The effect of lesion characteristics at baseline on subsequent de- and remineralisation behaviour

The aim was to study the effect of lesion characteristics at baseline on subsequent de- and remineralisation behaviour. Artificial lesions used during in vitro and intra-oral studies exhibit an increasing tendency toward net remineralisation with increasing integrated mineral loss at baseline (DeltaZ(base)). Proposed explanations include: (i) small lesions may be more vulnerable to demineralisation, and (ii) large lesions may be more difficult to remineralise. To evaluate these hypotheses, subsurface lesions were created in numerous blocks of human and bovine enamel, with a range of depths and DeltaZ(base), measured by microradiography. One group of lesions was further demineralised, a second group remineralised, and subsequently, both groups re-analysed. Under demineralising conditions, there was a marked decrease in further mineral loss with increasing DeltaZ(base). Under remineralising conditions lesions gained mineral in proportion to DeltaZ(base). The decrease in demineralisation of lesions with larger DeltaZ(base) may be partially a result of decreased intrinsic solubility through modified chemical composition, e.g. loss of magnesium, carbonate etc. The results may explain the tendency toward net remineralisation with increasing DeltaZ(base) in pH-cycling regimes.