A study conducted by the Faculty of Dentistry at Malmo University in Sweden followed a group of dentists throughout their adult lives. The study began in 1949 with plaster molds that were made of the jaws of dental students, who were in their 20s at the time. Then years later, the procedure was repeated. Then, again 40-years after the original molds, researchers were in contact with 18 of the original 30 participants and molds were done one final time.
Lars Bondemark, DDS, PhD, a professor of orthodontics, was one of the doctors who analyzed the materials, and he said, “We found that over these 40 years, there was less and less room for teeth in the jaw.”
According to the study, crowded teeth comes from shrinkage of the jaw, in both length and width. The lower jaw showed more shrinkage than the upper. And while this change in length and width is only a matter of a few millimeters, it is enough to crowd the front teeth. Furthermore, the study revealed that even people with no wisdom teeth showed crowding with age. This means that the idea of wisdom teeth causing crowded can be eliminated.
Of course, how much the jaw shrinks is different for each individual, but for some patients, the changes are sufficient to cause them to perceive a change in their bite.
Dentists should take these findings into consideration when they plan to perform major bite reconstruction on a patient because the jaw shrinkage will continue to happen with age. It’s not known why the jaw changes throughout life, but it is likely that hereditary and anatomical factors play into the equation.
It could be said that orthodontic treatment to correct crowding and to fine-tune the bite should be followed with a lifetime plan to wear removable retainers to help prevent relapse later in life.
