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1
Angker, L., e M. V. Swain. "Nanoindentation: Application to dental hard tissue investigations". Journal of Materials Research 21, n. 8 (1 agosto 2006): 1893–905. http://dx.doi.org/10.1557/jmr.2006.0257.
Testo completoAbstract (sommario):
In the last decade, most publications on the mechanical properties of dental calcified tissues were based on nanoindentation investigation. This technique has allowed a better understanding of the mechanical behavior of enamel, dentin, and cementum at a nanoscale. The indentations are normally carried out using pointed or spherical indenters. Hardness and elastic modulus are measured as a function of indenter penetration depth and from the elastic recovery upon unloading. The unique microstructure of each calcified tissue significantly contributes to the variations in the mechanical properties measured. As complex hydrated biological composites, the relative proportions of the composite components, namely, inorganic material (hydroxyapatite), organic material, and water, determines the mechanical properties of the dental hard tissues. Many pathological conditions affecting dental hard tissues cause changes in mineral levels, crystalline structures, and mechanical properties that may be probed by nanoindentation. This review focuses on relevant nanoindentation techniques and their applications to enamel, dentin, and cementum investigations.
2
Řehounek, Luboš, Aleš Jíra e František Denk. "Influence of Dental Caries for Dental Materials and their Micromechanical Properties". Applied Mechanics and Materials 827 (febbraio 2016): 371–74. http://dx.doi.org/10.4028/www.scientific.net/amm.827.371.
Testo completoAbstract (sommario):
The presented paper is mainly focused on nanoindentation of damaged human teeth, which have been treated with amalgam filling and describing the micromechanical properties (reduced elastic modulus Er and hardness H). The analysis was carried out on two samples of tooth no. 37, the first from a woman (48 years old) and the second from a man (26 years old). For both teeth was the main cause of the extraction an advanced stage of periodontitis chronica. The provided treatment of the tooth decay has been realized using amalgam filling with a different depth of cavity drilling. Within the analysis, we have made a series of indentation experiments in the transversal sections of the teeth. In these sections, we have measured the mechanical properties in individual dental materials for the sake of determining the influence of the degradation of dentin damaged by tooth decay. The differences of micomechanical parameters occur in the dentin area (Er ≈ 7.6 GPa in the dentin-amalgam interface and Er ≈ 30.2 GPa in the center of the dentin wall). Lesser variance of values is present in the enamel area, where the difference is less than 11 % in the enamel-amalgam interface.
3
Chang, Shou-Yi, Ren-Jei Chung, Fang-Cheng Chou, Hsiang-Long Hsiao e Hung-Bin Hsu. "Effect ofStreptococcus mutanson mechanical properties of human dental structures". Journal of Materials Research 24, n. 7 (luglio 2009): 2301–6. http://dx.doi.org/10.1557/jmr.2009.0275.
Testo completoAbstract (sommario):
In this study, the mechanical properties of human dental structures have been investigated by using instrumented nanoindentation. Immersion in solutions containingStreptococcus mutans, which is the principal cause of dental caries, was applied to tooth specimens to clarify its effect on the microstructure and mechanical properties of the dental structures. With an extended time of up to 16 h, the pH value of theS. mutanssolutions dropped from 7.3 to 5.8. Therefore, after immersion in theS. mutanssolutions for 16 h, slight erosions of the dental structures began; after 64 h, severe tooth decay occurred with obviously etched dental features. After 128 h, the elastic modulus of enamel and dentine dropped to 85 and 67%, respectively, of the original values of untreated specimens, and the hardness dropped to 88 and 55%, respectively.
4
Cui, Fu Zhai, Zhen Jiang Chen e Jun Ge. "Nanomechanical Properties of Tooth and Bone Revealed by Nanoindentation and AFM". Key Engineering Materials 353-358 (settembre 2007): 2263–66. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2263.
Testo completoAbstract (sommario):
In this paper, an overview on nanoindentation and its combination with AFM is presented with regard to current instrument technology and applications on dental and bony tissues. Nanoindentation has been a widely used technique to determine the mechanical properties such as nanohardness and Young’s modulus for nanostructured materials. Especially, atomic force microscopy (AFM) combined with nanoindentation, with the pit positions controlled accurately, become a powerful technique used to measure mechanical properties of materials on the nanoscale, and has been applied to the study of biological hard tissues, such as bone and tooth. Examples will be shown that significantly different nanohardness and modulus in the isolated domains within single enamel, the prisms, interprisms, the surrounding sheaths and the different parts of skeletal bone, could been distinguished, while such information was unable to be obtained by traditional methods of mechanical measurements.
5
Arsecularatne, J. A., e M. Hoffman. "Anin vitrostudy of the microstructure, composition and nanoindentation mechanical properties of remineralizing human dental enamel". Journal of Physics D: Applied Physics 47, n. 31 (11 luglio 2014): 315403. http://dx.doi.org/10.1088/0022-3727/47/31/315403.
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Houari, S., E. Picard, T. Wurtz, E. Vennat, N. Roubier, T. D. Wu, J. L. Guerquin-Kern et al. "Disrupted Iron Storage in Dental Fluorosis". Journal of Dental Research 98, n. 9 (22 luglio 2019): 994–1001. http://dx.doi.org/10.1177/0022034519855650.
Testo completoAbstract (sommario):
Enamel formation and quality are dependent on environmental conditions, including exposure to fluoride, which is a widespread natural element. Fluoride is routinely used to prevent caries. However, when absorbed in excess, fluoride may also lead to altered enamel structural properties associated with enamel gene expression modulations. As iron plays a determinant role in enamel quality, the aim of our study was to evaluate the iron metabolism in dental epithelial cells and forming enamel of mice exposed to fluoride, as well as its putative relation with enamel mechanical properties. Iron storage was investigated in dental epithelial cells with Perl’s blue staining and secondary ion mass spectrometry imaging. Iron was mainly stored by maturation-stage ameloblasts involved in terminal enamel mineralization. Iron storage was drastically reduced by fluoride. Among the proteins involved in iron metabolism, ferritin heavy chain (Fth), in charge of iron storage, appeared as the preferential target of fluoride according to quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry analyses. Fluorotic enamel presented a decreased quantity of iron oxides attested by electron spin resonance technique, altered mechanical properties measured by nanoindentation, and ultrastructural defects analyzed by scanning electron microscopy and energy dispersive x-ray spectroscopy. The in vivo functional role of Fth was illustrated with Fth+/-mice, which incorporated less iron into their dental epithelium and exhibited poor enamel quality. These data demonstrate that exposure to excessive fluoride decreases ameloblast iron storage, which contributes to the defective structural and mechanical properties in rodent fluorotic enamel. They raise the question of fluoride’s effects on iron storage in other cells and organs that may contribute to its effects on population health.
7
Frýdová, B., J. Šepitka, V. Stejskal, J. Frýda e J. Lukeš. "Nanoindentation mapping reveals gradients in the mechanical properties of dental enamel in rat incisors". Computer Methods in Biomechanics and Biomedical Engineering 16, sup1 (luglio 2013): 290–91. http://dx.doi.org/10.1080/10255842.2013.815874.
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Ctvrtlik, Radim, e Jan Tomastik. "Wear Behavior of Hard Dental Tissues and Restorative Materials". Applied Mechanics and Materials 486 (dicembre 2013): 72–77. http://dx.doi.org/10.4028/www.scientific.net/amm.486.72.
