Flying blind: trying to find solutions to Indigenous oral health

Additional keywords: Aboriginal and Torres Strait Islander, Australia, caries, child, decay, prevalence.

Dental caries (dental decay) is a largely preventable disease, but is known to be more common and widespread in Indigenous than non-Indigenous children in Australia.^1–3 Oral health is fundamental to both overall health and quality of life and is determined and influenced by a range of socioeconomic, environmental, behavioural, biological and cultural factors.^4,5 For children, poor oral health can negatively impact speech, development and learning, sleeping patterns, self-esteem and psychological and social well being.⁶ Furthermore, poor oral health in childhood tracks into adulthood and has lifelong effects.

The National Oral Health Plan 2004–2013⁷ highlighted Aboriginal and Torres Strait Islander people (within this paper referred to as Indigenous) as a priority population group for targeting improvements in oral health. That document was released in 2003 and recommended several actions to be implemented, including providing culturally appropriate and accessible oral health services through partnerships between mainstream and Indigenous-specific oral health services and improving access to oral hygiene products, such as toothpaste and toothbrushes, for Indigenous people.

Victorian policy identifies Indigenous people as a priority group for accessing public oral healthcare services (https://www2.health.vic.gov.au/primary-and-community-health/dental- health/access-public-dental-services; verified 27 October 2015). It is estimated that 47 333 Indigenous people were residing in Victoria on the 2011 Census night.⁸ However, little is known about the oral health of Victorian Indigenous people, and it is therefore important to locate and examine existing Australian data to understand the oral health of Indigenous people.

Prior to the 1980s, Indigenous children in Australia were recognised as having better oral health than non-Indigenous children.⁹ More recently, however, reports suggest that dental decay in Indigenous children is rising,^1,10 and decay in deciduous teeth has been estimated to be twice as high as for non-Indigenous children.¹⁰ This may be due to the complex interaction of factors such as increased access to processed Western/non-traditional diets, including sweetened drinks, rural location (which can be associated with lack of access to fluoridated water and reduced access to dental services) and social disadvantage. However, data available for Indigenous oral health remains limited. A key action of the National Oral Health Plan 2004–2013⁷ was to improve the collection and quality of oral health information of Indigenous people through regular standardised collection and dissemination of the data. An evidence base is needed to provide an understanding of the oral health needs of Indigenous people living in Australia and to identify ways to close the gap on oral health for this population group.

The aim of the present study was to undertake a review of the peer-reviewed literature and document the published prevalence rates and level of dental caries in Indigenous children to provide a robust evidence base for the purposes of policy and program planning. The review also aimed to investigate the associations between caries and oral health risk factors and to examine studies that reported and compared caries prevalence and severity in Indigenous and non-Indigenous children.

PubMed was searched independently by two authors (AG and JM-K) using the following search terms: ‘Aboriginal’, ‘Indigenous’, and ‘Torres Strait Islander’ in association with ‘oral health’, ‘oral disease’, ‘rural and remote’, ‘models of care’, ‘primary care’, ‘dental caries’, ‘periodontal disease’, ‘DMFT/dmft’, ‘dental decay’, ‘oral disease prevention’, ‘fluoride’, ‘access to dental services’, ‘dental services’, ‘oral hygiene’, ‘oral health care’ and ‘oral health interventions’. The search had no date limitations and was undertaken between January and September 2014. Only journal articles were included in the present study; no grey literature was searched.

Abstracts were reviewed independently by the same two authors (AG and JM-K) to determine whether the papers reported the prevalence, or levels, of caries, periodontal disease or oral cancer in Indigenous children. Following this screening process, full-length articles were retrieved and the inclusion and exclusion criteria were applied. For abstracts where it was unclear whether clinical data were reported, full-length articles were obtained. Studies were included if they measured a clinical outcome obtained during clinical examination of Indigenous children. Clinical outcomes included in the search were caries (decay) and periodontal disease. Papers were excluded if the data they cited were not obtained through a clinical examination (e.g. self-reported dental experience or dental health), if they reported the prevalence of oral disease in dental admission patients only, and not a general population; and if they were reviews.

Data extraction was undertaken by all authors independently and data from each paper was extracted twice by two separate authors. Data extracted included dental caries prevalence and experience, the clinical criteria used for diagnosis, the age of the population sample, study design, year of study, year of data collection and any data looking at risk factors and their effect on oral disease. Caries experience was measured by the decayed, missing and filled teeth index for deciduous/primary teeth (dmft) and for permanent teeth (DMFT). Both indices measure how many teeth (t/T) are decayed (d/D), missing (m/M) or filled (f/F). Caries prevalence data were extracted from the papers. Some studies reported caries prevalence, but most studies reported the proportion of the study population that was caries free. Because of these variations in reporting, the caries-free proportion was calculated from papers that reported caries prevalence (percentage with caries). Data were entered into a Microsoft Excel (Redmond, WA, USA) spreadsheet and examined for any duplication of data in studies by the same authors. Rural and urban location was extracted from papers where this was reported. For those papers that did not report this, an electronic search was undertaken to identify whether the location of the study was rural or urban, and this information was presented in the tables for data completeness. Because of the variation in ages and reporting within the studies, no statistics were undertaken and no trend analysis was possible. Data are reported as presented within the papers included in the study.

