Dental health is a key child health issue: New Zealand children's dental health has declined since the early 1990s. Nurses who work with children have a key role to play in reversing that trend.

EVERY CHILD who has been through the New Zealand school system will have encountered the school dental nurse. Providing oral health services to children has long been the domain of the school dental nurse, now known as dental therapist, with the involvement of dentists and other specialists as required.

Providing this service, which began in the early 1920s, put New Zealand to the forefront in managing dental caries in children. (1) Since the early 1990s, however, there has been a decline in oral health status. (2) One explanation is the change in provision of school dental services and the ongoing decline in the number of dental therapists. (1) But the effects of socio economic disadvantage and high sugar intake are cited as the main factors. (2,3,4,5) This phenomenon is not unique to New Zealand. It is also evident in the United Kingdom (5) and the United States, where oral health is considered to be the largest unmet health care need of children. (3)

With fewer dental therapists and the fact some families find it difficult to visit a dental therapist, it is important all child health nurses are aware of the impact poor oral health has oil a child's well-being. Health care workers must also consider oral health as an integral part of systemic health. (6)

The New Zealand Health Strategy identifies improving oral health as one of 13 key population health objectives. Child health nurses, regardless of where they work or their primary role, are well positioned to help meet this objective. They interact more frequently with children and their families than most health workers and have an opportunity to provide education, support and referral if necessary in the area of oral health. However, nurses often lack the knowledge to assess oral hygiene and it is frequently given low priority, especially in busy hospital settings. (7) Nurses should be able to identify basic abnormalities in the oral cavity and be alert to changes, which can indicate the presence of oral disease. (8)

Although oral health refers to the oral mucosa, teeth, tongue and surrounding cranio-facial structures, the main issue for most children is that of dental caries. (5,18) Dental caries is the most common chronic infectious disease of childhood and may be the most prevalent disease to affect humans. (5,6,9,10)

Oral disease has wide ranging effects. A healthy mouth is necessary for nutrition and communication, which affects growth and development. Severe dental caries can cause chronic pain and systemic infection. Children suffering from this condition are often malnourished, because it is painful to eat; they are frequently absent from school; may have difficulty sleeping and socialising; and have low self esteem. (2,5,6,9) Early recognition and conservative management can help prevent future treatment, which is costly, painful and possibly disfiguring. (6)

On a purely functional level, teeth are important for eating and speaking. Different teeth allow for cutting, tearing and grinding food. Teeth also affect facial appearance and are very important for socialisation. Teeth have many components and damage to any of them can compromise their durability and ability to perform their basic function or cause them to fall out. Humans usually have 20 primary teeth, also known as deciduous or shedding teeth, and 32 permanent teeth. Dentition begins at approximately six weeks in utero and continues into late adolescence. (21)

Formation of dental caries requires three elements: a susceptible tooth surface; a mouth colonised by cariogenic bacteria; and the presence of sucrose. (1,3) The bacteria produce lactic acid from fermentation of the carbohydrate, which then begins to dissolve the tooth enamel. Although potentially cariogenic bacteria have always colonised humans, the increase in sugar consumption has contributed to the huge increase in dental caries. (3)

Bacteria associated with human caries are known as mutans streptococci (MS), which are the prime cariogenic bacteria. They usually colonise the oral cavity after the eruption of the first teeth. This period of colonisation is coined the "window of infectivity", as it is thought the bacteria are transmitted by the child's primary caregiver, in most cases the mother. (3,12,13) A second window of opportunity may be present when the permanent teeth emerge.

Early childhood caries (ECC) describes a pattern of dental caries in young children. Usually the primary upper anterior teeth are the worst affected. The lower teeth are usually protected by the tongue and pooling of saliva. Risk can be increased with the presence of pre-existing hypoplasia of the enamel. ECC is usually associated with prolonged bottle feeding, especially if the bottle contains juice or sweetened milk, and if the child is put to bed with a bottle. The effect of human breast milk on ECC is not clear. Human breast milk does not have the same cariogenic effect as formula and actually deposits enamel mineral on the teeth. However, in the presence of other sugars, breast milk becomes cariogenic, therefore once baby is eating solids or taking other fluids, the anti cariogenic properties of breast milk are lost. (13) There is evidence against allowing a baby to fall asleep while breastfeeding, particularly after eruption of the first tooth, as this allows milk to pool in the mouth, which is associated with development of ECC. (13)