Testo completoAbstract (sommario):
Human teeth are exposed to various chemical and mechanical factors. From mechanical point of view it includes attrition, abrasion or their combination. Teeth and dental restorative materials are subjected to normal and shear loads. Therefore the contact-based stresses during mastication and teeth wear are of considerable importance. In order to study wear behavior of enamel, dentine and two dental restorative composite materials scratch test at various contact conditions was employed. Hardness and elastic modulus were measured using nanoindentation with spherical and pyramidal indenters. Residual wear tracks were observed using laser scanning confocal microscopy.
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Meng, Zhao Qiang, e Dan Yu Jiang. "Measuring Mechanical Properties of Zirconia Dental Crowns by Nanoindentation". Key Engineering Materials 591 (novembre 2013): 150–53. http://dx.doi.org/10.4028/www.scientific.net/kem.591.150.
Testo completoAbstract (sommario):
Mechanical properties of dental materials are increasingly studied via nanoindentation testing. Due to the excellent mechanical properties, 3-mol%-Yttria-Stabilized Tetragonal Zirconia (3Y-TZP) has become an attractive high-toughness core material for fixed dental restorations. In this paper, the mechanical properties of 3Y-TZP were studied by nanoindentation. The continuous stiffness measurement (CSM) and the single load/unload cycle test controlled by displacement and load respectively were performed with a Berkovich indenter.
10
Dong, Zhi Hong, e Chang Chun Zhou. "Particle Size of 45S5 Bioactive Glass Affected the Enamel Remineralization". Materials Science Forum 815 (marzo 2015): 396–400. http://dx.doi.org/10.4028/www.scientific.net/msf.815.396.
Testo completoAbstract (sommario):
In order to repair the etched human dental enamel, 45S5 bioactive glass with different particle size was used to remineralization enamel in vitro. 45S5 bioactive glass powder was sieved, and divided into the three groups. Freshly sound human second molar teeth from patients were extracted and specimens of dentine-enamel junction were prepared under water-cooled diamond saw, then the enamel surface was polished and finally rinsed. The enamel samples were soaked in simulated oral fluid (SOF) for 5 days. Particle size distribution, topological images and mechanical properties such as hardness and reduced modulus of enamel surface were evaluated by the laser particle size analyzer, atomic force microscope (AFM) and nanoindentation technology. The results indicated that the adhered particle size onto the enamel surface was concentrated on the 1-10 μm. With the decreasing particle size, adhesive capacity onto the enamel surface increased, but the mechanical properties decreased gradually after soaking in SOF for 5 days. In a short period time, Group 2 particles are suitable of repair the etched enamel, and further improve its mechanical properties. This study suggests that proper size 45S5 bioactive glass may be used to repair the acid etched teeth as a toothpaste additive.
11
Fong, Hanson, Mehmet Sarikaya, Shane White e Malcolm Snead. "Micro & Nano-Scale Structure of Enamel and Dentin-Enamel Junction of Human Teeth". Microscopy and Microanalysis 5, S2 (agosto 1999): 1010–11. http://dx.doi.org/10.1017/s1431927600018377.
Testo completoAbstract (sommario):
Enamel, which covers the anatomical crown of the tooth, is the hardest tissue in human body. Supported by a soft but tough dentin structure, the tooth is an advanced nanocomposite that can endure mastication stresses throughout a lifetime. A detail understanding the structure of the tooth, and sepecifically detin-enamel junction (DEJ), not only provides a sound basis for a model for synthetic dental restoration, but also provides lessons from nature on biomimetic regeneration with mechanical integrity. Enamel is a non-growing mineralized tissue and is subjected to most mechanical abuse. Dentin-enamel junction plays a critical role of distributing load between two very dissimilar materials - enamel and dentin. Bulk scale mechanical tests have shown that induced cracks on enamel tend to be arrested DEJ. Furthermore, nanoindentation measurements have also shown that there is a gradual decrease in hardness from enamel to dentin in the DEJ zone suggests a strong mechanical coupling in both deciduous and adult incisors. The objective of this investigation, through microscopical study, is to understand how these two dental hard tissues structurally couple through their junction zone.
12
Peskersoy, Cem, e Osman Culha. "Comparative Evaluation of Mechanical Properties of Dental Nanomaterials". Journal of Nanomaterials 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/6171578.
Testo completoAbstract (sommario):
This study examines the properties of nanobased dental restorative materials with nanoindentation method in a precise, repeatable, and comparable way. Microhybrid and nanohybrid composites, conventional glass ionomer materials, and light cured nanoionomer materials were utilised for the study. Specimen discs (r=10 mm,h=2 mm) were prepared to test the hardness, modulus of elasticity, yield strength, and fracture toughness values for each sample in a nanoindentation device with an atomic force microscopy add-on (n=25). Comparative analyses were performed by one-way ANOVA and post hoc Tukey tests. The hardness and modulus of elasticity values of nanocomposite were higher (2.58 GPa and 32.86 GPa, resp.) than those of other dental materials. Although glass ionomer exhibited a hardness that was similar to a nanoionomer (0.81 versus 0.87 GPa), glass ionomer had the lowest fracture toughness value (Kc=0.83 MPa/mm0.5). The mechanical properties of resin composites improve with additional nanoscale fillers, unlike the glass ionomer material.
13
Manda, Marianthi G., e Katerina E. Aifantis. "Nanoindentation derived mechanical properties of experimental dental restorative material". Ceramics International 41, n. 3 (aprile 2015): 4882–89. http://dx.doi.org/10.1016/j.ceramint.2014.12.047.
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Shahmoradi, Mahdi, Neil Hunter e Michael Swain. "Efficacy of Fluoride Varnishes with Added Calcium Phosphate in the Protection of the Structural and Mechanical Properties of Enamel". BioMed Research International 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/7834905.
Testo completoAbstract (sommario):
The aim of this study was to investigate the efficacy of various fluoride varnishes in the protection of the structural and nanomechanical properties of dental enamel. Demineralized enamel specimens were imaged using a high-resolution micro-CT system and lesion parameters including mineral density and lesion depth were extracted from mineral density profiles. Nanoindentation elastic modulus and hardness were calculated as a function of penetration depth from the load-displacement curves. The average depth of the lesion in specimens with no prior fluoride varnish treatment was 86±7.19 μm whereas the varnish treated specimens had an average depth of 67±7.03 μm (P<0.05). The mineral density of enamel lesions with no fluoride varnish treatment had an average of 1.85 gr/cm3 which was 25% lower than the corresponding value in varnish treated enamel and 37% lower than sound enamel. While, in the varnish treated group, elastic modulus and hardness values had decreased by 18% and 23%, respectively, the corresponding values in the non-varnish treated specimens had a reduction of 43% and 54% compared to the sound enamel. The findings from this study highlight the preventive role of fluoride varnishes. Addition of calcium and phosphate does not seem to enhance or inhibit the prevention or remineralization performance of fluoride varnishes.
15
Walch, Emmanuel Bastien Tommy, e Christian Roos. "Measurement of the mechanical properties of silver and enamel thick films using nanoindentation". International Journal of Applied Glass Science 11, n. 1 (23 settembre 2019): 195–206. http://dx.doi.org/10.1111/ijag.13875.
