Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of cleaning.The typical ...Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of cleaning.The typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the substrate.This firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel substrate.The aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including firing.The FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating layer.The validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the substrate.The results reveal that the FE analysis results agree well with the experimental results with 8% error.展开更多
Decorative enameled porcelain was used by the imperial court during the reigns of Kangxi, Yongzheng and Qianlong of the Qing Dynasty. It was a new kind of art which blended French enameling skills with Chinese traditi...Decorative enameled porcelain was used by the imperial court during the reigns of Kangxi, Yongzheng and Qianlong of the Qing Dynasty. It was a new kind of art which blended French enameling skills with Chinese traditional porcelain craftsmanship. First made in the reign of Kangxi, the porcelainware decorated with展开更多
Enamel demineralization,the formation of white spot lesions,is a common issue in clinical orthodontic treatment.The appearance of white spot lesions not only affects the texture and health of dental hard tissues but a...Enamel demineralization,the formation of white spot lesions,is a common issue in clinical orthodontic treatment.The appearance of white spot lesions not only affects the texture and health of dental hard tissues but also impacts the health and aesthetics of teeth after orthodontic treatment.The prevention,diagnosis,and treatment of white spot lesions that occur throughout the orthodontic treatment process involve multiple dental specialties.This expert consensus will focus on providing guiding opinions on the management and prevention of white spot lesions during orthodontic treatment,advocating for proactive prevention,early detection,timely treatment,scientific follow-up,and multidisciplinary management of white spot lesions throughout the orthodontic process,thereby maintaining the dental health of patients during orthodontic treatment.展开更多
A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in ...A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in this study to conduct a comprehensive analysis on the newly discovered specimen.Based on a morphological comparison,the new specimen was identified as Hulgana cf.H.ertnia within the Ischyromyidae family.Incisive enamel microstructure analysis revealed the typical pauciserial enamel structure of Hulgana.Bone histological analysis indicates that the specimen represents a juvenile individual,which is consistent with the ontogenetic stage indicated by dental developmental stage and wear pattern.The application of geometric morphometrics to the calcaneus and bone histology of the femur and phalanx further substantiates the taxonomic classification of Hulgana as a terrestrial and cursorial rodent,exhibiting a degree of fossorial ability.This classification is analogous to that of certain extant cricetids and ground squirrels.展开更多
Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especial...Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.展开更多
Inside a small shop on Lhasa's Barkhor Street,Namgyal Dorje,a young man born after 1995,delicately embeds copper wire across a wooden board.Although not born into a traditi onal Thangka pain ting family,Namgyal Do...Inside a small shop on Lhasa's Barkhor Street,Namgyal Dorje,a young man born after 1995,delicately embeds copper wire across a wooden board.Although not born into a traditi onal Thangka pain ting family,Namgyal Dorje uses copper wire and enamel glaze to push the boundaries of traditional Thangka art-both in innovation and accessibility.展开更多
Inspired by the layered structure of dental enamel in the human body,a superhydrophobic coating with an elastic gradient was developed and placed on the inner wall of a gas transmission pipeline to reduce erosion and ...Inspired by the layered structure of dental enamel in the human body,a superhydrophobic coating with an elastic gradient was developed and placed on the inner wall of a gas transmission pipeline to reduce erosion and corrosion.The coating comprises a hard bionic superhydrophobic top coating and a hydrogel layer underneath for buffering and self-repair.To improve the impact resistance of the top coating,layered structures with different viscoelasticities were constructed by controlling the content of lauric acid(LA)@TiO_(2) particles and carbon nanotubes(CNTs).The amylose hydrogel underlayer not only acts as a shock absorber but also restores potential damage in the top layer,bringing an additional benefit to the corrosion resistance of the coating.Thanks to these three cooperative approaches,the coating exhibits excellent mechanical durability(800 cycles with 600-mesh sandpaper under a 49 kPa load)and corrosion resistance(with a corrosion potential of-0.21 V).Moreover,it maintains its superhydrophobicity after sanding,bending,soaking,and scratching,demonstrating its potential for application to protect transmission pipelines from erosion and corrosion.展开更多
