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Reyes‐Gasga, J.; Álvarez-Fregoso, O.; Chávez-Carvayar, José Álvaro; Vargas-Ulloa, Laura

doi:10.1023/a:1004540617013

Cited by 14 publications

(10 citation statements)

References 5 publications

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“…Fereira et al (2008), in analysing enamel and dentin samples calcined between 20°C and 1150°C observed that a slow heating minimises fracture damage. In addition to this, Reyes-Gasga et al (1999) reported the insulator-conductor transition in human tooth enamel around 350°C in air.…”

Section: Introductionmentioning

confidence: 77%

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Reyes‐Gasga¹,

Becerril²

2019

Journal of Microscopy

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Summary Samples of enamel and dentin from human molar teeth were heated in air from room temperature (25°C) up to 1200°C and the phase transition from hydroxyapatite (HAP) to tricalcium phosphate (β‐TCP) was recorded. The changes produced in morphology and chemical composition in the tooth during heating were analysed by light microscopy, scanning electron microscopy (SEM), characteristic x‐ray energy dispersion spectroscopy (EDS), x‐ray diffraction (XRD), electron diffraction, transmission electron microscopy (TEM) and high‐resolution electron microscopy (HRTEM). The results indicated a high correlation relationship among Ca content, P content, O content and Na content, and the existence of the Kirkendall effect during the HAP‐ β‐TCP phase transition. Lay Description This work is related with tooth materials. Samples of enamel and dentine from human molar teeth were heated in air from 25°C up to 1200°C and the phase transition from hydroxyapatite (HAP) to tricalcium phosphate (β‐TCP) was recorded. The β‐TCP phase is also known as whitlockite. The changes produced in morphology and chemical composition in the tooth during heating were analysed by electron microscopy and X‐ray diffraction. The results indicated a high correlation relationship among Ca, P, O and Na contents, and the existence of the Kirkendall effect, the atomic diffusion producing voids, during the HAP‐ β‐TCP phase transition.

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Section: Introductionmentioning

confidence: 77%

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Reyes‐Gasga¹,

Becerril²

2019

Journal of Microscopy

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“…Fereira et al [14] analyzed bulk tooth samples in the range 20˚C to 1150˚C and observed that teeth gradually heated in air showed minimal damage by fracture, but with fast heating dentin and enamel are abruptly separated at the enamel-dentin junction and the fracture damage is severe. In addition, Reyes-Gasga et al [15] reported a dielectric-conductive transition in human tooth enamel above 250˚C in air and in vacuum.…”

Section: Introductionmentioning

confidence: 99%

Structural Changes in Human Teeth after Heating up to 1200&deg;C in Argon Atmosphere

Vargas-Becerril¹,

Garcı́a-Garcı́a²,

Reyes‐Gasga³

2018

MSA

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The phase transformation of hydroxyapatite (HAP, Ca 10 (PO 4) 6 (OH) 2) to the beta tricalcium phosphate phase (β-TCP, β-Ca 3 (PO 4) 2) at 1100˚C is well known. However, in the case of human tooth, the HAP phase transformation is still an open area. For example, the CaO phase has sometimes been reported in the set of phases that make up the teeth. In this study, physical changes of human teeth when subjected to heat treatment in inert atmosphere (argon) were studied. The results were compared with those obtained in air atmosphere, from room temperature (25˚C) up to 1200˚C. Morphological changes were analyzed by light and scanning electron microscopy (SEM). The HAP to β-TCP phase transformation was followed in powder samples by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Heating of teeth results in the removal of organic material and structural water before the HAP to β-TCP phase transformation, the increment in hardness and the induced crystal growth. The percentage of the phases, crystal growth and lattice parameter variations as a function of temperature was quantified by Rietveld analysis. The black color was observed in dentin heated under argon atmosphere. Differences in expansivity produce fractures in dentin at 300˚C in argon and at 400˚C in air. In dentin, the coexistence of the HAP and β-TCP phases was observed after 800˚C in argon and after 600˚C in air; in enamel it was observed at 600˚C in argon compared with 400˚C in air. In general, the role played by the argon atmosphere during the thermal treatment of the teeth is to retard the processes observed in air.

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“…The inorganic material is mainly composed of a calcium phosphate mostly in the form of hydroxyapatite, Ca 10 (PO 4 ) 6 (OH 4 ) 2 with different crystallites. Enamel has been always observed as a non electrical conductive material; it is in fact an insulator at room temperature (Reyes-Gasgam et al, 1999). Dentin is made up of 70% inorganic materials, 20% organic materials and 10% water by weight; 90% of the organic material is collagen type 1 and the remaining 10% ground substance which includes dentine-specific proteins (Cate, 1998).…”

Section: Introductionmentioning

confidence: 99%

Structural and Dielectrical Properties of Sterilized Human Teeth

Eissa¹

2012

Physics International

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Problem statement:This study investigated the changes in crystallinity and dielectrical properties (conductivity) that could be demonstrated in extracted human teeth (enamel and dentin) subjected to γ-radiation at the sterilization dose (25 kGy). Approach: Twenty human third molar teeth were used in the study. Teeth were prepared so forty enamel and dentin samples were obtained. The samples were divided into two groups. The first group contains twenty samples of enamels. The second ones contains twenty samples of dentins. Each group was further subdivided into two subgroups (10 samples each), one for control while the other for irradiated samples. The X-ray Diffraction Pattern (XDR) studies for the control and irradiated enamel and dentin samples were carried out by X-ray diffractometer. In addition, the microhardness test for the present samples were investigated. Results: The crystallinity in irradiated enamel samples was better than that in dentin where the average crystallite size in enamel was larger than that in dentin. Also, it was found that the dielectrical conductivity for dentin increased with frequency after exposure to γ-radiation. Accordingly, the number and mobility of charge carriers were increased. Conclusion: Exposure of human teeth to gamma radiation at the sterilization dose decreases the hardness of both enamel and dentin.

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Cited by 14 publications

References 5 publications

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Structural Changes in Human Teeth after Heating up to 1200&deg;C in Argon Atmosphere

Structural and Dielectrical Properties of Sterilized Human Teeth

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Untitled

Cited by 14 publications

References 5 publications

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Electron microscopy analysis of the thermal phase transition from hydroxyapatita to β‐TCP observed in human teeth

Structural Changes in Human Teeth after Heating up to 1200&amp;deg;C in Argon Atmosphere

Structural and Dielectrical Properties of Sterilized Human Teeth

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Product

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Structural Changes in Human Teeth after Heating up to 1200°C in Argon Atmosphere