The PubMed searches identified journal articles published from 1971 to October 2014 (including one early access publication, available in September 2014); Fig. 1 documents the search results. The initial search included studies involving Indigenous adults as well as children because of the search terms used. The abstracts were screened and studies were included if they reported clinical oral health information in Australian Indigenous children. For several abstracts it was unclear whether the paper would include clinical oral health data for Indigenous children, and these papers were downloaded for review. Articles were included in the review if they reported clinical dental outcomes determined under clinical examination in Indigenous children in Australia. During this process, it was identified that only one peer-reviewed paper included periodontal disease in Indigenous children; the remainder of papers reported only caries. During the screening process, 32 papers were identified as meeting the criteria for caries prevalence or severity in Indigenous children. The details of these papers are summarised in Table 1.

Fig. 1.  Overview of search results.

Table 1.  Characteristics of included studies
dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; ARCPOH, Australian Research Centre for Population Oral Health; RCT, randomised control trial; decayed, missing, filled and extraction required permanent teeth; defx, decayed, missing, filled and extraction required deciduous teeth ; DMFXS, decayed, missing, filled, and tooth requiring extraction surfaces (permanent teeth); defxs, decayed, extracted, filled, tooth requiring extraction surface (deciduous dentition); dmfs, decayed, missing, filled surfaces (deciduous teeth) SiC10, Significant Caries Index 10; SiC, Significant Caries Index; WHO, World Health Organization

Of the 32 papers included in the study, 9% were published in the 1970s, 6% were published in the 1980s, 13% were published in the 1990s, 44% were published in the 2000s and 28% were published in the current decade. Table 2 summarises the studies by publication date and jurisdiction represented. Twenty-seven of the studies were undertaken in a single jurisdiction; the other five studies looked at the oral health of Indigenous children living in multiple jurisdictions. Two studies involved six jurisdictions, including Tasmania and the Australian Capital Territory (ACT), although one of these studies did not publish data by individual jurisdiction. There were no studies reporting oral health data for Indigenous children living in Victoria. Figure 2 summarises the number of studies publishing data for each jurisdiction, with total Indigenous population numbers.

Table 2.  Studies by publication date and jurisdiction included in the study

Fig. 2.  Estimated Indigenous population and number of studies reporting on the oral health of Indigenous children in each jurisdiction. NSW, New South Wales; NT, Northern Territory; SA, South Australia; Qld, Queensland, WA, Western Australia; Tas., Tasmania, ACT, Australian Capital Territory; Vic., Victoria.

Many papers reported oral health data for Indigenous children living in rural areas; some studies reported data across a jurisdiction that included Indigenous children living in rural and metropolitan areas. However, the data reported were generally for that jurisdiction rather than reporting the data by metropolitan or rural/remote locations. Of the studies, 15 were undertaken in rural locations (47%) and three in urban locations (9%). All three studies in urban locations were undertaken in Queensland. The remainder of the studies were undertaken in both rural and urban locations (44%), although only one of these studies reported the data separately by rural and urban location. Fluoridation status was extracted from the papers with the aim of determining whether fluoridation had an effect on the caries experience. However, fluoride information was often not reported or data were not separated by fluoride status. Six studies (19%) reported that the study location was fluoridated, six studies reported the study locations were in non-fluoridated areas (19%), nine studies (28%) reported the study was undertaken in both fluoridated and non-fluoridated locations and 11 studies (34%) did not state the fluoride status of the study’s location.

There was variation in the caries indices used in the studies. The earliest studies used the decayed, extracted, filled teeth and teeth requiring extraction (defx/DEFX) index. One study used the decayed, indicated for extraction, missing, and filled teeth (dimft/DIMFT) index, one study only used the decayed and filled teeth (dft) rather than dmft index and 9% of studies used the significant caries index (SiC) and significant caries index 10 (SiC10), to measure the severity of decay, in addition to dmft/DMFT indices. Approximately one-third of papers reported dmft/DMFT data but did not report which dmft/DMFT index was used. Six papers (19%) did not use a published caries index and either used clinical judgement or visible cavitation in the enamel surface as the measure for decay. The caries data (dmft, DMFT and percentage caries-free data) is tabulated in chronological order by jurisdiction in Tables 3–9.

