1.High-resolution electron microscopy of carious dissolution of enamel nano-crystals.
Wei ZHAO ; Shuo-zhi WANG ; Ming-wen FAN ; Zhi CHEN ; Shi-feng YU
Chinese Journal of Stomatology 2003;38(6):408-410
OBJECTIVESTo investigate the carious dissolution mechanism of enamel apatite nano-crystals at lattice fringe level and the possible correlation between the carious dissolution and the appearance of central dark line (CDL) in enamel crystals.
METHODSThe body of the lesion in incipient enamel caries was observed by high resolution transmission electron microscopy (HRTEM, JOEL-2010 operating at 200 kv), combined with selected-area argon-ion-beam thinning technique.
RESULTSIn the body of the lesion, the preferential core dissolution was found in most of enamel nano-crystals, whereas the peripheral dissolution of individual crystal could be occasionally observed. The initial carious dissolution of individual enamel apatite crystal occurred as a number of small electron-lucent spots along the central dark line with blurry, bent or disconnected lattice fringes. These small electron-lucent spots fused with each other to form large electron-lucent areas. Finally the central perforation was frequently seen in the crystals. The CDL always appeared in the same place with central perforation in carious crystals, which could be seen to extend along the CDL.
CONCLUSIONSThe initial carious dissolution is directly related to the lattice defects in the enamel nano-crystals. The preferential core dissolution can be partly ascribed to the CDL, which is presumed to be particularly susceptible area to caries.
Dental Caries ; metabolism ; Dental Enamel Solubility ; Humans ; Microscopy, Electron, Scanning
2.The experimental study of the effect of zinc phosphate cement on the solubility of enamel.
Korean Journal of Orthodontics 1975;5(1):21-24
The purpose of this study was to investigate the effect of sinc phosphate cement on the enamel surface of extracted teeth. The tooth was placed in a test tube, which was subjected to 5ml of 0.2M acetate buffer at pH 4 by "window technique." The calcium content of the acetate buffer was determined by the Perkin-Elmer Model 303 Atomic Absorption Spectrophotometer. The obtained results were summarized in the following. 1. The solubility of enamel is 0.92mg/cm2. ml in control group. 2. The solubility of enamel is increased by treating these with zinc phosphate cements. 3. The solubility of enamel is 0.69mg/cm2. ml by treating with Lee Smith cement. 4. The solubility of enamel is 0.30mg/cm2. ml by treating with G-C's cement.
Absorption
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Calcium
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Dental Enamel*
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Hydrogen-Ion Concentration
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Solubility*
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Tooth
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Zinc Phosphate Cement*
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Zinc*
3.Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide.
Meng DENG ; Hai-Lin WEN ; Xiao-Li DONG ; Feng LI ; Xin XU ; Hong LI ; Ji-Yao LI ; Xue-Dong ZHOU
International Journal of Oral Science 2013;5(2):103-110
Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.
Animals
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Biomimetic Materials
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analysis
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therapeutic use
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Cattle
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Ceramics
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analysis
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chemistry
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Chemical Phenomena
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Color
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Colorimetry
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Dental Enamel
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drug effects
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ultrastructure
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Electron Probe Microanalysis
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Glass
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analysis
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chemistry
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Hardness
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Hydrogen Peroxide
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pharmacology
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Hydrogen-Ion Concentration
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Microscopy, Electron, Scanning
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Protective Agents
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analysis
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therapeutic use
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Random Allocation
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Solubility
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Spectroscopy, Fourier Transform Infrared
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Time Factors
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Tooth Bleaching
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methods
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Tooth Bleaching Agents
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pharmacology
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Water
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chemistry
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X-Ray Diffraction