The episode of "Even Stevens" that aired on 12/24/06 on Cable Superstation WGN in the States had a girl who couldn't wait to get her braces off (which were shown in the show's beginning).  Unfortunately for her, once they were off, she looked worse, as she had puffy cheeks when she smiled, which ruined her school yearbook portrait.  I didn't see the rest of it, but I understand that the story revolved around her effort to get her picture retaken.

Comment on Season 1 Episode 8 (108) - Family Picnic

from: https://dereferer.me/?https://dereferer.me/?http://www.tv.com/even-stevens/family-picnic/episode/37503/summary.html

During the kayak race, Louis can be seen wearing a retainer. He doesn't wear it during the rest of the show, or in any other Even Stevens episode, as far as we know. Shia LaBeouf, the actor who plays Louis, has been seen wearing the retainer in some of the promos he's done on the Disney Channel.

... In one episode a guy in a high pull headgear is one of the kids at a party, sitting on his hands with the other ...

In an episode (title unknown), Ren Stevens works at the school office. A girl presented at the office because it has lost its retainer, probably during his meal at the school restaurant. Ren opens a drawer and there are many retainers and gives to the girl, the girl testing the retainer but that is not his.

Season and episode tittle unknown.

It's  S01E19 - Strictly Ballroom
Es ist S01E19 - Der den Rumba tanzt

Sad/funny part is that in 1968 I was the kid at the party making his first public appearance wearing headgear.  Like the sign said LOSER.  I had just gotten braces and my mother's cousin's daughter was having a party and I was told I was going.  Knowing my horror at the thought of having to actually go out in public wearing the damn thing Mom said she would call the next day to check, and I knew she would.  I had to wear it 16 hours a day at first so basically all the time except during school.  After school it went right on. Hated every minute of it but I guess I should be proud to have helped establish the instant geekiness only headgear can bestow.

The named scene in Even Stevens Season 1 Episode 19 - Strictly Ballroom (at 3:30):

https://dereferer.me/?https://dereferer.me/?http://nullrefer.com/?https://dereferer.me/?https://dereferer.me/?http://www.youtube.com/watch?v=nDfsLbyu0X0

I love the dialogue:
- Try this! I found it in the cafeteria on the floor.
- It's a little loose...
- You know what  - you'll grow into it. Bye bye - there's the door! 

The very short scene in Even Stevens Season 2 Episode 21 - Gutter Queen (at 18:48):

https://dereferer.me/?https://dereferer.me/?http://nullrefer.com/?https://dereferer.me/?https://dereferer.me/?http://www.youtube.com/watch?v=QzH41lTeNoA (youtube does not ask your credit card number...)

Hi Marty,

The youtube video is of poor quality because it lacks a portion of the screen.

The scene at 18 minutes 48, it is very short. A girl, friend (Ruby in the French version) of Ren Stevens seeks his retainer, she finds it has stuck a bowling ball.

Not a great scene....