Orthodontics alone can only move the teeth so far. Sometimes the problem is in the position or shape of the jaw bones. If the bones are too long or too short or too narrow, the teeth cannot be aligned properly with braces alone. The teeth would be pulled out of the bones to get them in the proper position. In the past, the only way to solve this was with corrective jaw surgery. This is sometimes still the only way to fix severe problems.
Today, however, other techniques have come along to help orthodontic alignment. These help move the bones, along with the teeth. They are still surgical procedures, but much less costly and traumatic.
Strategic cuts can be made in the jaw bones to facilitate their movement. The most common of this would be a mid-palatal split to widen the upper arch, called a surgically assisted rapid palatal expansion. Boney cuts can be made around teeth to accelerate their movement. This is a concept called accelerated osteogenic orthodontics. Bone can be weakened for movement of a tooth in a certain direction and stimulated to heal at the same time.
Bone anchors in the form of screws and bone plates can be implanted in the jaws to pull against. Orthodontics requires anchorage to move teeth. This means enough stability to move what you want to move, not what you are anchored against (the other teeth). In the past head gear has been used for some forms of anchorage. This is outdated now because we can place implant anchors directly in the jaws bones. Many forms of orthodontic problems can be corrected with bone anchors, eliminating major reconstructive jaw surgery.