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Paulette Spencer - One of the best experts on this subject based on the ideXlab platform.
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fatigue life prediction of dentin Adhesive Interface using micromechanical stress analysis
Dental Materials, 2011Co-Authors: Viraj Singh, Anil Misra, Orestes Marangos, Jonggu Park, Qiang Ye, Sarah L Kieweg, Paulette SpencerAbstract:Abstract Objectives The objective of this work was to develop a methodology for the prediction of fatigue life of the dentin–Adhesive (d–a) Interface. Methods At the micro-scale, the d–a Interface is composed of dissimilar material components. Under global loading, these components experience different local stress amplitudes. The overall fatigue life of the d–a Interface is, therefore, determined by the material component that has the shortest fatigue life under local stresses. Multiple 3d finite element (FE) models were developed to determine the stress distribution within the d–a Interface by considering variations in micro-scale geometry, material composition and boundary conditions. The results from these models were analyzed to obtain the local stress concentrations within each d–a Interface component. By combining the local stress concentrations and experimentally determined stress versus number of cycle to failure (S–N) curves for the different material components, the overall fatigue life of the d–a Interface was predicted. Results The fatigue life was found to be a function of the applied loading amplitude, boundary conditions, microstructure and the mechanical properties of the material components of the d–a Interface. In addition, it was found that the overall fatigue life of the d–a Interface is not determined by the weakest material component. In many cases, the overall fatigue life was determined by the Adhesive although exposed collagen was the weakest material component. Comparison of the predicted results with experimental data from the literature showed both qualitative and quantitative agreement. Significance The methodology developed for fatigue life prediction can provide insight into the mechanisms that control degradation of the bond formed at the d–a Interface.
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Histomorphologic characterization of noncarious and caries-affected dentin/Adhesive Interfaces.
Journal of Prosthodontics, 2006Co-Authors: Mary P. Walker, Yong Wang, Karen B. Williams, Paulette SpencerAbstract:Purpose: The purpose of this study was to compare the dentin/Adhesive interfacial characteristics when bonding to noncarious as well as caries-affected dentin. Materials and Methods: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one-half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO Adhesive according to the manufacturer's instructions for the wet-bonding technique and under environmental conditions present in the oral cavity. Dentin/Adhesive Interface sections of each half-tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and Adhesive penetration was analyzed qualitatively. Results: The degree and extent to which the Adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries-affected dentin sections. The overall mean widths of exposed collagen were significantly (p≤ .05) greater at the caries-affected dentin/Adhesive Interface, 8.6 (1.7) μm, as compared with those at the noncarious dentin/Adhesive Interface, 6.0 (1.5) μm. Conclusions: The morphologic characteristics of the caries-affected dentin/Interface suggest an increase in the exposed collagen zone and a decrease in the quality of the Adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/Adhesive Interface structure.
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physicochemical interactions at the dentin Adhesive Interface using ftir chemical imaging
Journal of Biomedical Optics, 2005Co-Authors: Paulette Spencer, Lawrence J Katz, Yong Wang, Anil MisraAbstract:To date, much of our understanding of dentin bonding has been based on investigations performed on sound, healthy dentin. This is not the substrate generally encountered in clinical practice, rather dentists must frequently bond to caries-affected dentin. Because of the extreme complexity and variability of the caries-affected dentin substrate, conventional characterization techniques do not provide adequate information for defining those factors that impact bond formation. Using Fourier-transform infrared imaging, we characterized the inhomogeneities and compositional differences across the length and breadth of the caries-affected dentin/Adhesive Interface. Differences in mineral/matrix ratio, crystallinity, and collagen organization were noted in the comparison of caries-affected and healthy dentin. As compared to healthy dentin, there were striking differences in depth of demineralization, Adhesive infiltration, and degree of conversion at the Interface with caries-affected dentin.
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Physicochemical interactions at the dentin/Adhesive Interface using FTIR chemical imaging.
Journal of Biomedical Optics, 2005Co-Authors: Paulette Spencer, Yong Wang, J. Lawrence Katz, Anil MisraAbstract:To date, much of our understanding of dentin bonding has been based on investigations performed on sound, healthy dentin. This is not the substrate generally encountered in clinical practice, rather dentists must frequently bond to caries-affected dentin. Because of the extreme complexity and variability of the caries-affected dentin substrate, conventional characterization techniques do not provide adequate information for defining those factors that impact bond formation. Using Fourier-transform infrared imaging, we characterized the inhomogeneities and compositional differences across the length and breadth of the caries-affected dentin/Adhesive Interface. Differences in mineral/matrix ratio, crystallinity, and collagen organization were noted in the comparison of caries-affected and healthy dentin. As compared to healthy dentin, there were striking differences in depth of demineralization, Adhesive infiltration, and degree of conversion at the Interface with caries-affected dentin.
