The classifications are:
- Class I malocclusions: Dental arches may be creating too much space or become crowded. A class I malocclusion may be accompanied by overlapping teeth, or crossbites and rotations.
- Class II malocclusions: Upper molars meet slightly forward to the lower molars, forcing the chin to shift backward.
- Class III malocclusions: Lower molars meet forward to the upper molars, causing the chin to protrude. The lower molars are far forward and do not fit into their corresponding upper molars. A class III malocclusion may be accompanied by a crossbite.
Generally, braces are worn for as long as three years; some people respond quickly to braces, and can have them removed after only a period of a year or less. Everyone is different.