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Manda, Marianthi, Nikolaos Moschakis, Avraam Konstantinidis, Demetrios Christophilos, Lambrini Papadopoulou, Petros Koidis e Elias Aifantis. "Probing the mechanical properties of dental porcelain through nanoindentation". Journal of the Mechanical Behaviour of Materials 21, n. 1-2 (1 novembre 2012): 41–46. http://dx.doi.org/10.1515/jmbm-2012-0029.
Testo completoAbstract (sommario):
AbstractThe purpose of this short communication is to report on some micro/nanoscale aspects of the mechanical behavior of dental porcelain. Specimens were characterized by micro-Raman spectroscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Massive nanoindentation experiments on the surface of the specimens were performed, and typical load-displacement or load-depth (P-h) curves were obtained, which in turn were used to determine the Young modulus (E) and nanoindentation hardness (n-H), based on the Oliver-Pharr method [1]. Statistical analyses were carried out to determine the Spearman’s rank correlation coefficient (Spearman’s ρ), along with non-parametric linear regression analysis by employing Kolmogorov-Smirnov and Two-Step Cluster tests. Densification due to grain boundary diffusion and open-pore elimination was revealed by SEM. EDS analysis indicated a leucite-dispersed silicate glass matrix, as well as its contamination by traces of other minerals. Raman spectroscopy supported the EDS assignments. The P-h curves suggested that inelastic deformation and material flow increases at larger depths. Spearman’s ρ value showed strong dependence of E and n-H on h, indicating the occurrence of a size effect. The logarithmic data of E and n-H as functions of h were fitted by using linear regression analysis. The data did not obey a normal distribution (as the Kolmogorov-Smirnov test showed) due to the chemical heterogeneity involved. The Two-Step Cluster analysis indicated clustering in four groups associated with the chemical heterogeneity of the surface. Similar works using nanoindentation to determine the mechanical properties of dental materials can be found, for example, in [2, 3]. Corresponding methods for extracting the values of E and n-H from P-h experimental curves can be found, for example, in [4–6].
17
Raue, Lars, e Helmut Klein. "Location Depending Textures of the Human Dental Enamel". Solid State Phenomena 160 (febbraio 2010): 281–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.160.281.
Testo completoAbstract (sommario):
Dental enamel is the most highly mineralised and hardest biological tissue in human body [1]. Dental enamel is made of hydroxylapatite (HAP) - Ca5(PO4)3(OH), which is hexagonal (6/m). The lattice parameters are a = b = 0.9418 nm und c = 0.6875 nm [1]. Although HAP is a very hard mineral, it can be dissolved easily in a process which is known as enamel demineralization by lactic acid produced by bacteria. Also the direct consumption of acid (e.g. citric, lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. These processes can damage the dental enamel. It will be dissolved completely and a cavity occurs. The cavity must then be cleaned and filled. It exists a lot of dental fillings, like gold, amalgam, ceramics or polymeric materials. After filling other dangers can occur: The mechanical properties of the materials used to fill cavities can differ strongly from the ones of the dental enamel itself. In the worst case, the filling of a tooth can damage the enamel of the opposite tooth by chewing if the interaction of enamel and filling is not equivalent, so that the harder fillings can abrade the softer enamel of the healthy tooth at the opposite side. This could be avoided if the anisotropic mechanical properties of dental enamel would be known in detail, hence then another filling could be searched or fabricated as an equivalent opponent for the dental enamel with equal properties. To find such a material, one has to characterise the properties of dental enamel first in detail for the different types of teeth (incisor, canine, premolar and molar). This is here exemplary done for a human incisor tooth by texture analysis with the program MAUD from 2D synchrotron transmission images [2,3,4].
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Baldassarri, M., H. C. Margolis e E. Beniash. "Compositional Determinants of Mechanical Properties of Enamel". Journal of Dental Research 87, n. 7 (luglio 2008): 645–49. http://dx.doi.org/10.1177/154405910808700711.
Testo completoAbstract (sommario):
Dental enamel is comprised primarily of carbonated apatite, with less than 1% w/w organic matter and 4–5% w/w water. To determine the influence of each component on the microhardness and fracture toughness of rat incisor enamel, we mechanically tested specimens in which water and organic matrix were selectively removed. Tests were performed in mid-sagittal and transverse orientations to assess the effect of the structural organization on enamel micromechanical properties. While removal of organic matrix resulted in up to a 23% increase in microhardness, and as much as a 46% decrease in fracture toughness, water had a significantly lesser effect on these properties. Moreover, removal of organic matrix dramatically weakened the dentinoenamel junction (DEJ). Analysis of our data also showed that the structural organization of enamel affects its micromechanical properties. We anticipate that these findings will help guide the development of bio-inspired nanostructured materials for mineralized tissue repair and regeneration.
19
Zha, Chao, Jianhua Hu, Ainong Li, Shangyu Huang, Hanxing Liu, Gang Chen, Zuoqi Zhang, Bei Li e Zhengzhi Wang. "Nanoindentation study on mechanical properties and curing depth of dental resin nanocomposites". Polymer Composites 40, n. 4 (maggio 2018): 1473–80. http://dx.doi.org/10.1002/pc.24886.
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Zhou, Yang, Yanling Zhou, Long Gao, Chengtie Wu e Jiang Chang. "Synthesis of artificial dental enamel by an elastin-like polypeptide assisted biomimetic approach". Journal of Materials Chemistry B 6, n. 5 (2018): 844–53. http://dx.doi.org/10.1039/c7tb02576a.
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Koldehoff, Jasmin, e Gerold A. Schneider. "Effect of deproteinization treatments on the structure and mechanical properties of dental enamel". Materialia 16 (maggio 2021): 101088. http://dx.doi.org/10.1016/j.mtla.2021.101088.
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Kohda, Naohisa, Masahiro Iijima, Takeshi Muguruma, William A. Brantley, Karamdeep S. Ahluwalia e Itaru Mizoguchi. "Effects of mechanical properties of thermoplastic materials on the initial force of thermoplastic appliances". Angle Orthodontist 83, n. 3 (4 ottobre 2012): 476–83. http://dx.doi.org/10.2319/052512-432.1.
Testo completoAbstract (sommario):
ABSTRACT Objective: To measure the forces delivered by thermoplastic appliances made from three materials and investigate effects of mechanical properties, material thickness, and amount of activation on orthodontic forces. Materials and Methods: Three thermoplastic materials, Duran (Scheu Dental), Erkodur (Erkodent Erich Kopp GmbH), and Hardcast (Scheu Dental), with two different thicknesses were selected. Values of elastic modulus and hardness were obtained from nanoindentation measurements at 28°C. A custom-fabricated system with a force sensor was employed to obtain measurements of in vitro force delivered by the thermoplastic appliances for 0.5-mm and 1.0-mm activation for bodily tooth movement. Experimental results were subjected to several statistical analyses. Results: Hardcast had significantly lower elastic modulus and hardness than Duran and Erkodur, whose properties were not significantly different. Appliances fabricated from thicker material (0.75 mm or 0.8 mm) always produced significantly greater force than those fabricated from thinner material (0.4 mm or 0.5 mm). Appliances with 1.0-mm activation produced significantly lower force than those with 0.5-mm activation, except for 0.4-mm thick Hardcast appliances. A strong correlation was found between mechanical properties of the thermoplastic materials and force produced by the appliances. Conclusions: Orthodontic forces delivered by thermoplastic appliances depend on the material, thickness, and amount of activation. Mechanical properties of the polymers obtained by nanoindentation testing are predictive of force delivery by these appliances.
