Almost half of all Lakes district preschoolers have tooth decay, government statistics show - and those that do have an average of nearly five rotting teeth.
The most recent Ministry of Health figures showed 49 per cent of children examined at age 5 in the Lakes District Health Board area had tooth decay.
Of those with decay present, each child had 4.7 teeth affected by rot.
Child and Youth Health manager for Lakes DHB, Pip King, said the single biggest factor in decay was sugar.
"We are very concerned," Ms King said.
"There's only one cause of tooth decay and that is a diet high in sugar - particularly sugary drinks, and there are other food products high in sugar.
"Tooth decay is largely preventable, but it remains one of the most common diseases of childhood."
Statistically, the situation was an improvement. In 2013, 56 per cent of 5-year-olds had decaying teeth.
"There can be significant flow-on effects of having high levels of tooth decay as a 5-year-old. Poor oral health at 5 years of age can profoundly affect a child's health and wellbeing.
Basic dental care was free for everyone up to the age of 18. District health boards encouraged parents to take advantage of this and sign their kids up with an oral health service as early as possible, with a target of 95 per cent enrolment.
A number of countries have debated the value of a tax on high sugary drinks. Fizzy drinks receive the most scrutiny, but some fruit drinks, flavoured milks and sports drinks have just as much sugar.
The World Health Organisation (WHO) recently urged governments to put a 20 per cent tax on high-sugar drinks to lessen negative health effects.
The UK committed to doing so by 2018, following France, Hungary, Norway and Mexico.
Mexico's sugar tax has led to declines in consumption of fizzy drinks of 5.5 and 9.7 per cent in the first two years.
New Zealand Dental Association spokesperson Rob Beaglehole said the Government must implement a tax on sugary drinks, among other measures.
"It's scandalous, how much unnecessary pain and suffering is caused by these sugary drinks," Dr Beaglehole said.
"It's very awkward the Government is not taking note and introducing an evidence-based policy, particularly when the WHO urgently recommends all countries to adopt a tax."
Dr Beaglehole pointed to the Government being very committed to adding essentially the same discouragement tax on a harmful product such as tobacco.
Health Minister Jonathan Coleman said he was not yet convinced on the benefits of such a tax on sugary drinks, for tooth decay or obesity - the third highest in the OECD.
"There is still no evidence a tax would actually decrease obesity," he has said.
"If they're not interested in reducing the pain and suffering of young children, hopefully they're interested in reducing the burden on taxpayers in terms of the amount of money [the health effects of decay and obesity] is costing," Dr Beaglehole said.
Nationally, 29,000 children aged 1-14 had teeth removed due to decay in the last 12 months, according to Ministry of Health figures. This excludes accidents and other medical reasons.
The Rotorua area does not have fluoridated water. Before it rose for the election this month, a bill before Parliament allowing district health boards to direct councils to fluoridate community water supplies was expected to pass. The bill now has a more uncertain future.