懂你英语Level4-Unit1-Part3-[3]Vocabu

1. A dental cavity is a hole in a tooth.

2. A cavity is caused by bacteria in the mouth.

3. Brushing your teeth frequently and regularly can help prevent cavities.

4. A cracked tooth can be caused by biting down on something hard.

5. Dentists treat a cracked tooth by covering it with a crown.

6. A dental x-ray is a picture of your teeth and gums.

7. An x-ray shows what can't be seen on the surface of the teeth and gums.

8. Braces are used by dentists to straighten teeth over a period of years.

9. Though braces are usually for children, they can also be used for adults with crooked teeth.

10. To extract a tooth means to remove it from the mouth.

11. Dentists have to pull hard to extract a tooth.

Dentists often inject something into the gum to block the pain during the extraction process.（前文未见生句）