SA-Best leader Nick Xenophon wants health insurers to provide equal rebates no matter which health care provider a patient chooses.
The former senator said big private health funds such as BUPA and Medibank Private were paying almost double the rebate to people who use their contracted dentists.
Mr Xenophon will push for changes to consumer protection laws, should SA-BEST hold the balance of power after the March 17 state election.
He wants private health funds to offer the same rebate for the same type of treatment.
"What is happening now is private health funds are putting the squeeze on family dentists and other health professionals by offering differential rebates," Mr Xenophon told reporters on Friday.
"This sort of predatory, anti-competitive behaviour is destroying the livelihood of independent dentists and other allied health professionals."
The Australian Dental Association said the proposed legislation was "desperately needed", as patients should have the full pick of providers and not be penalised for their choice.
"When private health insurance was introduced one of the main principals was for patients to have a choice of provider," SA branch president Dr Anthony Smerdon said.