Since drooling typically ends when a child finishes teething, a child who is drooling at age 3 needs the special help you will providing. I would recommend first asking the parent’s about the child’s tooth brushing routine and make sure that the child has been taught to (independently or with help from the parent) brush teeth after each meal and rinse the mouth out. A vibrating toothbrush can be used to “wake up” the mouth and provide oral motor stimulation. Most children of this age have been drooling so long that they are also unaware of the sensation that their chin or face is wet, so doing a lot of training and cueing for recognizing a wet and dry face is needed. You can start with using toys and sponges that are wet or dry and then their hands to make sure the child cognitively understands what the words mean before attempting to get them to recognize the sensation on their face. Use a mirror so the child can visually see the drooling as well as feel it. Prompt the child to “wipe your mouth/chin” so they get used to doing it themselves.
Preschool aged children who wear a bib may get teased, so instead let them carry a small cloth in their pocket or use a tissue. Implement oral motor exercises to wake up the mouth, like toweling or massaging before meals. Practice eating foods of various textures, intense flavors and temperatures. Use Nuk brushes for oral stimulation. Play games that involve blowing, sucking, pursing lips, etc. Make sure the child uses an open cup or straw cup as much as possible, not a sipper cup with a spout to promote more mature oral motor patterns. Have the child blow cotton balls on a table using their mouth and then a straw. Let them suck milkshakes and thicker liquids through a straw. Have them blow bubbles. Have them blow up a balloon. Be certain the child knows how to swallow properly. Be sure the child has seen a dentist and doctor to be certain their are no issues related to the teeth or oral cavity contributing to drooling. Sometimes and ENT appointment is helpful too if the child continually has an open mouth posture that could be related to enlarged adenoids or chronic congestion. There are also medical treatments for drooling if the child perhaps has cerebral palsy or another diagnosis.