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Dr. Universe: How does toothpaste clean your teeth? -Lucy, 10, Pullman, WA

Dear Lucy, If you are anything like me, every day you squeeze a little toothpaste onto your toothbrush and brush your teeth. Toothpaste gets its cleaning power from a few different ingredients. My friend Mark Leid was happy to tell us about how they work. Leid spent part of his career teaching future dentists. He is also dean of the Washington State University College of Pharmacy and Pharmaceutical Sciences. First, he told me the outer covering of a tooth is called enamel. It’s the hardest tissue in the whole human body—even harder than bone—and it helps with things like chewing your food. Read More ...

Dr. Universe: With the coronavirus why is it effective to wear a mask? How does it make life safer? - Marin, age 12, in Ohio

Dear Marin, Whenever I go out and about, I make sure to wear my face mask. Like you, I wanted to find out exactly how they work. First, I talked to Marian Wilson, an assistant professor and nurse at Washington State University who is curious about how face masks protect people. “When we talk, sneeze, sing, or laugh, we spread droplets into the air all the time,” she said. “With the COVID-19 pandemic going on, we know people may have virus in their droplets.” Read More ...

Dr. Universe: Why are dogs important to humans? Stephani R., 9, Washington State

Dear Stephani, Dogs are important to humans in all kinds of ways. The connection between the two goes back thousands of years. A long time ago, wolves would trail along after humans on hunting trips and eat any scraps they could find. Eventually these wolves evolved into dogs that helped protect the hunters and gatherers. Read More ...