There is a conflict of interest in health care. Providers want to make money selling services, the more the better. Patients want to buy what is necessary, but not more than they need. And while dedication to the patient's interest is supposed to be the rule for health-care providers, we are human. The line between serving patients and serving self-interest is frequently crossed.

We most often think of this in medical care, but I am a dentist, and dentistry also provides examples. I worked in one office where the managing dentist did the exams and other dentists did the work he prescribed. "Corporate" had been berating him for low production at this office. So in walked a woman who had had only two small fillings in her 20-some years, expecting just another cleaning. She ended up in my chair thoroughly flustered, because the managing dentist had diagnosed a need for 12 fillings. Fifteen hundred dollars.

She was upset, but never thought to question this sudden onslaught of cavities. When I checked before doing any drilling, I found solid tooth structure in all but two of the supposed problem spots. The managing dentist had diagnosed tea stain as decay. We dentists identify that kind of decay by probing with a little pick, not visually, and this is so basic that it could not have been a mistake. The managing dentist was trying to generate more money.

I crossed off 10 of the planned fillings, did the two tiny ones, and sent her on her way. She was angry and gave the managing dentist a piece of her mind on the way out. I was let go the next day.

Such practices are common because they serve the business interest and the self-interest of the health-care provider, corporate or individual. The extra work associated with a deep cleaning may not be truly justified. A judgment call for crowns rather than fillings may be overzealous. Or perhaps the patient is on low-level maintenance with an older dentist when he retires and the new dentist suddenly discovers a pressing need for lots of treatment. What has changed? The new dentist has to make big loan payments for the purchase of the practice.

A provider has great power when he or she makes recommendations because the patient is not knowledgeable, and in that power there is potential for abuse. The cure is to make the patient knowledgeable. A second opinion can do that, but to be properly impartial, that consulting doctor or dentist should not make money by selling the treatment that he or she diagnoses. We must remove the potential for financial bias.

Knowledge is power. Give patients that power and their consumer skills will come into play. An individual consumer's skill can reduce costs and reform services throughout health care in ways that government and insurance companies cannot.

Ken Hajek, a dentist who runs a diagnostic practice called Straight Talk Dental in Carmichael, Calif., is the author of "The Patient is a Pigeon.”