A 22-year-old fake dentist and two assistants have been charged by Czech police after treating dozens of patients using instructions found on the internet.

Police said the three family members opened a surgery without a licence in their home in Havlickuv Brod two years ago and treated patients without any “necessary professional knowledge”.

They added that the 22-year-old man extracted teeth, performed complex root canals and applied anaesthesia, drawing on information he had obtained online.

All pleaded guilty to a number of charges, police said, and face up to eight years in prison. Police did not say whether any of their patients had complained about their treatment.

A 50-year-old woman worked as a nurse, while a 44-year-old man produced prosthetic devices for patients.

The illegal clinic treated dozens of patients and made four million Czech koruna (£137,827, $185,500), police said.

“The woman, who worked in the health sector, provided anaesthetics but also other dental material to which she had access, such as fillings, cleaning powder, glue, impression material and much more,” police said in a statement.

“A 22-year-old man posed as a dentist, although he lacked the necessary professional knowledge.”

Police spokeswoman Michaela Lebrova declined to comment on whether the force was acting on complaints from patients.

All three were arrested earlier this month, before being charged this week with operating an illegal business, money laundering, attempted assault, drug dealing and theft. All have pleaded guilty, police said.

The president of Czech dental chamber, Roman Šmucler, said that he had an average of 10 fake dentist cases reported a year in the country.

“I have two more submissions today, so today there are three cases in the Czech Republic,” Šmucler told Czech media outlet Radiožurnál.

The Czech parliament last year passed a bill facilitating the employment of dentists from countries outside the EU.