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.
Invisalign braces are just another type of orthodontic appliance used to create a constant force on the teeth in order to move them. When worn correctly they will move the teeth. Anytime teeth are moved the body produces chemicals to help the teeth move and the bone remodel around the teeth. These chemicals, while helping the body move the teeth will also produce soreness and sensitivity around the teeth.