*3.3. Periodontitis*

Table 5 presents the percentage of Australian dentate adults aged ≥15 years with moderate/severe periodontitis. Accordingly, the overall prevalence of moderate or severe periodontitis among the Australian dentate population was 30.1%. In contrast to gingivitis, the prevalence of moderate or severe periodontitis significantly increased with age: almost 70% of dentate adults aged ≥75 years experienced periodontitis. The prevalence of periodontitis among participants of all ages was lowest in Indigenous Australians (11.0) and highest in those participants who had Year 10 or less of schooling (45%). Males, individuals without a degree or higher qualification, those who were eligible for public dental care, those not dentally insured and those who usually visited a dentist for a dental problem experienced significantly greater periodontitis levels than their counterparts.

### *3.4. Tooth Loss*

In general, 4% Australian adults aged ≥15 years had lost all their teeth (Table 6). While complete tooth loss was non-existent among the 15–34-year age group, the proportion of adults with complete tooth loss steadily increased from 1.1% among 35–54 year olds to 20.5% for those aged ≥75. Among all age groups, the dentally uninsured had the highest prevalence of complete tooth loss (10.5%), while those who with a degree or above qualification reported the lowest prevalence (0.7%). There was a subtle difference between Indigenous and non-Indigenous adults in regard to complete tooth loss, however, a significantly higher proportion of Indigenous adults aged 55–74 years reported complete tooth loss (29.3%) as opposed to their non-Indigenous equivalents (7.7%). Among all age groups, those with Year 10 or less level of schooling, those without a degree or higher qualification, people who were eligible for public dental care, the dentally uninsured and

those who usually visited a dentist for a dental problem had significantly higher levels of complete tooth loss than their counterparts did.

Table 7 shows the severity of tooth loss due to pathology in Australian adults aged 15 years and over. In general, Australian adults had lost, on average, 4.4 teeth due to pathology. The mean number of teeth lost due to pathology increased consistently with age, from 0.6 at 15–34 years to 13.2 at 75 years and above. Among all age groups, the mean number of teeth lost due to pathology was lowest among those who had a degree or above qualification (2.3) and highest among those who were eligible for public dental care (7.7). In addition, people residing in rural/remote areas, those with Year 10 or less level of schooling, those dentally uninsured and those who usually visited a dentist for a dental problem had a significantly higher mean number of teeth lost due to pathology.

#### *3.5. Time Trends in Oral Health*

Over the past three decades, three national surveys of adult oral health have been carried out in Australia, namely, the National Oral Health Survey of Australia 1987–88 [18], the National Survey of Adult Oral Health 2004–06 [19], and the National Study of Adult Oral Health 2017–18 [12]. Accordingly, trends in oral health are sourced from these three national surveys, based on three time points. Given comparable data for periodontal disease were not available in the National Oral Health Survey of Australia 1987–88, an analysis of time trends in periodontal disease was not possible. Therefore, only a comparison of the prevalence of moderate or severe periodontitis between 2004–06 and 2017–18 surveys is presented.

Figure 1 presents the trends in the severity of dental caries experience in Australian adults aged ≥15, as denoted by mean DMFT. There has been a consistent declining trend in the mean DMFT over 30 years, from 14.9 in 1987–88 to 12.6 and 11.2 in 2004–06 and 2017–18, respectively. It was revealed that substantial reductions in all three components of the mean DMFT over 30 years have contributed to this declining trend. For example, the mean number of decayed teeth (D) and missing teeth due to pathology (M) declined from 1.5 (1987–88) to 0.8 (2017–18) and 5.7 (1987–88) to 4.4 (2017–18), respectively, whereas the average number of filled teeth (F) reduced from 7.8 in 1987–88 to 5.9 in 2017–18.

Figure 2 shows time trends in the proportion of Australian adults with complete tooth loss by age. It is apparent that there has been a steady decline in the overall proportion of Australian adults with complete tooth loss during three time points, from 14.4% in 1987–88 to 6.4% in 2004–06, and to 4% in 2017–18. This decline is reflected across all age groups, particularly among those aged 35–44 years and above, showing substantial reductions in complete tooth loss among them since 1987–88. For instance, there were only 1.7% of individuals aged 45–54 years with complete tooth loss in 2017–18, compared to 16.8% in 1987–88. The proportion of edentulous persons among 55–64-year-olds declined from 27.8% in 1987 to 5.8 in 2017–18. Likewise, nearly one in six adults aged 75+ were edentulous in 1987–88 compared to just one in three in 2017–18.

A comparison of the proportions of Australian adults with moderate or severe periodontitis by age is depicted in Figure 3. The overall prevalence of periodontal disease increased from 22.9% in 2004–06 to 30.1% in 2017–18. This was reflected in a consistent inclination of the proportion of Australian adults affected with periodontal disease across all age groups between 2004–06 and 2017–18. For example, the proportions of Australians aged 15–34 years and 75+ years with periodontitis increased from 7.4% to 12.2% and from 60.8% to 69.3, respectively, between 2004–06 and 2017–18.
