Dr Koos Marais said he had been battling to obtain the product Scandonest 3%, a local anaesthetic without vasoconstrictors (a drug that causes narrowing of a blood vessel).
"I have only two weeks' supply left and suppliers say they can't get hold of it."
He said the shortage would force dentists to use other local drugs containing vasoconstrictors that posed a higher risk for weaker and older patients.
"Patients might experience palpitations, anxiety or fainting. In some cases it could have serious consequences such as heart attacks and cardiac arrest."
No alternative available
Marais reportedly said there was no good alternative available on the South African market.
"Many dentists will be afraid to speak up because they might frighten patients, but people's lives are at stake, there is no room for compromise," he was quoted as saying.
A spokesperson for importer and distributor Dental Warehouse, said current stock had been quarantined in their warehouse because the product had to be tested.
The manufacturer had changed the source from where the active ingredient was obtained. Tests had to be conducted to see if this product was of the same quality as previous stock.