A lisp is a speech impediment characterized by difficulty pronouncing the "s" and "z" sounds. It can be caused by a variety of factors, including tongue-tie, dental problems, and neurological disorders. In some cases, a lisp can be corrected with speech therapy. However, in other cases, it may require dental intervention.
Dentists can fix a lisp by correcting the underlying dental problems that are causing the speech impediment. This may involve orthodontics to correct the position of the teeth, or surgery to remove a tongue-tie. In some cases, a dentist may also recommend speech therapy to help the patient learn to pronounce the "s" and "z" sounds correctly.