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micromechanical analysis of dentin Adhesive Interface by the finite element method
Journal of Biomedical Materials Research Part B, 2004Co-Authors: Anil Misra, Paulette Spencer, Yong Wang, Orestes Marangos, Lawrence J KatzAbstract:The interfacial microstructure and spatial distribution of the modulus of elasticity have a profound effect on load transfer at the dentin/Adhesive (d/a) Interface. The microstructure is influenced by the varying degree of demineralization of intertubular and peritubular dentin during etching as well as the depth of Adhesive penetration into the hybrid layer. These factors lead not only to a unique microstructure in the vicinity of the dentinal tubules, but also to a mechanically graded hybrid layer. This article investigates the micromechanical stress distribution at a d/a Interface with the use of finite element analysis (FEA). Such analysis is now feasible given the newly measured moduli of elasticity at micro- and nanoscales. The results indicate that the morphological and micromechanical properties of the d/a Interface affects the stress field such that the fracture/failure is likely to initiate in the stress-concentration zone of peritubular dentin next to the hybrid/exposed-collagen layer. The results suggest that devising a full-depth high modulus hybrid layer may considerably reduce the stress concentration zone and the magnitude of stress concentration in the peritubular dentin next to the hybrid/exposed-collagen layer.
Junji Tagami - One of the best experts on this subject based on the ideXlab platform.
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effect of hybridization on bond strength and Adhesive Interface after acid base challenge using 4 meta mma tbb resin
Dental Materials Journal, 2009Co-Authors: Tomohiro Takagaki, Satoko Tsuchiya, Toru Nikaido, Richard M Foxton, Masaomi Ikeda, Junji TagamiAbstract:The purposes of this study were twofold, namely to evaluate: (1) the effect of hybridization on microtensile bond strength (μTBS) to dentin, and (2) the ultrastructure of the dentin-Adhesive Interface with 4-META/MMA-TBB resin after acid-base challenge. Dentin surfaces, which received no treatment (NT), 65% phosphoric acid (PA), or 10% citric acid-3% ferric chloride (10-3), were bonded with a 4-META/MMA-TBB resin. To evaluate dentin bond strength, μTBS test was performed at a crosshead speed of 1 mm/min. For ultrastructural evaluation of the Adhesive Interfaces, SEM was used to examine the Interfaces of the bonded specimens after acid-base challenge. The μTBS of NT was not determined, while that of 10-3 was significantly higher than that of PA (p<0.05). With PA and 10-3, the hybrid layer was clearly observed, but no so for the acid-base resistant zone. Wall lesion was found in NT only. In conclusion, hybridization is vital to improving μTBS to dentin and enhancing resistance at the Adhesive Interface against acid-base challenge.
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Effect of hybridization on bond strength and Adhesive Interface after acid-base challenge using 4-META/MMA-TBB resin.
Dental Materials Journal, 2009Co-Authors: Tomohiro Takagaki, Satoko Tsuchiya, Toru Nikaido, Richard M Foxton, Masaomi Ikeda, Junji TagamiAbstract:The purposes of this study were twofold, namely to evaluate: (1) the effect of hybridization on microtensile bond strength (μTBS) to dentin, and (2) the ultrastructure of the dentin-Adhesive Interface with 4-META/MMA-TBB resin after acid-base challenge. Dentin surfaces, which received no treatment (NT), 65% phosphoric acid (PA), or 10% citric acid-3% ferric chloride (10-3), were bonded with a 4-META/MMA-TBB resin. To evaluate dentin bond strength, μTBS test was performed at a crosshead speed of 1 mm/min. For ultrastructural evaluation of the Adhesive Interfaces, SEM was used to examine the Interfaces of the bonded specimens after acid-base challenge. The μTBS of NT was not determined, while that of 10-3 was significantly higher than that of PA (p
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qualitative analysis of Adhesive Interface nanoleakage using fe sem eds
Dental Materials, 2007Co-Authors: Yang Yuan, Yasushi Shimada, Shizuko Ichinose, Junji TagamiAbstract:Abstract Objectives The purpose of this study was to evaluate the quality of short term sealing of current Adhesives. Methods Five Adhesive systems were used and evaluated in this study; two kinds of two-step Adhesives (Single Bond and Clearfil SE Bond) and three one-step Adhesives (Clearfil S 3 Bond, G Bond and One-Up Bond F-plus). Flat occlusal superficial dentin surfaces from extracted human third molars were finished with wet 600-grit silicon-carbide paper and bonded with one of the Adhesives. After 24 h storage at 37 °C in water, the bonded assemblies were sectioned into approximately 1 mm thick slabs. Two central slabs from each tooth were chosen and immersed