According to the Cleveland Clinic, in certain cases, crooked teeth are straightened with the use of retainers. Most people, however, need braces to fix bite and alignment.
The Bow Lane Dental Group describes two kinds of removable, clear retainers that adjust crooked teeth. "Invisalign" is a series of retainers. Each set is worn for about two weeks while the teeth slowly straighten. The retainers do not need to be worn when eating or drinking. The whole process takes one to two years. An "Inman Aligner" works more quickly. Results are sometimes noticeable within six weeks. This type of correction works only on front teeth. Top and bottom teeth each use one retainer during the process.