Ronnie Barogiannis pled guilty to working without General Dental Council (GDC) registration at the Bridge of Don Dental Clinic and Research Centre, Aberdeen, after police were called in to investigate staffing arrangements.
The police probe was launched at around the same time that NHS Grampian said they were contacting 900 patients of the surgery to warn them of a risk of blood borne infections given hygiene concerns raised during an inspection.
NHS Grampian said last night they were not aware of any patients who had come forward with any problems after the alert.
Mr Barogiannis has vowed to rebuild his career after being fined £500 for failing to have the correct legal documentation in place.
He said he had applied to the GDC for his registration documents in advance of relocating to Aberdeen from his home country of Greece, but that he stepped in to help out in the early days of the surgery's opening before receiving his papers.
Mr Barogiannis has now not worked as a dentist for more than two years given the prosecution, the dentist said.
Mr Barogiannis, 40, said: "This whole thing has been terrible. I made a stupid mistake and it has been a very difficult experience for me. I will have to start my career all over again.
"I am sorry about what has happened. I haven't worked as a dentist in more than two years but I made a mistake and it was wrong. You have to pay for your mistakes and then hopefully I can move on."
Mr Barogiannis, who said he qualified at Malmo University in Sweden, said he had been answering calls at reception since the case was brought to light.
He said: "I have been sitting here in civilian clothes, just so no one can mistake me as a dentist."
He pled guilty to practising illegally between January 3 and March 5 last year, although later claimed he had worked only for a single day without the necessary paperwork.
The dentist said he had paid around £600 to the General Dental Council in October 2011 while still living in Greece and in preparation of his move to Scotland.
A spokesman for the GDC said that Mr Barogiannis had made "two or three" applications since June 2011 but that they had been incomplete. The dentist said he would reapply for registration in the near future.
An NHS Grampian spokeswoman added: "Dr Barogiannis has never applied to be included in the Dental List of NHS Grampian in order to provide treatment under NHS regulations. Significant documentary evidence is required for such an application. The most basic of these is to be registered with the General Dental Council. "
A spokesman for the GDC said: "By law all dentists, dental nurses, dental technicians, clinical dental technicians, dental hygienists, dental therapists and orthodontic therapists must be registered with the GDC to work in the UK. This is to ensure only appropriately qualified and skilled dental professionals are part of the dental team looking after patients."