The time zones known as Greenwich Mean Time and the International Date Line are sometimes alternatively used to demark the western from eastern hemispheres, but the would not be true hemispheres as those time zones are not straight longitudes.
The final part of braces are interarch rubber bands, which are used to adjust bite and jaw position. These are connected to the brackets with hooks, often connecting the top tooth bracket with the bottom tooth bracket to help adjust the position of the teeth in the mouth and the position of the jaw.
When you go to the orthodontist to get your braces put on, they will first take your spacers out, which are rubber pieces wedged between your teeth so the metal bands will fit. Then, the orthodontist puts a plastic lip separator in your mouth, which keeps your lips from going on your teeth.