eli5: If osteoclasts and osteoblasts restructure bone density while wearing braces, why do teeth shift back to their original positions if a retainer isn’t regularly worn? Why isn’t the change in bone density permanent?

Question

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In: Biology

Answer 1

Sometimes the configuration of our teeth is affected by other things like the way our jaw structure affects our bite, the way we swallow, tongue habits, and things like that. Those don’t change after you have braces. So, for example, a retainer might help keep your teeth in place even though all night long you are unconsciously pushing out on them with your tongue.

Answer 2

Each tooth has a ligament at the base called the periodontal ligament. When we wear braces, we shift the bone structure to adjust to the new position of the tooth, but if the teeth are crooked due to genetics (as opposed to pressure from other teeth for example), that ligament will pull on the tooth once you remove the braces and can bring them back to their original position

Aside from that, teeth grinding, bad pronunciation habits or bad resting tongue placement in the mouth can exacerbate that effect