Jerome Groopman wrote a book titled How Doctors Think, and it became a best-seller. A book titled How Dentists Think would likely beat a quick path to the remainder bin. But to understand the crisis in dentistry, it's necessary to consider how the world looks to a dentist.

Dentists earn their living in a way that's markedly different from the way doctors do. Somewhere between 80 percent and 85 percent of American dentists practice as owner-operators, as compared with only about 20 percent of physicians. Group practices, which are common for doctors, are rare for dentists—about 63 percent work solo, 20 percent practice with one other dentist, and 17 percent are in business with two or more dentists. A dentist's "income" is therefore typically the difference between the fees she receives and the expenditures she lays out, which are considerable. This is usually true even for dental specialists.

In contrast to the surgical specialties of medicine, which are delivered in ambulatory care centers and hospital operating rooms, where the operating expenses and the cost of equipment and support staff are borne by hospitals rather than individual doctors, dental surgeons must pay for equipment, supplies, the electricity that powers drills and X-ray machines, malpractice insurance, rent on office space big enough to house the reception, a waiting room, clinical areas, and—often the biggest expense of all—staff to make appointments, submit insurance claims, and provide support services as dental assistants and dental hygienists. Unlike hospitals, which buy in bulk, dentists have very little leverage to negotiate discounts for fixtures and supplies.

The economic inefficiency of dentists' working solo is mitigated by other factors. Expensive drugs, frequent technological advancements, and endless tests of dubious diagnostic value—all significant drivers of medical inflation—are largely absent from the dental world. Because every procedure typically incurs only a single charge, billing is much more straightforward and transparent than it is in most areas of medicine. Although dentists prefer to leave the money talk to their billing manager, they usually know the cost of every procedure, which isn't necessarily true of physicians. The solitary nature of most dental practices also steers most dentists away from the excessive and costly specialization that bedevils the rest of medicine. Only 21 percent of dentists are specialists, compared with 60 percent of physicians.

Overall, dentists are doing very well, thank you. According to the American Dental Association, in 2006 the median income for a dental general practitioner was $180,000. That's a whisker below the median annual wage for primary care physicians ($182,000), and on an hourly basis it's probably higher. The median for a dental specialist was $296,640. (To see how much dentists' income increased between 1982 and 2000, see Table 2 in this paper from the March 2005 issue of JADA.)

Hospitals never close, but dentists' offices are often open only four days a week or less. That's mainly because staffing is a dentist's biggest operational cost; the fewer days the office stays open, the less a dentist has to shell out to office personnel. (Of course, dentists do respond to emergency calls. On more than one occasion, my Seattle dentist opened up her office to treat a problem that had cropped up on a day her shop was closed. Needless to say, on those occasions she worked without an assistant.)

Like many small-business operators, dentists often work toward a predefined goal. As Burton Edelstein, the chairman of Columbia University's Department of Social and Behavioral Sciences and the founder of the Children's Dental Health Project, explains, "Everybody—not just dentists—who has control over their income will design their time to reach their target. So long as dentists can reach their target income with ease, there's little incentive for putting in more hours. It's hard work." With a limited number of appointments available and—for many dentists—enough full-fee patients to fill the slots, there's little incentive to serve the low-income people who need them most.

Of course, money isn't everything. Dentists know that few of their patients enjoy seeing them. Indeed, fear of the dentist is so prevalent that there are several competing measures of this anxiety. (The Corah Dental Anxiety Scale and the Kleinknecht Dental Fear Survey seem to be most widely used.) According to a study in the February 1998 JADA, "When the data are extrapolated to the U.S. population, they translate to an approximate 45 million people being very nervous or terrified about visiting the dentist; 23 million avoiding dental care because of fear; and almost 23 million willing to go to the dentist more frequently if general anesthesia and conscious sedation were more readily available."

Improvements in dental technology—faster drills, more effective anesthetics—mean that dental treatment is far less painful than it was just a few decades ago, but there's always at least a little discomfort, usually when the local anesthetic isn't completely effective or wears off before the dentist has finished working. That's where the storytelling arts come in. The best dentists are great monologuists—after all, during most procedures, the patient is in no position to join in the conversation. The Washington Post's Liza Mundy loves her dentist as much for her banter as for her clinical skills: "All during the procedure she riffs and chats—about her boys, her life, her mom, her latest dress. It's a deft and wonderful—and I'm quite sure deliberate—distraction."

Dentists may inspire fear, but they also inspire trust. In 2003, 61 percent of respondents to a CNN/USA Today/Gallup poll said the honesty and ethical standards of dentists were "high" or "very high." Of the 23 professions included in the poll, only nurses, medical doctors, veterinarians, and pharmacists were rated higher. (By way of comparison, journalists scored just 25 percent, lawyers 16 percent, and car salesmen 7 percent.) It may be that patients trust dentists because they lack the means to second-guess them. Although there's enough medical information available online to generate a whole new diagnosis, cyberchondria, there's no dental equivalent of WebMD, MayoClinic.com, or the thousands of disease-specific forums on the Internet. Many of the people I spoke to while researching this series wondered whether the treatments their dentist had recommended were really necessary. In the August 2001 issue of JADA, Dr. Gordon Christensen worried that dentists were harming the profession's image by planning and carrying out excessive treatment, charging high fees without justification, and refusing to accept responsibility when treatment fails prematurely.

Dentists benefit financially from rising expectations. Dental health has improved enormously in the post-fluoride era, but Americans' satisfaction with the way their teeth look has declined. An ADA poll cited by my Slate colleague David Plotz found that during the 1990s, the percentage who were "very satisfied" with their teeth dropped from 57 percent to 46 percent. "Dentists have learned to play on this vanity and anxiety," Plotz wrote, "encouraging dental care that is medically unnecessary but attractive to patients"—cosmetic procedures like teeth-whitening, veneers, and bonding. According to Dr. Christensen, at least 50 percent of the average dentist's income now comes from elective cosmetic procedures.

That, of course, is how capitalism is supposed to work: Patients are willing to pay for the social and professional benefits of an attractive smile, and dentists are more than happy to provide them. Even so, when I asked public health dentists what would most help their profession better serve the broad population, they all answered with variations on the same theme: dial back the obsession with aesthetics. If dentists spent less time giving wealthier Americans artificially whitened grins, they would have more time to treat the serious oral disease that plagues millions of poorer Americans. "What would I do if I could start over?" mused Edelstein. "Part of it would be to dissuade people from making expenditures for intensities of care that are not necessary, that don't affect the state of health."

In the U.S. economy, lots of goods are distributed unequally, but perhaps none more conspicuously than healthy smiles.

Next: Why Poor Folks Are Short on Teeth

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