into 50% (w/v) solution of silver ammoniacal nitrate for 18 h and exposed to photodeveloping solution for 6 h. The specimens were then slightly polished, argon ion-etched. In order to examine the nanoleakage within the resin/dentin Interface, penetration of silver was observed in a field emission (FE)-SEM using yttrium–aluminium–garnet (YAG) backscattered electron mode. EDS analysis was also carried out in parallel to identify the existence of metallic silver particles. Results The penetration pattern of silver depended on the Adhesive used, indicating different nanoleakage in different Adhesive systems. Single Bond, One-Up Bond F-plus and G Bond showed clear silver uptake in both the Adhesive and hybrid layer. Clearfil SE Bond showed less silver penetration and slight silver peak on the elemental energy spectroscopy of EDS. Clearfil S 3 Bond did not display clear silver penetration under 2000× magnification by FE-SEM, and no existence of metallic silver of the Clearfil S 3 Bond group by EDS, could be detected. Significance The nanoleakage, as well as its location depends on the Adhesives. Different nanoleakage expressions were revealed between two-step and one-step Adhesives and also among one-step Adhesives themselves.
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elemental distributions and microtensile bond strength of the Adhesive Interface to normal and caries affected dentin
Journal of Biomedical Materials Research Part B, 2005Co-Authors: Masatoshi Nakajima, Richard M Foxton, Yuichi Kitasako, Mamiko Okuda, Junji TagamiAbstract:The aim of this study was to evaluate the microtensile bond strength (μTBS) and the elemental contents of the Adhesive Interface created to normal versus caries-affected dentin. Extracted human molars with coronal carious lesions were used in this study. A self-etching primer/Adhesive system (Clearfil Protect Bond) was applied to flat dentin surfaces with normal and caries-affected dentin according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were cross-sectioned and subjected to a μTBS test and electron probe microanalysis for the elemental distributions [calcium (Ca), phosphorus (P), magnesium (Mg), and nitrogen (N)] of the resin–dentin Interface after gold sputter-coating. The μTBS to caries-affected dentin was lower than that of normal dentin. The demineralized zone of the caries-affected dentin–resin Interface was thicker than that of normal dentin (approximately 3 μm thick in normal dentin; 8 μm thick in caries-affected dentin), and Ca and P in both types of dentin gradually increased from the Interface to the underlying dentin. The caries-affected dentin had lost most of its Mg content. The distributions of the minerals, Ca, P, and Mg, at the Adhesive Interface to caries-affected dentin were different from normal dentin. Moreover, a N peak, which was considered to be the collagen-rich zone resulting from incomplete resin infiltration of exposed collagen, was observed to be thicker within the demineralized zone of caries-affected dentin compared with normal dentin. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 268–275, 2005
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elemental distributions and microtensile bond strength of the Adhesive Interface to normal and caries affected dentin
Journal of Biomedical Materials Research, 2005Co-Authors: Masatoshi Nakajima, Richard M Foxton, Yuichi Kitasako, Mamiko Okuda, Junji TagamiAbstract:The aim of this study was to evaluate the microtensile bond strength (μTBS) and the elemental contents of the Adhesive Interface created to normal versus caries-affected dentin. Extracted human molars with coronal cariouslesions were used in this study. A self-etching primer/Adhesive system (Clearfil Protect Bond) was applied to flat dentin surfaces with normal and caries-affected dentin according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were cross-sectioned and subjected to a μTBS test and electron probe microanalysis for the elemental distributions [calcium (Ca), phosphorus (P), magnesium (Mg), and nitrogen (N)] of the resin-dentin Interface after gold sputter-coating. The μTBS to caries-affected dentin was lower than that of normal dentin. The demineralized zone of the caries-affected dentin-resin Interface was thicker than that of normal dentin (approximately 3 μm thick in normal dentin; 8 μm thick in caries-affected dentin), and Ca and P in both types of dentin gradually increased from the Interface to the underlying dentin. The caries-affected dentin had lost most of its Mg content. The distributions of the minerals, Ca, P, and Mg, at the Adhesive Interface to caries-affected dentin were different from normal dentin. Moreover, a N peak, which was considered to be the collagen-rich zone resulting from incomplete resin infiltration of exposed collagen, was observed to be thicker within the demineralized zone of caries-affected dentin compared with normal dentin.
