Chemical Wear (Erosive Tooth Wear)

The chemical dissolution of mineralized tooth substance can be caused by acid originating from either intrinsic or extrinsic sources. Acids of intrinsic source, coming from hydrochloric acid produced by the parietal cells in the stomach, cause ETW by gastric acid reaching the oral cavity and the teeth, and acting regularly on the mineralized tooth substance over a period of time. This may be the result of chronic vomiting, persistent regurgitation, or rumination. The acidity of the gastric juice ranges from pH 1 to 3, so it is conceivable that regurgitation or vomiting into the mouth might result in marked tooth destruction in the form of ETW. Conditions which are associated with chronic vomiting or regurgitation and therefore can predispose an individual to the risk of erosion are (a) certain medical conditions, such as gastro-esophageal reflux disease (GERD), bulimia nervosa, anorexia nervosa, cyclic vomiting syndrome (CVS), psychogenic vomiting syndrome, pregnancy-induced vomiting and (b) certain lifestyles, such as Chronic alcoholism and Binge drinking. Acids of extrinsic sources come from (a) items that are ingested, such as acidic food and beverages, (b) occupational related, (c) medications, and (d) certain lifestyles.

However, regardless of the origin of the acid, the effect is the same: a low pH environment in the oral cavity. The initial reaction is that enamel first undergoes softening, the loss of mineral from a layer extending a few micrometers below the surface. As softening progresses over time, dissolution can completely remove portions of enamel, or the whole enamel layer, exposing the dentin underneath. When dentin is exposed to acid, first there is dissolution at the junction of the peritubular and intertubular dentin. Next, there is loss of the peritubular dentin and widening of the tubule lumina. Finally, there is the formation of a demineralized collagenous mix that provides some protection of the underlying tissue. However, this layer is also vulnerable to damage and can ultimately be eroded away as well.⁸