Environmental concerns - rather than health worries - are mainly behind one DHB's move to phase out the use of amalgam fillings.
The European Union is to ban the use of amalgam fillings in children and pregnant or breast-feeding women from July this year and a local dentist told RNZ last week that New Zealand needed to follow suit.
Some district health boards are already taking steps to eliminate it, or are using very little of it.
The Waikato District Health Board has recently gone amalgam free, and principal dental officer Rob Aitken told Summer Report it had been in the pipeline since 2016, but it was not mainly because of the perceived health risk.
"It's more to do with the environmental damage, because mercury is a cumulative poison and it builds up in the environment, so this is something that across the world DHBs and health professionals are moving to eliminate."
He said amalgam should "definitely" be phased out for this reason, even though it was durable and outlasted almost all other filling material.
Dr Aitken said amalgam became an environmental problem when it was accidentally spilled, or when mercury vapour was released into the environment when people were cremated.
"I have a foolish suggestion I should tattoo across my forehead 'potential biohazard' as I age."