Orthodontist Melvyn Megitt, from Sale, Greater Manchester, was nicknamed "Superdentist" and is believed to have been the highest-paid dental surgeon on the NHS payroll in 1994-95 because of his caseload.
The hearing was told his patients were often left unattended - he allegedly ignored a boy who collapsed in his waiting room - and others were said to have sufferedyears of pain through unnecessary dental work.
Eight allegations have been made against Mr Megitt - who did not attend the professional conduct committee hearing of the General Dental Council - including "failing to exercise a proper degree of skill and attention" and claiming NHS fees for treatment not provided.
Mr Megitt ran surgeries in Altrincham, Oldham, Sale and Salford until he ceased work after an investigation by the Dental Practice Board.
Solicitors acting for former patients - most of them children or young people - said that they were seeking compensation for the work Mr Megitt carried out.
Ann Alexander, for the council, said one of Mr Megitt's former patients, Rachel Grice, now 18, had undergone years of painful treatment and wore a brace for five years, from the age of 10. "It was only when she saw another dentist that she was told she need only have worn a brace for 18 months to two years," Miss Alexander said. "It shows a pattern of treatment over a much longer period of time than was necessary. This child had years more suffering than was necessary.
"In another case, the orthodontist removed two permanent teeth from a girl of around the same age and failed to appreciate that she had some teeth already absent. He then continued treatment with a brace for a much longer period than was needed."
Miss Alexander said that she was preparing compensation claims on behalf of six former patients and was being contacted by others. The total number of claims could run into "scores", she said.
The hearing was told how Mr Megitt earned pounds 600,000 in one year compared with an average of pounds 80,000 for other dental practitioners. The Dental Practice Board inquiry found that in 1995 he was provided with 1,058 dental appliances, such as braces. He then claimed for 6,466 repairs - an average of six repairs per appliance. This was 10 times the average of claims by others in the profession and more than twice as high as any other dentist.
Mr Megitt had "an abnormally high patient load", the hearing was told, with between 100 and 150 patients a day. He would take most of their records home at night to update them - "a totally impossible task" in the circumstances, said Tim Preston, for the General Dental Council. He said the orthodontist treated up to 1,500 cases a year, making him one of the highest earners in general dentistry. In some cases, work carried out on children at too young an age had gone on unnecessarily for a decade with no satisfactory outcome.
Mr Preston said Mr Megitt was said to have "expressed no concern for or interest in that patient's condition".
Mr Megitt's solicitor, Christina Lambert, unsuccessfully applied for the charges against her client to be kept private. She said he is now suffering from psychiatric problems.
The hearing resumes today, when a decision is expected.Reuse content