For much of my childhood, around once a year or so, my parents would drive me across town to a new orthodontist’s office, where they’d receive yet another written recommendation for braces to send to our insurance provider. After the company inevitably declined to cover the cost, for any one of a dozen reasons—my teeth were moving too much, or they weren’t in enough disorder, or they were in too much disorder to make braces worthwhile without some surgery—we’d immediately start strategizing for the next year.

Today, some 4 million Americans are wearing braces, according to the American Association of Orthodontists, and the number has roughly doubled in the U.S. between 1982 and 2008. The dental braces we know today—a series of stainless-steel brackets fixed to each tooth and anchored by bands around the molars, surrounded by thick wire to apply pressure to the teeth—date to the early 1900s. But cultural and social concerns about crooked teeth are much older than that.

Some of the earliest medical writings speculate on the dangers of dental disorder, a byproduct of evolution that left homo sapiens with smaller jaws and narrower dental arches (to accommodate their larger cranial cavities and longer foreheads). In Hippocrates’s Corpus Hippocraticum, he notes that people with irregular palate arches and crowded teeth were “molested by headaches and otorrhea [discharge from the ear].” The Roman physician Aulus Cornelius Celsus recommended that children’s caregivers use a finger to apply daily pressure to new teeth in an effort to ensure proper position. Egyptian mummies have been found with gold bands around some of their teeth, which researchers believe may have been used to close dental gaps with catgut wiring.

Until relatively recently, though, tooth-straightening was a secondary concern among dentists; first was tooth decay. Before modern dentistry, dental pain was often attributed to either fabular tooth-worms or an imbalance of the four humoral fluids. The most common treatments were bloodletting, to drain the offending liquid from the gums or cheeks, or extraction. During the Middle Ages, tooth-drawing was a relatively easy vocation that anyone could learn and, with a little promotional savvy, a person could set up shop in a local market or public square. The trend continued for several centuries—in The Excruciating History of Dentistry, James Wynbrandt notes that there were around 100 working dentists in the United States in 1825, but more than 1,200 by 1840. The reason for the surge: After the financial panic of 1837, many of the nation’s newly unemployed mechanics and manual laborers turned to the crude art of tooth extraction.

The haphazard nature of early dentistry encouraged more serious practitioners to distinguish themselves by focusing on dentures. As The L.A. Times noted in a 2007 piece on the history of dentures, from ancient times until the 20th century, they were made from a wide variety of materials—including hippopotamus ivory, walrus tusk, and cow teeth. Pierre Fauchard, the 18th-century French physician sometimes described as the “father of modern dentistry,” was the first to keep his patients’ dentures in place by anchoring them to molars, formalizing one of the basic principles of contemporary braces. Fauchard developed a number of other techniques for straightening teeth, including filing down teeth that jutted too far above their neighbors and using a set of metal forceps, commonly called a “pelican,” to create space between overcrowded teeth. He also developed what many consider to be the first orthodontic appliance: the bandeau, a metallic band meant to expand a person’s dental arch, without necessarily straightening each tooth.

Around the same time that Fauchard practiced, the desire for a symmetrical set of teeth was taking root among the wealthy in Europe and the U.S. Thomas Berdmore, the personal dentist to England’s King George III, made the case for both the medical and social benefits of a symmetrical set of teeth, writing that they “give a healthy juvenile air to the countenance, improve the tone of the voice, render pronunciation more agreeable and distinct, help mastication, and preserve the opposite teeth from growing prominent.”

In A Brief History of the Smile, Angus Trumble describes how these class-centric attitudes contributed to a cultural association between crooked teeth and moral turpitude. Painters of the period used the open mouth as a “convenient metaphor for obscenity, greed, or some other kind of endemic corruption,” he wrote:

Most teeth and open mouths in art belonged to dirty old men, misers, drunks, whores, gypsies, people undergoing experiences of religious ecstasy, dwarves, lunatics, monsters, ghost, the possessed, the damned, and—all together now—tax collectors, many of whom had gaps and holes where healthy teeth once were.

The American dentist Eugene S. Talbot, one of the early proponents of X-Rays in dentistry, argued that malocclusion—misalignment of the teeth—was hereditary and that people who suffered from it were “neurotics, idiots, degenerates, or lunatics.”

