How do elastics not pull the tray off?

[BA5]

I understand that Invisalign uses "buttons" that attach directly to the teeth, and you attach one end of a rubberband to that. The other end is sometimes attached to a hook cut out in the tray itself. How does that not just pull the tray off?

As shown here, for example:
http://www.archwired.com/phpbb2/viewtop ... 29#p286329

I had hooks placed on the bottom of my lower canines and they cut a slanted slit in the upper aligners on the outside of the first molars. I put the bands in the slits before i put the upper aligners on, then pull the bands over the hooks on the lower canines.

It seems like as soon as you opened your mouth to talk, or yawn, it would take down the top tray.

Thanks.

[kittenpoint]

The buttons and the overall tightness of the trays keeps them from being pulled off. Depending on the size of your elastics you really can't yawn very wide as the force from the elastics keep you from really opening your mouth too far.

Don't worry about pulling the trays out with the elastics, I've had elastics for 20 weeks and never had them budge once.

[BA5]

Thanks kittenpoint.

Do you also have buttons on the bottom, and hooks cut in the top tray?

Do you know why they don't cut hooks in the bottom tray? I wonder if the bottom trays don't hold as well?

Thanks.

[dahlia]

My situation is a little different (no tray on top, tray on bottom with slits cut for hooks). The hooks stick out far enough so that the elastics don't touch the tray, at least that's the way mine work. So there's no chance tension from the elastic would pull the tray up. I'm probably explaining it poorly.

[kittenpoint]

Thanks kittenpoint.

Do you also have buttons on the bottom, and hooks cut in the top tray?

Do you know why they don't cut hooks in the bottom tray? I wonder if the bottom trays don't hold as well?

Thanks.

Yes I have metal buttons on the bottom and hooks cut out from the top tray. I don't know why they don't cut out hooks from the bottoms other than it might have to do with comfort. The hooks stick out a little bit and were a little scratchy at first but I no longer feel them; I think that if they used them on the bottom it would be uncomfortable because the hooks would constantly poke you. The buttons however are smooth and you can't feel them.

[DrJasonKTam]

Attachments on the other teeth serve as anchors for the tray not to be displaced when using elastics. Here's some more info to distinguish between buttons, attachments and hooks.

Buttons are actual physical buttons or brackets bonded to the teeth.
Attachments are the resin material bonded on the teeth in various shapes.
Hooks are actual physical hooks cut in the aligners to allow elastics to be attached.