Ecological hypothesis of dentin and root caries

Key Points

• A selection of abstracts of clinically relevant papers from other journals.

• The abstracts on this page have been chosen and edited by John R. Radford.

Abstract

'...questionable whether bacteria play a role in the initial stages of the degradation of the organic components of teeth.'

Main

Takahashi N, Nyvad B. Caries Res 2016;50: 422–431

At the heart of this commentary, these authors refine what they refer to as their 'ecological caries hypothesis'; acid formation favours 'bacterial acid-induced adaptation and selection' that tilts the balance from remineralisation towards demineralisation. In the shaping of the hypothesis to include dentine and root caries, bacterial acidification 'induces the exposure of organic matrix and the activation of dentin-embedded and salivary MMPs (matrix metalloproteinases)/cathepsins.' These proteases, embedded within the dentine, begin the degradation of the organic components. Yet this has to be reconciled with the optimal pH for MMPs lying around neutral, although cathepsins are active under acidic conditions. Proteolytic bacteria, particularly Prevotella intermedia, have been isolated from dentine caries and may also contribute to dentine matrix degradation. This putative role of MMPs and cathepsins in dentinal caries would suggest novel approaches for prevention. Examples of MMP inhibitors are modified tetracyclines, zoledronate, chlorhexidine, silver diamine fluoride and various metal ions such as zinc.