The oral cavity is a portal of entry for pathogens and untreated caries can lead to systemic disease. (5) Facial cellulitis may result from dental infection and accounts for half the facial cellulites in children, especially in the mandibular region. (3) Pus from an untreated infection can accumulate in the pulp chamber and cause excrutiating pain. A fistula can develop to drain pus from an untreated infection in the pulp chamber of the tooth. This alleviates the pain and, unless identified, may go untreated. (3)

Untreated caries cause pain, difficulty eating which can be associated with failure to thrive, loss of schooling, social and sporting activities. Premature loss of first teeth can lead to malocclusion of permanent teeth. (5)

Gingivitis is the inflammation of gum tissue, often with associated bleeding. This condition is reversible, but left untreated can lead to periodontitis, which is inflammation of all the tissues supporting the teeth, including the bone. (14) This condition is severe and irreversible. (8)

The prevention of caries requires removing at least one of the components that contributes to their formation. This includes reducing cariogenic bacteria in the oral cavity, reducing exposure to cariogenic substrate (plaque) by cleaning and flossing, and increasing the decay resistance of teeth. (6) The most effective way to reduce caries is to reduce sugar intake. The prevalence of refined sugar in the Western diet, particularly in manufactured foods, makes it very hard to avoid. Advertising, especially on television during children's programmes, has a huge influence on the dietary preferences of children. New Zealand children watch an average of two hours television day, with approximately 20 minutes of advertising in this period. Many of these advertisements are for foods high in sugar and fat. Government policy advocates decreased sugar intake, yet there are no controls on these types of advertisements. (15)

There is a perception that first teeth don't matter as they are replaced by permanent teeth. Deciduous teeth are very important, as, besides the functions already identified, they help hold space for the permanent teeth that are developing while the first teeth are in place. (11) It is important to educate caregivers of young children about the importance of first teeth, and of developing good oral hygiene practices that will hopefully stay with children throughout their lives.

The easiest way to detect decay in young children is to gently lift the upper lip and look at the four front teeth. (3,12,13) Take note of any chalky white or stained marks which indicate the early stages of decay. If any marks are seen, the child should see a dental therapist as soon as possible, as at this stage the decay is reversible. Parents and caregivers should be encouraged to make this simple check at least once a month. (12)

Dietary advice is to avoid high-sugar foods, especially sticky, chewy foods such as muesli bars or fruit leathers, which adhere to the teeth. Carbonated fizzy drinks are particularly bad, as they are very acidic and can erode enamel without the action of the bacteria. (4) Some foods have anti-cariogenic properties, most notably cheese and human breast milk. Good snacks are crackers, cheese, fruit and vegetables, non-sugared popcorn and sandwiches, but not with honey or jam. The more frequently sugar is eaten, the higher the risk of acid forming, therefore it is best to eat sweet foods at meal times, and not dish out sweets as treats over a prolonged period. (12)

Avoid prolonged bottle feeding, putting baby to sleep with a bottle of milk or juice or on the breast, and avoid using sweeteners on pacifiers. Encourage children to drink from a cup around their first birthday. Give young children water to drink and give juice only at mealtimes. For children who are used to drinking juice, try gradually diluting it with water, so they become used to the taste.

Discourage caregivers from chewing their child's food before the child eats it, tasting their baby's bottle or kissing their baby on the mouth. These can all lead to transmission of bacteria to the baby. (12)

Begin teeth cleaning after eruption of the first tooth. Use a soft bristled toothbrush with a smear of toothpaste only. Young children typically swallow up to 60 per cent of toothpaste. Child-strength toothpastes are available, and it is particularly recommended to use these in areas where water is fluoridated. Encourage children to spit out after cleaning. Keep toothpaste out of reach of children, as they usually like the taste and will eat it. Twice-daily cleaning is preferable, but it should be done at least once daily before bed. (4,6)

