Patterns of orthodontic treatment of children in Australia: a national population-based study

When planning for population healthcare provision, policymakers must know the ‘lie of the land’. Information regarding the level of treatment need, how many people and which groups receive treatment, the types of treatment that are being provided and by whom, must be considered to ensure the optimal allocation of resources.

The 2012 to 2014 Australian National Child Oral Health Survey (NCOHS) was a national collaborative effort, involving the Australian Research Centre for Population Oral Health, state and territory health departments and the Commonwealth Department of Health, to provide a snapshot of the oral health of children in Australia.¹ The information gathered included data regarding orthodontic treatment need and the use of orthodontic services. To the best of current knowledge, there had been no prior nationwide study conducted to examine the orthodontic status of children in Australia and patterns of access to orthodontic services. Only two state level investigations have been reported,^2,3 in contrast with the situation in other countries.^4–7 Allister et al. found that, in the late 1980s in South Australia, the majority of fixed orthodontic treatment was performed by orthodontists, whilst most orthodontic extractions and removable appliance treatment were provided by public sector general dentists.² Sivaneswaran and Darendeliler, in a New South Wales study using private insurance records from 1992 to 1995, found that the majority of orthodontic treatment was provided by orthodontists (80%) and, also, that most fixed orthodontic treatment was provided by orthodontists.³ These previous state-level studies indicated that orthodontic care in Australia was largely provided in the private sector by orthodontists.^2,3 A patient’s eligibility for publicly funded orthodontic care in Australia usually requires ownership of a means-tested health care eligibility card. As orthodontic care through the private sector is comparatively expensive, and eligibility for public treatment is limited, a proportion of the population may be unable to access treatment during their adolescent years. However, the growing social acceptance of adult orthodontics and increased options for aesthetic appliances, has led to many individuals, whose parents could not afford treatment for them as children, to seek treatment as young adults.⁸

The national Australian orthodontic ‘landscape’ is uncharted territory which the present study hopes to identify. Using NCOHS data, the present study aimed to describe the patterns of orthodontic treatment for children in Australia aged 5 to 14 years according to sociodemographic characteristics, the types of treatment provided, and orthodontic treatment need for those aged 12 to 14 years.

The present study used data from the 2012-2014 NCOHS¹ which involved 24,644 children, aged 5 to 14 years, from 841 participating schools across all Australian states and territories. A multistage, stratified sampling design was employed to obtain a representative sample of children, with weighting procedures used to account for possible variations in the probabilities of selection and response rates.¹ Data were gathered via questionnaires completed by the children’s parents and standardised oral examinations conducted by calibrated dental professionals.

Of the wide range of areas investigated by the parental-completed questionnaire, the present study examined questions pertaining to sociodemographic characteristics (age, gender, indigenous identity, parents’ country of birth, parental education, and household income) and the use of orthodontic services. The use of orthodontic services was assessed by asking parents:

“Has your child been to see an orthodontist?”,

Parents were asked whether their child had received any of the following treatments:

“Planned (Orthodontic) Extractions”,

Parents were also asked whether their child had received orthodontic treatment from any of these providers:

“Public Clinic”,

The standardised oral examination involved the recording of occlusal traits of children aged 12-14 years and grading the traits using the Dental Aesthetic Index (DAI) by calibrated dental professionals.⁹ The DAI has been used as a tool to evaluate dental aesthetics, to determine eligibility for public programs, and in epidemiological surveys to assess treatment need in populations.¹⁰ Ten occlusal index traits (with various weightings) are scored and summed to generate a level of malocclusion severity or treatment need.^9,11,12 The occlusal components assessed were: missing anterior teeth, anterior crowding, anterior spacing, diastemata, the greatest upper anterior irregularity, the greatest lower anterior irregularity, maxillary overjet, mandibular overjet, open-bite, and molar relationship.

The four levels of malocclusion severity and/or treatment need were (1) Normal occlusion or minor malocclusion (with no treatment need or slight treatment need), (2) Definite malocclusion (for which treatment is considered elective), (3) Severe malocclusion (for which treatment is considered highly desirable), and (4) Very severe or handicapping malocclusion (for which treatment is considered mandatory).

