Early enamel lesion

The initial enamel lesion results when the pH level at the tooth surface is lower than that which can be counterbalanced by remineralisation in depth, but is not low enough to inhibit surface remineralisation. The acid ions penetrate deeply into the prism sheath porosities leading to subsurface demineralisation. The tooth surface may remain intact because remineralisation occurs preferentially at the surface due to increased levels of Ca2+ and HPO43- ions, fluoride ions, and buffering by salivary products.

The clinical characteristics of these lesions include

1. loss of normal translucency of enamel with a chalky white appearance, particularly when dehydrated.

2. a fragile surface layer susceptible to damage from probing, particularly in pits and fissures.

3. increased porosity, particularly of the subsurface with increased potential for uptake of stain

4. reduced density of the subsurface, which may be detectable radiographically or with transillumination.

5. a potential for remineralisation, with an increased resistance to further acid challenge particularly with the use of enhanced remineralisation treatments

The size of the sub-surface lesion may progress until the underlying dentine becomes involved and demineralised. Interproximal lesions, will then become detectable radiographically. Even so, the surface of the tooth may remain intact, and the lesion may still be reversible.

In reversing incipient enamel lesions, the ideal is to regain the original density of enamel. In reality, there may be only partial replacement of subsurface density. Even so the partially remineralised incipient lesion in the enamel will be more resistant to further acid demineralisation than normal enamel and physically stronger as well. Hence, it is preferable, where the patient is maintaining good home care, to observe the lesion over time rather than restore immediately and deny possible remineralisation.