The dental board called it "unprofessional". Patients called it excruciating after a dentist allowed her boyfriend, who had no dental training, to work on more than 600 of them. The General Dental Council this week struck off Mogjan Azari, 39, who was the principal dentist at two practices in south London, for "dishonest" conduct "contrary to the best interests of patients".

Azari allowed Omid Amidi-Mazaheri to carry out procedures including drilling cavities without anaesthetic, which frequently left patients in agony. He gave them fillings that crumbled in days, and may have put them at risk of blood infections such as HIV and hepatitis A and B.

The pair also defrauded the National Health Service of about £30,000 for work that was never done. In March last year Amidi-Mazahari was jailed for two years after pleading guilty to several counts of obtaining money by deception, and Azari was jailed for 12 months on the same charges.

In its determination, handed down on Monday, the dental council said Azari, a Swedish-Iranian, ignored repeated requests from Croydon primary care trust to prove her 42-year-old Iranian lover was registered as a dentist. In January 2003 Azari assured her local practice manager that Amidi-Mazaheri would no longer be allowed to wield the drill at her practice, but she still permitted him to carry on working there.

During the court hearing of deception charges against Amidi-Mazaheri, patients said he carried out complex treatments using drills, probes and syringes, despite having no medical training. One patient told the court Amidi-Mazaheri had dropped a piece of dental equipment down his throat while administering an injection. Amidi-Mazaheri, who stole the identity of a dead dentist to carry out his deceptions, told the court that he had been a dentist in Iran, but Judge Paul Dodgson said he thought this unlikely.

The dental council barred Azari from working as a dentist in the UK again.