The first thing you should do is make an appointment with your dentist and an orthodontist in order to have a medical examination of the condition of your teeth and to see what can be done about the problem of crooked teeth. To straighten crooked teeth you have several options, but you should always seek the advice of a professional in the field to find out more information before you decide which route to take.
Braces are one first solution for straightening crooked teeth; they are devices that put pressure on the teeth forcing them to shift into the right place. The most common materials for braces are ceramics, metal and plastic; once a month the wires that make the device are tightened until crooked teeth actually shift into the desired position. Ceramic braces are the least noticeable, as the brackets are applied directly to the front teeth by a special glue.
The straightening of crooked teeth is not over with the simple use of braces; when the device is removed, most likely you will need to wear a retainer for a while, to prevent your teeth from shifting back into the original incorrect position. One more thing worth mentioning concerns the possibility of tooth extraction whenever the orthodontist considers it necessary in order to make room for the straightened teeth.
An alternative to braces is the use of removable aligners that squeeze the teeth forcing them to move into the correct position. Known as Invisalign, this technique is more expensive than braces, and it is used only for mild cases of crooked teeth.
There are many more advanced and rapid ways of dealing with crooked teeth, but they are both expensive and pretty complex involving a lot more stress at the teeth and tongue level. Most orthodontists will inform you of the possibility of using accelerated orthodontics in order to get the perfect smile you may have been looking for. However, be ready to cope with a little pain and the discomfort of wearing lingual braces; fortunately, the whole process is four times quicker than the regular orthodontic procedure, thus instead of two years, you'd only need six months to straighten crooked teeth.