J D Witt - One of the best experts on this subject based on the ideXlab platform.
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Chemical characterization of the dentin/Adhesive Interface by Fourier transform infrared photoacoustic spectroscopy
Dental Materials, 2003Co-Authors: Paulette Spencer, Thomas J Byerley, J D Eick, J D WittAbstract:Abstract Irreversible bonding of composite materials to tooth structure depends on chemical as well as mechanical adhesion. The proposed bonding mechanism for several commercial dental Adhesives is chemical adhesion to the dentin surface. The purpose of this in vitro investigation was to characterize the chemical nature of the surface interaction between dentin and two commercial Adhesives by use of Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS). The occlusal thirds of the crown of freshly extracted, non-carious, unerupted human molars were sectioned perpendicular to the long axis. Dentin disks, 6mm × 2 mm, were prepared from these sectioned teeth. The exposed dentin surface was treated with either Scotchbond 2, a BIS-GMA resin, or Dentin-Adhesit, a polyurethane resin. All spectra were recorded from 4000 to 400 cm −1 by use of an Analect RFX-65 FTIR spectrometer equipped with an MTEC Photoacoustics Model 200 photoacoustic cell. An initial spectrum of the dentin surface was collected. This surface was primed according to manufacture's instructions and spectra recorded of the primed surface plus one to three layers of Adhesive. By comparison of these spectra, it was possible for us to record changes in the phosphate and amide I and II bands due to surface interactions between the Adhesive and the dentin. Although early results do not indicate covalent bonding between the dentin and these Adhesives, this technique presents several advantages for spectroscopic evaluation of the dentin/Adhesive Interface.
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chemical characterization of the dentin Adhesive Interface by fourier transform infrared photoacoustic spectroscopy
Dental Materials, 1992Co-Authors: Paulette Spencer, Thomas J Byerley, J D Eick, J D WittAbstract:Abstract Irreversible bonding of composite materials to tooth structure depends on chemical as well as mechanical adhesion. The proposed bonding mechanism for several commercial dental Adhesives is chemical adhesion to the dentin surface. The purpose of this in vitro investigation was to characterize the chemical nature of the surface interaction between dentin and two commercial Adhesives by use of Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS). The occlusal thirds of the crown of freshly extracted, non-carious, unerupted human molars were sectioned perpendicular to the long axis. Dentin disks, 6mm × 2 mm, were prepared from these sectioned teeth. The exposed dentin surface was treated with either Scotchbond 2, a BIS-GMA resin, or Dentin-Adhesit, a polyurethane resin. All spectra were recorded from 4000 to 400 cm −1 by use of an Analect RFX-65 FTIR spectrometer equipped with an MTEC Photoacoustics Model 200 photoacoustic cell. An initial spectrum of the dentin surface was collected. This surface was primed according to manufacture's instructions and spectra recorded of the primed surface plus one to three layers of Adhesive. By comparison of these spectra, it was possible for us to record changes in the phosphate and amide I and II bands due to surface interactions between the Adhesive and the dentin. Although early results do not indicate covalent bonding between the dentin and these Adhesives, this technique presents several advantages for spectroscopic evaluation of the dentin/Adhesive Interface.
Yong Wang - One of the best experts on this subject based on the ideXlab platform.
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Histomorphologic characterization of noncarious and caries-affected dentin/Adhesive Interfaces.
Journal of Prosthodontics, 2006Co-Authors: Mary P. Walker, Yong Wang, Karen B. Williams, Paulette SpencerAbstract:Purpose: The purpose of this study was to compare the dentin/Adhesive interfacial characteristics when bonding to noncarious as well as caries-affected dentin. Materials and Methods: Seven extracted, unerupted, third molars were sectioned into halves. Artificial caries was created on one-half of each tooth, leaving the other half as a control. Dentin surfaces were treated with UNO Adhesive according to the manufacturer's instructions for the wet-bonding technique and under environmental conditions present in the oral cavity. Dentin/Adhesive Interface sections of each half-tooth were stained with Goldner's trichrome, a classic bone stain, and examined using light microscopy. The width of exposed collagen was measured directly from photomicrographs, and Adhesive penetration was analyzed qualitatively. Results: The degree and extent to which the Adhesive encapsulated the demineralized dentin matrix were reflected in the color difference in the stained sections with the noncarious dentin sections showing a degree of collagen encapsulation superior to that of the caries-affected dentin sections. The overall mean widths of exposed collagen were significantly (p≤ .05) greater at the caries-affected dentin/Adhesive Interface, 8.6 (1.7) μm, as compared with those at the noncarious dentin/Adhesive Interface, 6.0 (1.5) μm. Conclusions: The morphologic characteristics of the caries-affected dentin/Interface suggest an increase in the exposed collagen zone and a decrease in the quality of the Adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/Adhesive Interface structure.
