Dental erosion Caries initially presents as a sub-surface lesion caused by organic acids in the overlying plaque. This lesion may then cavitate and spread to give the characteristic lesion such as the one shown above. Erosion is a surface event caused by frequent exposure of the tooth to acidic conditions. Excessive consumption of carbonated drinks can cause erosion as can frequent vomiting. A small rise in pH as a result of, say, increased flow rate when the bicarbonate concentration rises dramatically can be enough to instigate calcium phosphate precipitation.
Salivary bicarbonate is in equilibrium with the intra-oral gaseous carbon dioxide.
At elevated concentrations it can be rapidly lost with a resulting drop in salivary pH. The highest bicarbonate concentrations are found adjacent to the openings of the salivary ducts where an equilibrium has not had chance to establish. This, therefore, is the region where salivary calcium phosphate is at its most unstable. The calcium phosphate precipitates in these regions, helped by certain plaque bacteria which can act as nucleating centres and further de-stabilising the system. This is advanced dental calculus which has formed on the buccal surfaces of anterior teeth in the region of the opening of the submandibular-sublingual salivary glands. Fluoride and remineralisation The profound effect of fluoride on reducing the incidence of caries is well documented.