16.

  1. In six months.
  2. Every now and then.
  3. Not mentioned.
  4. In two weeks.

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17.

  1. Have the dentist floss her teeth twice a year.
  2. Use tartar-free toothpaste when she brushes.
  3. Brush her teeth twice a day and floss every day.
  4. Use a toothpick to clean her teeth after every meal.

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18.

  1. It causes decay.
  2. It hurts the gums.
  3. It makes brushing difficult.
  4. It makes chewing difficult.

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19.

  1. It sticks to the bacteria.
  2. It drags the tooth.
  3. It brushes the gum line.
  4. It loosens the tartar.

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20.

  1. Show the woman how to use floss.
  2. Show the woman the correct way to brush her teeth.
  3. Continue cleaning the woman's teeth.
  4. Show the woman what tartar looks.

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M:Now all the tartar is gone; your teeth are clean. I'd like you to come in again in six months. Between now and then, you need to make an effort to keep your teeth clean.
W:What should I do?
M:There are several things to do. First of all, be sure to brush at least twice a day, and floss your teeth every day. There are some other devices on the market that may help you; we'll talk about those later. The basic things to do are brushing and flossing.
W:I'm not sure how to do that. I've never flossed my teeth before.
M:Well, dental floss is a thin string. You can buy it at any drug store. I'll give you a sample when you leave. With the floss, you can drag the tartar from between your teeth at the gum line.
W:But what is tartar?
M:Tartar is the white gummy stuff that stays between your teeth on the gum line after eating. It's composed of bacteria, and that's what makes our teeth decay.
W:Oh, I guess I'd better start flossing right away.
M:Yes. Good. Flossing helps keep your teeth clean because it helps prevent the build-up of tartar.
W:OK. Can you show me again how to use it?
M:Sure. Take a piece of floss about this long and hold it like this in two hands. Here's a mirror. Now open your mouth again and watch me as I pull it between your teeth.