Tooth eruption is the process where a developed tooth grows into the mouth. Tooth eruption can occur as early as 3 or 4 months of age. This development is usually associated with a low grade fever, discomfort, excess drooling, and many children will constantly place their hands in their mouths for comfort. It usually takes a few weeks for a tooth to erupt and using Children’s Tylenol® or Motrin® can help ease discomfort.