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S J Marshall - One of the best experts on this subject based on the ideXlab platform.
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Peritubular Dentin lacks piezoelectricity
Journal of Dental Research, 2007Co-Authors: Stefan Habelitz, B. J. Rodriguez, S J Marshall, Sergei V Kalinin, G W Marshall, Alexei GruvermanAbstract:Dentin is a mesenchymal tissue, and, as such, is based on a collagenous matrix that is reinforced by apatite mineral. Collagen fibrils show piezoelectricity, a phenomenon that is used by piezoresponse force microscopy (PFM) to obtain high-resolution images. We applied PFM to image human Dentin with 10-nm resolution, and to test the hypothesis that zones of piezoactivity, indicating the presence of collagen fibrils, can be distinguished in Dentin. Piezoelectricity was observed by PFM in the Dentin Intertubular matrix, while the peritubular Dentin remained without response. High-resolution imaging of chemically treated Intertubular Dentin attributed the piezoelectric effect to individual collagen fibrils that differed in the signal strength, depending on the fibril orientation. This study supports the hypothesis that peritubular Dentin is a non-collagenous tissue and is thus an exception among mineralized tissues that derive from the mesenchyme.
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Local mechanical and optical properties of normal and transparent root Dentin
Journal of Materials Science: Materials in Medicine, 2001Co-Authors: M. Balooch, J H Kinney, G W Marshall, S. G. Demos, G. Balooch, S J MarshallAbstract:The mechanical and optical properties of healthy and transparent root Dentin are compared using atomic force microscopy (AFM), micro-Raman and emission spectroscopies and fluorescence microscopy. The elastic modulus and hardness of Intertubular and peritubular transparent and healthy Dentin did not differ appreciably. The tubule filling material in the transparent zone, however, exhibited values between peritubular and Intertubular Dentin. Raman spectroscopy revealed a shift in the 1066 cm^−1 band to 1072 cm^−1 from normal to transparent Intertubular Dentin. The material filling the tubule lumen in transparent Dentin showed an increase in frequency of the band near 1070 cm^−1 as well. The emission spectral characteristics under 351 nm photoexcitation indicate differences between normal and transparent Intertubular Dentin. A transition region of about 300 μm between normal and transparent Dentin was identified. In this region the Intertubular emission properties were the same as for normal Dentin, but tubules were filled. The filling material had emission characteristics closer to the normal Intertubular than to transparent Intertubular Dentin. © 2001 Kluwer Academic Publishers
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Collagen orientation and crystallite size in human Dentin: A small angle X-ray scattering study
Calcified Tissue International, 2001Co-Authors: J H Kinney, John A. Pople, G W Marshall, S J MarshallAbstract:The mechanical properties of Dentin are largely determined by the Intertubular Dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. We performed a small angle X-ray scattering (SAXS) study on fully mineralized human Dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the Dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-Dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the Dentino-enamel junction. The thickness of these crystallites, approximately 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of Dentinogenesis and maturation.
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Mineral Distribution and Dimensional Changes in Human Dentin during Demineralization
Journal of Dental Research, 1995Co-Authors: John H. Kinney, S J Marshall, Mehdi Balooch, D. L. Haupt, Grayson W. MarshallAbstract:Many bonding agents require the Dentin surface to be acid-etched prior to being bonded. Understanding the stability and morphology of the etched Dentin surface is important for improving bond strength and reliability in these systems. In this study, the atomic force microscope was used to quantify dimensional changes that occur to fully hydrated Dentin during demineralization with a pH 4.0 lactic acid gel. A high-resolution microtomography instrument, the x-ray tomographic microscope, was also used to quantify the mineral density distribution in the Dentin as a function of etching time. The Intertubular Dentin surface shrank by less than 0.5 μm during etching, while the peritubular Dentin receded at an initially rapid linear rate. The Dentin surface retained its initial morphology, although it was more porous with the removal of the peritubular Dentin. Beneath the etched surface, there were three major zones characterized by mineral density differences. The first zone was a fully demineralized collagen la...
J H Kinney - One of the best experts on this subject based on the ideXlab platform.
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collagen orientation and crystallite size in human Dentin a small angle x ray scattering study
Calcified Tissue International, 2001Co-Authors: J H Kinney, John A. Pople, G W Marshall, Sally J. MarshallAbstract:The mechanical properties of Dentin are largely determined by the Intertubular Dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. The authors perform a small angle x-ray scattering (SAXS) study on fully mineralized human Dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the Dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-Dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the Dentino-enamel junction. The thickness of these crystallites, {approx} 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of Dentinogenesis and maturation.