23
Muntean, Alexandrina, Sorina Sava, Sarosi Codruta, Marioara Moldovan, Mariana Pacurar e Ada Gabriela Delean. "Assessment of Water Sorption, Solubility and Interface Properties for Two Different Pit and Fissure Sealants". Materiale Plastice 57, n. 3 (30 settembre 2020): 81–88. http://dx.doi.org/10.37358/mp.20.3.5382.
Testo completoAbstract (sommario):
The purpose of modern dental medicine is to prevent dental caries and promote minimally invasive techniques at the expense of invasive methods. Dental sealants are largely recommended for occlusal surfaces protection, but concerns are related about microleakage at material-enamel interface. This in vitro study aimed to investigate the association between chemical structure, sealing capacity and marginal infiltration for 2 fluoride F containing commercially available resin-based sealants: Pit&Fissure� Sealant (DMP) and Fissurit FX� (Voco) in order to achieve a better description and ensure adequate material selection in every day practice. An optimal resin-based sealant should mimic the structural, physical and mechanical characteristics of enamel. The main difference between the sealing materials tested is based on the amounts of inorganic filler and on the various shapes of the particles in the filler. Pit&Fisure� Sealant express less attachment at enamel interface, higher sorption and greater water solubility, when compared to Fissurit FX�. The better sealing capacity of Fissurit FX� can be described by the homogeneity of the material and the very small size of the inorganic fillers. Dental materials properties used as pit and fissure sealants are sensitive to mechanical, thermic and chemical stress from oral cavity. Regular dental check-up can detect the presence and integrity of sealant and ensure preventive effect in time.
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Raue, Lars, Helmut Klein e Christiane Hartmann. "Elastic Modulus of Human Dental Enamel from Different Methods". International Journal of Biomaterials Research and Engineering 1, n. 1 (gennaio 2011): 39–48. http://dx.doi.org/10.4018/ijbre.2011010104.
Testo completoAbstract (sommario):
Knowing the elastic modulus of human dental enamel is of high importance since dental filling materials should posses equal mechanical properties as enamel itself. If this demand is not fulfilled, the interaction between filling and enamel is not equivalent, so that healthy enamel could be simply abrased during chewing. Hence it is astonishing that the literature shows a big variety of suggestions for the elastic modulus. This paper will give a short overview about some existing results (maybe not all) and tries to compare and evaluate them. The experiments have been done too, trying to make it more easy for the experienced reader to make up his own mind about the elastic modulus of human dental enamel.
25
Kim, Hee-Kyung. "Optical and Mechanical Properties of Highly Translucent Dental Zirconia". Materials 13, n. 15 (31 luglio 2020): 3395. http://dx.doi.org/10.3390/ma13153395.
Testo completoAbstract (sommario):
The aim was to evaluate the translucency, opalescence, and fluorescence of highly translucent zirconia, lithium disilicate, and bovine teeth. One mm-thick specimens of five monolithic zirconia systems, two glass-ceramics, and bovine enamel/dentin were investigated. A spectrophotometer (Ci7600) was used to measure the CIELab color coordinates, and the translucency and opalescence values were obtained. For evaluating the fluorescence emission, the differences in spectral reflectance by the UV component of illumination were calculated. The microstructures of ceramic specimens were examined with a scanning electron microscope and the chemical compositions were determined with an X-ray fluorescence spectrometer. Mechanical properties were appraised with three-point bending strength, indentation fracture toughness, and Vickers hardness. Data were analyzed using a one-way ANOVA, followed by Tukey’s multiple comparison test (α = 0.05). A higher yttria content (5 mol%) significantly improved the translucency of zirconia ceramics, while they were less translucent than lithium disilicate (p < 0.05). Lowering the alumina content below 0.05 wt.% enhanced the translucency (p < 0.05), but a small amount of alumina was still required to obtain full densification. 0.05 wt.% Fe was used to increase the chroma of zirconia specimens without compromising their mechanical properties. The Er-containing zirconia specimen showed a maximal fluorescence emission at 430 nm. The degree of opalescence was affected by the microstructures of ceramic materials. The microstructure, incorporation of a secondary phase, and sintering behavior can have a strong impact on the final mechanical and optical properties of dental ceramics. Addition of small amounts of metal oxides can affect the translucency, opalescence or fluorescence qualities of zirconia
26
Raue, Lars, e Helmut Klein. "Calculation of anisotropic properties of dental enamel from synchrotron data". Journal of Synchrotron Radiation 18, n. 4 (12 maggio 2011): 550–56. http://dx.doi.org/10.1107/s0909049511011071.
Testo completoAbstract (sommario):
Obtaining information about the intrinsic structure of polycrystalline materials is of prime importance owing to the anisotropic behaviour of individual crystallites. Grain orientation and its statistical distribution,i.e.the texture, have an important influence on the material properties. Crystallographic orientations play an important role in all kinds of polycrystalline materials such as metallic, geological and biological. Using synchrotron diffraction techniques the texture can be measured with high local and angular resolving power. Here methods are presented which allow the spatial orientation of the crystallites to be determined and information about the anisotropy of mechanical properties, such as elastic modulus or thermal expansion, to obtained. The methods are adapted to all crystal and several sample symmetries as well as to different phases, for example with overlapping diffraction peaks. To demonstrate the abilities of the methods, human dental enamel has been chosen, showing even overlapping diffraction peaks. Likewise it is of special interest to learn more about the orientation and anisotropic properties of dental enamel, since only basic information is available up to now. The texture of enamel has been found to be a tilted fibre texture of high strength (up to 12.5×). The calculated elastic modulus is up to 155 GPa and the thermal expansion up to 22.3 × 10−6 °C−1.
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Mystkowska, Joanna. "Mechanical and Physicochemical Properties of Tetric EvoCeram® - Dental Composite Material". Solid State Phenomena 147-149 (gennaio 2009): 807–12. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.807.
Testo completoAbstract (sommario):
This work presents results of research of fluoride release, microhardness and surface roughness and wear of the Tetric EvoCeram material. Wear tests were carried out by means of special tribotester for tooth analysis and by pin-on-disc tribometer. The wear of composite material and counterface (human enamel) were measured. Finally, investigations showed that fluoride ions from commerce material were slightly released. However, the amount of fluoride ions release was depended on pH and temperature of agent solution. Fluorine emission from composite material changed its surface roughness and microhardness. The using method of wear process influenced on friction coefficient value. During friction process the wear layer on composite surface was formed.
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Petrović, Bojan, Evgenija Marković, Tamara Perić e Sanja Kojić. "Challenges in Experimental Evaluation of Morphological, Chemo-Mechanical and Adhesive Properties of Glass-ionomer Based Dental Materials". Advanced Technologies & Materials 44, n. 2 (20 dicembre 2019): 26–30. http://dx.doi.org/10.24867/atm-2019-2-005.
