A receptionist who posed as a dentist was fined R5000 (or one year in jail) by the Bloemfontein District Court on Monday, the Hawks said.
Elmarie Harms (23) was also sentenced to 20 months' imprisonment, suspended for five years, spokesperson McIntosh Polela said.
The Hawks investigated when it was reported in August that Harms was conducting an after-hours dental practice from her house. She was found to have a fraudulent qualification from the University of Pretoria.
"She was caught in the act while checking the teeth of one of our undercover investigators who pretended to be a patient in December."
Officials found medication and dental apparatus in one of her rooms.
"We are not entirely certain how many patients she dealt with since she started her bogus practice," Polela said.