Fuming about a billing dispute with his dentist, Robert Allen Lee posted his complaints on two consumer review Web sites, triggering a legal battle over a technique designed to snuff out negative online commentary.

In late August, a day after Lee posted his comments on Yelp and DoctorBase, he received a letter from the dental practice threatening to sue him for at least $100,000 for “defamation, slander and libel.” The letter reminded him that he’d signed an agreement with his dentist that barred him from publishing a critique of her or her office.

While extreme, such do-not-talk contracts underscore the struggle between consumers that are eager to share their thoughts online and companies that are looking for ways to protect their reputations in an environment in which social media helps shape opinions on just about everything.

In the political sphere, social media helped fuel the demonstrations of the Arab Spring. Everywhere else, online chatter informs our decisions on which hotel to book, what to read, which plumber to hire, where to eat — even who to date.

But rating doctors is another matter. While 80 percent of adults say they use the Internet to search for health information, only 16 percent use it to look for reviews of doctors and far fewer post such reviews, according to a Pew Research Center survey.

Consumers spend more time shopping for a refrigerator or car than they do for a health-care plan or doctor, according to a survey by the Altarum Institute, a nonprofit health systems research and consulting group. Although 60 percent of the respondents said they engaged in detailed research when car shopping, fewer than one in three devoted much time to vetting a doctor.

“There’s a case to be made that the average consumer has a good basis for judging if a meal is tasty or the plumber fixed the leak,” said James B. Speta, an Internet policy professor at Northwestern University School of Law. “But medical services are specialized. When you start talking about whether the treatment was the correct one, it’s highly technical. . . . One can ask: ‘What is the value of the consumer input?’ ”

That’s what consumers and the medical community are trying to figure out.

Michael Fertik said doctors are the fastest-growing client group at his company, Reputation.com, which helps its customers investigate their online reputations and suppress negative comments. Fertik said his firm does not remove reviews. But it provides doctors with tools to solicit and post comments from real patients — as opposed to a disgruntled former employee or ex-spouse who has an ax to grind.

“When you talk to doctors, they totally understand that they’re going to be discussed. They get it,” Fertik said. “They just want a fair shake. The deck is stacked against them because people tend to review stuff when they’re unhappy.” Maybe that doesn’t hold true for movies or hotels, he said. “But nobody says: ‘Oh my God, I have the greatest accountant in the world.’”

‘Gag orders’

The type of agreement Lee signed had become widespread enough that RateMDs.com posted a “Wall of Shame” on its site outing doctors who use “gag orders” to squelch online commentary. Angie’s List alerts its users about doctors who use these forms by posting a notice on a doctor’s profile. And Yelp said it notifies consumers and refers them to legal resources when a doctor demands that a review be taken down.

Consumer advocates say such agreements could not withstand a legal challenge. Still, they fear that the tactic or similar ones will intimidate consumers and undermine the free-flowing exchange of information on consumer review Web sites.

“It threatens to starve patients of the ability to get the information they need to know to make smart choices,” said Eric Goldman, a professor at Santa Clara University School of Law who has a Web site devoted to these types of contracts. “It’s a hack on the system.”

For Lee, the trouble began with an aching tooth while he was living in New York late last year.

Before treating him, the dental office handed him papers to sign, including an agreement that prohibited him from publishing his views of the dentist online or elsewhere. In exchange, the dentist agreed not to market Lee’s patient information to third parties.

“That struck me as strange,” said Lee, who now lives in Calvert County. But he signed, forgot about it and paid $4,766 to have an infection drained and his tooth filled, he said. About nine months later, frustrated by the runaround he got when he tried to file an insurance claim, Lee unloaded his grievances about the dentist online.

“Avoid at all cost! Scamming their customers!” Lee’s posting said. “Overcharged me by about $4,000 for what should have been only a couple hundred dollar procedure. Refuses to submit the claim to my insurance company. When asked for records to submit the claim myself they referred me to a 3rd party that wants 5 percent of the bill ($268) to get the records of me.”

A day later, Lee received the first letter reminding him of the agreement.

Legal battle ensues

The consumer advocacy group Public Citizen filed a class-action lawsuit in November against the dental practice and the dentist, Stacy Makhnevich. With Lee as the lead plaintiff, the lawsuit challenges the methods used to repress Lee’s complaints.

