Microhardness and chemical composition of human tooth

Abstract

Hardness of human tooth, both in enamel and dentin, has been measured at different sites using a Vicker's diamond. In this work we show that these values are almost constant all along the enamel and dentin thicknesses. Indentations were done from outer enamel surface to inner dentin layer, going through the enamel-dentin junction, both in transverse and longitudinal samples. Geometrical well-shape indentation uniformity was checked both with light and with scanning electron microscopes, and the chemical composition of the tooth was analyzed with characteristic X-ray energy dispersive spectroscopy. Hardness measurements were in the range from 270 to 360 VHN for enamel and 50 to 60 VHN for dentin. Cervical zone in longitudinal section showed the lowest value while in transverse sections the highest. All the hardness values were statically significative. Tour results indicate that the difference between enamel and dentin hardness has nothing to do with the content of Na, Cl and Mg, but the percentage of organic and inorganic materials in enamel and dentin.

Effect of indentation load and time on knoop and vickers microhardness tests for enamel and dentin

“…For dentin, the hardness has been reported in the range of 52 to 64 KHN 14,19 or 46 to 53 VHN 15 . The standard deviation of hardness in this study showed a broad variation, similar to previous reports 16 . This broad variation of hardness values can be produced by factors such as specimen preparation, diagonal length reading error 16 , variation in chemical composition 20 , age, and location in the tooth 21 .…”

“…The standard deviation of hardness in this study showed a broad variation, similar to previous reports 16 . This broad variation of hardness values can be produced by factors such as specimen preparation, diagonal length reading error 16 , variation in chemical composition 20 , age, and location in the tooth 21 . In this study, the KHN and VHN values of enamel are in approximately the same range, while dentin obtained KHN values higher than VHN values for every variation of indentation load and time.…”

“…Therefore in a pre-post experimental study of, for instance, enamel erosion, it is necessary to apply a small load for a comparison between the baseline surface and the eroded surface for the same indentation load. Gutiérrez-Salazar and Reyes-Gasga 16 proposed that in tooth hardness studies the Vickers indenter is more useful than the Knoop because a square shape must always be conserved, and because the indentation produced on a non-flat surface, or by the difference in hardness of enamel and dentin, is easily detected. Meredith et al 17 reported that the Knoop has been the most popular method.…”

Evaluati̇on of Physi̇cal and Opti̇cal Properti̇es of Hybri̇d Cad/Cam Materi̇als

“…İçeriğinde rezin miktarı az olan Enamic ile rezin bulundurmayan Suprinity malzemelerinin ise yaşlandırma sonucu yüzey sertliği değişmemiştir. Ayrıca 270-360 VHN olan mine sertliğine 6 en yakın malzeme, 262 VHN ile Enamic olarak tespit edilmiştir. Dental materyallerin yüzey sertlikleri, aşınma dirençleri ile ilişkili olduğundan yaşlandırma sonrası yüzey sertliğinin değişmesi malzemenin kullanımı sırasında aşınabileceğini gösterebilir.…”

“…5 Eğer malzeme mine ile temas ediyorsa yüzey sertliğinin 270-360 VHN 'ye yakın olması ve değişmemesi beklenmektedir. 6 Dental materyallerin yüzey pürüzlülüğü ve sertliği gibi optik özellikleri de zamanla değişebilmektedir.…”