If a patient has a deep bite, braces can be used to move teeth both horizontally and vertically. Horizontal tooth movement is much more common, but braces can also be used to correct dental problems such as a deep bite, in which the upper teeth overlap the lower teeth, or if one of the patient's teeth is longer than it should be. Braces can push teeth toward the palate, but they can also pull teeth out toward the lips. Shape-memory wire arcs made of nickel-titanium are used to pull teeth forward.
The wire bends to attach to the tooth support, and over time it returns to its original U-shape, bringing the tooth forward. It is not the braces themselves that move the teeth, but rather the pressure created by the arc of wire. Once the wire is placed along the irregular trajectory of the patient's misaligned teeth, it attempts to return to its original shape, moving the teeth with it. Initially, flexible cables are used and then replaced by stronger cables as treatment progresses.
Invisalign braces and aligners cannot cure or reverse gum recession, but they can sometimes offer a small aesthetic improvement. For example, if a prominent tooth has a recession, re-aligning it can improve its appearance. Elastics are normally placed from one or more of the upper straps to one or more of the lower straps. Tooth movement is the body's natural response to the slight pressure applied by braces over a period of time.
When braces move a tooth to the right, the ligament on the right compresses and new bone forms on the left to fill the space.