When a baby begins to grow teeth, the first set of teeth have to push out through the baby's gums. This is often painful, and is called teething pain. Babies are given teething rings to chew on to help the teeth break through and come out. Note: The verb "to teethe" is to grow the first set of teeth, called 'baby teeth'. Do not confuse this with the word "teeth" (no e at the end) which is the plural of the noun "tooth."