The categories were established using a sample of 1306 study models of untreated adolescents from the National Centre of Health Statistics and meant to be representative of US youths aged 12 to 17 years. An evaluation of the study models indicated that 45.8% had a normal occlusion or mild malocclusion, 25.2% had a definite malocclusion, 15% had a severe malocclusion, and 14% had a handicapping malocclusion.^11,12

STATA 16.0 (StataCorp LLC, College Station, Texas) was used to generate descriptive statistics to estimate proportions, means, and 95% confidence intervals (CIs). Variables included sociodemographic characteristics, the types of treatment provided, the identity of the treatment providers, the frequency of planned (orthodontic) extractions, treatment need (overall and by sociodemographic characteristics), and access to orthodontic services according to malocclusion severity and sociodemographic characteristics. Statistical differences were denoted by non-overlapping 95% CIs.

To assess access to orthodontic services according to malocclusion severity and sociodemographic characteristics, children aged 12 to 14 years and evaluated by the DAI were dichotomised into two groups.¹³ Group 1 comprised children who had a normal occlusion or mild malocclusion, or definite malocclusion, (for which treatment would be considered unnecessary or elective). Group 2 comprised children who had a severe or handicapping malocclusion (for which treatment would be considered highly desirable or mandatory). The degree to which these two groups accessed orthodontic services was then assessed overall and by sociodemographic characteristics.

The present study appears to be the first nationwide survey conducted to examine the orthodontic status of children and access to orthodontic services in Australia. The findings provide valuable information regarding the sociodemographic characteristics of the child orthodontic population and patterns of orthodontic treatment provision. It also explored the relationship between orthodontic treatment need and the prevalence of orthodontic attendance by sociodemographic characteristics and malocclusion severity.

The findings indicated that adolescents, children from higher income households, children with tertiary-level educated parents, and those with handicapping malocclusions were more likely to visit an orthodontist, which supports previous literature. Adolescence is when most people seek orthodontic treatment.^6,14–22 This may be due to the recent establishment of the permanent dentition,²³ treatment taking advantage of growth,²⁴ and possibly the social norm of having treatment at this time in life. Those with higher incomes, greater socioeconomic status, and affluence were more likely to access treatment, whilst those with lower incomes were less likely.^{4,6,7,16,22,25–31} This may be because those with the financial means to access treatment were more likely to seek care regardless of the level of objective treatment need. Those of higher education backgrounds tend to access orthodontic services more commonly.^{6,19,20,26,28} This association may be related to higher income and/or an increased awareness of orthodontic problems and services. Females seek orthodontic treatment to a greater extent compared to males across the different age groups, time periods, and countries.^{2,4,6,14–17,19,20,22,27,28,30–34} This difference between the genders may be due to differing self-perceived or parentally perceived aesthetics, treatment need or differing societal demands.³³

The current study revealed that pre-adolescent children mainly attended for a consultation only, were predominantly treated using removable appliances, compared to adolescents who were mostly treated using fixed appliances. Furthermore, private specialists and orthodontists provided most treatment. The methodological differences between previous Australian state-based studies make direct comparison challenging.^2,3 However, there appears to have been relatively little change when assessing treatment providers. In South Australia, Allister et al. found in the late 1980s that specialist orthodontists had provided most fixed orthodontic treatment.² Furthermore, in NSW, Sivaneswaran and Darendeliler found that specialist orthodontists provided 80% of all treatment and 91% of fixed appliance treatment.³ These figures are similar to the findings of the present study, in which private specialists and orthodontists remained the providers of fixed appliances (91.4%) and all treatment at approximately 80%.

The reported frequency of orthodontic extractions in the present study was 31.0% overall and 33.8% in conjunction with fixed appliance treatment in children aged 12 to 14 years. This is comparable to extraction rates reported elsewhere which range from 15% to 45.8% and is reflective of the changes in extraction rates over the past three decades.^5,35–38 However, these data must be interpreted with caution as there is reliance on parents correctly understanding and recalling what was meant by ‘orthodontic extractions’. A recent 2022 Australian survey by Meade and Dreyer found the frequency of extractions in Class I malocclusions with moderate crowding for all ages was just over 20%.³⁹ The decrease in extraction frequency was attributed, in part, to increased interproximal reduction and arch lengthening procedures. Care is also advised as the survey finding was based on respondent estimates, and not a scientific evaluation of orthodontic extraction practices.

The distribution of malocclusion severity found in the present study was comparable to that of the original benchmarks from the National Centre of Health Statistics used to create the malocclusion severity categories of the DAI.^11,12 Of children between the ages of 12 to 14 years, 48.4% had a normal occlusion or mild malocclusion, 23.3% had a definite malocclusion, 14.2% had a severe malocclusion, and 14.0% had a handicapping malocclusion.

