A father and son pair of millionaire French dentists were sentenced to five and eight years, respectively, for drilling thousands of needless root canals into the teeth of hundreds of patients to enrich themselves.

The court meted out the punishment on Thursday against Lionel Guedj, 41, and his father, Carnot Guedj, 70, who worked with his son part time.

The younger Guedj drilled 3,900 root canals into the perfectly healthy teeth of 327 patients from 2006 to 2012 to rake in more money from social security to pay for the surgery, according to the Guardian. The two also adopted an "industrial" model of dentistry in order to make as much money as possible, working on a huge number of patients in as short a time as possible, making Lionel Guedj the single-highest-earning dental surgeon in France by 2010.

The trial, which ended in April, heard the testimonies of just a few of the hundreds of low-income residents of the city of Marseilles, many of whom were left with permanent damage from the procedures.

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“I have pain 24 hours a day. … My life is on standby," one former patient testified. “You want to crawl into a hole and never come out again, even to work.”

The woman went to the dentist for a minor tooth enamel problem, only to have him pull out 24 of her fully healthy teeth.

Lionel Guedj fitted 28 times more bridges than the average dentist, France's national health service said, according to AFP.

Surgeries that normally take 45 minutes would be finished in 10 minutes without proper safety procedures. Serious infections would result, at which point they would assign patients a large amount of antibiotics, earning even more money. Lionel Guedj made almost $3 million in fees in 2010.

Testimonies from former patients fit into a common theme; the Guedjs' procedures left them with permanent pain and insecurities, with many feeling afraid of going out into public or even opening their mouths. One woman quit her job at a bakery after a constant foul odor began emanating from her mouth from the constant infections. Another man said Lionel Guedj filed his teeth down so much that they looked like those of a mouse.

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The pair were booed by crowds that gathered at the courthouse on their way in, according to AFP. Those boos turned into cheers as the pair were sentenced to a combined 13 years in prison. The sentence will begin immediately regardless of whether they plan to appeal.