Fluoride Distribution and the Incremental Line in Human Cementum

Abstract

The effect of the incremental line of human cementum on the distribution of fluoride was examined by abrasive micro-sampling (Weatherell et al., 1985) and the histological observation. The cementum materials used were removed from subjects aged 42 to 61 years old. Two mesiodistal sections about 300μm thick were cut parallel to the longitudinal axis of the mesio-buccal roots. A sliced section of the unexposed cementum near the apex was observed after staining with hematoxylin to provide a detailed histological picture. Phosphorus distributions were also determined by X-ray micro-analysis of one of the remaining portions of the root. Layers of cementum were removed from the other specimen by abrasive microsampling. Fluoride and phosphorus concentrations were determined with a fluoride electrode (Hallsworth et al., 1976) and the colourimetric procedure of Chen et al. (1956).
The results were as follows;
1) The incremental line of cementum was observed in every cementum examined. Phosphorus concentration was relatively high at the incremental line.
2) The fluoride concentration did not coincide with the incremental line at the external layers of the tissue. However, it decreased markedly towards the interior of the tissue.
3) Fluoride concentration tended to be high at the incremental line, as was the phosphorus concentration, but showed a greater variation than that of phosphorus.
4) It was concluded that the fluoride concentration was high on the incremental line probably due to cementum growth and its relatively high mineral content.