Yukitaro Sakakibara

Distribution of fluoride across human dental enamel, dentine and cementum

This was determined across the entire width of sections from 20 mandibular premolars, containing enamel, coronal dentine, root dentine and cementum. An abrasive technique was used to sample all three dental tissues in a single experiment. In the profiles of fluoride distribution, fluoride concentration was thus precisely related to the position of the tissue sample. There was a marked increase in the fluoride content of coronal and root dentine, at least until the age of about 50 years. There had been uptake of fluoride by the root dentine and cementum throughout the life of the tooth. There was no evidence of any change in the fluoride content of enamel with age.

Fluoride distribution and histological structure of human cementum

Thirty-one teeth taken post-mortem from 10 subjects aged from 40 to 66 years were studied. A close relationship was found between fluoride (F) distribution and histological structure. Although, as in all mineralized tissues, F concentrations tended to be highest towards the external surface, individual patterns of F distribution also seemed to reflect the histological pattern, especially the distribution of cellular or acellular cementum. In general, F concentrations were high in acellular and low in cellular cementum.

The distribution pattern of fluoride concentrations in human cementum.

The distribution of fluoride across human cementum has been determined on 59 individual teeth taken post mortem from five subjects aged 30, 43, 54, 66 and 70 years. Eight teeth of different types were examined from each of the five subjects together with a further 19 teeth from the 54-year-old, making a total of 27 teeth from this subject. As in a previous study, F concentrations were generally higher towards the surface of the cementum, but there were considerable variations between F gradients. The teeth from each subject seemed to comprise a family of profiles, characteristic of the individual.

Distribution of fluoride in the enamel of rat incisors examined by an abrasive microsampling technique

This study was undertaken to reveal detailed changes in fluoride distribution at different developmental stages of upper incisor enamel under various fluoride administration regimes. Four groups of Wistar rats received water containing 0, 25, 50 and 100 parts/10(6) fluoride respectively for 10 weeks. Five different enamel specimens were removed from the developing enamel, excluding the matrix-formation stage. Fluoride distribution in each specimen was analysed from the surface to the enamel-dentine junction using an abrasive microsampling technique. Fluoride concentration was invariably highest at the surface and decreased sharply towards the interior at every site in both control and experimental groups. The concentration throughout the tissue increased with fluoride intake at each stage of development. The fluoride-gradient curves were similar at each of the different sites of tooth development. However, the fluoride concentration of the enamel interior was significantly higher at early maturation than at the other four sites.

The dissolution rate of enamel in acid in developing rat incisors.

This study was undertaken to determine the changes in this dissolution rate at different developmental stages after different fluoride dietary regimes. Four groups of Wistar rats received water with 0, 25, 50 and 100 parts/10(6) fluoride respectively for 10 weeks. Six exposed windows of 2 mm2 were prepared on the enamel surface of the upper incisors, corresponding to six different developmental stages. The acid-dissolution rates were determined at each window by using 1.4 M sodium acetate-hydrochloric acid buffer (pH 2.3). The rate of enamel dissolution was highest in the matrix-formation stage and dropped sharply in a step-wise fashion towards the stages of secondary mineralization and iron deposition. The dissolution rate in the maturation stage decreased significantly with increasing intake of fluoride. However, in the pigmented enamel, the opposite occurred. The iron pigmentation or the porosity in this region of fluorosed enamel might be responsible for the change in the dissolution rate of the pigmented enamel.