From behind a door comes the whine of a highspeed drill. When my name is called, I am ushered into an examining room and welcomed with a nutcracker handshake by the dentist, a graying at the temples man.

Soon I am staring toward the white cork ceiling while my teeth are probed, poked, tapped, and tugged. The numbers of my teeth are called out to an assistant, who jots the information on a chart: “No. 11, crown; No. 13, MOD; No. 14, MO… ” A few minutes later comes the verdict: I need 11 crowns, plus other work. It will cost $8,347.

“Do this and you will have no worries about your teeth for the next 30 years, ” the dentist purrs. Somehow I doubt that. Then he adds, “You and I are going to become great friends.”

Somehow I doubt that too. I was there in Dayton, Ohio, as part of an assessment of the consistency and fairness of American dentistry. Since Americans spend about $42 billion a year on their teeth, it seemed like a reasonable assignment: visit 50 dentists, show them your teeth and a set of X-rays, and ask each what needs to be done.

Four months, 50,000 miles, and 50 exams later, I concluded that going to the dentist is nothing to smile about. Dentistry is a stunningly inexact science. Even expecting that different dentists would have different, yet valid, opinions did not prepare me for the astounding variation in diagnoses I received. Some wanted only $500 to bring me up to good dental health. Others wanted ten, 20, even 50 times that amount. Surely they could not all be right.

I randomly selected the dentists from the Yellow Pages in 28 states and the District of Columbia. At each of the offices, I told the same story: I was moving to the area and wanted to become a patient; I had recently come through successful gum surgery; my dental expenses were covered through a direct reimbursement program with my employer; I was interested in maintaining good oral health and was satisfied with the appearance of my teeth. Because I said I was in a direct reimbursement program, I got a written treatment plan and a cost estimate from each dentist.

Before embarking on my journey, I went to the Lebanon  Pa., office of Warren Daugherty my personal dentist for the past 15 years, and a man I trust. “You look really good,” he said after examining me and my X-rays, “but I want to put a crown on No. 30. ”

“Roughly how much money are we talking about?” I asked.

“Under $500. ”

I asked several other dentists, who had no financial interest in my teeth, to assess their condition so that I would have a basis for comparison with what I found on the road. Joining Daugherty on my panel were Dr. John Mayes of Hershey, Pa., a fellow of the Academy of General Dentistry, who took the X rays; Dr. John Dodes of Woodhaven, N.Y., a practicing dentist and the dental expert for the National Council Against Health Fraud; and Dr. Alvin Morris of Pawley’s Island, S. C., the former dean of the University of Kentucky’s College of Dentistry and recipient of the Distinguished Service Award from the American Dental Association in 1985.

All agreed that my oral health was good and I had only one immediate problem, the No. 30 tooth, a molar that needed a cap or a filling. Each panelist said there was room for disagreement on tooth No. 18, but that the total should not exceed $1,500 if two crowns were recommended.

I began my odyssey in Madison, Wis., where my grave-faced examiner informed me that I needed five teeth crowned, including No. 30, plus additional work. The estimated cost was $3,110.

The next day I visited Davenport, Iowa, where the verdict was the same: five