which combine to form a new, more fluoride-rich surface on the tooth that can better resist demineralization by acid. Fluoride speeds this process by attaching to the surface of the tooth and attracting calcium ions. Consequently, the use of fluoridated toothpaste and fluoride mouthwash increases the reservoir of fluoride in the mouth and aids the remineralization process.

This new understanding of tooth decay as a process is changing the way that tooth decay is treated. Treatments now focus on preventing, stopping, or reversing tooth decay and reducing the risk factors that lead to demineralization rather than waiting to treat the hole in the tooth with a filling. Maintaining a healthy diet, reducing the frequency of snacking, using fluorides, keeping the teeth clean, and having regular checkups can go a long way to maintain a healthy mouth.

Brushing the Teeth

Because fluoride plays such a pivotal role in preventing demineralization and enhancing remineralization, brushing the teeth with fluoride toothpaste is an essential practice for maintaining oral health. Dental professionals recommend brushing after eating or at least two times per day, preferably in the morning and in the evening. The step-by-step procedure for brushing effectively is outlined in the take-home activity, Brushing to the Beat! Dental professionals may recommend additional fluoride for people who are at higher risk for tooth decay.

Sealants

girl in a dentist's chair
Photo: Corel

Sealants are another highly effective way to protect teeth from decay. Sealants are thin plastic coatings that are applied to the chewing surfaces of the molars.2 The chewing surfaces of the molars have small pits and grooves that trap food particles and bacteria. These areas cannot be cleaned well with a toothbrush. Sealants cover the pits and grooves and form a physical barrier that protects the teeth from the decay-causing acids produced by oral bacteria. Bacteria that are trapped beneath the sealant cannot spread because they cannot reach their food supply.3

Most tooth decay in children and adolescents occurs in the molars. Sealants are most effective when applied soon after the molars erupt and before decay begins. The first molars appear when a child is around six years of age; the second molars erupt when a child is around twelve years old. Sealants are an excellent way to prevent tooth decay. Along with saving the tooth structure, sealants save money, time, and the discomfort of some dental procedures. One sealant application may last from five to ten years, but sealants should be checked regularly to ensure that they are intact.

A Healthy Diet

Choosing healthy foods helps us grow and keeps our mouths and bodies healthy. Our eating habits, including our food choices, directly affect the health of our teeth. Sugars belong to the carbohydrate group of nutrients. This group includes simple sugars such as sucrose (table sugar), fructose (fruit sugar), and glucose. The group also includes complex carbohydrates such as starches. Foods containing sugars and starches contribute to tooth decay because oral bacteria use these carbohydrates efficiently and produce acids that damage the tooth's enamel. The more often you eat foods that contain sugars and starches, and the longer these foods remain in your mouth before you brush your teeth, the greater your risk for tooth decay.

Some high-sugar foods, such as candy, cookies, and soft drinks, provide calories but lack the nutrients that our bodies need. Other foods, including fruits, milk, yogurt, bread, cereals, and vegetables, also contain sugars and starches, but these foods nourish the body by providing important vitamins, minerals, and fiber.4

The best way to maintain good health for both the body and the mouth is to eat a balanced diet that gives your body the nutrients it needs.5 Choose foods according to the food pyramid of the U.S. Department of Agriculture (USDA). The USDA recommends eating a majority of foods from the grain, vegetable, and fruit groups, followed by foods from the milk and meat groups. The food pyramid specifies that fats and sweets should only be eaten occasionally. Take care not to let soft drinks or other sweets crowd out other foods you need to maintain health.5

boy eating celeryRemember the demineralization-remineralization tug of war? Every time we eat foods containing sugars, we get an acid attack that lasts approximately 20 minutes. If nothing else containing sugars is eaten, the saliva in the mouth will fight off the acid attack. However, if we eat frequently, especially sugars and refined carbohydrates, the repeated cycles of acid attack will cause greater tooth demineralization to occur. Limiting between-meal snacks will reduce the number of acid attacks on your teeth. Also, eating or drinking sweet or starchy foods between meals is more likely to harm teeth than eating the same foods with meals. Saliva production increases during meals and helps buffer the acids and rinse food particles from the mouth. It's best to eat sweets as dessert after a main meal instead of several times a day between meals.6

To protect teeth from decay, remember to:

IN ADVANCE

Activities that include the Web site
Activity Number Web Version
Activity 1 yes
Take-home Activity no

Photocopies
Activity Number Master Number Number of Copies
Activity 1 none none
Take-home Activity Master 5.1, Take-home Activity 3: Brushing to the Beat! 1 copy for each student

Materials
Activity 1
For the class:
  • Web site address
  • computer with Internet access
  • 1 skein of red yarn
  • 12-15 pads of small sticky notes, any color
  • 1 small whiskbroom with handle (or another type of small brush to use as a pretend toothbrush)
  • 1 sheet of white construction paper, 8½ -by-11 inches
  • 1 sheet of black construction paper, 8½ -by-11 inches
  • 2 sheets of construction paper, 11-by-17 inches, any color
  • old magazines that contain pictures of a variety of foods
  • scissors
  • glue
  • 1 bicycle helmet (or an umbrella)
Take-home Activity
For each student:
  • 1 copy of Master 5.1, Take-home Activity 3: Brushing to the Beat!

Preparation

Tip from the field test: If you run out of time to make the food collages, hold a brainstorming session with students to list foods that belong in each category. Write the lists on two separate pieces of construction paper and use them in the dramatization in place of the collages.

Return to Lesson Plans
     1 | 2    next