Although the present study found higher levels of severe and handicapping malocclusions in males, indigenous children, and children from lower income households, this should be interpreted with caution due to overlapping CIs. A similar finding was seen in the UK, where two studies found that those of lower income or socioeconomic background had higher levels of treatment need.^4,5 Potential explanations are that those from lower income households are less able to afford treatment or children from lower income households have higher levels of dental disease (early loss of primary teeth can lead to crowding or impactions of permanent teeth due to space loss).⁴⁰

The findings of the present study indicated that those with very severe malocclusions were more likely to receive orthodontic treatment (46.6%), which corresponded with previous studies.^{18,20,29,31,34} However, an increase in the severity of malocclusion did not necessarily mean a child was more likely to access orthodontic services, as those with a normal occlusion or a mild malocclusion (33.0%) were more likely to have visited an orthodontist than those with a definite malocclusion (26.3%) and a severe malocclusion (29.4%). This suggested that the severity of a malocclusion was only a consideration when accessing orthodontic services in the most severe cases, with other factors driving the decision to seek treatment in those with mild and moderate malocclusions. Possible reasons why a substantial proportion of those with severe malocclusions (70.6%) and why even more than half of those with handicapping malocclusions (53.4%) have not accessed orthodontic services include: children or parents not perceiving any aesthetic, functional, or health problems that would call for treatment,⁴¹ or parents not being able to afford or access treatment for their children.⁴²

Disparities persist when examining access to orthodontic services in relation to malocclusion severity. Children from lower income households and males access treatment less compared to children from higher income households, females, and those with greater malocclusion severity. The disparities are further increased as a higher proportion of both of these groups were found to have severe and handicapping malocclusions. The findings highlight the importance of ensuring public dental services identify and reach those from disadvantaged groups with severe malocclusions. A notable difference when comparing the prevalence of orthodontic attendance between children with lower and higher malocclusion severities, was that, although indigenous children possessing a lower malocclusion severity appeared less likely to have access to treatment (10.1%), those with a higher malocclusion severity potentially had the highest level of access to treatment (50.7%) compared to other sociodemographic groups. This finding suggests that government programs may have their intended effect in increasing access to treatment for indigenous children with high treatment need.⁴³

Given the evident shortfall in access to treatment in certain sociodemographic groups for those with more severe malocclusions, the current framework of orthodontic service provision clearly has shortcomings. There are a number of possible pathways to increase access for those with greater treatment need. However, existing services in the public sector need to judiciously prioritise those with the greatest treatment need, and a further step would be the expansion of existing services. In the private sector, increased access can possibly be achieved by increasing the supply of available treatment providers and the encouragement of pro bono work. However, decisions should be tempered with the awareness that, for most people, orthodontic treatment is an elective procedure, which may have psychosocial and aesthetic benefits, but is unlikely to have a significant benefit towards oral health.^44,45

As with all studies, there are several potential limitations. Response bias is a risk in surveys as the information gathered in the questionnaire relies on parents correctly understanding the questions and providing accurate responses. Furthermore, possible changes may have occurred in the past decade since data collection, and comparison with other studies is difficult due to differing methodologies. However, this was the first Australian national-level survey of its kind, and provides valuable information to healthcare planners, dental educators, and health funds. It also establishes baseline data for future comparisons within Australia and abroad. A second NCOHS, with a review of some of the children from the first study is planned. In addition, the population sample only extended up to 14 years of age. Further research is required to investigate the patterns and characteristics of orthodontic treatment of older children. Further research is also required to investigate the associations that sociodemographic characteristics may have with malocclusion severity and access to orthodontic treatment, as explanations of these associations are presently speculation. The use of the DAI to assess malocclusion severity also has its limitations. The weightings of the malocclusion traits and the malocclusion categories may no longer be applicable to contemporary aesthetic standards. However, all malocclusion indices have their shortcomings and the use of a widely applied index such as the DAI allows easier comparison between studies. Future surveys that seek to update the orthodontic ‘landscape’ could explore additional areas to provide more information. Possibilities are the inclusion of clear aligners as a mode of treatment, extending the upper age limit of children, and including another index to assess treatment need, such as the Index of Orthodontic Treatment Need.^46,47