Marked lower anterior crowding (late crowding or post-adolescent crowding) often develops at about the time of third molar eruption.1,2,3 Many studies2–12 have implicated the presence of third molars as a cause of this crowding. Despite the fact that there is no clear evidence that this is the case,3–17 many orthodontists and their patients’ referring dentists routinely remove third molars at the retention stage of treatment to prevent crowding later; Ricketts