Donald Richardson said he was given a general anaesthetic by Harry Robertson, who worked at Kelburne Dental Surgery in Paisley, Renfrewshire. However, it has emerged that Mr Robertson, from Glasgow, was not qualified to carry out the procedure.
Mr Richardson, 52, had requested the anaesthetic for root canal treatment and fillings because he has a fear of needles. He said: "Not only will I have to go through a test where I'll have to face a needle, but I now know that this man wasn't even qualified to perform a general anaesthetic on me, which is more worrying.
"This is a complicated procedure even for a qualified anaesthetist, because if you don't get the levels right you can kill someone.
"This dentist put my life at risk by doing it himself and I will pursue him legally as far as I can take it now."
Mr Robertson yesterday declined to comment on the fresh claims.
Mr Richardson has made an official complaint to NHS Greater Glasgow and Clyde.
A spokeswoman said: "We have received an email from Mr Richardson and will respond to him direct."