Table 3.  Caries prevalence and experience in Indigenous children living in the Northern Territory
F, fluoridated; NF, non-fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; ARCPOH, Australian Research Centre for Population Oral Health; ABC Study, Aboriginal Birth Cohort Study; NT, Northern Territory

Table 4.  Caries prevalence and experience in Indigenous children living in Western Australia
F, fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; ARCPOH, Australian Research Centre for Population Oral Health; WA, Western Australia

Table 5.  Caries prevalence and experience in Indigenous children living in Queensland
F, fluoridated; NF, non-fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; ARCPOH, Australian Research Centre for Population Oral Health; Qld, Queensland; dft, decayed and filled deciduous teeth

Table 6.  Caries prevalence and experience in Indigenous children living in South Australia
F, fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; ARCPOH, Australian Research Centre for Population Oral Health; SA, South Australia

Table 7.  Caries prevalence and experience in Indigenous children living in New South Wales
F, fluoridated; NF, non-fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; NSW, New South Wales

Table 8.  Caries prevalence and experience in Indigenous children living in Tasmania
dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; ARCPOH, Australian Research Centre for Population Oral Health

Table 9.  Caries prevalence and experience in Indigenous children (multi-jurisdiction)
F, fluoridated; NF, non-fluoridated; dmft, decayed, missing and filled deciduous teeth; DMFT, decayed, missing and filled permanent teeth; –, not reported; NSW, New South Wales; NT, Northern Territory; SA, South Australia; Qld, Queensland, WA, Western Australia; Tas., Tasmania, ACT, Australian Capital Territory

Most studies did not have a non-Indigenous population included as a comparison group and so we have not presented caries data for non-Indigenous children in this paper.

There was a large variation in how the studies reported oral health data by age. Six studies reported data by single ages of 6 and 12 years and six studies reported data by individual ages ranging between 4 and 15 years or 6 and 14 years. Many studies reported an age range, but there was no consistency with the age range chosen. Age ranges included 0–4, 0–8, 1–3, 1.5–4, 2–4, 2–5, 3.5–5.9, 4–6, 4–9, 5–9, 10–12, 4–13, 5–10, 10–14, <10 and >6 years. Because of this variation, the data for 6- and 12-year-old Indigenous children has been focused on, which are the World Health Organization’s (WHO) benchmark ages.⁴⁰ Figs 1–4 show the changes in caries and percentage caries-free for 6- and 12-year-old children over time.

Fig. 3.  Decayed, missing and filled deciduous teeth (dmft) for 6-year-old Indigenous children in (a) the Northern Territory, (b) Western Australia, (c) South Australia and (d) Queensland over time.

Fig. 4.  % Caries-free 6-year-old Indigenous children in (a) the Northern Territory, (b) Western Australia, (c) Queensland and (d) South Australia over time.

Figs 3 and 4 show the dmft and percentage caries-free data, by jurisdiction, for 6-year-old Indigenous children. When looking at caries levels for 6-year-old children based on all dmft records identified within this study, the proportion of Indigenous children in the 1960s and 1970s who were caries-free was generally much higher than the data suggests is now the case. These data were from rural Western Australia and since that time only one other study has reported caries prevalence data in that state (in 2010). Data collected in 2000 and beyond suggest that the proportion of 6-year-old children who are caries-free is between 15% and 35%. It appears that the proportion of Indigenous children who are caries-free is decreasing in the Northern Territory and Western Australia, although trend analysis was not possible. These two jurisdictions also have the largest number of studies containing caries prevalence.

Data for dmft in 6-year-old children was not conclusive in terms of appearing to trend in dmft scores when looking at all available data across Australia. One study in 1971 (Northern Territory) reported a dmft of 10, whereas most recent studies report a dmft no higher than 6.4, with most ranging between 2 and 5.5. The dmft from Northern Territory showed a decrease between 1971 and 1989, plateauing until 2000, at which time dmft begins to rise again. Other jurisdictions had a small number of studies reporting dmft data and any changes were difficult to determine.

Figures 5 and 6 show the DMFT and percentage caries-free data, by jurisdiction, for 12-year old Indigenous children. For 12-year-old Indigenous children, the proportion of children who were caries-free (based on DMFT) was between 30% and 40%, and this increased to just above 50% in 1992 and 2002. More recent data collected show that 25%–45% of Indigenous 12-year-old children are caries free. When looking at the data by jurisdiction, the percentage of Indigenous 12 year olds in the Northern Territory who are caries free appears to have been similar between 1989 and 2002 but has dropped in 2010. Most jurisdictions had a small number of studies that reported the caries-free proportion, making it difficult to identify any changes over time.

