Quantifying the volume of a foreign liquid infiltrated into carious enamel. Part I

Quantification of the volume of a foreign liquid into enamel has challenged scientists for almost a century. Darling et al. (Arch Oral Biol, 1961) were the first to present a semi-quantitative approach to quantify the volume infiltrated by quinoline and alcohols of different molecular sizes. There still remained a limitation related to the fact that the measured volumes were relative, not absolute. They could not sum the volume of the foreign liquid and the mineral volume and yield 100% of the enamel volume. Their mineral volume data were not determined experimentally.

  The figure shown below illustrates a natural enamel caries lesion under water and air immersion. Under air, most of the surface layer and body of the lesion get opaque so that no birefringence can be measured. How to measure firmly and loosely bound water volumes? This problem has been recently solved by Meira et al. (Arch Oral Biol, 2015; http://dx.doi.org/10.1016/j.archoralbio.2015.03.001). Poole at al (Nature, 1961) and Darling et la (Arch Oral Biol, 1961) discussed that opacity in the body of the lesion was one of the main reasons why their measurements were from the dark zone. To solve the problem, the volume of water removed by drying (loosely bound water volume) have to measured in opaque enamel. This the volume that can be filled by the foreign liquid. The solution will be discussed later in a future post.