In the 20th century, tooth decay was finally tamed through advancements in microbiology, which established connections between cavities and diets heavy in sugar and processed flour. Especially in the U.S., as orthodontics advanced and tooth extraction became less common, a proud open-mouthed smile became the cultural norm. From cigarettes to dish soap, television commercials and magazine ads were punctuated with glinting smiles. Sharing a smile with someone wasn’t just good manners, but a sign that the smiler was a willing recipient of the wonders of modern medicine.

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By the early 20th century, Edward Angle, an American pioneer in tooth “regulation,” had been awarded 37 patents for a variety of tools that he used to treat malocclusion, including a metallic arch expander (called the E-Arch) and the “edgewise appliance,” a metal bracket that many consider the basis for today’s braces. Angle sold all of these standardized parts, in various configurations, as the “Angle system.” Other orthodontists could purchase and use Angle’s inventions in their own practices, thus eliminating the need to design and produce appliances for each new patient.

Today’s orthodontic practices rely on equal parts individual diagnosis and mass-produced tool, often in pursuit of an appearance that’s medically unnecessary. Basic advances in brushing, flossing, and microbiology have largely defeated the problem of widespread tooth decay—yet the perceived problem of oral asymmetry has remained and, in many ways, intensified. The choice to leave one’s mouth in aesthetic disarray remains an implicit affront to medical consumerism.

“The smile has always been associated with restraint,” Trumble writes, “with the limitations upon behavior that are imposed upon men and women by the rational forces of civilization, as much as it has been taken as a sign of spontaneity, or a mirror in which one may see reflected the personal happiness, delight, or good humor of the wearer.” And so orthodontics persists to address a genuine medical necessity, but also (and more often) to enable unnecessary self-corrections.

With an often-unnecessary product—the perfect smile—as the basis of its livelihood, the orthodontics industry has embraced the placebo effect. “A great smile helps you feel better and more confident,” argues the website for the American Association of Orthodontists. “It can literally change how people see you—at work and in your personal life.”

In recent years, however, this promise has collided with the high cost of orthodontics to foster a dangerous new subculture of home remedies for teeth straightening. Guided by YouTube videos and homeopathy websites, some people are attempting to align their own teeth with elastic string or plastic mold kits, an amateur approximation of what an orthodontist might do. This practice has become so widespread that The American Journal of Orthodontics and Dentofacial Orthopedics issued a consumer alert, warning that such unsupervised procedures could lead to lesions around the root of a tooth and in some cases cause it to fall out completely. Excessive pressure can wreak havoc on a mouth and interfere with the root resorption necessary to anchor a tooth in its new position. Yet the popularity of the practice is, in some ways, a product of the orthodontics industry’s own marketing history, which has compensated for empirical uncertainty about its medical necessity by appealing to aesthetic concerns.

It certainly worked on me. When I was 21, just starting my senior year of college, my parents finally succeeded in navigating the bureaucratic maze of our family’s insurance company after years of rejection. I remember sitting in the examining rooms with the orthodontist who would finally apply my own braces, watching a digitally manipulated image of my face showing how two years of orthodontics might change it. I gazed at computer screen as the orthodontist walked me through all of the things that would be changed about my face, the collapsing wreckage of my lower teeth drawn into a clean arc. I tried to hold onto this image of my reordered face as the brackets were applied and the first uncomfortable sensation of tightening pressure began to radiate through my skull.

I was 24 when I finally had my braces taken off. After the removal, I walked unsteadily to my car through the orthodontist’s parking lot, struggling to stay upright. After almost three years of sensing constant pressure against my teeth, it felt like a 10-pound weight had been removed from the front of my face. The ground swayed beneath my feet and I moved slowly to make sure I wouldn’t trip. When I closed my mouth, my teeth felt unfamiliar, a landscape of little bones that met in places where they hadn’t before.

For a few days, chewing produced new and unexpected sensations in my gums. Each piece of food was a new experience, revealing qualities that I’d been numb to before. But after a week or so, normalcy returned. My meals were just meals again. Biting into an apple no longer felt like a moonwalk. Swishing water through the spaces between my teeth lost its thrill. Eventually, I forgot that my mouth had ever been different at all.