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physicochemical interactions at the dentin Adhesive Interface using ftir chemical imaging
Journal of Biomedical Optics, 2005Co-Authors: Paulette Spencer, Lawrence J Katz, Yong Wang, Anil MisraAbstract:To date, much of our understanding of dentin bonding has been based on investigations performed on sound, healthy dentin. This is not the substrate generally encountered in clinical practice, rather dentists must frequently bond to caries-affected dentin. Because of the extreme complexity and variability of the caries-affected dentin substrate, conventional characterization techniques do not provide adequate information for defining those factors that impact bond formation. Using Fourier-transform infrared imaging, we characterized the inhomogeneities and compositional differences across the length and breadth of the caries-affected dentin/Adhesive Interface. Differences in mineral/matrix ratio, crystallinity, and collagen organization were noted in the comparison of caries-affected and healthy dentin. As compared to healthy dentin, there were striking differences in depth of demineralization, Adhesive infiltration, and degree of conversion at the Interface with caries-affected dentin.
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Physicochemical interactions at the dentin/Adhesive Interface using FTIR chemical imaging.
Journal of Biomedical Optics, 2005Co-Authors: Paulette Spencer, Yong Wang, J. Lawrence Katz, Anil MisraAbstract:To date, much of our understanding of dentin bonding has been based on investigations performed on sound, healthy dentin. This is not the substrate generally encountered in clinical practice, rather dentists must frequently bond to caries-affected dentin. Because of the extreme complexity and variability of the caries-affected dentin substrate, conventional characterization techniques do not provide adequate information for defining those factors that impact bond formation. Using Fourier-transform infrared imaging, we characterized the inhomogeneities and compositional differences across the length and breadth of the caries-affected dentin/Adhesive Interface. Differences in mineral/matrix ratio, crystallinity, and collagen organization were noted in the comparison of caries-affected and healthy dentin. As compared to healthy dentin, there were striking differences in depth of demineralization, Adhesive infiltration, and degree of conversion at the Interface with caries-affected dentin.
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micromechanical analysis of dentin Adhesive Interface by the finite element method
Journal of Biomedical Materials Research Part B, 2004Co-Authors: Anil Misra, Paulette Spencer, Yong Wang, Orestes Marangos, Lawrence J KatzAbstract:The interfacial microstructure and spatial distribution of the modulus of elasticity have a profound effect on load transfer at the dentin/Adhesive (d/a) Interface. The microstructure is influenced by the varying degree of demineralization of intertubular and peritubular dentin during etching as well as the depth of Adhesive penetration into the hybrid layer. These factors lead not only to a unique microstructure in the vicinity of the dentinal tubules, but also to a mechanically graded hybrid layer. This article investigates the micromechanical stress distribution at a d/a Interface with the use of finite element analysis (FEA). Such analysis is now feasible given the newly measured moduli of elasticity at micro- and nanoscales. The results indicate that the morphological and micromechanical properties of the d/a Interface affects the stress field such that the fracture/failure is likely to initiate in the stress-concentration zone of peritubular dentin next to the hybrid/exposed-collagen layer. The results suggest that devising a full-depth high modulus hybrid layer may considerably reduce the stress concentration zone and the magnitude of stress concentration in the peritubular dentin next to the hybrid/exposed-collagen layer.