BACKGROUND Celiac disease(CD)is an autoimmune disease triggered by the ingestion of gluten in genetically predisposed individuals.It is more commonly diagnosed in children presenting typical clinical signs and symptom...BACKGROUND Celiac disease(CD)is an autoimmune disease triggered by the ingestion of gluten in genetically predisposed individuals.It is more commonly diagnosed in children presenting typical clinical signs and symptoms but most of the CD patients diagnosed in the developed world are silent cases with no prominent gastrointestinal features.Thus,there are silent forms of the disease in which oral manifestations are the first sign.In the pediatric population oral health can affect growth and self-esteem and have a negative impact in their life quality.AIM To assess the prevalence and types of oral manifestations in pediatric patients with CD.METHODS We performed a comprehensive literature search in PubMed,Scielo,Cochrane Library and Lilacs databases from 2014-2024.Three independent researchers screened and extracted the information,applying the eligibility criteria and bias was assessed using Joanna Briggs Institute tools.RESULTS Of the initial 241 articles,14 studies fulfilled the proposed objectives and were included in the review.The main oral manifestations found were recurrent aphthous stomatitis and enamel defects.Additionally,delayed tooth eruption,angular cheilitis,glossodynia and xerostomia were also reported.CONCLUSION Assessing oral manifestations is crucial,especially in underdiagnosed cases of children with CD.Recognizing these signs helps pediatricians or general practitioners identify them during routine exams,enabling early diagnosis and treatment to prevent negative impacts on the child’s and family’s quality of life.展开更多
CHINESE Cloisonneis the centuries-old handicraft of creating designs on copper bodies with colored-enamel placed within divisions made of copper wires,which are bent to follow the outline of decorative patterns.This f...CHINESE Cloisonneis the centuries-old handicraft of creating designs on copper bodies with colored-enamel placed within divisions made of copper wires,which are bent to follow the outline of decorative patterns.This form of art originated in the Arab world and was introduced to China during the late Yuan Dynasty(1271-1368),and since then it has become a favorite of the country’s emperors.展开更多
[Objective] The aim of this study was to investigate the effects of salt stress on cell expansion in Arabidopsis thaliana rosette leaves.[Method] Arabidopsis seedlings were treated by sodium chloride at the concentrat...[Objective] The aim of this study was to investigate the effects of salt stress on cell expansion in Arabidopsis thaliana rosette leaves.[Method] Arabidopsis seedlings were treated by sodium chloride at the concentration of 0,100 or 150 mmol/L. At the 7th and 14th d of treatment,with nail enamel printing mark method and computer software,the leaf blades area and abaxial epidermal pavement cells area was measured and compared using statistical analysis in Excel. [Result] The growth of Arabidopsis rosette leaves was inhibited under salt stress. Leaves treated for 7 or 14 d expanded less compared with controls. The salt-mediated decrease in leaf expansion is associated with a decrease in abaxial pavement cell expansion. [Conclusion] The decreased leaf and epidermal cell expansion under salt stress is the most important characteristic of plant physiological response to salt stress.展开更多
A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondar...A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondary insulations;?i.e.: enamel and varnish, has been compared to this recent technique which only uses one component,?i.e.: self-bonding wires. Self-bonding wires polymerization is very quick compared to that of the conventional technique. Environmental impact and both dielectric and mechanical properties of these two techniques have been estimated and compared. The goal is to estimate if this recent technique has not only a better environmental footprint but also good technical properties. The dielectric properties that have been measured are the dielectric strength and?the lifetime under pulse?voltage while mechanical consists in measuring the bonding strength that is crucial for impregnation.?For that purpose, a Life Cycle Assessment (LCA) that can simultaneously evaluatenumerous impacts on ground, water and air,?has been performed. The results show clearly that the recent technique significantly reduces the environmental footprint. Both mechanical and dielectric properties are then compared and analyzed.展开更多
‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from out...‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from outside to inside. These attributes confer human teeth with effective mastication ability. Understanding the various mechanical properties of human teeth and dental materials is the basis for the development of restorative materials. In this study, the elastic properties, dynamic mechanical properties （visco-elasticity） and fracture mechanical properties of enamel and dentin were reviewed to provide a more thorough understanding of the mechanical properties of human teeth.展开更多