Fig. 5.  Decayed, missing and filled permanent teeth (DMFT) for 12-year-old Indigenous children in (a) the Northern Territory, (b) Western Australia, (c) Queensland and (d) South Australia over time.

Fig. 6.  % Caries-free 12-year-old Indigenous children in (a) the Northern Territory, (b) Western Australia and (c) Queensland over time.

DMFT data for 12-year-old Indigenous children showed that the highest reported mean DMFT was collected in Western Australia in 1968; however, two other datasets from Western Australia in 1963 and 1968 reported a much lower DMFT. Generally, 12-year-old Indigenous children in the Northern Territory have higher mean DMFT scores; recent DMFT data for this age group (studies in South Australia and Queensland) suggest DMFT scores of between 1 and 4.

Both nationally and within state policy, Indigenous people are a priority group for public oral health.⁷ In order to develop oral health policy and improve the oral health of Indigenous people, we wanted to identify all available oral health data in peer-reviewed journals for Indigenous children to determine the level of oral disease and whether there was an association between oral health risk factors and oral disease. The present review documents the dental caries data, collected under clinical examination conditions, for Indigenous children published in the peer-reviewed literature to October 2014. The present review has identified that limited data exist for the oral health of Indigenous children living throughout Australia. It also identifies inconsistencies in data captured and reporting that limits meaningful comparisons and analysis.

It is known that approximately 670 000 Indigenous people, or 3% of the Australian population, reside throughout Australia,⁸ and many live in metropolitan locations. However, this review identified that most studies reported the oral health of Indigenous children living in rural and remote locations. There is a need for more data on the oral health of Indigenous children living in urban areas. Studies that look at the oral health of children living in rural and urban locations need to report the data by location (rural, remote and metropolitan) so that it can be determined whether there are differences in the oral health of Indigenous children living in these locations. Of significant interest is the absence of any oral health data for Indigenous children living in Victoria. This is an important gap to identify because it known that more than 47 000 Indigenous people live in Victoria;⁸ however, no oral health data have been published in the scientific literature for Indigenous children living within the state.

It was not possible to undertake trend analysis, or any other statistical analysis, on the data extracted because of reporting inconsistencies. Some studies did not even report the year that the data were collected. Data were reported variously be age bands (e.g. 1–3, 5–9 years) or by a single age. Often the studies only reported within an age range and not by the individual age, although in most cases it appears that this would have been possible for the authors to report. When collating and comparing the data, it was extremely difficult to find enough data for a particular age to allow meaningful comparisons. In an attempt to examine trends, we chose the WHO recommended ages of 6 and 12 years to compare the existing data. Only some of the studies reported data for these two time points. There were more data available for 6- than for 12-year-old Indigenous children. For 6-year-old children, the percentage of children who are caries free appears to decrease over time. However, the earlier studies in the 1960s were undertaken in remote locations in Western Australia.^11–13 The mean dmft data for 6 year olds appears to remain relatively constant across the time points apart from two studies showing that the dmft was above 6.^11,29 Data analysis for 12-year-old Indigenous children was difficult because available data from jurisdictions were limited and most jurisdictions did not have DMFT or caries-free data across a range of time points.

An inconsistency identified through the present review was the wide variation in the methods and caries indices used to measure and report dental caries, and the variations in reporting of Indigenous oral health data. This limits our ability to assess the data and make meaningful comparisons between studies and time points. Another important finding from the present review is that although risk factors for oral health are well established in the general population, very few of the studies included in this analysis have actually measured the known risk factors and examined the associations with caries in Indigenous children. Some of the papers did discuss the risk factors known to lead to poorer oral health, but did not attempt to measure the relationship between these risk factors and the development of caries. Reporting only the prevalence of oral disease does not assist in developing solutions and it is time that we go beyond simply describing the disease. The authors are aware of several intervention trials,^41,42 but these are limited in number and applicability to the context of Indigenous people living in metropolitan and regional communities.

The present review highlights that despite Indigenous people being a priority group for the public oral health care system, we actually do not have robust statistics to inform future activities. Because of variations in data capture, limited numbers of studies and the different age groups studied, comparisons are impossible to make.

For future research into Indigenous child oral health, we recommend the following:

• consistency in the reporting of caries data in relation to child age, study location (including whether rural or urban; and fluoridation status)

• more data are collected for Indigenous children living in metropolitan and regional areas of Australia

• data for Indigenous children living in Victoria are collected and reported to enable evidence-based decision making in relation to policy and program development

• studies examining oral health inequities include risk factor analysis within the design

• studies go further than simply describing oral disease, and undertake a more sophisticated exploration of the issues involved, and explore possible solutions.

The authors have no competing interests to declare.