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Local mechanical and optical properties of normal and transparent root Dentin
Journal of Materials Science: Materials in Medicine, 2001Co-Authors: M. Balooch, J H Kinney, G W Marshall, S. G. Demos, G. Balooch, S J MarshallAbstract:The mechanical and optical properties of healthy and transparent root Dentin are compared using atomic force microscopy (AFM), micro-Raman and emission spectroscopies and fluorescence microscopy. The elastic modulus and hardness of Intertubular and peritubular transparent and healthy Dentin did not differ appreciably. The tubule filling material in the transparent zone, however, exhibited values between peritubular and Intertubular Dentin. Raman spectroscopy revealed a shift in the 1066 cm^−1 band to 1072 cm^−1 from normal to transparent Intertubular Dentin. The material filling the tubule lumen in transparent Dentin showed an increase in frequency of the band near 1070 cm^−1 as well. The emission spectral characteristics under 351 nm photoexcitation indicate differences between normal and transparent Intertubular Dentin. A transition region of about 300 μm between normal and transparent Dentin was identified. In this region the Intertubular emission properties were the same as for normal Dentin, but tubules were filled. The filling material had emission characteristics closer to the normal Intertubular than to transparent Intertubular Dentin. © 2001 Kluwer Academic Publishers
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Collagen orientation and crystallite size in human Dentin: A small angle X-ray scattering study
Calcified Tissue International, 2001Co-Authors: J H Kinney, John A. Pople, G W Marshall, S J MarshallAbstract:The mechanical properties of Dentin are largely determined by the Intertubular Dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. We performed a small angle X-ray scattering (SAXS) study on fully mineralized human Dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the Dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-Dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the Dentino-enamel junction. The thickness of these crystallites, approximately 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of Dentinogenesis and maturation.
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atomic force microscope measurements of the hardness and elasticity of peritubular and Intertubular human Dentin
Journal of Biomechanical Engineering-transactions of The Asme, 1996Co-Authors: J H Kinney, G W Marshall, M. Balooch, Sally J. Marshall, Timothy P WeihsAbstract:: An atomic force microscope was used to measure the hardness and elasticity of fully-hydrated peritubular and Intertubular human Dentin. The standard silicon nitride AFM tip and silicon cantilever assembly were replaced with a diamond tip and stainless steel cantilever having significantly higher stiffness. Hardness was measured as the ratio of the applied force to the projected indentation area for indentations with depths from 10-20 nm. The sample stiffness was measured by imaging specimens in a force-modulated mode. Hardness values of 2.3 +/- 0.3 GPa and 0.5 +/- 0.1 GPa were measured for the peritubular and Intertubular Dentin, respectively. Stiffness imaging revealed that the elastic modulus of the peritubular Dentin was spatially homogeneous; whereas, there was considerable spatial variation in the elasticity of the Intertubular Dentin. The atomic force microscope can be used to measure the mechanical properties of fully hydrated calcified tissues at the submicron level of spatial resolution, thus augmenting more traditional depth sensing probes.
Jerome D. Adey - One of the best experts on this subject based on the ideXlab platform.
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Effect of calcium hydroxide and four irrigation regimens on instrumented and uninstrumented canal wall topography.
Journal of Endodontics, 1999Co-Authors: Cynthia T. Tatsuta, Leslie A. Morgan, J. Craig Baumgartner, Jerome D. AdeyAbstract:The topography of instrumented and uninstrumented canal walls exposed to calcium hydroxide and four different irrigation regimens was observed by scanning electron microscopy. After chemomechanical debridement, one tooth in each matched pair was medicated with calcium hydroxide. One week later, the teeth were irrigated and split longitudinally for evaluation. When no calcium hydroxide was used, preDentin and pulpal debris covered the Dentinal tubules of the uninstrumented surfaces in specimens irrigated with water or EDTA, but was absent on uninstrumented surfaces in specimens irrigated with NaOCl or NaOCl and EDTA. A typical smear layer was absent in instrumented specimens irrigated with NaOCl and EDTA, but covered the Dentinal tubules of the instrumented surfaces of the EDTA irrigated specimens (partially) and the water or NaOCl irrigated specimens (completely). Calcospherites or their remnants were seen on the uninstrumented canal walls of specimens irrigated with NaOCl or NaOCl and EDTA, respectively. Calcium hydroxide use did not alter the surface topography in specimens irrigated with water, EDTA, or NaOCl, but seemed to erode the Intertubular Dentin in specimens irrigated with NaOCl and EDTA. All irrigants seemed to effectively remove most of the calcium hydroxide.