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 appl...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.展开更多
This in vitrostudy aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal...This in vitrostudy aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal （Group LP）, disto-buccal （Group P）, mesio-lingual （Group NP） and disto-lingual （Group L） specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L~ but decrease in a＊ and b＊, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization.展开更多
The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin(RI/CR) when used with deproteinised and etc...The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin(RI/CR) when used with deproteinised and etched occlusal subsurface lesions(International Caries Detection and Assessment System code 2). This combined treatment procedure was compared with the exclusive use of flowable composite resin(CR) for fissure sealing. Twenty premolars and 20 molars revealing non-cavitated occlusal carious lesions were randomly divided into two groups and were meticulously cleaned and deproteinised using Na OCl(2%). After etching with HCl(15%), 10 premolar and 10 molar lesions were infiltrated(Icon/DMG; rhodamine B isothiocyanate(RITC)-labelled) followed by fissure sealing(G-?nial Flo/GC; experimental group, RI/CR). In the control group(CR), the carious fissures were only sealed. Specimens were cut perpendicular to the occlusal surface and through the area of the highest demineralisation(DIAGNOdent pen, Ka Vo). Using confocal laser-scanning microscopy, the specimens were assessed with regard to the percentage of caries infiltration, marginal adaption and internal integrity. Within the CR group, the carious lesions were not infiltrated. Both premolar(57.9% ± 23.1%) and molar lesions(35.3% ± 22.1%) of the RI/CR group were uniformly infiltrated to a substantial extent, albeit with significant differences(P = 0.034). Moreover, microleakage(n = 1) and the occurrence of voids(n = 2) were reduced in the RI/CR group compared with the CR group(5 and 17 specimens,respectively). The RI/CR approach increases the initial quality of fissure sealing and is recommended for the clinical control of occlusal caries.展开更多
Periodontal regenerative techniques have been proposed; however, the outcomes remain debatable. The present investigation assessed the regenerated cementum following enamel matrix derivative application in dehiscence-...Periodontal regenerative techniques have been proposed; however, the outcomes remain debatable. The present investigation assessed the regenerated cementum following enamel matrix derivative application in dehiscence-type defects. Buccal osseous dehiscences were surgically created on the maxillary cuspid, and the second and fourth premolars in five female beagle dogs. The treatment group （n=15 sites） received the enamel matrix derived application, whereas the control groups （n=15） did not. The dogs were sacrificed 4 months following treatment and the specimens were histologically and histometrically examined. The newly formed cementum was uneven in thickness and mineralization, overlapped the old cementum and exhibited functional orientation, cementocyte lacunae and collagen fibril bundles. Most of the histological specimens showed the presence of a gap between the newly formed cementum and the underlying dentin. Control sites did not exhibit any cementum formation. The present study concluded that newly formed cementum is of cellular type and exhibits multiple characteristics.展开更多
Aim The effect of Galla chinensis on de-/re-mineralization of advanced enamel lesions was investigated by using micro-CT in a prolonged in vitro experiment. Methodology Baseline mineral contents of sound enamels were ...Aim The effect of Galla chinensis on de-/re-mineralization of advanced enamel lesions was investigated by using micro-CT in a prolonged in vitro experiment. Methodology Baseline mineral contents of sound enamels were first analyzed. Then lesions were produced in an acidic buffer solution （2.2 mmol.L-1 Ca（NO3）2, 2.2 mmol-L1 KH2PO4, and pH=4.5） for 21 days, with thrice daily three-minute treatments, divided into four groups： Group A, 4 000 ppm crude aqueous extract of Galla chinensis （GCE）; Group B, 4 000 ppm gallic acid; Group C, 1 000 ppm F aq. （as NaF, positive control）; Group D, deionized water （negative control）. Next, the blocks were immersed in a remineralization solution （1.5 mmol.Lz CaC12, 0.9 mmol.L1 KH2PO4, 0.1 ppm F, and pH=7,0） for 200 days. Mineral loss （ML） in each region of interest （ROI） and integrated mineral loss （IML） of the lesions were calculated （comparing with baseline mineral content of sound enamel） at different time points. Results After 21 days demineralization, fluoride treatment showed a statistically significant demineralization-inhibiting effect among the four groups, and after 200 days of remineralization, mineral content recovery was ordered （lowest to highest） as A=C〈B〈D. Conclusion GCE could slow down the remineralization of enamel in the surface layer and thereby facilitate ion transport into the lesion body. The mechanism of Galla chinensis in enhancing the remineralization of dental caries is different from fluoride.展开更多
