If you are suffering from malocclusion (bad bite) then orthodontic treatment is needed to prevent any long term problems. Misaligned teeth, especially the back teeth can become excessively worn down as a result of misalignment or overcrowding.
Problems with your bite can also affect your ability to speak as well as the appearance of your jaw line. From a cosmetic perspective it also affects your smile.
Another factor in this is the risk of tooth decay: a regular dental hygiene routine can help to look after your teeth and reduce this risk. But, if your teeth are out of position, misshapen or there are simply too many of them then this will affect your ability to keep them clean. A poor or irregular oral hygiene routine increases the risk of dental decay.
Corrective orthodontic treatment can help to deal with any of these as well as giving you a better looking smile.