Abstract
The Distribution of fluoride in different dental tissues such as enamel, dentine, and cementum, of the same tooth could be important in evaluating the fluoride uptake during the life of tooth. However, there have been few studies reporting the complete distribution profiles of fluoride in three different hard tissues of the same tooth.
In the present study, the distribution of fluoride was examined across the entire width of enamel, dentine, and cementum of the same tooth section. Sections about 300gμm thick were prepared on the bucco-lingual aspect of 20 mandibular premolars from male individuals of different ages. Parallel blocks of tissues, about 1mm wide, extending from the surface of enamel or cementum across the dentine, were removed under a dissecting microscope using a thin diamond disk.
The specimems were then mounted vertically on brass rods. Using a Mikrokator, the layers of known thickness were serially removed by abrasion with a lapping film. The material was extracted from the abrasive surface with perchloric acid. Fluoride and phosphorous concentrations were determined as previously described (Weatherell et al. Caries Res 19: 97-102, 1985).
The results are summarized as follows:
1) Concentration of fluoride was the highest in the outermost layer of the enamel, and there was a marked decrease in concentration from the surface to a distance of 100-200μm. In the middle and inner third of the enamel, concentration tended to level off with a small increase at a distance of 50μm adjacent to the enamel dentine junction (EDJ).
2) A higher level of fluoride in the coronal dentine than in the enamel was observed at the enameldentine junction (EDJ), and it continued to a distance of about 300μm from the pulpal surface of the coronal dentine. There was a great increase of fluoride concentration in the coronal dentine near the pulp. The level of fluoride increased with age.
3) Fluoride concentration was maximal at or near the surface of the cementum and decreased toward the interior of the cementum. There were different types of fluoride distribution in the cementum. The level of fluoride concentration increased with age.
4) Concentration of fluoride decreased after cementum-dentine junction (CDJ), reached the lowest value in the middle of the root dentine, and rose again toward the surface of the pulpal dentine.
5) Although Total Fluoride, Average Fluoride, and Maximum Fluoride in the enamel showed no clear tendency of increase with age, those of the coronal dentine increased with age until a plateau was reached at about 50 years.
6) Increases in Total Fluoride, Average Fluoride, and Maximum Fluoride in both root dentine and cementum continued to a higher age of the tooth than in the coronal dentine. Particularly, Total Fluoride increased in the cementum more than in any other tissues examined.
7) It was concluded that, although the fluoride concentration in the enamel could have been changed due to its post-eruptive environment, the coronal dentine takes up fluoride from the pulp until about the age of 50 and the root dentine and the cementum take up fluoride from both the pulp and the periodontal ligament all during the life of the tooth.
