(FORTUNE Magazine) – Dentists just can't help smiling these days. Although cavities are down sharply, Americans continue to put plenty of money where their mouths are: an estimated $36 billion this year, rising at the rate of $1.6 billion annually. The future looks even whiter. The country's graying population has many more teeth intact than did previous generations. Dentists have done such a good preservation job that only 4% of all adults under 65 will ever wear dentures. That means more teeth to care for. An older clientele has special problems, notably gum disease and root decay. Not that dentists are ignoring the other end of the demographic spectrum. Pediatric dentistry has soared with the baby-boomers' baby boomlet. Practitioners ply their trade in brightly colored offices replete with toys and videogames, to make a child's stay child's play. For the vast population both young and old, cosmetic dentistry is the new come-on. Dentists have popularized innovative procedures like veneering and bonding that cover stains, close gaps, and repair chips. Says Dr. Arthur Dugoni, president of the American Dental Association: ''Bonding allows the patient to become the Mr. or Ms. America of his or her dreams with a beautiful smile.'' By the turn of the century, Dugoni says, cosmetic dentistry could make up 40% of the industry's total take. To cap it all, the job market for dentists looks cheerier than ever. The ratio of dentists to the U.S. population is poised to fall precipitously from < the current 60.2 per 100,000 to 44.8 by 2020, the lowest since World War I. Enrollment at dental schools, down by a third since 1978, has been hit by high tuition and cuts in federal funds. That's bad news for patients, who could soon find themselves waiting four to six weeks for an appointment.