This book is exciting and funny. Little boy Mr. Bean has a lot of questions in his head. When mom and dad tell him to brush his teeth, he would think of many animals who do not brush their teeth. Then he asks, "Why does hippo not brush his teeth?" The twins called "Teeth Broker" slip into Mr. Bean's book and try to steal delicious meals, food chippings in animals' mouths. Along with Mr. Bean's bunch of questions about why animals do not brush their teeth, the brokers start their passage through animals' mouths and teeth simultaneously. Readers could learn about teeth-brushing habits with scientific knowledge related to animals in the book.