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identification of collagen encapsulation at the dentin Adhesive Interface
Journal of Adhesive Dentistry, 2004Co-Authors: Paulette Spencer, Yong Wang, J L KatzAbstract:PURPOSE: The purpose of this study was to investigate the dentin/Adhesive interfacial characteristics of three current commercial Adhesives with different relative hydrophilic/hydrophobic composition, using a nondestructive staining technique. MATERIALS AND METHODS: Dentin surfaces of 18 unerupted human third molars were randomly selected for treatment with one of three commercial dentin bonding agents according to manufacturers' instructions for the "wet" bonding technique. The Adhesives were ranked based on hydrophilic/hydrophobic component ratios (ie, ability to dissolve in water), highest to lowest, as follows: Uno (Pulpdent) > Prime&Bond NT (PBNT, Dentsply Caulk) > Single Bond (SB, 3M ESPE). Dentin/Adhesive (d/a) Interface sections were stained with Goldner's trichrome, a classical bone stain, and examined using light microscopy. RESULTS: The extent and degree to which the Adhesive encapsulates the demineralized dentin matrix is reflected in the color differences in the stained sections. The depth of demineralization appeared comparable among these bonding systems, but Adhesive infiltration varied from highest to lowest as follows: Uno > PBNT > SB. CONCLUSIONS: The differential staining technique provided a clear representation of the depth of dentin demineralization and extent/degree of Adhesive encapsulation of the exposed collagen at the d/a Interface. This technique provides a mechanism for readily identifying vulnerable sites at the d/a Interface. The composition of the one-bottle Adhesive systems has a substantial effect on the interfacial structure of the d/a bond.
Lawrence J Katz - One of the best experts on this subject based on the ideXlab platform.
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physicochemical interactions at the dentin Adhesive Interface using ftir chemical imaging
Journal of Biomedical Optics, 2005Co-Authors: Paulette Spencer, Lawrence J Katz, Yong Wang, Anil MisraAbstract:To date, much of our understanding of dentin bonding has been based on investigations performed on sound, healthy dentin. This is not the substrate generally encountered in clinical practice, rather dentists must frequently bond to caries-affected dentin. Because of the extreme complexity and variability of the caries-affected dentin substrate, conventional characterization techniques do not provide adequate information for defining those factors that impact bond formation. Using Fourier-transform infrared imaging, we characterized the inhomogeneities and compositional differences across the length and breadth of the caries-affected dentin/Adhesive Interface. Differences in mineral/matrix ratio, crystallinity, and collagen organization were noted in the comparison of caries-affected and healthy dentin. As compared to healthy dentin, there were striking differences in depth of demineralization, Adhesive infiltration, and degree of conversion at the Interface with caries-affected dentin.
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micromechanical analysis of dentin Adhesive Interface by the finite element method
Journal of Biomedical Materials Research Part B, 2004Co-Authors: Anil Misra, Paulette Spencer, Yong Wang, Orestes Marangos, Lawrence J KatzAbstract:The interfacial microstructure and spatial distribution of the modulus of elasticity have a profound effect on load transfer at the dentin/Adhesive (d/a) Interface. The microstructure is influenced by the varying degree of demineralization of intertubular and peritubular dentin during etching as well as the depth of Adhesive penetration into the hybrid layer. These factors lead not only to a unique microstructure in the vicinity of the dentinal tubules, but also to a mechanically graded hybrid layer. This article investigates the micromechanical stress distribution at a d/a Interface with the use of finite element analysis (FEA). Such analysis is now feasible given the newly measured moduli of elasticity at micro- and nanoscales. The results indicate that the morphological and micromechanical properties of the d/a Interface affects the stress field such that the fracture/failure is likely to initiate in the stress-concentration zone of peritubular dentin next to the hybrid/exposed-collagen layer. The results suggest that devising a full-depth high modulus hybrid layer may considerably reduce the stress concentration zone and the magnitude of stress concentration in the peritubular dentin next to the hybrid/exposed-collagen layer.
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micromechanics of the dentin Adhesive Interface
Journal of Biomedical Materials Research, 2001Co-Authors: Lawrence J Katz, Sauwanan Bumrerraj, Joseph Dreyfuss, Yong Wang, Paulette SpencerAbstract:Scanning acoustic microscopy (SAM) was used in the burst mode at 400 MHz, nominal lateral resolution 2.5 μm, to study the micromechanical properties of the dentin/Adhesive Interface. Corresponding specimens from the same tooth were investigated using μ Raman spectroscopy, light microscopy, and scanning electron microscopy.1, 2 The elastic moduli of the components of the dentin/Adhesive Interface were determined by comparing the recorded acoustic impedance values to a calibration curve generated on standard materials. The standard materials, which include polypropylene, Teflon, PMMA, pyrex glass, aluminum, titanium, and stainless steel, provide the appropriate range of acoustic impedance values. The elastic moduli of the components of the dentin/Adhesive Interface are: partially demineralized dentin, 13 Gpa; mineralized dentin, 28 GPa; Adhesive, 5.0 GPa; and unprotected protein at the Interface < 2.0 GPa. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 366–371, 2001
