A study done by Faculty of Dentistry at Malmö University that followed a cohort of dentists throughout their adult lives, show that our jaws decreases with age. The study showed that over forty years there was less and less room for teeth in the jaw. This crowdedness comes from shrinkage of the jaw, primarily the lower jaw, both in length and width. While this is only a matter of a few millimeters, but it is enough to crowd the front teeth.