🔬 ScienceGrade 2Lesson 31
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Teeth and Dental Care

Lesson preview: the Mini Lesson and Vocabulary are open to everyone. Guided practice, exercises, the parent checklist and the printable PDF worksheet come with full access (free 7-day trial or membership).

Learning Objectives

  • 1Name the four types of teeth and the job of each one
  • 2Explain how plaque and acid cause cavities
  • 3Put the seven teeth-brushing steps in the correct order
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Mini Lesson

Your teeth do much more than help you smile! They are essential tools for chewing food, helping you speak clearly, and shaping your face. You only get two sets of teeth in your life — baby teeth and adult teeth — so learning to care for them well now will pay off for decades.

The four types of teeth

  • Incisors (8 total): The flat, sharp teeth at the front. They cut and bite into food.
  • Canines (4 total): The pointed teeth beside the incisors. They tear and grip food.
  • Premolars (8 total): Located behind the canines. They crush and grind food.
  • Molars (8–12 total): The large, flat teeth at the back. They do the heavy grinding work — perfect for tough foods like carrots and bread.

How cavities form

  • After you eat, tiny bacteria in your mouth feed on leftover sugar and starch and produce acid.
  • Over time, bacteria and food form a sticky film on teeth called plaque.
  • Plaque acid slowly dissolves the hard outer layer of teeth — the enamel. Once the enamel is gone, a hole called a cavity forms.
  • Cavities are painful and must be repaired by a dentist. Unlike bones, teeth cannot repair themselves once enamel is lost.

The correct brushing routine

  1. Put a pea-sized amount of toothpaste on a soft-bristled toothbrush.
  2. Brush the outer surfaces of all teeth — angling the bristles toward the gumline.
  3. Brush the inner surfaces of all teeth.
  4. Brush the biting surfaces (tops) of the back teeth.
  5. Gently brush the tongue to remove bacteria.
  6. Spit out the toothpaste — do not swallow it.
  7. Floss between every tooth to remove food and plaque the brush cannot reach.
  • Brush for at least 2 minutes, twice a day — morning and before bed.
Four types of teeth shown on an upper jaw diagramAn upper jaw showing the four tooth types with labels: incisors at the front that cut and bite, canines beside them that tear and grip, premolars behind that crush and grind, and molars at the back that do heavy grinding.Four Types of TeethIncisors — cutCaninestear & gripPremolarscrushMolars — grindIncisorsCaninesPremolarsMolars
Upper jaw showing the four tooth types — incisors, canines, premolars, molars.
How a cavity forms in four stepsFour numbered steps showing how cavities form: food left on a tooth, bacteria make plaque and acid, acid dissolves enamel, and a cavity forms.How a Cavity Forms1. Food stays on toothSugar coats the surface2. Bacteria make plaqueSticky plaque releasesacid3. Acid dissolves enamelOuter enamel wears away4. Cavity formsDentist must repair it
The four steps: food feeds bacteria, plaque acid dissolves enamel, a hole (cavity) forms.
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Ask yourself: Can I name the four tooth types and put the brushing steps in the correct order?

Vocabulary
Incisor
A flat, sharp front tooth that cuts and bites into foode.g. the four teeth in the very front of the upper jaw
Canine
A pointed tooth beside the incisors that tears and grips foode.g. the sharp tooth on each side of the front teeth
Molar
A large, flat back tooth that grinds tough food into tiny piecese.g. the wide teeth used to chew carrots and bread
Enamel
The hard outer layer of a tooth — the hardest material in the bodye.g. enamel protects the softer inside of each tooth
Plaque
A sticky film of bacteria that forms on teeth and makes acide.g. plaque builds up if you do not brush well
Cavity
A hole in a tooth made when acid dissolves the enamele.g. a cavity must be repaired by a dentist
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