Kiwi kids are missing out on their free dental check ups.

Ministry of Health figures reveal more than 118,000 kids under the age of 18 are behind on their dental check ups - 20,000 more than last year.

It comes as dentists say they're sick of treating third world style teeth problems in this country.

But Dental Association president elect, Katie Ayers, told Mike Hosking it comes down to accessibility and availability.

She says increasing workforce issues and ageing population means there aren't always enough staff to go around all the children.