Testo completoAbstract (sommario):
Changes in composition and new material characteristics require verification in clinical and experimental studies. Investigating glass-ionomer cements under laboratory conditions encounters problems in interpreting the results and in comparing them with other types of materials tested in the same way. As the connection between the glass-ionomer cements and the dental tissues is delicate, it is often the case that the impact of fractures and other artifacts is either underestimated or over-dimensioned when interpreting the results. A critical review was performed, with defining the main problems regarding the usage of SEM, EDX and nanoindentation techniques in glass-ionomer based materials evaluation.
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Palacios, Teresa, Sandra Tarancón e José Ygnacio Pastor. "On the Mechanical Properties of Hybrid Dental Materials for CAD/CAM Restorations". Polymers 14, n. 16 (10 agosto 2022): 3252. http://dx.doi.org/10.3390/polym14163252.
Testo completoAbstract (sommario):
Two hybrid dental materials available for computer-aided design and manufacturing (CAD/CAM) dental restorations have been selected to explore their potential. On the one hand, the scarcely investigated polymer-based material Vita Enamic® (VE) and, on the other hand, the leucite-based material IPS Empress® CAD (EC). Their micro-structure and mechanical performance were analyzed in two environments: directly as received by the manufacturer (AR), and after immersion and storage in artificial saliva (AS) for 30 days to determine the influence of the saliva effect. To avoid an inappropriate selection of materials for clinical use, a full understanding of their mechanical behavior is essential. Therefore, this investigation aims to determine the micro-structural and chemical composition by field emission scanning electron microscopy (FE-SEM) and X-ray fluorescence analysis, establishing the density, micro- and nano-hardness, the nano-elastic modulus, and the flexural strength and fracture toughness (by introducing a femto-laser notch to replicate a real crack). In addition, fracture surfaces of the broken samples were analyzed to correlate the failure micro-mechanisms with their mechanical properties. Results indicate that while the crystalline phase of the materials is very similar (composed of SiO2 and Al2O3), the micro-structure and mechanical behavior is not. The material EC, with finer micro-structure, exhibits a higher mechanical performance but with greater variability of results. Furthermore, the material VE, with a 25 vol.% polymer phase, shows a mechanical performance similar to enamel and dentin and therefore more similar to human behavior.
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Tokunaga, Jumpei, Hiroshi Ikeda, Yuki Nagamatsu, Shuji Awano e Hiroshi Shimizu. "Wear of Polymer-Infiltrated Ceramic Network Materials against Enamel". Materials 15, n. 7 (25 marzo 2022): 2435. http://dx.doi.org/10.3390/ma15072435.
Testo completoAbstract (sommario):
Polymer-infiltrated ceramic network materials (PICNs) have high mechanical compatibility with human enamel. However, the wear properties of PICN against natural human enamel have not yet been clarified. We investigated the in vitro two-body wear behaviors of PICNs and an enamel antagonist. Two PICNs were used: Experimental PICN (EXP) prepared via the infiltration of methacrylate-based resin into the porous silica ceramic network and commercial Vita Enamic (ENA). Two commercial dental ceramics, lithium disilicate glass (LDS) and zirconia (ZIR), were also characterized, and their wear performance was compared to PICNs. The samples were subjected to Vickers hardness tests and two-body wear tests that involve the samples being cyclically impacted by enamel antagonists underwater at 37 °C. The results reveal that the Vickers hardness of EXP (301 ± 36) was closest to that of enamel (317 ± 17). The volumetric wear losses of EXP and ENA were similar to those of LDS but higher than that of zirconia. The volumetric wear loss of the enamel antagonist impacted against EXP was moderate among the examined samples. These results suggest that EXP has wear behavior similar to that of enamel. Therefore, PICNs are mechanically comparable to enamel in terms of hardness and wear and are excellent tooth-restoration materials.
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Hernández-Vázquez, Rosa Alicia, Guillermo Urriolagoitia-Sosa, Rodrigo Arturo Marquet-Rivera, Beatriz Romero-Ángeles, Octavio-Alejandro Mastache-Miranda e G. Guillermo Urriolagoitia-Calderón. "Numerical Analysis of a Dental Zirconium Restoration and the Stresses That Occur in Dental Tissues". Applied Bionics and Biomechanics 2019 (5 settembre 2019): 1–13. http://dx.doi.org/10.1155/2019/1049306.
Testo completoAbstract (sommario):
When it is about restorative dental materials, aesthetics is traditionally preferred. This has led to the selection of materials very visually similar to the enamel, but unfortunately, their mechanical properties are not similar. This often translates into disadvantages than advantages. In the present work, a comparison is made of the stresses that occur during dental occlusion (dental bit) in a healthy dental organ and those that are generated in a dental organ with a dental zirconium restoration. Numerical simulation was carried out by means of the Finite Element Method, in computational biomodels, from Cone-Beam Tomography, to obtain the stresses generated during dental occlusion. It was found that the normal and von Mises stresses generated are substantially greater in the molar with restoration compared to those produced in the healthy molar. In addition, the normal function of the enamel and dentin to disperse these stresses to prevent them from reaching the pulp is altered. Therefore, it is necessary to analyze the indiscriminate use of this restoration material and consider other aspects, in addition to aesthetics and biocompatibility for the choice of restorative materials such as biomechanical compatibility.
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Vrbova, Radka, Pavel Bradna, Martin Bartos, Lucie Himmlova e Tomas Horazdovsky. "THE CURRENT VIEW ON THE USE OF RECONSTRUCTION MATERIALS IN DENTISTRY". Acta Polytechnica CTU Proceedings 8 (30 giugno 2017): 27–29. http://dx.doi.org/10.14311/app.2017.8.0027.
Testo completoAbstract (sommario):
The hardest tissue in the human body is the enamel which covers the anatomical crowns of teeth. It must be resistant to mechanical stress and the chemical attack of many substances from food, drinks and products of the metabolism of bacteria present in the oral cavity. These low pH substances dissolve the mineral components of enamel, cause tooth demineralization, and lead to decay or erosion damage with the irreversible loss of dental hard tissues and the necessity of their reconstruction. The range of dental materials intended for dental tissue reconstruction is extensive. Dental amalgam can be mechanically applied into the strongly stressed lateral segments of teeth. The use of amalgam is, however, in decline, with the possible health risks attributed to it, coupled with the need to extensively prepare tooth tissue promoting a shift towards using aesthetically and biologically favourable dental ceramic and polymeric materials instead. Current developments also concentrate on these materials to reinforce this, with polymeric composite materials based on methacrylates with varying amounts of inorganic fillers at the forefront. These materials are distinguished by their good mechanical and aesthetic properties and wear resistance. However, polymerization shrinkage and a strong hydrophobic nature does not allow for their direct bonding to hard dental tissues. Risks associated with the release of residual free monomers from the structure to the environment, which may cause health complications, mainly allergic reactions in sensitive individuals, have been monitored recently. Further development in the field of composite materials aims to reduce or completely eliminate these negatives.
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Hernández-Vázquez, Rosa Alicia, Beatriz Romero-Ángeles, Guillermo Urriolagoitia-Sosa, Juan Alejandro Vázquez-Feijoo, Ángel Javier Vázquez-López e Guillermo Urriolagoitia-Calderón. "Numerical Analysis of Masticatory Forces on a Lower First Molar considering the Contact between Dental Tissues". Applied Bionics and Biomechanics 2018 (2018): 1–15. http://dx.doi.org/10.1155/2018/4196343.
