Since the early 1980s root caries has become a subject of interest in dental research and practice.
Improved life expectancy and reduction of tooth loss have led to more natural teeth are being
retained for longer. While these are significant public health and dental health successes, it may
put the older population at a higher risk of root caries. The current international scientific
literature reports that root caries is observed in a significant proportion of older adults. Thus, it
was hypothesised that retaining more natural teeth in older adults would elevate root caries to
being a more prominent problem in the current generation than in the previous generation. This
presumption was congruent with the ‘failure of success’ and ‘more teeth, more disease’ theories
accepted in both the medical and dental fields. While this has been demonstrated in a cross-sectional
study of coronal and root caries, these theories have not yet been verified in studies
across the generations. This study aimed to contribute to the understanding of root caries and its
risk factors in the contemporary population of older adults. In particular, this study tested the
‘failure of success’ or ‘more teeth, more disease’ theories in relation to root caries among
Australian older adults by studying root caries across generations over a 22-year period.
This thesis combines a systematic review, meta-analysis and meta-regression study, with three
empirical studies using the National Survey of Adult Oral Health 2004-06, the South Australian
Dental Longitudinal Study 1 (SADLS1) (started in 1991/1992) and the Intergenerational Change
in Oral Health Study in Australia (SADLS2) (started in 2013-2014).
This study found that there were a diverse range of root caries studies presented around the
world. There is a need to conduct and report root caries research in a globally consistent way to
be able to take advantage from a ‘pooled estimate’ of root caries in a future meta-analysis. This
study found that root caries has remained a dental public health problem among Australian adults
and older adults. The profile of risk indicators of root caries has remained stable across
generations. The risk indicators are slightly different between untreated root caries (root DS),
and treated related-root caries (root FS and root DFS). Root caries was also found to increase
continuously, even among healthier adults.
The most important finding of this study was that, despite a higher retention of natural teeth, and
a high prevalence of gingival recession in the current generation of Australians, they experienced
less root caries than the previous generation. Improvements in the upstream determinants of oral health such as living conditions, expansion of water fluoridation and wider use of dental services
might have played a role in protecting the oral health of the older population.
In conclusion, the ‘failure of success’ or ‘more teeth, more disease’ theories were not supported
in this study of root caries across generations of Australian older adults. The findings support the
current population-based program of water fluoridation, and the promotion of healthy lifestyle in
order to prevent root caries.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, Adelaide Dental School, 201