Children should be enrolled with the dental service at birth and the first visit should be around the child'a first birthday, or earlier if any problems develop on eruption of the teeth. Remind caregivers that this is a free service and is free until the child is 16, or 18 if still at school. (12)

Fluoride is found naturally in water, soil, atmospheric gases, many plants and most animal tissues. It is not fully understood how fluoride helps combat caries. Early assumptions were that the primary action of fluoride was systemic. (6) It is now known the beneficial effects of systemic fluoride are minor, and topical applications have greater benefit, including flouride that has been systemically absorbed and is then excreted in saliva. Fluoride, along with the calcium and phosphate present in saliva, helps remineralise enamel but this is possible only in the first stage of decay if the outer surface of enamel is intact. The remineralised enamel is actually stronger than the original. (12,16)

Since the association between fluoride and decrease in tooth decay was made, fluoride has been made available in many forms. It is added to most toothpastes and many mouthwashes. Fluoride tablets have been available for many years, but are now associated with fluorosis, if not given appropriately and they can be toxic if excessive numbers are ingested. As with any medication, fluoride tablets should be kept in child-proof containers in a locked cupboard. The Ministry of Health now recommends fluoride tablets be given only to children who have an unfluoridated water supply with low naturally occurring levels and who are at risk of developing decay. (17)

There are many controversial issues surrounding the fluoridation of water supplies. Fluoridation of public water supplies is claimed to be the single most effective intervention in reducing the level of dental caries. It is estimated between 2.4 and 12 less decayed, missing or filled teeth per person in New Zealand are attributable to fluoridation of water supplies. (16) Fluoride in this form is available to all populations with access to flouridated water supplies and goes across socio-economic barriers.

Although some children are born with predisposing factors placing them at increased risk of developing dental caries, there is still no definitive way to determine one child's increased development of caries, when all other factors are equal.

There are many complex medical conditions that can affect a child's oral health, most of which are congenital and require specialist medical and dental treatment. Oral care is considered to be the largest unmet health need in children with special needs. This can be because of positioning difficulties or a child's refusal or inability to sit still and respond appropriately to the dental therapist or other health worker attempting to examine the child's mouth. (5)

Saliva is the bodies' greatest defence against caries. It washes away food and other particles. Saliva also acts as a buffer, neutralising the acid produced by cariogenic bacteria. It is also suggested that saliva has some antibacterial properties. (6) Children with normal tooth structure and salivary flow and exposed to fluoride are at the lowest risk of developing caries.

Salivary glands do not function spontaneously at night. Therefore the most important time to remove plaque, by brushing and flossing, is before sleep. Some medications can cause xerostomia (salivary gland dysfunction causing a dry mouth (14)) and children on these need increased oral hygiene measures. These medications include antihistamines and anticonvulsants. (18)

Maternal oral health can affect that of the baby. There is a demonstrated link between cariogenic bacteria being transmitted from mother to baby. Studies have found links between periodontal disease in pregnant women and prematurity and low birth weight of their babies. (18) Women who take little care of their own oral health are less likely to demonstrate good practices to their children, thus repeating the cycle. Low maternal age and poor education also increases the child's risk. (5)

Hypoplastic enamel can be caused by prematurity and low birth weight. This is where the enamel is of normal hardness, but is pitted and creased and thinner. This increases a baby's susceptibility to ECC. Hypomineralisation of enamel is rare. This is where the enamel is soft and may come off the tooth. Ambient fluoride in the oral cavity can promote remineralisation. (6)

The decline in oral health among New Zealans children since the early 1990s is a real concern. Changes in structure and funding of children's dental services have meant fewer dental therapists being shared among schools. This may have contributed to the fall in oral health. (1)

Maori outcomes

Maori and Pacific children are more likely to have poor health outcomes than the general population. (2) As with other health issues, oral health cannot be viewed in isolation. Maori have lower levels of academic achievement and younger maternal age than Pakeha. Oral health must be part of the overall health message and must relate to life in Maori communities. Health education should ideally be delivered by Maori and have the involvement and support of key Maori in the community. (19)

There are similar issues with Pacific children's health. Of particular significance are the high rates of rheumatic heart disease. Infection in the oral cavity for these children can have life threatening sequalae. Reducing inequalities and promoting a healthy lifestyle include improving nutrition, which is aimed at reducing obesity and improving oral health care.

