Papers by Author: D. Das

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Authors: T.M. Sridhar, A. Kishen, S. Shanmugaraj, R. Praveen, S.K. Srinivas, D. Das, A. Subbiya
Abstract: Human teeth has “structure” and yet is mostly treated as material. Differentiation between material and structure is crucial to understand complex biological material such as human dentine. The aim of the present work is to determine the bioceramic gradient phases of the crystal structure of the teeth across the crown and root region with age. Around 50 samples of teeth of different age groups were collected, decontaminated and sintered at 400, 600 and 800°C. After removal of the enamel the root and crown regions were machined and characterized for their vibrational states by FTIR investigations. The studies indicate the presence of hydroxyapatite as the major phase after sintering along with the typical hydroxyl peaks. A weight loss ranging from 7 - 42 % after sintering at 400 and 800°C respectively was observed across the different age groups. A through analysis would provide us an understanding in studying the desired nature of the teeth and kinetics of tooth mineralization.
Authors: T.M. Sridhar, R. Praveen, S. Shanmugaraj, S.K. Srinivas, D. Das
Abstract: Bone is a complicated heterogeneous, viscoelastic, anisotropic material. Its properties depend on the nature of mechanical forces in addition to the location as well as the age, sex and race of the subject. Human humerus bones retrieved from cadavers were selected and separated in to cortical and cancellous parts. They were heat treated at different temperatures 400°C, 600°C and 800°C respectively to study the crystalline nature and composition of cortical and cancellous region of the humerus bone separately. Hydroxyapatite (HAP) was present as the major phase in the bone powders at 600 and 800°C with well resolved peaks along with other mineral phases of calcium phosphate. No amorphous phases were present indicating that the crystal structure of calcium phosphate compounds is present in crystalline form. FTIR studies further confirm the presence of phosphate vibrational modes of the entire bone mineral along with the presence of carbonates and hydroxyl groups.
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