The tooth enamel development gene, enamelin （ENAM）, showed evidence of positive selection during a genome-wide scan of human and primate DNA for signs of adaptive evolution. The current study examined the hypothesis...The tooth enamel development gene, enamelin （ENAM）, showed evidence of positive selection during a genome-wide scan of human and primate DNA for signs of adaptive evolution. The current study examined the hypothesis that a single-nucleotide polymorphism （SNP） C14625T （rs7671281） in the ENAM gene identified in the genome-wide scan is associated with a change in enamel phenotype. African Americans were selected as the target population, as they have been reported to have a target SNP frequency of approximately 50%, whereas non-Africans are predicted to have a 96% SNP frequency. Digital radiographs and DNA samples from 244 teeth in 133 subjects were analysed, and enamel thickness was assessed in relation to SNP status, controlling for age, sex, tooth number and crown length. Crown length was found to increase with molar number, and females were found to have thicker enamel. Teeth with larger crowns also had thicker enamel, and older subjects had thinner enamel. Linear regression and generalized estimating equations were used to investigate the relationship between enamel thickness of the mandibular molars and ENAM SNP status; enamel in subjects with the derived allele was significantly thinner （P= 0.040） when the results were controlled for sex, age, tooth number and crown length. The derived allele demonstrated a recessive effect on the phenotype. The data indicate that thinner dental enamel is associated with the derived ENAM genotype. This is the first direct evidence of a dental gene implicated in human adaptive evolution as having a phenotypic effect on an oral structure.展开更多
FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM...FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM20A in dental tissues and to assess the pathological changes when this molecule is specifically nullified in individual tissues. Recently, we generated mice with a Fam2OA-floxed allele containing the beta-galactosidase reporter gene. We analysed FAM20A expression in dental tissues using X-Gal staining, immunohistochemistry and in situ hybridization, which showed that the ameloblasts in the mouse mandibular first molar began to express FAM20A at 1 day after birth, and the reduced enamel epithelium in erupting molars expressed a significant level of FAM2OA. By breeding K14-Cre mice with Fam20An^x/fl^x mice, we created K14-Cre;Fam20Af/flox/flox （conditional knock out, cKO） mice, in which Fam20A was inactivated in the epithelium. We analysed the dental tissues of cKO mice using X-ray radiography： histology and immunohistochemistry. The molar enamel matrix in cKO mice was much thinner than normal and was often separated from the dentinoenamel junction. The Fam2OA-deficient ameloblasts were non-polarized and disorganized and were detached from the enamel matrix. The enamel abnormality in cKO mice was consistent with the diagnosis of amelogenesis imperfecta. The levels of enamelin and matrix metalloproteinase 20 were lower in the ameloblasts and enamel of cKO mice than the normal mice, The cKO mice had remarkable delays in the eruption of molars and hyperplasia of the gingival epithelium. The findings emphasize the essential roles of FAM20A in the development of dental and oral tissues.展开更多
基金Project(NRF-2012R1A5A1048294)supported by the National Research Foundation of Korea(NRF)Grant funded by the Ministry of Education,Science and Technologythe LG Electronics
文摘Porcelain enamel coatings were widely applied for the protection of steel products because they offered high corrosion protection,resistance to heat and abrasion,high hardness,hygiene and ease of cleaning.The typical process to produce enameled steels is roughly divided into two stages:the first stage consists of a forming process to give the desired shape to a steel substrate,and the second stage consists of a firing process to bond enamel frits on the substrate.This firing process requires a high temperature above 800 °C,which may lead to austenitic transformation and severe thermal deformation of the steel substrate.The aim of this study is to develop a finite element analysis (FE analysis) technique to predict the mechanical and thermal deformations of the enameled steels during forming and any further enameling process,including firing.The FE analysis involves analyzing the strain history of the steel substrate,which comprises the stress and thickness distributions of the substrate and its deformed shape,and the high-temperature behavior of the enamel coating layer.The validity of the FE analysis is verified through the U-bending test and firing test with various numbers and positions of enamel coating layers on the substrate.The results reveal that the FE analysis results agree well with the experimental results with 8% error.