Testo completoAbstract (sommario):
The aim of the present work is to identify the reactions of the dental organs to the different forces that occur during chewing and the transcendence of the union and contact maintained by the dental tissues. The study used a lower first molar biomodel with a real morphology and morphometry and consisting of the three dental tissues (enamel, dentin, and pulp) each with its mechanical properties. In it, two simulations were carried out, as would the process of chewing a food. One of the simulations considers the contact between the enamel and the dentin, and the other does not take it into account. The results obtained differ significantly between the simulations that consider contact and those that do not, establishing the importance of taking this contact into account. In this way, the theories that establish horizontal and lateral occlusion forces are present during the functional chewing process which are viable to be correct. The case studies carried out present not only the reasons for the failure of enamel but also the failure of the restoration materials used. This reflection will allow the development of more adequate materials, mechanical design of prostheses, implants, and treatment.
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Asrar, Shafaq, Ambreen Azmat, Iftikhar Ahmed Channa, Jaweria Ashfaq, Faraz Sufyan, Sarmad Feroze, Ali Dad Chandio, Muhammad Ali Shar e Abdulaziz Alhazaa. "Comparative Study of TiMn and TiAlV Alloys via the Nanoindentation Technique". Crystals 12, n. 11 (28 ottobre 2022): 1537. http://dx.doi.org/10.3390/cryst12111537.
Testo completoAbstract (sommario):
There are two common categories of implants that are used in medical sciences, i.e., orthopedic and dental ones. In this study, dental implant materials are focused such as Ti6Al4V alloys that are used for the replacement of lost teeth due to their high strength and biocompatibility. However, they cause infections in nearby tissues due to elemental release (potentially Al and V). Thus, manganese is selected to be incorporated into the alloy since it is also present in the human body in the form of traces. Different sets of implants were produced, i.e., Ti5Mn and Ti10Mn (where 5 and 10 describe the percentage of Mn) by using the powder metallurgy technique. This was followed by characterization techniques, including X-ray fluorescence spectroscopy (XRF), X-ray diffractometer (XRD), optical microscope (OM), and nanoindenter. The very aim of this study is to compare the microstructural evolutions, density, and mechanical properties of reference alloys and the ones produced in this study. Results show the microstructure of Ti6Al4V consists of the alpha (α) and beta (β) phases, while Ti5Mn and Ti10Mn revealed the beta (β) phases. The Ti5Mn alloy showed excellent mechanical properties than that of the Ti6Al4V counterpart. Extensive discussion is presented in light of the observed results. The relative density of Ti5Mn alloy was found to be enhanced than that of reference alloy.
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Zhang, H., M. B. Chavez, T. N. Kolli, M. H. Tan, H. Fong, E. Y. Chu, Y. Li et al. "Dentoalveolar Defects in the Hyp Mouse Model of X-linked Hypophosphatemia". Journal of Dental Research 99, n. 4 (24 gennaio 2020): 419–28. http://dx.doi.org/10.1177/0022034520901719.
Testo completoAbstract (sommario):
Mutations in PHEX cause X-linked hypophosphatemia (XLH), a form of hypophosphatemic rickets. Hyp ( Phex mutant) mice recapitulate the XLH phenotype. Dental disorders are prevalent in individuals with XLH; however, underlying dentoalveolar defects remain incompletely understood. We analyzed Hyp mouse dentoalveolar defects at 42 and 90 d postnatal to comparatively define effects of XLH on dental formation and function. Phex mRNA was expressed by odontoblasts (dentin), osteocytes (bone), and cementocytes (cellular cementum) in wild-type (WT) mice. Enamel density was unaffected, though enamel volume was significantly reduced in Hyp mice. Dentin defects in Hyp molars were indicated histologically by wide predentin, thin dentin, and extensive interglobular dentin, confirming micro–computed tomography (micro-CT) findings of reduced dentin volume and density. Acellular cementum was thin and showed periodontal ligament detachment. Mechanical testing indicated dramatically altered periodontal mechanical properties in Hyp versus WT mice. Hyp mandibles demonstrated expanded alveolar bone with accumulation of osteoid, and micro-CT confirmed decreased bone volume fraction and alveolar bone density. Cellular cementum area was significantly increased in Hyp versus WT molars owing to accumulation of hypomineralized cementoid. Histology, scanning electron microscopy, and nanoindentation revealed hypomineralized “halos” surrounding Hyp cementocyte and osteocyte lacunae. Three-dimensional micro-CT analyses confirmed larger cementocyte/osteocyte lacunae and significantly reduced perilacunar mineral density. While long bone and alveolar bone osteocytes in Hyp mice overexpressed fibroblast growth factor 23 ( Fgf23), its expression in molars was much lower, with cementocyte Fgf23 expression particularly low. Expression and distribution of other selected markers were disturbed in Hyp versus WT long bone, alveolar bone, and cementum, including osteocyte/cementocyte marker dentin matrix protein 1 ( Dmp1). This study reports for the first time a quantitative analysis of the Hyp mouse dentoalveolar phenotype, including all mineralized tissues. Novel insights into cellular cementum provide evidence for a role for cementocytes in perilacunar mineralization and cementum biology.
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Heboyan, Artak, Anna Vardanyan, Mohmed Isaqali Karobari, Anand Marya, Tatevik Avagyan, Hamid Tebyaniyan, Mohammed Mustafa, Dinesh Rokaya e Anna Avetisyan. "Dental Luting Cements: An Updated Comprehensive Review". Molecules 28, n. 4 (8 febbraio 2023): 1619. http://dx.doi.org/10.3390/molecules28041619.
Testo completoAbstract (sommario):
The cementation of indirect restoration is one of the most important steps in prosthetic and restorative dentistry. Cementation aims to bond the prosthetic restoration to the prepared enamel or enamel and dentine. Successful cementation protocols prevent biofilm formation at the margin between tooth and restoration and minimize mechanical and biological complications. With the advancements in dental cements, they have been modified to be versatile in terms of handling, curing, and bond strengths. This review presents updates on dental cements, focusing on the composition, properties, advantages, limitations, and indications of the various cements available. Currently, dental restorations are made from various biomaterials, and depending on each clinical case, an appropriate luting material will be selected. There is no luting material that can be universally used. Therefore, it is important to distinguish the physical, mechanical, and biological properties of luting materials in order to identify the best options for each case. Nowadays, the most commonly used dental cements are glass-ionomer and resin cement. The type, shade, thickness of resin cement and the shade of the ceramic, all together, have a tangible influence on the final restoration color. Surface treatments of the restoration increase the microtensile bond strength. Hence, the proper surface treatment protocol of both the substrate and restoration surfaces is needed before cementation. Additionally, the manufacturer’s instructions for the thin cement-layer thickness are important for the long-term success of the restoration.
37
Roh, Jiyeon, Hyunjung Shin e Min-Ho Hong. "Characteristics of 10-Methacryloyloxidecyl Dihydrogen Phosphate Monomer in Self-Etching Two-Bottled Dental Adhesive System: Comparison with Commercial Products". Materials 13, n. 16 (12 agosto 2020): 3553. http://dx.doi.org/10.3390/ma13163553.
