system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: why do we not use tooth filling to fill gaps between teeth and eliminate need for flossing?
gpt
Your lower jaw and skull are flexible, and your teeth shift with each bite.

If you connect each tooth to each other with fill material, it would crack them with each movement of your jaw.

Braces are something that take advantage of this by connecting each tooth with strong ductile wire that causes teeth to shift more, and in a restricted direction, with each movement of the jaw.