Changing Paradigms in Concepts on Dental Caries: Consequences for Oral Health Care

Abstract

Kuhn proposed in his Structure of Scientific Revolutions (1962) that the theoretical framework of a science (paradigm) determines how each generation of researchers construes a causal sequence. Paradigm change is infrequent and revolutionary; thereafter previous knowledge and ideas become partially redundant. This paper discusses two paradigms central to cariology. The first concerns the most successful caries-preventive agent: fluoride. When it was thought that fluoride had to be present during tooth mineralisation to ‘improve’ the biological apatite and the ‘caries resistance’ of the teeth, systemic fluoride administration was necessary for maximum benefit. Caries reduction therefore had to be balanced against increasing dental fluorosis. The ‘caries resistance’ concept was shown to be erroneous 25 years ago, but the new paradigm is not yet fully adopted in public health dentistry, so we still await real breakthroughs in more effective use of fluorides for caries prevention. The second paradigm is that caries is a transmittable, infectious disease: even one caused by specific microorganisms. This paradigm would require caries prevention by vaccination, but there is evidence that caries is not a classical infectious disease. Rather it results from an ecological shift in the tooth-surface biofilm, leading to a mineral imbalance between plaque fluid and tooth and hence net loss of tooth mineral. Therefore, caries belongs to common ‘complex’ or ‘multifactorial’ diseases, such as cancer, cardiovascular diseases, diabetes, in which many genetic, environmental and behavioural risk factors interact. The paper emphasises how these paradigm changes raise new research questions which need to be addressed to make caries prevention and treatment more cost-effective.

A new understanding of the relationship between sugars, dental caries and fluoride use: implications for limits on sugars consumption

“…The most remarkable data on the relationship between dietary sugars and caries in man come from the meticulous sequential studies in Japan (15)(16)(17)(18)(19)(20) where it became clear that the dose-response relationship is log-linear or arithmetically curvilinear even though the diagnostic level of caries used was cavitation; a late stage of caries (39) . There is no evident threshold for sugars below which there are no adverse effects.…”

Inhibition of Streptococcus mutans biofilm formation, extracellular polysaccharide production, and virulence by an oxazole derivative

“…However, without targeting and reducing dental plaque, fluoride products are unable to completely inhibit dental caries (Fejerskov 2004). Natural products and derivatives, such as green tea catechins (Hirasawa et al 2006), cranberry constituents , Galla chinensis (Xie et al 2008), citrus lemon oil (Liu et al 2013), mushroom extracts (Yano et al 2010), and several bioactive macromolecules (Shang et al 2014;Lee and Park 2015), have been reported to be effective against the growth and adherence of S. mutans.…”

Therapeutic potential of Brazilian fluoride varnishes: an in vivo study

“…Dental caries is a multifactorial disease defined as a result of loss of mineral leading to dissolution of dental hard tissues by substantial pH fluctuations within the biofilm on the tooth surface (1)(2)(3).…”