Testo completoAbstract (sommario):
Dentin bonding is a key in restorative dentistry. Here, we developed a self-etching two-bottle adhesive system containing 10-methacryloyloxidecyl dihydrogen phosphate monomer (MDP) and the physical, mechanical, and biocompatible properties were evaluated. The characteristics of MDP were analyzed using nuclear magnetic resonance (NMR). Tests for water sorption and solubility, the shear-bond strengths to dentin and enamel, and cytotoxicity were performed. The newly-blended experimental group showed the lowest thickness and water sorption and solubility values. The shear bond strength of enamel and dentin were comparable to control groups (the three other products were ClearfilTM, UniFil®, and AdheSE®). All test groups showed 60% of cell viability. In this study, the properties of the newly-synthesized adhesive are comparable with the others. The fundamental goal of this study is to get the MDP patent released, as it is intended for domestic production. For this purpose, this dentin adhesive was developed and compared with the commercial product.
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Dorado, Saúl, Ana Arias e Jesus R. Jimenez-Octavio. "Biomechanical Modelling for Tooth Survival Studies: Mechanical Properties, Loads and Boundary Conditions—A Narrative Review". Materials 15, n. 21 (7 novembre 2022): 7852. http://dx.doi.org/10.3390/ma15217852.
Testo completoAbstract (sommario):
Recent biomechanical studies have focused on studying the response of teeth before and after different treatments under functional and parafunctional loads. These studies often involve experimental and/or finite element analysis (FEA). Current loading and boundary conditions may not entirely represent the real condition of the tooth in clinical situations. The importance of homogenizing both sample characterization and boundary conditions definition for future dental biomechanical studies is highlighted. The mechanical properties of dental structural tissues are presented, along with the effect of functional and parafunctional loads and other environmental and biological parameters that may influence tooth survival. A range of values for Young’s modulus, Poisson ratio, compressive strength, threshold stress intensity factor and fracture toughness are provided for enamel and dentin; as well as Young’s modulus and Poisson ratio for the PDL, trabecular and cortical bone. Angles, loading magnitude and frequency are provided for functional and parafunctional loads. The environmental and physiological conditions (age, gender, tooth, humidity, etc.), that may influence tooth survival are also discussed. Oversimplifications of biomechanical models could end up in results that divert from the natural behavior of teeth. Experimental validation models with close-to-reality boundary conditions should be developed to compare the validity of simplified models.
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Gao, Q. P., Yong Lie Chao, X. Ch Jian, F. Guo, Y. K. Meng, H. Wang, Jun Cui, Wei Qun Zhang e Y. F. Tian. "Wear Behavior of Enamel/Dentine and Veneering Ceramics". Key Engineering Materials 330-332 (febbraio 2007): 1251–54. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.1251.
Testo completoAbstract (sommario):
This in vitro study compared the wear behavior between the enamel/dentine, two types of dental veneering ceramics for all-ceramic restorations (Vita-alpha，Vintage -AL ). A variety of factors including hardness, fracture toughness, flexural strength, frictional coefficients, wear scar width, element concentrations were considered. The wear scars of the samples were characterized by dynamic atomic force microscopy (DFM). The element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS). In this study Enamel/dentine, Vita-alpha and Vintage-AL have showed good wear resistance. The results also showed that there were statistical significance in samples. The friction coefficient varied from time in each kind of materials. The analytical differences between materials were observed in wear width and properties of materials (p<0.05). The wear ability among four materials ranked from highest to lowest as follows, Vintage-AL, Vita-alpha, enamel and dentine. DFM results demonstrated the wear patterns of natural tooth detected as abrasive and denaturation of dental texture. Wear patterns of tested veneering ceramics consisted mainly of abrasive wear, adhesion and fatigue wear and the different pattern plays different roles in Vita-alpha and Vintage-AL. The EDS results showed the element concentration of Fe was obviously found on the samples. Resistance ability against wear of veneering ceramics is better than that of natural human teeth. And the ability may have some correlation with the ceramics mechanical properties.
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Řehounek, Luboš, e Aleš Jíra. "NUMERICAL AND MECHANICAL ANALYSES OF A 3D-PRINTED TITANIUM TRABECULAR DENTAL IMPLANT". Acta Polytechnica 57, n. 3 (30 giugno 2017): 218–28. http://dx.doi.org/10.14311/ap.2017.57.0218.
Testo completoAbstract (sommario):
The main focus of this paper is to investigate and describe a novel biomaterial structure. The trabecular structure has only recently been recognized as a viable alternative for prostheses and implants and seems to have very promising biocompatibility and mechanical properties. The 3D printing technique was used to create test specimens. These specimens were then tested by nanoindentation and tensile and compression tests. A numerical model was created and curve-fitted to represent the mechanical behavior of the trabecular structure. A significant reduction in the values of Young’s modulus <em>E</em> was observed. The values of <em>E</em> for conventional implant materials are approximately 110–120GPa and the trabecular structure reached a value just below 1GPa. The next effort will be to apply the model onto a real implant. It is the “four leaf clover” implant variant by authors F. Denk Jr., A. Jíra and F. Denk Sr.
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Ciocan, Lucian Toma, Elena Iuliana Biru, Vlad Gabriel Vasilescu, Jana Ghitman, Ana-Roxana Stefan, Horia Iovu e Roxana Ilici. "Influence of Air-Barrier and Curing Light Distance on Conversion and Micro-Hardness of Dental Polymeric Materials". Polymers 14, n. 24 (7 dicembre 2022): 5346. http://dx.doi.org/10.3390/polym14245346.
Testo completoAbstract (sommario):
This study aims to assess the conversion degree and hardness behavior of two new commercial dental restorative composites that have been submitted to light curing in different environments (air and glycerin, respectively) at various distances from the light source (1 to 5 mm) and to better understand the influence of the preparation conditions of the restorative materials. Through FT-IR spectrometry, the crosslinking degree of the commercial restorative materials have been investigated and different conversion values were obtained (from ~17% to ~90%) but more importantly, it was shown that the polymerization environment exhibits a significant influence on the crosslinking degree of the resin-based composites especially for obtaining degrees of higher polymerization. Additionally, the mechanical properties of the restorative materials were studied using the nanoindentation technique showing that the nano-hardness behavior is strongly influenced not only by the polymerization lamp position, but also by the chemical structure of the materials and polymerization conditions. Thus, the nanoindentation results showed that the highest nano-hardness values (~0.86 GPa) were obtained in the case of the flowable C3 composite that contains BisEMA and UDMA as a polymerizable organic matrix when crosslinked at 1 mm distance from the curing lamp using glycerin as an oxygen-inhibitor layer.
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Van der Laan, H. L., S. L. Zajdowicz, K. Kuroda, B. J. Bielajew, T. A. Davidson, J. Gardinier, D. H. Kohn et al. "Biological and Mechanical Evaluation of Novel Prototype Dental Composites". Journal of Dental Research 98, n. 1 (6 settembre 2018): 91–97. http://dx.doi.org/10.1177/0022034518795673.