There are societal benefits to living in an environment where people are healthy. The monetary cost of dental treatment, sometimes requiring hospitalisation and general anaesthesia, is significant. Loss of school days, decreased education and decreased self esteem all contribute to undermining the child's attempts to reach goals and succeed in society. The long-term effects of these are incalculable.

The goal of improving health status in any society must include oral health. It is the responsibility of all health care professionals to work towards reducing inequalities in health, particularly for young children who are totally dependent on others for their health care.

Dental caries is an infectious disease and child health nurses must be aware of the long-term sequalae of untreated caries and poor oral health practices.

Nurses who work with children and their families, particularly in primary health, are well positioned to develop relationships where they can educate and support families, often in families' homes. This education and support must include oral health because of its impact on children's overall health status.

REFERENCES

(1) Strategic Partners. (2001) Review of publicly funded oral health care in New Zealand, Wellington: Ministry of Health.

(2) Hodges, I., Maskill, C. Coulson, J. Christie, S. & Quigley, R. (1998) Our children's health: Key findings on the health of New Zealand children.

(3) Caufield, P.W. & Griffen, A.L. (2000) Dental caries: An infectious and transmissible disease. Pediatric Clinics of North America; 47: 5,1001-1020,

(4) Kmietowicz, Z. (1998) Decline and fill. Nursing Times; 18: 94, 28-29.

(5) Mouradian, W.E., Wehr, E. & Crall, J.J. (2000) Disparities in children's oral health and access to dental care. JAMA; 284: 20,2625-2631.

(6) Schafer. T.E. & Adair, S.M. (2000) Prevention of dental disease: The role of the pediatrician. Pediatric Clinics of North America,. 47: 5, 1021-1042.

(7) Thurgood, G. (1994) Nurse maintenance of oral hygiene. British Journal of Nursing; 3: 7.

(8) Gelbart, M. (1998) All mouth. Nursing Times; 18: 94, 26-28.

(9) Edelstein, B.L. (2000).Public and clinical policy considerations in maximizing children's oral health. Pediatric Clinics of North America: 47: 5, 1177-1190.

(10) King, A. (2000) The New Zealand health strategy. Wellington: Ministry of Health.

(11) Wright, J.T. (2000) Normal formation and development defects of the human dentition. Pediatric Clinics of North America; 47: 5.

(12) Lockett, C. (2001) Keep me smiling: Lift the lip. Auckland Regional Dental Services.

(13) Nowak, A.J. & Warren, J.J. (2000) Infant oral health and oral habits. Pediatric Clinics of North America: 47: 5, 1043-1066.

(14) O'Toole, M. (ed) (1992) Miller-Keane encyclopedia & dictionary of medicine, nursing & allied health. (5th ed.) Philadelphia: W.B. Saunders Company.

(15) Kedgley, S. (2000) Green calls for controls on food advertising to children. Retrieved January 1, 2002, from http://www.greens.co.nz/searchdocs/PR3088.html.

(16) Public Health Commission. (1995) Fluoride and oral health. Wellington: Public Health Commission.

(17) Bates, M. (2000) Fluoridation of water supplies--an evaluation of the recent epidemiological evidence. Porirua: Kenepuru Science Centre.

(18) Casamassimo, P.S. (2000) Relationships between oral and systemic health. Pediatric Clinics of North America, 47: 5, 1149-1158.

(19) Edward, S.J. (1992) How the Maori community sees the dental-care system. New Zealand Dental Journal; 88, 128-131.

(20) Brown, R.H. & Treasure, E.T. (1992) Inequalities in oral health: implications for the delivery of care and health promotion. New Zealand Dental Journal, 88, 132-138.

(21) National Health Committee. (1998) "The social, cultural and economic determinants of health in New Zealand." Action to improve health. Wellington: National Advisory Committee on Health and Disability.

Sally Birse, RCpN, BHSc, PGDip, is a paediatric nurse specialist with Kidz First Home Care Nurses' Service, Counties Manukau District Health Board.