Why do teeth move?
Wolff’s law, coined in the 1800’s by German surgeon Julius Wolff, observes that bones adapt (change shape) according to forces acting upon them. And though teeth are not bone, they do sit within bone, and are subject to an array of forces.
Normal forces that move teeth
From lips and tongue: Tongue pressure, occurs in swallowing, eating and talking and is a major force for tooth position. Persistent habits such as chewing or rolling the tongue, place unnatural asymmetrical pressure on the lower teeth.
Other habits – for example chewing on the lower lip or thumb-sucking – will over time, push the top teeth forward. This can also occur in cases of a ‘short top lip’ when the lips don’t come to rest together, remaining slightly parted. The top lip then is not in a position to oppose the normal tongue thrust as it should.
The loss of a tooth through decay or trauma creates a space, and the teeth nearby move or lean in towards the gap. And the opposing tooth – the upper or lower tooth that would normally meets it when biting – lengthens.
Biting and chewing place tremendous vertical forces on and through our teeth. With age, teeth wear and the enamel grows thinner, meaning they are less able to withstand these forces and become more prone to shifting.
These are some of the reasons why wearing retainers after orthodontic treatment remains a life-long responsibility to avoid teeth returning to their original position.
However, as seen in the photo above, slight imperfections in a smile can be hard to notice – and may even add to its appeal!