A recent article titled “A 40 years follow-up of dental arch dimensions and incisor irregularity in adults.” by Nokolasos, Tsiopas, Maria Nilner, Lars Bondemark, and Krister Bjerklin, appearing the The European Journal of Orthodontics Advance Access published October 19, 2011, explores how the jaw is affected over a 40 year time period.
The study started in 1949 with 22 males and 13 females (35 total) and after 40 years in 1989, 18 of these participants were still able to participate. Three dental stone study casts were made for the 18 participants who completed the 40 years of the study.
The authors state:
“The present study showed that the occlusion, overbite, and overjet was stable, but dentoalveolar changes occur in the adult dentition. In the anterior part of the dentition, decreases in arch length and width lead to anterior crowding. There was also an increase in dental arch width at the first permanent molar.”
The authors conclude the article by saying
“The dentoalveolar processes continue to undergo physiological changes throughout adult life. Of particular clinical relevance is the finding that decreases in arch length and depth result in a decrease in intercanine width and increased crowding of the anterior teeth. These findings have important clinical implications in orthodontic practice, particularly in treatment planning and long-term post-treatment stability/retention.”
A key finding from this study is “We can also eliminate wisdom teeth as the cause, because even people who have no wisdom teeth have crowded front teeth.”
This study indicates that dentists should take into account that the lower jaw shrinks a few millimeters with age and this can crowd the front teeth.
Additional Source: Dentistry.co.uk. Jaws shrink with age and impact on teeth. November 7, 2011. http://www.dentistry.co.uk/news/4584–Jaws-shrink-with-age-and-impact-on-teeth