文摘Decorative enameled porcelain was used by the imperial court during the reigns of Kangxi, Yongzheng and Qianlong of the Qing Dynasty. It was a new kind of art which blended French enameling skills with Chinese traditional porcelain craftsmanship. First made in the reign of Kangxi, the porcelainware decorated with
基金funded with National Key R&D Program of China(2022YFC2405904)National Natural Science Foundation of China(11932012,and 32171348).
文摘Enamel demineralization,the formation of white spot lesions,is a common issue in clinical orthodontic treatment.The appearance of white spot lesions not only affects the texture and health of dental hard tissues but also impacts the health and aesthetics of teeth after orthodontic treatment.The prevention,diagnosis,and treatment of white spot lesions that occur throughout the orthodontic treatment process involve multiple dental specialties.This expert consensus will focus on providing guiding opinions on the management and prevention of white spot lesions during orthodontic treatment,advocating for proactive prevention,early detection,timely treatment,scientific follow-up,and multidisciplinary management of white spot lesions throughout the orthodontic process,thereby maintaining the dental health of patients during orthodontic treatment.
文摘A relatively well-preserved rodent fossil,including its incisors,cheek teeth,and postcranial skeleton,was collected from the Baiyin Obo in Siziwang Banner,Nei Mongol.A multifaceted research approach was undertaken in this study to conduct a comprehensive analysis on the newly discovered specimen.Based on a morphological comparison,the new specimen was identified as Hulgana cf.H.ertnia within the Ischyromyidae family.Incisive enamel microstructure analysis revealed the typical pauciserial enamel structure of Hulgana.Bone histological analysis indicates that the specimen represents a juvenile individual,which is consistent with the ontogenetic stage indicated by dental developmental stage and wear pattern.The application of geometric morphometrics to the calcaneus and bone histology of the femur and phalanx further substantiates the taxonomic classification of Hulgana as a terrestrial and cursorial rodent,exhibiting a degree of fossorial ability.This classification is analogous to that of certain extant cricetids and ground squirrels.
基金Supported by the National Natural Science Foundation of China(61988102,62401113,92463308)。
文摘Enamel demineralization often occurs in the early stage of dental caries.Studying the microscopic mechanism of enamel demineralization is essential to prevent and treat dental caries.Terahertz(THz)technolo⁃gy,especially continuous wave(CW)THz near-field scanning microscopy(THz-SNOM)with its nanoscale reso⁃lution,can be promising in biomedical imaging.In addition,compared with traditional THz time-domain spec⁃troscopy(TDS),portable solid-state source as the emission has higher power and SNR,lower cost,and can ob⁃tain more precise imaging.In this study,we employ CW THz-SNOM to further break the resolution limitations of conventional THz imaging techniques and successfully achieve the near-field imaging of demineralized enamel at the nanoscale.We keenly observe that the near-field signal of the enamel significantly lowers as demineralization deepens,mainly due to the decrease in permittivity.This new approach offers valuable insights into the micro⁃scopic processes of enamel demineralization,laying the foundation for further research and treatment.
文摘Inside a small shop on Lhasa's Barkhor Street,Namgyal Dorje,a young man born after 1995,delicately embeds copper wire across a wooden board.Although not born into a traditi onal Thangka pain ting family,Namgyal Dorje uses copper wire and enamel glaze to push the boundaries of traditional Thangka art-both in innovation and accessibility.
