Orthodontics is the practice of straightening teeth and correcting how they line up. One of the reasons why straight teeth are important is because they are easier to brush and floss properly.
People have been trying to correct tooth alignment for thousands of years, but modern orthodontics began around 1850. During this time, people were trying to correct tooth alignment by pulling on their teeth so that they would be in different positions.
In the 1890s, people started taking out their old teeth and putting in false teeth. Also in the these years, Dr. Edward Angle developed a classification system for how teeth and jaws are supposed to line up. This helped establish what is considered normal occlusion, or normal bite.
Now that orthodontists knew what was the normal bite, they could figure out how to fix misaligned teeth and jaws.
Today, orthodontists use a variety of tools to correct crooked teeth and jaws, like brackets attached to the teeth with wires between the brackets. Some other ways to fix crooked teeth are with elastic bands, expanders, and special headgear.
Once a person's teeth and jaws are corrected, you need to use a retainer to hold them in the proper position until the bones around the teeth grow solid.