A dental cavity is a hole in the tooth that can grow bigger and deeper over time. More to Know Cavities (also called caries) happen when bacteria (germs) and food left on the teeth after eating are not brushed or flossed away. The bacteria make acid that softens the tooth's outer hard surface (called the enamel). Once this happens, the acids can cause decay deeper in the tooth. This can lead to a cavity that sometimes causes tooth pain or sensitivity. Many kids get cavities but certain things make developing cavities more likely. These include drinking a lot of sugary drinks, using a sippy cup or bottle (filled with something other than water) throughout the day or while in bed, not getting enough fluoride, being around cigarette smoke, and taking liquid medication for a long time. Keep in Mind To treat a cavity, a dentist will first numb the tooth and gum area. The decayed part of the tooth is removed with a special drill, then a filling is put into the hole. Sometimes, the decay is very deep and the dentist may recommend a root canal (removing the nerve and pulp, then cleaning and sealing the inside of the tooth) or removing the tooth. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Gum Disease Gum disease doesn't just happen to people your grandparents' age - it can happen to teens too. Get the details here. Read More Going to the Dentist What happens when you go to the dentist? Find out in this article for kids. Read More How Do I Care for My Baby's Teeth? Find out what the experts have to say. Read More Fluoride and Water Keeping kids' teeth healthy requires more than just daily brushing. Learn about fluoride, a substance found naturally in water that plays an important role in healthy teeth. Read More Taking Care of Your Teeth The healthier your teeth are, the happier you look. That's why it's important to take great care of your teeth by brushing, flossing, and visiting the dentist. Learn more. Read More Mouth and Teeth Did you know that your mouth is the first step in the body's digestive process? Or that the mouth and teeth are essential for speech? Learn about the many roles your mouth and teeth play. Read More Your Teeth There's much more to a tooth than meets the eye. This article for kids gives you the inside story. Read More Taking Care of Your Teeth There's a lot more to taking care of your teeth than breath mints and mouth sprays. Read this article to learn the facts on flossing, how to give plaque the brush-off, and much more. Read More Mouth and Teeth Our mouth and teeth play an important role in our daily lives. Here's a course on the basics - including common problems of the mouth and teeth. Read More Keeping Your Child's Teeth Healthy Here are the basics about how to care for your child's teeth - and when. Read More What's a Cavity? Cavities are small holes in your teeth that need to be filled. Find out what causes tooth decay and how dentists handle it. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.