**3. Results**

A total of 15,731 Australians aged 15 years and over completed an interview, and of them, 5022 dentate participants were orally examined. This resulted in overall participation rates of 39.7% (interview) and 33.6% (examination). Intra-class correlation coefficients (ICC) calculated to assess inter-examiner reliability were above 0.9 and 0.7 for diagnosing dental caries and periodontal disease, respectively. Weighting ensured that, approximately, an equal proportion of males (49.2%) and females (50.8) participated in the study. Given that

oral health status varies considerably with age, population estimates were calculated for four age groups—15–34 years, 35–54 years, 55–74 years and ≥75 years. Tables 1–7 present the distribution of dental caries, periodontal disease and tooth loss, and Figures 1–3 depict the time trends of these three conditions.

**Table 1.** Proportion of Australian dentate adults aged 15 years and over with untreated coronal caries.


\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution.

**Table 2.** Mean number of decayed tooth surfaces per person in the Australian dentate adults aged 15 years and over.


\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution.



\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution. NP: Not publishable due to small cell counts.

**Table 4.** Percentage of people with gingival inflammation in the Australian dentate population.


\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution. NP: not publishable due to small cell counts.


**Table 5.** Proportion of people with moderate or severe periodontitis in the Australian dentate population.

\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution. NP: not publishable due to small cell counts.

> **Table 6.** Proportion of adults with complete tooth loss in the Australian population.


\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution.


**Table 7.** Mean number of missing teeth for pathology per person in the Australian dentate population.

\* Indicates a relative standard error of at least 25%, and hence should be interpreted with caution.

**Figure 1.** Trends in dental decay experience among dentate Australians aged 15 years and over, 1987–88, 2004–06 and 2017–18.

**Figure 2.** Trends in complete tooth loss among Australians aged 15 years and over, 1987–88, 2004–06 and 2017–18.

**Figure 3.** Comparison of the prevalence of moderate or severe periodontitis among dentate Australians aged 15 years and over between 2004–06 and 2017–18.

### *3.1. Dental Caries*

Table 1 shows the proportion of Australian dentate adults aged 15 years and over with untreated coronal caries (one or more decayed surfaces on crowns of their teeth). Nearly one third of Australian adults (32.1%) had at least one tooth surface affected by untreated dental caries. The proportion of adults with dental caries across the four age groups varied, with the prevalence being highest in 35–54-year-olds (35.4%) and lowest among those aged 75 years and over (24.5%). The highest prevalence of untreated dental caries among participants of all ages was reported in those who visited a dentist for a dental problem (43.5%), while participants who visited the dentist for a check-up had the lowest prevalence (24.3%). Higher proportions of untreated dental caries were seen for males, those eligible for public dental care and those without dental insurance. Across age groups, higher proportions were seen for Indigenous people aged 55–74 years and those aged 35–54 years with Year 10 or less level of schooling than their counterparts.

The mean number of decayed tooth surfaces per person in Australian dentate adults aged 15 years and over is presented in Table 2. Overall, Australian dentate adults aged 15 years and over had, on average, 1.4 decayed tooth surfaces. The mean number of decayed tooth surfaces among all ages was lowest in participants who usually visited a dentist for a check-up (0.7), and usually visiting the dentist for a problem was strongly associated with higher mean number of decayed tooth surfaces across all age groups. Those who reported visiting for dental problems had, on average, 2.3 decayed surfaces. In addition, participants who had Year 11 or more schooling, a degree or higher educational qualification, those who were not eligible for public dental care and those with dental insurance had a lower mean number of decayed tooth surfaces than their counterparts.

Table 3 shows the mean number of decayed, missing or filled tooth surfaces (DMFS) per person in the Australian population. On average, Australian dentate adults aged 15 years and over had, on average, 29.7 decayed, missing or filled tooth surfaces, and it increased gradually across four age groups, with people aged ≥75 years having the highest mean DMFS (75.3). Among individuals of all ages, those who were eligible for public dental care had the highest mean DMFS (44.8), and Indigenous people had the lowest mean DMFS (18.7). Moreover, males, individuals with higher levels of schooling and degree or higher qualifications, and those who usually visited a dentist for a check-up had significantly lower mean DMFS as opposed to their counterparts.