David Schwartz, Makhnevich’s lawyer, said his client denies all allegations and stands by the contract. He declined to discuss specifics because of patient confidentiality laws.

“We stand by any or all actions taken by Dr. Makhnevich as of this date, including the document,” Schwartz said.

Paul Alan Levy, one of Lee’s lawyers, said the contract Lee signed came from Medical Justice, a firm that specializes in services and contracts designed to protect doctors and dentists against frivolous lawsuits. The Greensboro, N.C., firm is not named in the lawsuit, but a separate group, the Center for Democracy and Technology, filed a complaint around the same time asking the FTC to investigate what it describes as the firm’s deceptive marketing practices.

Jeffrey Segal, founder of Medical Justice, said that his firm has since abandoned the contracts because it has moved onto “the next natural point of evolution.” The rating sites have become more balanced, he said. Now, the firm is focused on “getting real reviews from confirmed patients,” he said, “and let the chips fall where they may.”

Segal, a neurosurgeon, said his firm started offering the contracts in 2007 when the rating sites were relatively new. Several health-care providers his firm works with (of about 3,500 in all) were complaining that they were unfairly targeted in anonymous postings that they could not publicly challenge because of federal and state privacy laws.

Federal law protects Web sites from liability for the reviews its users publish. But the law carves out exceptions for intellectual property rights, including copyright. So Medical Justice’s contract assigned copyright in a patient review to the doctor, enabling the doctor to claim copyright infringement and demand that a Web site remove the comments.

Does Segal regret having used the tactic? “I do not. Maybe, in hindsight, we would have retired them a little sooner. But we don’t regret having been the grain of sand in the mouth of the oyster to try and make a pearl out of the rating sites,” he said. “Even in 2012, we’re not there, yet. We’ll know we’re there when doctors and nurses use these sites to pick their doctor.”

Goldman, the Santa Clara professor and former general counsel of review site Epinions, said he’s contacted roughly a dozen Web sites that publish patient reviews and all of them said that if a doctor sent a “take-down” notice based on copyright issues, they would not honor it.

Yelp said it did not honor the request from Lee’s dentist to take down his notice. “If we are contacted by a doctor or dentist with a take-down notice based on a contract restricting the patient’s right to free speech, we will not honor the request (and will inform them of that),” Chantelle Karl, a Yelp spokesperson, said in an e-mail.

John Swapceinski, co-founder of RateMDs.com, said these contracts are nothing more than a “bully tactic.” His company has not honored such notices and yet no doctor pushed back and took the company to court.

Goldman said Medical Justice’s reasoning that doctors are defenseless is misleading. Doctors can respond in ways that are not specific to the patient, he said. They can also ask the patient for permission to discuss specifics. And if information is defamatory, they can take the patient to court.

Many fears ‘unwarranted’

Many fears raised by the medical community are unwarranted, said Tara Lagu, a doctor and research scientist at Baystate Medical Center, affiliated with Tufts University School of Medicine.

In 2009, Lagu and her colleagues scoured 33 consumer rating sites to examine the comments made about 300 doctors and specialists in the Boston region, a technology-savvy area with plenty of doctors. They found that 88 percent of the comments were positive.

The findings, published in the Journal of General Internal Medicine, also debunked concerns that patients would write about medical problems, thereby preventing doctors from responding because of privacy laws. Very few commented on specific aspects of their care, Lagu said. Instead, they focused on parking, wait times and other topics that the doctor could respond to, though doing so could be time-consuming, she said.

In addition, the reviews were scarce. Of the 300 doctors sampled, there were reviews for only 30 percent. And only 60 of the reviews had narrative comments, she said. In contrast, a search of restaurants in Boston’s Beacon Hill neighborhood, where several of the doctors’ offices were located, pulled up 38 narrative reviews for a single Lebanese restaurant on six sites.

As for the phony patients, Lagu said her team did not detect any. In fact, they suspected the opposite was taking place. Some reviews were “qualitatively different,” with detailed information that the patient would not typically know, suggesting that they may have been written by the doctor, Lagu said.

A few doctors, the study said, have admitted to posting reviews about themselves, including this posting from a doctor on one popular site: “Every anonymous review I’ve written on myself has been glowing.”