NHS dental care information needs greater attention, Medicash has advised.
Half a million patients a year have unnecessarily paid to receive private dental treatment, according to the OFT, following incomplete information from dentists about entitlements.
It has been suggested by some that dentists have deliberately mislead patients to cash in on private care costs.
Sue Weir, chief executive of Medicash, said: "The findings by the OFT are troubling. In this difficult economic climate where household budgets and disposable incomes are tighter than ever, people are more concerned about the bill than the drill, so putting structures in place to ensure they get accurate information is crucial."
The OFT has called for major changes to the UK dentistry market in the UK, stating that some restrictions were unjustified.