基金supported by the National Natural Science Foundation of China(22375047,51972063,and 22075046)the National Key Research and Development Program of China(2022YFB3804905,2022YFB3804900,and 2019YFE0111200)+3 种基金the Natural Science Foundation for Distinguished Young Scholar of Fujian Province(2020J06038)the Natural Science Foundation of Fujian Province(2020J05098 and 2019J01256)111 Project(D17005)China Postdoctoral Science Foundation(2022M723497)。
文摘Inspired by the layered structure of dental enamel in the human body,a superhydrophobic coating with an elastic gradient was developed and placed on the inner wall of a gas transmission pipeline to reduce erosion and corrosion.The coating comprises a hard bionic superhydrophobic top coating and a hydrogel layer underneath for buffering and self-repair.To improve the impact resistance of the top coating,layered structures with different viscoelasticities were constructed by controlling the content of lauric acid(LA)@TiO_(2) particles and carbon nanotubes(CNTs).The amylose hydrogel underlayer not only acts as a shock absorber but also restores potential damage in the top layer,bringing an additional benefit to the corrosion resistance of the coating.Thanks to these three cooperative approaches,the coating exhibits excellent mechanical durability(800 cycles with 600-mesh sandpaper under a 49 kPa load)and corrosion resistance(with a corrosion potential of-0.21 V).Moreover,it maintains its superhydrophobicity after sanding,bending,soaking,and scratching,demonstrating its potential for application to protect transmission pipelines from erosion and corrosion.
文摘BACKGROUND Celiac disease(CD)is an autoimmune disease triggered by the ingestion of gluten in genetically predisposed individuals.It is more commonly diagnosed in children presenting typical clinical signs and symptoms but most of the CD patients diagnosed in the developed world are silent cases with no prominent gastrointestinal features.Thus,there are silent forms of the disease in which oral manifestations are the first sign.In the pediatric population oral health can affect growth and self-esteem and have a negative impact in their life quality.AIM To assess the prevalence and types of oral manifestations in pediatric patients with CD.METHODS We performed a comprehensive literature search in PubMed,Scielo,Cochrane Library and Lilacs databases from 2014-2024.Three independent researchers screened and extracted the information,applying the eligibility criteria and bias was assessed using Joanna Briggs Institute tools.RESULTS Of the initial 241 articles,14 studies fulfilled the proposed objectives and were included in the review.The main oral manifestations found were recurrent aphthous stomatitis and enamel defects.Additionally,delayed tooth eruption,angular cheilitis,glossodynia and xerostomia were also reported.CONCLUSION Assessing oral manifestations is crucial,especially in underdiagnosed cases of children with CD.Recognizing these signs helps pediatricians or general practitioners identify them during routine exams,enabling early diagnosis and treatment to prevent negative impacts on the child’s and family’s quality of life.
文摘CHINESE Cloisonneis the centuries-old handicraft of creating designs on copper bodies with colored-enamel placed within divisions made of copper wires,which are bent to follow the outline of decorative patterns.This form of art originated in the Arab world and was introduced to China during the late Yuan Dynasty(1271-1368),and since then it has become a favorite of the country’s emperors.
文摘[Objective] The aim of this study was to investigate the effects of salt stress on cell expansion in Arabidopsis thaliana rosette leaves.[Method] Arabidopsis seedlings were treated by sodium chloride at the concentration of 0,100 or 150 mmol/L. At the 7th and 14th d of treatment,with nail enamel printing mark method and computer software,the leaf blades area and abaxial epidermal pavement cells area was measured and compared using statistical analysis in Excel. [Result] The growth of Arabidopsis rosette leaves was inhibited under salt stress. Leaves treated for 7 or 14 d expanded less compared with controls. The salt-mediated decrease in leaf expansion is associated with a decrease in abaxial pavement cell expansion. [Conclusion] The decreased leaf and epidermal cell expansion under salt stress is the most important characteristic of plant physiological response to salt stress.
文摘A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondary insulations;?i.e.: enamel and varnish, has been compared to this recent technique which only uses one component,?i.e.: self-bonding wires. Self-bonding wires polymerization is very quick compared to that of the conventional technique. Environmental impact and both dielectric and mechanical properties of these two techniques have been estimated and compared. The goal is to estimate if this recent technique has not only a better environmental footprint but also good technical properties. The dielectric properties that have been measured are the dielectric strength and?the lifetime under pulse?voltage while mechanical consists in measuring the bonding strength that is crucial for impregnation.?For that purpose, a Life Cycle Assessment (LCA) that can simultaneously evaluatenumerous impacts on ground, water and air,?has been performed. The results show clearly that the recent technique significantly reduces the environmental footprint. Both mechanical and dielectric properties are then compared and analyzed.
