MALMÖ, Sweden: The size of our jaws decreases with age, research conducted at the Faculty of Dentistry at Malmö University has found. The study, started in 1949, followed a cohort of dentists throughout their adult lives.

For the study, plaster moulds were made of the jaws of dental students, who were then in their twenties. Ten years later, the procedure was repeated, and again in 1989, forty years after the first moulds. At that time, the researchers were in touch with 18 of the original 30 participants.

“We found that over these forty years there was less and less room for teeth in the jaw,” Lars Bondemark, Professor of Orthodontics, said. Bondemark analysed the material together with his colleague Maria Nilner, Professor of Clinical Bite Physiology at the College of Dentistry, Malmö University.

According to the researchers, the crowdedness results from shrinkage of the jaw, primarily the mandible, in both length and width. This was only a matter of a few millimetres, but it is enough to crowd the front teeth, they stated.

“We can eliminate wisdom teeth as the cause, because even participants who have no wisdom teeth have crowded front teeth.”

How much the jaw shrinks depends on each individual. However, for some patients, the changes are sufficiently great for them to perceive that something is happening to their bite.
“In that case it is good to know that this is normal,” said Bondemark, who asserts that dentists need to take the continuous shrinking of the jaws into consideration in planning major bite constructions on their patients.

“We are working against nature, and it is hard to construct something that is completely stable.”
The reason that jaws change throughout life is yet unknown, but the magnitude of the change is probably determined by both hereditary and anatomical factors, including what the patient’s bite looks like, the researchers stated.