James Doundoulakis is a connoisseur of smiles.

“There’s an infinite number of tooth colors – but there are only 20 families of smiles,” the Harvard-trained prosthodontist said, noting that contemporary understanding of the physiology of the smile owes much to a 19th-century French neurologist, Guillaume Duchenne. Using electrical voltage on cadavers, he discovered that 10 of the face’s 100 muscles were involved in producing smiles.

For his efforts, Duchenne was honored by having a smile named after him. The Duchenne Smile is what dentists call a “genuine smile” because its possessor fully employs the zygomaticus muscle that connects the corners of the mouth with the cheekbone.

Is the Duchenne Smile the “perfect smile”?

“That depends on the person’s perception of just what a smile is,” Dr. Doundoulakis said. “Some people like their smiles to be bold and sharp, others want their teeth to display an intense pointy smile.

“Me? I like soft smiles,” Dr. Doundoulakis said.

Although he says that “every dentist should have done to them what they do to others,” Dr. Doundoulakis possesses a “soft smile,” one that owes more to the genes he inherited from his parents, Helias and Areti, both of Greek origin, than to cosmetic dentistry.

In the last two decades that he’s been practicing cosmetic dentistry on Manhattan’s Upper East Side, Dr. Doundoulakis has created smiles of choice for hundreds of CEOs, young people, everyday New Yorkers, and celebrities.

His enterprise has made him into a celebrity himself. His new book, “The Perfect Smile” – written with Warren Strugatch – is in bookstores around the country. In the last few weeks, Dr. Doundoulakis has appeared on a number of radio and television programs, including “The View.” One of the show’s regulars, Barbara Walters, is his patient and a friend.

So is the actress Elizabeth Rohm. So is the chef David Bouley. And George Stephanopoulos, the political activist turned-television performer. The late Telly Savalas, star of the long-running TV series, “Kojak,” was also a patient.

While he’s understandably reticent about disclosing the size of his practice, Dr. Doundoulakis allows that it’s been growing healthily.

The growth reflects the popularity of cosmetic dentistry across America, with at least 10% of the dental industry’s annual take of $200 billion attributed to revenues from specialists such as prosthodontists, who restore, beautify, or replace teeth; endodontists, who deal with difficult root canal treatment; orthodontists, who straighten multiple teeth using braces, among other devices, and oral surgeons, who typically operate on jaws and surgically place dental implants.

Such specialists account for only a fraction of America’s 200,000 dentists, but their individual incomes can match those of the top specialists among the nation’s 811,000 physicians.

And while a majority of dental specialists are in private practice, many of them are also affiliated with both private and public medical centers. There are 6,007 such centers in America, not including government-run hospitals for veterans and military health care facilities.

Dr. Doundoulakis, for example, is currently director of implant prosthetics at Mount Sinai Medical Center. Earlier, he was an assistant clinical professor at the Columbia University School of Dental and Oral Surgery and the New York University of School of Dentistry. He was also an associate editor of the Journal of the American Dental Association.

One advantage of being affiliated with such institutions is that Dr. Doundoulakis has access to the latest in dental technology and research.

“My field is becoming more and more technology-driven,” he said. “We’re in partnership with technology.”

In the foreseeable future, that partnership may produce dramatic developments such as tissue and genetic engineering, or what Dr. Doundoulakis calls “test tube teeth.”

“We may be able to replace real teeth with lab-created real teeth,” he said.

Does that mean he’s unsatisfied with the current state of the art?

“Not at all,” Dr. Doundoulakis said. “We can do so many things in our field at this stage that it’s as good as it gets.”

His field owes a lot to seminal research done in Sweden, Switzerland, and Germany, especially in dental implants, Dr. Doundoulakis said.

He particularly cited the work of Per-Ingvar Branemark, founder of the Branemark Osseointegration Center at the Carlander Medical Center Goteborg on the Swedish west coast.

Professor Branemark, a pioneer of dental implants, coined the term “osseointegration.” During a trip to America in 2003, Professor Branemark hugged Dr. Doundoulakis in front of 4,000 dentists at the Academy of Osseointegration’s world meeting in Boston. Dr. Doundoulakis was the academy’s president at the time. Professor Branemark’s public gesture was widely seen as recognition of Dr. Doundoulakis’s skills.

“It was one of the proudest moments of my life,” Dr. Doundoulakis said.