基金support from the National Natural Science Foundation of China(Nos.81170996,81070867 and 81100777)the Sichuan Province Science and Technology Innovation Team Program(2011JTD0006)
文摘‘Bronze teeth＇ reflect the mechanical properties of natural teeth to a certain extent. Their mechanical properties resemble those of a tough metal, and the gradient of these properties lies in the direction from outside to inside. These attributes confer human teeth with effective mastication ability. Understanding the various mechanical properties of human teeth and dental materials is the basis for the development of restorative materials. In this study, the elastic properties, dynamic mechanical properties （visco-elasticity） and fracture mechanical properties of enamel and dentin were reviewed to provide a more thorough understanding of the mechanical properties of human teeth.
基金supported by the Research Fund from Science and Technology Department of Sichuan Province (No. 2009FZ0065)Key Project of the Science and Technology Department of Sichuan Province (No. 2011SZ0101)+1 种基金Doctoral Fund of Ministry of Education of China (No. 20120181120002)supported by Open Fund of State Key Laboratory of Oral Diseases, Sichuan University
文摘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.
文摘This in vitrostudy aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal （Group LP）, disto-buccal （Group P）, mesio-lingual （Group NP） and disto-lingual （Group L） specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L~ but decrease in a＊ and b＊, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization.
文摘The aim of this ex vivo study was to evaluate the infiltration capability and rate of microleakage of a low-viscous resin infiltrant combined with a flowable composite resin(RI/CR) when used with deproteinised and etched occlusal subsurface lesions(International Caries Detection and Assessment System code 2). This combined treatment procedure was compared with the exclusive use of flowable composite resin(CR) for fissure sealing. Twenty premolars and 20 molars revealing non-cavitated occlusal carious lesions were randomly divided into two groups and were meticulously cleaned and deproteinised using Na OCl(2%). After etching with HCl(15%), 10 premolar and 10 molar lesions were infiltrated(Icon/DMG; rhodamine B isothiocyanate(RITC)-labelled) followed by fissure sealing(G-?nial Flo/GC; experimental group, RI/CR). In the control group(CR), the carious fissures were only sealed. Specimens were cut perpendicular to the occlusal surface and through the area of the highest demineralisation(DIAGNOdent pen, Ka Vo). Using confocal laser-scanning microscopy, the specimens were assessed with regard to the percentage of caries infiltration, marginal adaption and internal integrity. Within the CR group, the carious lesions were not infiltrated. Both premolar(57.9% ± 23.1%) and molar lesions(35.3% ± 22.1%) of the RI/CR group were uniformly infiltrated to a substantial extent, albeit with significant differences(P = 0.034). Moreover, microleakage(n = 1) and the occurrence of voids(n = 2) were reduced in the RI/CR group compared with the CR group(5 and 17 specimens,respectively). The RI/CR approach increases the initial quality of fissure sealing and is recommended for the clinical control of occlusal caries.
基金supported by grant from Eng.A.B.Growth Factors and Bone Regeneration Research Chair and number #LR0003
文摘Periodontal regenerative techniques have been proposed; however, the outcomes remain debatable. The present investigation assessed the regenerated cementum following enamel matrix derivative application in dehiscence-type defects. Buccal osseous dehiscences were surgically created on the maxillary cuspid, and the second and fourth premolars in five female beagle dogs. The treatment group （n=15 sites） received the enamel matrix derived application, whereas the control groups （n=15） did not. The dogs were sacrificed 4 months following treatment and the specimens were histologically and histometrically examined. The newly formed cementum was uneven in thickness and mineralization, overlapped the old cementum and exhibited functional orientation, cementocyte lacunae and collagen fibril bundles. Most of the histological specimens showed the presence of a gap between the newly formed cementum and the underlying dentin. Control sites did not exhibit any cementum formation. The present study concluded that newly formed cementum is of cellular type and exhibits multiple characteristics.