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Effect of calcium hydroxide and four irrigation regimens on instrumented and uninstrumented canal wall topography
Journal of Endodontics, 1999Co-Authors: Cynthia T. Tatsuta, Leslie A. Morgan, J. Craig Baumgartner, Jerome D. AdeyAbstract:The topography of instrumented and uninstrumented canal walls exposed to calcium hydroxide and four different irrigation regimens was observed by scanning electron microscopy. After chemomechanical debridement, one tooth in each matched pair was medicated with calcium hydroxide. One week later, the teeth were irrigated and split longitudinally for evaluation. When no calcium hydroxide was used, preDentin and pulpal debris covered the Dentinal tubules of the uninstrumented surfaces in specimens irrigated with water or EDTA, but was absent on uninstrumented surfaces in specimens irrigated with NaOCl or NaOCl and EDTA. A typical smear layer was absent in instrumented specimens irrigated with NaOCl and EDTA, but covered the Dentinal tubules of the instrumented surfaces of the EDTA irrigated specimens (partially) and the water or NaOCl irrigated specimens (completely). Calcospherites or their remnants were seen on the uninstrumented canal walls of specimens irrigated with NaOCl or NaOCl and EDTA, respectively. Calcium hydroxide use did not alter the surface topography in specimens irrigated with water, EDTA, or NaOCl, but seemed to erode the Intertubular Dentin in specimens irrigated with NaOCl and EDTA. All irrigants seemed to effectively remove most of the calcium hydroxide. Copyright © 1999 by The American Association of Endodontists.
G W Marshall - One of the best experts on this subject based on the ideXlab platform.
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Peritubular Dentin lacks piezoelectricity
Journal of Dental Research, 2007Co-Authors: Stefan Habelitz, B. J. Rodriguez, S J Marshall, Sergei V Kalinin, G W Marshall, Alexei GruvermanAbstract:Dentin is a mesenchymal tissue, and, as such, is based on a collagenous matrix that is reinforced by apatite mineral. Collagen fibrils show piezoelectricity, a phenomenon that is used by piezoresponse force microscopy (PFM) to obtain high-resolution images. We applied PFM to image human Dentin with 10-nm resolution, and to test the hypothesis that zones of piezoactivity, indicating the presence of collagen fibrils, can be distinguished in Dentin. Piezoelectricity was observed by PFM in the Dentin Intertubular matrix, while the peritubular Dentin remained without response. High-resolution imaging of chemically treated Intertubular Dentin attributed the piezoelectric effect to individual collagen fibrils that differed in the signal strength, depending on the fibril orientation. This study supports the hypothesis that peritubular Dentin is a non-collagenous tissue and is thus an exception among mineralized tissues that derive from the mesenchyme.
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collagen orientation and crystallite size in human Dentin a small angle x ray scattering study
Calcified Tissue International, 2001Co-Authors: J H Kinney, John A. Pople, G W Marshall, Sally J. MarshallAbstract:The mechanical properties of Dentin are largely determined by the Intertubular Dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. The authors perform a small angle x-ray scattering (SAXS) study on fully mineralized human Dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the Dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-Dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the Dentino-enamel junction. The thickness of these crystallites, {approx} 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of Dentinogenesis and maturation.
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Local mechanical and optical properties of normal and transparent root Dentin
Journal of Materials Science: Materials in Medicine, 2001Co-Authors: M. Balooch, J H Kinney, G W Marshall, S. G. Demos, G. Balooch, S J MarshallAbstract:The mechanical and optical properties of healthy and transparent root Dentin are compared using atomic force microscopy (AFM), micro-Raman and emission spectroscopies and fluorescence microscopy. The elastic modulus and hardness of Intertubular and peritubular transparent and healthy Dentin did not differ appreciably. The tubule filling material in the transparent zone, however, exhibited values between peritubular and Intertubular Dentin. Raman spectroscopy revealed a shift in the 1066 cm^−1 band to 1072 cm^−1 from normal to transparent Intertubular Dentin. The material filling the tubule lumen in transparent Dentin showed an increase in frequency of the band near 1070 cm^−1 as well. The emission spectral characteristics under 351 nm photoexcitation indicate differences between normal and transparent Intertubular Dentin. A transition region of about 300 μm between normal and transparent Dentin was identified. In this region the Intertubular emission properties were the same as for normal Dentin, but tubules were filled. The filling material had emission characteristics closer to the normal Intertubular than to transparent Intertubular Dentin. © 2001 Kluwer Academic Publishers
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Collagen orientation and crystallite size in human Dentin: A small angle X-ray scattering study
Calcified Tissue International, 2001Co-Authors: J H Kinney, John A. Pople, G W Marshall, S J MarshallAbstract:The mechanical properties of Dentin are largely determined by the Intertubular Dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. We performed a small angle X-ray scattering (SAXS) study on fully mineralized human Dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the Dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-Dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the Dentino-enamel junction. The thickness of these crystallites, approximately 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of Dentinogenesis and maturation.
