New Zealand is being urged to follow the European Union (EU) and ban the use of amalgam fillings for children and pregnant or breast-feeding women.
Amalgam is a mixture of metals including silver, copper and tin, to which mercury is added.
The EU is to ban the use of amalgam fillings in children and pregnant or breast-feeding women from July this year.
The EU's move is part of the Minamata Convention on Mercury - a global treaty to phase out the use of mercury - due to its toxicity.
Auckland-based dentist Hisham Abdalla said it was now time for New Zealand to follow the EU's example.
Dr Abdalla said concerns about amalgam mercury fillings were not new and ending its use needed to be seriously considered by the government.
He said it was strange that the ban on amalgam fillings was the last part of the wider phasing-out of mercury, when it was the most directly in contact with the human body and there were very strict guidelines for disposing of amalgam fillings.
"It is toxic and we're told to put it in. Why is it toxic when it is outside the mouth, or goes into the waterways or the fish or whatever, but when we put it inside the mouth it is safe?"
Dr Abdalla said New Zealand was way behind other countries in acting on mercury reduction.
He wanted to see the government funding the safer - but more expensive - alternatives to amalgam.
He said phasing out amalgam fillings in children, whose dental care was already funded, would be a great place to start as the longer you have the mercury in your mouth, the longer you have the risk.
However, the Ministry of Health said there was no scientific evidence that the fitting or removal of amalgam fillings during pregnancy or as a child was harmful.
It did say pregnant women should avoid elective dental procedures where possible.
"The Ministry supports the continued use of amalgam fillings as one of the options for the treatment of tooth decay," the ministry said in a statement, also pointing to its policy on amalgam.
In a statement, the NZ dental Association said it "affirmed the safety of dental amalgam as a filling material".
"Dental amalgam is a safe and durable material that has been used by dentists to restore teeth for well over 100 years."
However the NZDA said it did support continued research into the safety of all dental materials, including amalgam.