Examinando por Autor "Montoya, C."

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    Effect of aging on the microstructure, hardness and chemical composition of dentin
    (PERGAMON-ELSEVIER SCIENCE LTD, 2015-12-01) Montoya, C.; Arango-Santander, S.; Peláez-Vargas, A.; Arola, D.; Ossa, E.A.; Montoya, C.; Arango-Santander, S.; Peláez-Vargas, A.; Arola, D.; Ossa, E.A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Objective: Understanding the effects of biological aging on human tissues has been a topic of extensive research. With the increase in healthy seniors and quality of life that topic is becoming increasingly important. In this investigation the effects of aging on the microstructure, chemical composition and hardness of human coronal dentin was studied from a comparison of teeth within ``young'' and ``old'' age groups. Methods: The microstructure of dentin within three regions (i.e., inner, middle and outer) was analyzed using electron and optical microscopy. The mineral-to-collagen ratio in these three regions was estimated using Raman spectroscopy and the hardness was evaluated using microindentation. Results: Results showed that there were significant differences in tubule density, tubule diameter and peritubular cuff diameter with depth. Although there was no difference in tubule density and diameter of the tubules between the age groups, there was a significant difference in the occlusion ratio. A significant increase in hardness between young and old patients was found for middle and outer dentin. An increase in mineral-to-collagen ratio from inner to outer dentin was also found for both groups. In old patients, an increase in mineral content was found in outer coronal dentin as a consequence of tubule occlusion. Conclusions: An increase in occlusion ratio, hardness, and mineral content was found in the dentin of adult patients with age. This increase is most evident in the outer coronal dentin. (C) 2015 Elsevier Ltd. All rights reserved.
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    Importance of tubule density to the fracture toughness of dentin
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016-07-01) Montoya, C.; Arola, D.; Ossa, E.A.; Montoya, C.; Arola, D.; Ossa, E.A.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Objective: The fracture toughness of dentin is critical to the prevention of tooth fracture. Within the tooth crown, the mechanical properties of dentin are influenced by spatial variations in the density and diameter of the dentin tubules with distance from the pulp. There are also relevant changes to the microstructure of dentin with age. In this investigation the importance of tubule density to the fracture toughness of dentin was evaluated in ``young'' and ``old'' age groups. Methods: The variations in microstructure (density and diameter of tubules) from young and old donor teeth were studied by means of optical microscopy. Results: A reduction in the density and diameter of tubules was identified to occur with aging. An approach previously proposed to study the mechanical behavior of porous materials was used to model the fracture toughness of coronal dentin in terms of the tubule characteristics. Results were then compared with published results from previous studies. Conclusions: The model predictions were consistent with experimental results for the fracture toughness of dentin from young donor teeth, but overestimated the values that have been reported for ``old'' dentin. (C) 2016 Elsevier Ltd. All rights reserved.