In 2007, Americans spent $95.2 billion on dental care, or $315 per capita. That represents only 4.3 percent of the $2.2 trillion ($7,421 per capita) spent on health care overall. It's no wonder, then, that dentistry and dental costs tend to be overlooked when policymakers crunch numbers.

Still, most middle-class Americans—even those with health and dental insurance—tend to be more aware of the price of dental treatment because they're more likely to have to pull out their checkbooks when they visit the dentist. Although dental-insurance premiums remained relatively steady over the last decade, especially when compared with skyrocketing medical-insurance premiums, between 1998 and 2008 the increase in the cost of dental services exceeded that of medical care and far exceeded the overall rate of inflation. (The 30-year trend shows medical-care prices rising slightly more than dental prices. The chart below shows the overall consumer price index compared with the dental and medical indexes.) * And although spending on dental services is less than 4.5 percent of health care expenditures, a greater percentage comes out of patients' pockets. Whereas only 10.3 percent of physician costs, 3.3 percent of hospital care, and 26.8 percent of nursing-care expenses were paid out-of-pocket in 2007, Americans paid 44.2 percent of dental bills themselves. (See Table 2 of "Dentistry in Time of Recession" in the March 2009 issue of the New York State Dental Journal.)

This is mostly due to the nature of the coverage. When designing benefits packages, private employers and the federal government put a low priority on dental coverage, especially since the cost of providing medical insurance has exploded. For employees, this means "cost sharing"— high copayments even for people with "good" insurance plans. About 10 percent of private dental coverage isn't insurance at all, but, rather, a "discount plan" more analogous to shopping at Costco. Patients pay a membership fee, and when they go to a participating dentist they pay at a discounted rate. (Even the other 90 percent, some argue, doesn't fit the standard definition of insurance.) For low-income Americans enrolled in Medicaid, dental fees are set so low that many dentists won't treat them. Medicare, as I noted earlier, doesn't cover dental care except under a few unusual circumstances.

In her book Making the American Mouth, Alyssa Picard argues that the postwar orthodontics boom helped the upper middle class get in the habit of paying high out-of-pocket fees to care for its teeth. Ironically, this practice grew out of dentists' unfounded worry that their profession would go the way of the blacksmith as fluoridation reduced kids' immediate need for extractions and fillings. During the 1950s, the American Dental Association ran an advertising campaign to encourage orthodontic treatment. Gradually, paying for braces became an expected investment, part of the price of raising children, like test prep and college fees. Even now, dental plans rarely cover orthodontia, and the lifetime reimbursement limit is much less than the cost of braces, but parents feel pressured to buy their kids the straight, white smile that is the clearest physical indication of prosperity.

Despite its many limitations, it's better to have dental coverage than to be without it. The National Association of Dental Plans found that the 152 million Americans who had dental insurance in 2007 were 49 percent more likely to have visited the dentist for a checkup or cleaning in the previous six months and 42 percent more likely to take their children to the dentist twice a year.

As with medical insurance, Americans currently rely on their employers to provide dental coverage: 97 percent of people with private dental benefits receive them through work. Of that group, employers cover at least part of the premiums or fees for 70 percent of beneficiaries (pretty much all companies that offer medical insurance contribute to the cost of premiums). Twenty-two percent of employers offering dental plans cover the full cost of premiums. It's much easier to find individual dental insurance than individual medical insurance, but most people choose to skip it because long waiting periods and high copays make it hard to justify the expense.

A key difference between medicine and dentistry is the degree of control a patient has about whether, how, and when to treat a dental problem. When my dentist diagnosed internal resorption as the cause of the symptoms I described at the beginning of this series, he presented the treatment options in a way that made it clear he understood my decision would be based on what I could afford and/or wished to pay. In declining order of expense, the choices were implant, bridge, or gaping hole. (In real life that last option was never explicitly mentioned.) It's hard to imagine a physician offering such a range of choices. But the reality that dental problems, even serious ones, usually don't represent health emergencies demanding a specific, immediate remedy has its drawbacks, too. Chief among these is that it encourages patients to create a false mental separation between the mouth and the rest of the body. People are much more likely to leave a dental problem untreated than they are to ignore a medical issue. At least two of my friends are currently postponing root canals for financial reasons; I doubt either of them would request a delay if a physician told them they needed an operation. Of course, if they had medical insurance, doctor's orders would usually mean the cost of the operation would be covered.

Delaying dental treatment doesn't make a problem go away. Quite the opposite. As Dr. Albert Guay, the American Dental Association's chief policy adviser, put it, dental caries and periodontal disease are "chronic, progressive and destructive, and they become more severe over time." When patients eventually do seek care, the costs are generally higher than they would have been if they'd headed to the dentist's office at the first twinge of pain. That explains why dental plans usually offer complete reimbursement of cleanings and checkups.

The medical profession has struggled to replicate dentistry's achievements in disease prevention with its "health maintenance" model. Dentists, by emphasizing preventive measures—like biannual checkups and cleanings, fluoridation of community water supplies, the use of fluoride toothpaste, and encouraging patients to eat less sugar and processed foods—have reduced overall treatment costs as well as pain and suffering to a degree medical doctors can only dream of. They have done so in part through a structure of dental benefits that is far more punitive to those patients who slack off on prevention, or for whom prevention fails, than anything health insurers typically contemplate.

Contrary to the usual practice in health insurance, dental reimbursement levels tend to decrease as the level of complication (and expense) increases, and they're usually capped at around $1,200-$1,500 per year. This is not only to control costs but also to give the patient the strongest possible financial incentive to brush, floss, visit the dentist regularly, and eat sensibly.

It makes sense to me that affluent Americans are motivated to take good care of their teeth because they want to maintain the investment they (or their parents) have made in their mouths. And according to Evelyn Ireland, executive director of the NADP, fewer than 5 percent of people with dental coverage hit their annual maximum. That's the good news. The bad news is that if you're one of those 5 percent, you're going to pay, so to speak, through the mouth. It's financially brutal to be an oral have-not in America.

Next: How Dentists Think

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Correction, Sept. 30, 2009:  This piece originally used an inaccurate description of the chart. It shows the overall consumer price index compared to the dental and medical indexes, not inflation rates. We have also corrected the title of the chart. (Return to the corrected sentence.)