Catherine was off her food for weeks before finally admitting to a pain in her mouth. When she opened wide, the culprit seemed obvious: an adult molar blocked by an undislodged baby tooth was pushing sideways through the 10-year-old’s gum.

But when her mother phoned the dental clinic at her central Auckland school to arrange an appointment, she learned the dental therapist would not be there until the third term, in July. An answer-phone message referred her to a school 7km away, where the therapist was spending term one. The therapist, who covers four schools, was fully booked but agreed to squeeze Catherine in before her first scheduled appointment the next day.

On inspection, the dental therapist (the modern term for a dental nurse) said it looked as if the baby tooth would soon fall out and intervention was unnecessary.

But she found a different story on the other side of Catherine’s mouth. Two new molars were severely impacted and an abscess was forming in one. The offending baby teeth were painlessly extracted.

Catherine was lucky. If her mother hadn’t known her way around the system, or hadn’t been able to get her daughter across town, she would eventually have needed more complicated and painful treatment.

But the outlook is not so bright for the school dental service, allowed to decay to the point where only radical surgery – and an injection of taxpayers’ money – can save it.

A Ministry of Health review of the service follows mounting evidence that, after decades of steady improvement, the health of New Zealand children’s teeth is deteriorating. Even though dental care remains free for all New Zealanders under 18, many children are missing out.

The school dental service aims to check every child at primary and intermediate schools once a year and see “high needs” children every six months. Secondary school children can go to private sector dentists for free treatment. At least, that’s the theory.

Attendance of secondary school children at dentists has slipped below 40 per cent in many areas. Attendance rates for Maori and Pacific Island children and new migrants are even lower. Many dentists refuse to treat school children free because of a standoff with the Ministry over reimbursement.

The number of therapists in primary and intermediate schools has been whittled down from 1600 in 1987 to around 550, while the population has risen by about 500,000. Most of the growth is in Auckland where the 150 therapists who now do the rounds of three or four schools each are struggling to meet their target of checking all children at least once a year.

With clinics idle for much of the year, schools with growing rolls are increasingly reclaiming the space for office use. In Auckland’s new suburbs, schools are being built without clinics – despite often enrolling large numbers of migrants with high dental health needs. A Ministry of Education spokesman says few boards of trustees see clinics as a priority.

Growing parental concern is acknowledged by school principals: “Access for our children has become quite an issue,” said one. “Our school roll has grown so the dental nurse is seeing close to double the number of children but she’s covering three other schools with no clerical help or assistant. She doesn’t always manage to see all our year seven and eight children. They are certainly not seen every six months.”

Attendance of preschoolers at school dental clinics has slumped – it’s news to most parents, and particularly migrants, that they can enrol children as soon as their teeth come through.

Gaping differences in service levels and in therapists’ pay and conditions have emerged since responsibility for the service was devolved to district health boards. In high growth areas, many are so overworked that they focus solely on treatment, with no time for “preventive” work.

Dental surgeon Callum Durwood, who co-chairs the School and Community Dental Services Forum, says therapists are buckling under the strain in some areas, leading to burnout, overuse symptoms and tumbling morale. Dental graduates with crippling student loans are not attracted to the service and vacancies in the most needy areas go unfilled.

Auckland has eight vacancies and Northland four. With the average age of therapists approaching 50, more severe workforce shortages are predicted.

Durwood, who treats children at Green Lane Hospital, says growing variations in regional needs are not reflected by funding. “Areas like Bay of Plenty, Northland and Gisborne all have higher rates of decay and South Auckland is worse than other parts of Auckland. But they receive almost the same funding as Wellington which has low decay.”

Durwood says therapist numbers were reduced because, with fluoridation, the need wasn’t there. “But, particularly with younger children, dental health hasn’t continued to improve and in some areas it’s getting worse.

“If therapists were able to see all children annually and high-risk children twice a year, the fact they move around a number of schools wouldn’t make much difference. But in areas like Northland, where they should be seeing 40 per cent of children twice a year, it’s not happening.”

A big contributor to declining adolescent attendance is the refusal of many dentists to treat them. Dental Association president David Crum says the $24 flat fee comes nowhere near covering the cost of treatment.

Worst off are small provincial towns. Kaikohe dentist Paul Reeves did not renew his Government contract last year when he could not replace a colleague who left. A backlog of 100 children under-12 needing urgent treatment developed until a Kaitaia dentist stepped in to help. Many had to be operated on at Whangarei Hospital.

Crum says dentists are more likely to see children from affluent families who least need care. The association had suggested “a range of options” to give dentists flexibility to target treatment to children with higher needs. But the Government has ruled out part-charges, as happens with doctors’ visits, or fees for families that can afford to pay.

