Q&A: Could my 18-month-old have a cavity?

Yes, it is possible that he may have a cavity. A cavity is caused when holes are formed in a tooth's enamel and dentin (the outer two layers). Baby teeth are much more porous than adult teeth, leaving children more vulnerable to cavities.

Cavities are caused by diet, oral hygiene, and genetics. Genetics play a big role in the health of your child's teeth and makeup of his saliva. Clearly you cannot do anything about the genetics factor, but you can make sure that he eats healthy snacks—watch the sugar! You can also help him learn how to brush his teeth. Ideally his teeth should be brushed twice a day and, if possible, after snacking. If giving juice, water it down to prevent such a high concentration of sugar from lingering in your child's mouth.

The American Dental Association (ADA) recommends you bring your child in within six months of the appearance of his first tooth. (Teeth generally start appearing between 6 and 12 months of age.) The dentist can check your child's teeth and jaw structure and show you how to brush properly.

The following helpful tips, listed on the ADA website, will give your baby the best chance at maintaining good oral health and preventing early tooth decay:

• After each feeding, wipe Baby's gums with a clean gauze pad. Begin brushing your child's teeth when the first tooth erupts. Clean and massage gums in areas that remain toothless, and begin flossing when all the baby teeth have erupted, usually by age 2 or 2 1/2.
• Never allow your child to fall asleep with a bottle containing milk, formula, fruit juice, or sweetened liquids.
• If your child needs a comforter between regular feedings, at night, or during naps, give the child a clean pacifierrecommended by your dentist or physician. Never give your child a pacifier dipped in any sweet liquid.
• Avoid filling your child's bottle with liquids such as sugar water and soft drinks.
• If your local water supply does not contain fluoride (a substance that helps prevent tooth decay), ask your dentist how your child should get it.
• Start dental visits by your child's first birthday. Make visits regularly. If you think your child has dental problems, take him to the dentist as soon as possible.