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atomic force microscope measurements of the hardness and elasticity of peritubular and Intertubular human Dentin
Journal of Biomechanical Engineering-transactions of The Asme, 1996Co-Authors: J H Kinney, G W Marshall, M. Balooch, Sally J. Marshall, Timothy P WeihsAbstract:: An atomic force microscope was used to measure the hardness and elasticity of fully-hydrated peritubular and Intertubular human Dentin. The standard silicon nitride AFM tip and silicon cantilever assembly were replaced with a diamond tip and stainless steel cantilever having significantly higher stiffness. Hardness was measured as the ratio of the applied force to the projected indentation area for indentations with depths from 10-20 nm. The sample stiffness was measured by imaging specimens in a force-modulated mode. Hardness values of 2.3 +/- 0.3 GPa and 0.5 +/- 0.1 GPa were measured for the peritubular and Intertubular Dentin, respectively. Stiffness imaging revealed that the elastic modulus of the peritubular Dentin was spatially homogeneous; whereas, there was considerable spatial variation in the elasticity of the Intertubular Dentin. The atomic force microscope can be used to measure the mechanical properties of fully hydrated calcified tissues at the submicron level of spatial resolution, thus augmenting more traditional depth sensing probes.
Sally J. Marshall - One of the best experts on this subject based on the ideXlab platform.
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Structure and Properties of Murine and Human Dentin
MRS Proceedings, 2020Co-Authors: Stefan Habelitz, Grayson W. Marshall, Mehdi Balooch, Sally J. Marshall, Shabnam Zartoshtimanesh, Pamela K. DenbestenAbstract:AbstractMice are commonly considered the model mammal for many biomedical studies. In this work, mouse and human Dentin were compared to specify structural and mechanical differences to establish a baseline for comparison of dental tissues between these species. Atomic force microscopy revealed tubules of about 1.0 to 1.6 μm in diameter as the main structural feature in Dentin of both species. Nanoindentation yielded the elastic modulus about 15% lower in murine Intertubular Dentin while the hardness was almost equal. Dynamic stiffness mapping confirmed the lower elastic properties and also revealed that the peritubular region of increased mineralization around tubules is drastically reduced or maybe absent in murine Dentin of this age. This study suggests that structural and mechanical differences need to be considered when murine Dentin is used as a model system.
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Nanomechanical properties of endodontically treated teeth.
Journal of Endodontics, 2011Co-Authors: Robert A. Cheron, Sally J. Marshall, Harold E. Goodis, Ove A. PetersAbstract:Abstract Introduction Although it is apparent that teeth become more susceptible to fracture after root canal treatment, the contributing factors for this are not completely established. The purpose of this study was to determine whether there are changes in nanomechanical properties of Dentin in root canal–treated teeth compared with non–root canal–treated control teeth. Methods Atomic force microscopy–based nanoindentation testing was performed on root canal–treated teeth and age- and type-matched control teeth. Radicular Intertubular Dentin was indented in 6 locations, and triplicate measurements were averaged. Paired t tests were used to compare root canal–treated teeth with control teeth. Results The moduli of elasticity were 17.8 ± 2.9 GPa and 18.9 ± 2.9 GPa for root canal–treated teeth and controls, respectively; the hardness values for the 2 groups were 0.84 ± 0.25 GPa and 0.84 ± 0.18 GPa, respectively. Neither the modulus of elasticity nor the hardness differed between groups (P > .05). Conclusions It appears that root canal treatment does not result in nanomechanical changes to radicular Intertubular Dentin.