The gaps are beginning to show. The percentage of 5-year-olds with caries-free teeth, showing no signs of decay, fell from 56 per cent in 1997 to 53 per cent in 2001. The trend was the same for year eight children.

The national averages mask striking regional and ethnic variations. In Northland and Gisborne only 35 per cent of 5-year-olds were caries-free in 2001. In the Bay of Plenty, just 29 per cent of second formers had no decay, compared to 50 per cent in greater Auckland. Bay of Plenty 5-year-olds have an average of three “missing, filled or decayed” teeth; Wellington children average 1.4.

Maori and Pacific Islanders stand out with double the incidence of decay and lower rates of attendance for preschool and secondary school care.

The problem is worst in rural areas without fluoridation. Hawkes Bay dentist David Marshall last year reported seeing 3-year-olds in Wairoa needing half a dozen teeth removed and up to 10 fillings. “It’s pretty depressing to have to do these mutilating procedures when they’re entirely preventable,” he told Hawkes Bay Today.

How has it come to this? The modern school dental service is a far cry from the tortuous visits to the “murder house” that many parents still recall. Today’s highly trained therapists provide virtually painless dentistry using x-rays and local anaesthetics.

But the failure of the service in some areas is such that hundreds of children are being referred to public hospitals for dental surgery under general anaesthetic. Many spend months on antibiotics and painkillers awaiting treatment. The long-term prognosis is gum disease and expensive surgery in adult years.

To an extent, the school dental service was a victim of its own success when health administrators looked for soft targets during the cost-efficiency drive of the last decade’s health reforms. Historic gains in oral health – a combination of fluoridation, education and lifestyle improvements – meant twice-yearly checks for all were no longer justifiable. Therapist numbers were slashed and the profession reorganised.

But the problems now emerging are not solely due to the cleansing of the welfare state – parents and societal changes are playing their part.

A higher rate of decay for less-affluent children is linked to high consumption of fruit drinks and soft drinks, which are cheaper than milk, and high-sugar snack foods.

The fall in adolescent enrolment is attributed in part to families where working parents are too distracted to ensure Johnny keeps that dental appointment – or even enrols with a dentist. High mobility and a lack of monitoring mean children slip through the cracks.

Complacency is a factor: a generation of parents who experienced little tooth decay in childhood is failing to educate children about brushing teeth and avoiding sugary foods. Of course, there is suspicion that parental ignorance, and ambivalence, suits health sector bean counters – the fewer children enrolled, the less it costs, particularly for adolescents.

Callum Durward says the reversal in oral health trends is “largely a reflection of what’s going on in families at home – what they are eating and drinking and perhaps parents’ awareness of health.”

All the more need, then, for an effective safety net. But news this week of the Ministry of Health’s review has failed to soothe concerned school principals and parents.

The rationale given by the ministry – that clinics are costly to equip and maintain, and there may be better ways to deliver the service – sounds less than promising. District health boards will be asked to check whether clinics are cost-effective and meet health and safety requirements.

Review adviser Sue Dasler says older “two-chair” clinics no longer meet public expectations for privacy and it’s less desirable for therapists to work alone these days.

But Dasler and the Ministry’s oral health chief adviser, Clive Wright, are adamant the review can stop the rot and revive the ailing service.

The biggest centre, Auckland, has already had success with mobile services. District health boards will examine whether upgraded clinics at some schools can serve a wider catchment, allowing others to be closed.

“The underlying issue we must all be mindful of is access to services,” says Dasler.

Steps have already been taken to combat staff shortages. The Auckland University of Technology launched a three-year degree in oral health last year, offering an alternative to the Otago School of Dentistry. Changes to the Dental Act, under the Health Practitioners Competency Bill, are expected to make the profession more attractive by allowing therapists to broaden skills and work in private practice. Dental hygienists will take on preventive work.

But with an ageing workforce and demand for therapists overseas, particularly in Australia, the shortages won’t ease overnight. The growing market for “cosmetic” dental work is adding to graduates’ options. Durward says salaries have to become more attractive. “Therapists graduating with degrees will expect more.”

Wright, who was lured back from a research post in Australia to fill the new chief adviser role, stresses the need to make services appropriate to Maori and Pacific Islanders, as has happened in general healthcare with primary health organisations.

He says there may be scope for private dentists to take a “more innovative” approach to treating adolescents.

Whether the changes will allow a resumption of normal service for all remains to be seen. Just like teeth, it would seem that prevention is easier than the cure – and neglect is difficult to treat.