Differentiation of erosion and caries

Although both caries and erosion are at least partially acid driven processes, the causes, clinical and histological presentations and symptoms can be clearly differentiated. This explains why preventative and therapeutic approaches are different.

 

Erosion

Caries


Causes
Acids produced extra-orally (extrinsic and intrinsic)
Acids produced by bacteria within the oral cavity


Mechanisms
(ten Cate et al. 2008)
Tooth environment (direct contact):
  • Undersaturated with respect to hydroxyapatite
  • Undersaturated with respect to fluorhydroxyapatite and fluorapatite
  • pH below 4.0-4.5

Leading to:
  • Complete removal of outermost tooth surface layers in two steps:

    1. softening of tooth surface due to partial demineralisation
    2. destruction of tooth surface and tissue loss

Tooth environment (plaque fluid):

  • Undersaturated with respect to hydroxyapatite
  • Supersaturated with respect to fluorhydroxyapatite and fluorapatite
  • pH below 5.5

Leading to:
  • demineralisation below the intact tooth surface
  • This is due to formation of fluorhydroxyapatite and fluorapatite on the tooth surface

Clinically, the detection of tooth surface softening in the erosive lesion is not accessible by probing.