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.
Braces are external devices that support the muscular and bony structures of the spine. In the past, many spine patients were required to wear heavy plaster casts. Fortunately, patients that must wear braces today benefit from lighter weight plastic braces that have been designed with the patient's comfort in mind. Braces are categorized as rigid or soft. Rigid braces are used to restrict movement, while soft, elastic type braces provide muscular support while allowing movement.