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Evaluation of a new modulus mapping technique to investigate microstructural features of human teeth
Journal of Biomechanics, 2004Co-Authors: Guive Balooch, Grayson W. Marshall, Sally J. Marshall, Oden L. Warren, S. A. Syed Asif, Mehdi BaloochAbstract:Abstract Teeth contain several calcified tissues with junctions that provide interfaces between dissimilar tissues. These junctions have been difficult to characterize because of their small size. In this work a new technique using a combination of atomic force microscopy (AFM) and a force–displacement transducer was used to simultaneously study the surface topography and map mechanical properties of the junctions and adjacent hard tissues. Prepared specimens from human third molars were scanned by an AFM piezo-tube in contact mode. To measure the dynamic viscoelastic properties of the material a small sinusoidal force was superimposed on the contact force and the resulting displacement amplitude and the phase shift between the force and amplitude were measured. This force modulation technique was used to map the local variation of nanomechanical properties of Intertubular Dentin, peritubular Dentin, enamel, Dentin–enamel junction (DEJ) and peritubular–Intertubular Dentin junction (PIJ). This new technique allowed us to measure the widths of these junctions in addition to local variation in Dentin and enamel without causing plastic deformation to the material and with 2 orders of magnitude increase in spatial resolution compared with previous studies that used discrete nanoindentation techniques. Due to the ability to analyze the sample line-by-line, the distribution functions associated with the width of the DEJ and PIJ were conveniently obtained for specific intratooth locations. The data suggested, for three third molar specimens, a DEJ width of 2–3 μm with full-width half-maximum (FWHM) of 0.7 μm and PIJ width of 0.5–1.0 μm with 0.3 μm FWHM. The Intertubular Dentin storage modulus variation was between 17 and 23 GPa with a mean value of 21 GPa. The range of storage modulus for enamel near the DEJ was between 51 and 74 GPa with a mean value of 63 GPa.
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Etching kinetics of a self-etching primer.
Biomaterials, 2002Co-Authors: Sofia A. Oliveira, Sally J. Marshall, Joan F. Hilton, Grayson W. MarshallAbstract:Self-etching primers are thought to offer significant advantages over total-etch adhesive systems. The hypothesis tested in this study was that there was no difference in etching characteristics between a self-etching primer and a phosphoric acid solution at the same pH. Etching was assessed using atomic force microscopy (AFM) evaluation of site-specific changes in the height of the peritubular and Intertubular Dentin as a function of exposure time. Human Dentin disks (n ¼ 6/group), prepared with an acid-resistant glass reference layer, were etched with a self-etching primer and with 0.0134 m phosphoric acid (both pHD1.94). Depth changes relative to the reference layer were measured with the AFM after each etching interval, at 15 different locations, each in the peritubular and Intertubular Dentin. The total demineralization depth was measured in a scanning electron microscope. Peritubular Dentin etching rate was linear while it could be measured (up to 15 s) and was greater for the self-etching primer (po0:0001). Intertubular Dentin displayed a similar demineralization pattern with both acids, ultimately reaching a plateau in the majority of specimens. The self-etching primer attained a plateau after less recession than phosphoric acid (po0:0001). Dentin demineralization appears to be affected by other factors in addition to the pH of the etchant solutions. r 2002 Elsevier Science Ltd. All rights reserved.
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Nanomechanical Properties of Hydrated Carious Human Dentin
Journal of Dental Research, 2001Co-Authors: Grayson W. Marshall, Stefan Habelitz, R. R. Gallagher, Mehdi Balooch, Guive Balooch, Sally J. MarshallAbstract:Most restorative materials are bonded to caries-affected Dentin that has altered structure. We tested the hypothesis that hydrated Dentin of the transparent zone did not have increased hardness or elastic modulus. Nanoindentation by modified AFM was used to determine site-specific elastic modulus and hardness for components of hydrated Dentin from 8 carious and non-carious human teeth. Indentations in Intertubular Dentin were made at intervals from pulp through the affected layers (subtransparent, transparent, and discolored zones). The values of Intertubular Dentin increased slightly from near the pulp into the transparent zone, then remained constant or decreased slightly through transparent Dentin (E, 18.3 GPa; H, 0.8 GPa; confirming the hypothesis), and decreased markedly through the discolored region. Peritubular Dentin values were unaltered in transparent Dentin, and intratubular mineral had values between those of normal peritubular and Intertubular Dentin. Superficial areas contained distorted tub...
