John Nicol, 73, owner of Speedy Dentures, known locally as Glamorous Geggies, has made false teeth for other Craiglang characters customers over five decades.
But, he was caught practising as a dentist in March 2015 when a private investigator arranged for a woman to carry out detective work.
Lyndsay Grant, 46, took her mum who had a problem with her plate to see Nicol who suggested he could fix it or give her a new one - for a cost and offered to “impression her up”.
After a trial at Glasgow Sheriff Court, Nicol from Johnstone, was convicted of breaching the Dentist Act 1984 by holding himself out to be a dentist while not registered as a dentist or dental care professional.
Nicol - who was registered with the General Dental Council until 2011 - was fined £1800 for his crime.
He made the decision not to renew his registration when new rules came in that involved going on a £25,000 course abroad, and decided he was experienced enough to continue working.
Nicol made the famous dentures worn by Still Game’s Methadone Mick, a recovering drug addict who gets new teeth before a job interview.
And, the iconic teeth worn by Bob and Alan, electrical salesman in hit show Chewing the Fat.
Glaswegian band Belle and Sebastian also filmed part of their music video for Come on Sister at his shop.
Speaking outside court Nicol said: “It’s unfair. It’s a private transaction between people who choose to come to me because they’ve had terrible treatment from dentists.
“I don’t advertise as being a dentist and some dentists even refer people to me. I have customers from all over the world and have had repeat business from people since 1973.
“It’s a medal I should be getting.”
In evidence Mrs Grant said she was to find out if dentistry work was taking place on the premises and “if there was any fingers being inserted in to the mouth - wet work”.
She made the appointment and arrived at the Dumbarton Road shop in Partick where Nicol spoke to them and the pensioner explained her problem of a rubbing plate.
Procurator fiscal depute Mhairi Alexander asked: “What did he say?”
Mrs Grant said: “That he could assist her and I believe he gave two prices. One to make a new plate and one to make amendments to the current one.”
Miss Alexander asked what the witness’ impression of Nicole was and she said: “He was there to assist what problem my mother had and advise what he could.
“Mr Nicol was very chatty, very confident, made my mum feel at ease and seemed knowledgeable in what he was talking about.”
Mrs Grant said Nicol claimed he could help her mum with the problem and either make her a new plate or fix hers.
She added: “He was keen to, in his words ‘impression her up’.”
Mrs Grant said she expected it would happen “there and then” and he went away to do what she thought was prepare to make impressions.
But before any “wet work” could take place, the women made their excuses and left claiming they would make another appointment.
Asked what she could see in the shop she said: “I could see through the back that there was moulds and various bits of equipment there.”
Defence lawyer Gillian Barsanti argued that there was an “absence of vital evidence” and that the prosecution hadn’t successfully proved that Nicol was carrying out all of the work that amounted to being a dentist.
But, sheriff Barry Divers convicted the pensioner of the charge against him.