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.
The above is some information in concern with rubber band braces, why rubber bands are used and what effect do rubber bands have in the dental treatment. Always consult your dentist for a better overview of the things.