文摘Aim The effect of Galla chinensis on de-/re-mineralization of advanced enamel lesions was investigated by using micro-CT in a prolonged in vitro experiment. Methodology Baseline mineral contents of sound enamels were first analyzed. Then lesions were produced in an acidic buffer solution （2.2 mmol.L-1 Ca（NO3）2, 2.2 mmol-L1 KH2PO4, and pH=4.5） for 21 days, with thrice daily three-minute treatments, divided into four groups： Group A, 4 000 ppm crude aqueous extract of Galla chinensis （GCE）; Group B, 4 000 ppm gallic acid; Group C, 1 000 ppm F aq. （as NaF, positive control）; Group D, deionized water （negative control）. Next, the blocks were immersed in a remineralization solution （1.5 mmol.Lz CaC12, 0.9 mmol.L1 KH2PO4, 0.1 ppm F, and pH=7,0） for 200 days. Mineral loss （ML） in each region of interest （ROI） and integrated mineral loss （IML） of the lesions were calculated （comparing with baseline mineral content of sound enamel） at different time points. Results After 21 days demineralization, fluoride treatment showed a statistically significant demineralization-inhibiting effect among the four groups, and after 200 days of remineralization, mineral content recovery was ordered （lowest to highest） as A=C〈B〈D. Conclusion GCE could slow down the remineralization of enamel in the surface layer and thereby facilitate ion transport into the lesion body. The mechanism of Galla chinensis in enhancing the remineralization of dental caries is different from fluoride.
基金supported by an NSF-DIG grant (DEB-0709660)an NIH grant (HD057974)the University of Washington Hack Estate
文摘The tooth enamel development gene, enamelin （ENAM）, showed evidence of positive selection during a genome-wide scan of human and primate DNA for signs of adaptive evolution. The current study examined the hypothesis that a single-nucleotide polymorphism （SNP） C14625T （rs7671281） in the ENAM gene identified in the genome-wide scan is associated with a change in enamel phenotype. African Americans were selected as the target population, as they have been reported to have a target SNP frequency of approximately 50%, whereas non-Africans are predicted to have a 96% SNP frequency. Digital radiographs and DNA samples from 244 teeth in 133 subjects were analysed, and enamel thickness was assessed in relation to SNP status, controlling for age, sex, tooth number and crown length. Crown length was found to increase with molar number, and females were found to have thicker enamel. Teeth with larger crowns also had thicker enamel, and older subjects had thinner enamel. Linear regression and generalized estimating equations were used to investigate the relationship between enamel thickness of the mandibular molars and ENAM SNP status; enamel in subjects with the derived allele was significantly thinner （P= 0.040） when the results were controlled for sex, age, tooth number and crown length. The derived allele demonstrated a recessive effect on the phenotype. The data indicate that thinner dental enamel is associated with the derived ENAM genotype. This is the first direct evidence of a dental gene implicated in human adaptive evolution as having a phenotypic effect on an oral structure.
基金supported by the National Natural Science Foundation of China (Grant No. 81171744)the Natural Science Foundation of Heilongjiang Province of China (Grant H201418)
文摘FAM20A has been studied to a very limited extent. Mutations in human FAM20A cause amelogenesis imperfecta, gingival fibromatosis and kidney problems. It would be desirable to systemically analyse the expression of FAM20A in dental tissues and to assess the pathological changes when this molecule is specifically nullified in individual tissues. Recently, we generated mice with a Fam2OA-floxed allele containing the beta-galactosidase reporter gene. We analysed FAM20A expression in dental tissues using X-Gal staining, immunohistochemistry and in situ hybridization, which showed that the ameloblasts in the mouse mandibular first molar began to express FAM20A at 1 day after birth, and the reduced enamel epithelium in erupting molars expressed a significant level of FAM2OA. By breeding K14-Cre mice with Fam20An^x/fl^x mice, we created K14-Cre;Fam20Af/flox/flox （conditional knock out, cKO） mice, in which Fam20A was inactivated in the epithelium. We analysed the dental tissues of cKO mice using X-ray radiography： histology and immunohistochemistry. The molar enamel matrix in cKO mice was much thinner than normal and was often separated from the dentinoenamel junction. The Fam2OA-deficient ameloblasts were non-polarized and disorganized and were detached from the enamel matrix. The enamel abnormality in cKO mice was consistent with the diagnosis of amelogenesis imperfecta. The levels of enamelin and matrix metalloproteinase 20 were lower in the ameloblasts and enamel of cKO mice than the normal mice, The cKO mice had remarkable delays in the eruption of molars and hyperplasia of the gingival epithelium. The findings emphasize the essential roles of FAM20A in the development of dental and oral tissues.
