An emergency doctor says he sees a steady stream of people unable to afford dental care who turn up to hospital with complications like abscesses and fevers - some cases of which resulted in deaths.
The Green Party is promising free dental care for everyone, funded through a wealth tax.
Currently anyone aged over 18 years old pays for dental care.
Whangārei emergency medicine specialist Gary Payinda told Checkpoint it was expensive treating preventable dental problems, some that resulted in sepsis.
"We get a steady stream of people who are unable to afford dental care in the community and end up presenting to the emergency department basically when they can no longer tolerate it, when they have dental abscesses or fevers or sometimes even worse, where it's gone in their blood stream and they need surgical management."
Dental care on average cost about $350 on average a visit, Payinda said.
It was not just the very poorest in society struggling to pay for dental care, but a problem for millions of New Zealanders, he said.
"It is the bottom 40 percent of New Zealand that has trouble affording dental care that literally put off... dental care in the past year because they could not afford it.
"They may come in with a need for minor care, due to pain, or the need for a procedure to remove an abcess that's eroded through their facial bones or as I said, gotten into their brain or their bloodstream.
"So there's some really tragic cases, even some deaths."
"One of the worst aspects of it is it's virtually all preventable" - Whangārei emergency medicine specialist Gary Payinda
It was "incredibly expensive" to treat them like this, Payinda said. Every case resulting in a need for general anaesthetic came with a cost in excess of $4000, he said.
"There's a steady stream of these patients" and every age group was affected, he said.
"We know that dental decay is responsibly for worsening a host of conditions, everything from cancers to heart attacks and we know that simply it's a common cause of sepsis where the infection has gotten so out of control it's in your bloodstream and you need to be hospitalised.
"One of the worst aspects of it is it's virtually all preventable, if these patients had had access to preventive dental care, they wouldn't be in this situation."
Payinda said he would like dental care made free.
"If we think it's important to have a population that is healthy, not suffering, that is not missing work due to dental problems, if we want to have a functioning society we need to take care of people and one of the ways we can do that is providing low cost, public, subsidised dental care.
"I don't know why we think teeth can be ignored if we're willing to provide care for the rest of the patient, it should really be no different and it's certainly something we can afford.
"We're kidding ourselves if we think it's unaffordable because in the long run the cost to society, to the healthcare system and to productivity, is enormous."
'I accept there's unmet need in the present settings' - Health Minister
Health Minister Ayesha Verrall said she had seen in her own practice as a healthcare professional that people sometimes forwent dental care they needed because of cost.
She was aware it was an issue across the country, she said at Monday's post Cabinet press conference.
"I accept there's unmet need in the present settings but I think we've addressed an important component of that through the emergency dental grants.
"I think all of these issues come down to a matter of setting priorities."
It was not just a question of how much free dental care might cost but having the capacity to deliver that, she said.
"I think at the moment the system wouldn't have the capacity to be able to deliver it - and there would likely be significant investment required just in order to build capacity to meet the need for additional free dental care."
The Green Party proposal was "somewhat simplistic" and there would be a lot more to it than the party had set out, she said.