So does her best friend, and, by her count, so does nearly one in four of the kids in her fourth-grade class. On Reddit’s r/braces forum, a practitioner based in Frisco, Texas, said he was surprised by “how many parents ask me, ‘Hey, does my child need an expander? Everyone else seems to have one.’” His colleagues seemed to notice something similar. “Everybody’s being told they have a narrow jaw, and everyone's being given an expander,” Neal Kravitz, the editor in chief of the Journal of Clinical Orthodontics, told me.