Testo completoAbstract (sommario):
The breakdown of the polymeric component of contemporary composite dental restorative materials compromises their longevity, while leachable compounds from these materials have cellular consequences. Thus, a new generation of composite materials needed to be designed to have a longer service life and ensure that any leachable compounds are not harmful to appropriate cell lines. To accomplish this, we have developed concurrent thiol-ene-based polymerization and allyl sulfide–based addition-fragmentation chain transfer chemistries to afford cross-linked polymeric resins that demonstrate low shrinkage and low shrinkage stress. In the past, the filler used in dental composites mainly consisted of glass, which is biologically inert. In several of our prototype composites, we introduced fluorapatite (FA) crystals, which resemble enamel crystals and are bioactive. These novel prototype composites were benchmarked against similarly filled methacrylate-based bisphenol A diglycidyl ether dimethacrylate / triethylene glycol dimethacrylate (bisGMA/TEGDMA) composite for their cytotoxicity, mechanical properties, biofilm formation, and fluoride release. The leachables at pH 7 from all the composites were nontoxic to dental pulp stem cells. There was a trend toward an increase in total toughness of the glass-only-filled prototype composites as compared with the similarly filled bisGMA/TEGDMA composite. Other mechanical properties of the glass-only-filled prototype composites were comparable to the similarly filled bisGMA/TEGDMA composite. Incorporation of the FA reduced the mechanical properties of the prototype and bisGMA/TEGDMA composite. Biofilm mass and colony-forming units per milliliter were reduced on the glass-only-filled prototype composites as compared with the glass-only-filled bisGMA/TEGDMA composite and were significantly reduced by the addition of FA to all composites. Fluoride release at pH 7 was greatest after 24 h for the bisGMA/TEGDMA glass + FA composite as compared with the similarly filled prototypes, but overall the F- release was marginal and not at a concentration to affect bacterial metabolism.
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Milosevic, Milos, Uroš Tatić, Simon Sedmak, Jasmina Perović e Vesna Miletić. "Calculation of Maximum Tensile and Shear Forces in Restorative Materials Using Finite Element Method". Key Engineering Materials 601 (marzo 2014): 151–54. http://dx.doi.org/10.4028/www.scientific.net/kem.601.151.
Testo completoAbstract (sommario):
The purpose of this paper was to determine tensile loading that leads to dental restoration failure, i.e. the critical values of stress. In order to analyze stress distribution within the restoration and tooth, mechanical properties of materials and tissues, such as Young modulus and Poissons ratio were taken into account. An additional purpose of the paper was to determine whether tensile or shear stresses that occur in the restorative composite and the surrounding enamel cause this failure. Tensile stress is caused by forces acting in the direction perpendicular to the cross-section of a given element, whereas shear stresses are caused by forces parallel to said cross section. A 3D numerical model of a tooth including three different materials (dentine, enamel and composite) was made and used for these calculations. These results will be used as a base for the physical experiment.
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Daryakenari, G., H. Alaghehmand e A. Bijani. "Effect of Simulated Mastication on the Surface Roughness and Wear of Machinable Ceramics and Opposing Dental Enamel". Operative Dentistry 44, n. 1 (1 gennaio 2019): 88–95. http://dx.doi.org/10.2341/17-153-l.
Testo completoAbstract (sommario):
SUMMARY Objective: Computer aided design-computer aided machining (CAD-CAM) ceramic crowns are replacing ceramo-metal ones due to newly developed mechanical properties and esthetics. To obtain knowledge about their interactions due to polishing and occlusal contacts with the opposing dental enamel specimen, including surface roughness and wear, the three-body wear simulation was investigated. Methods and Materials: The surface roughness (RA) and wear rate (mm) of four CAD-CAM blocks with different compositions including Vita Mark II, e.max, Suprinity, and Enamic, after two surface treatments of glazing and polishing, and their opposing enamel specimens, were investigated using a mastication simulator and atomic force microscope. Results: The roughness of all ceramic and to a greater extent enamel samples, with the exception of enamel opposing polished Enamic samples, was decreased after wear. No significant difference in wear was evident for the ceramic samples between the glazed and polished treatments. Lower wear rates were recorded only for polished Vita Mark II and polished Enamic in comparison to the glazed ones. Conclusion: The newly developed polishing systems for CAD-CAM ceramics can be good alternatives to reglazing, because the roughness and wear rate of both the ceramic and the opposing enamel will either not change or decrease.
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Nizami, Mohammed Zahedul Islam, Veena W. Xu, Iris X. Yin, Ollie Y. Yu e Chun-Hung Chu. "Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review". Nanomaterials 11, n. 12 (20 dicembre 2021): 3446. http://dx.doi.org/10.3390/nano11123446.
Testo completoAbstract (sommario):
Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles’ nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.
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Shi, Zhuoyue. "Advances in biomimetic mineralization of tooth enamel based on cell-free strategies". MATEC Web of Conferences 363 (2022): 01032. http://dx.doi.org/10.1051/matecconf/202236301032.
Testo completoAbstract (sommario):
Tooth enamel is a highly-mineralized hard tissue covering the outermost layer of the dental crown, and amelogenesis is inseparable from the participation of necessary components such as ameloblasts, organic matrix proteins, and mineral ions, such as Ca2+ and PO43-. However, mature enamel is an acellular tissue and it is difficult to self-repair once damaged. The current treatment methods for enamel damage are filling or repairing with alloys, ceramics, or composite resins. However, the mechanical properties of these materials are quite different from the natural enamel and they can’t ensure a completely closed interface with the remaining enamel surface, which usually causes a series of post-repair problems. At present, the biomimetic mineralization of tooth enamel is a research hotspot in the field of prosthodontics, and has great clinical application needs and prospects, especially the researches on cell-free strategies have made significant accomplishment. Here, based on the cell-free strategies, we review the recent knowledge from ex situ and in situ two dimensions in the remineralization of tooth ename.
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Toledano-Serrabona, Jorge, Maria Ángeles Sánchez-Garcés, Cosme Gay-Escoda, Eduard Valmaseda-Castellón, Octavi Camps-Font, Pablo Verdeguer, Meritxell Molmeneu e Francisco Javier Gil. "Mechanical Properties and Corrosion Behavior of Ti6Al4V Particles Obtained by Implantoplasty: An In Vitro Study. Part II". Materials 14, n. 21 (29 ottobre 2021): 6519. http://dx.doi.org/10.3390/ma14216519.
Testo completoAbstract (sommario):
In the field of implant dentistry there are several mechanisms by which metal particles can be released into the peri-implant tissues, such as implant insertion, corrosion, wear, or surface decontamination techniques. The aim of this study was to evaluate the corrosion behavior of Ti6Al4V particles released during implantoplasty of dental implants treated due to periimplantitis. A standardized protocol was used to obtain metal particles produced during polishing the surface of Ti6Al4V dental implants. Physicochemical and biological characterization of the particles were described in Part I, while the mechanical properties and corrosion behavior have been studied in this study. Mechanical properties were determined by means of nanoindentation and X-ray diffraction. Corrosion resistance was evaluated by electrochemical testing in an artificial saliva medium. Corrosion parameters such as critical current density (icr), corrosion potential (ECORR), and passive current density (iCORR) have been determined. The samples for electrochemical behavior were discs of Ti6Al4V as-received and discs with the same mechanical properties and internal stresses than the particles from implantoplasty. The discs were cold-worked at 12.5% in order to achieve the same properties (hardness, strength, plastic strain, and residual stresses). The implantoplasty particles showed a higher hardness, strength, elastic modulus, and lower strain to fracture and a compressive residual stress. Resistance to corrosion of the implantoplasty particles decreased, and surface pitting was observed. This fact is due to the increase of the residual stress on the surfaces which favor the electrochemical reactions. The values of corrosion potential can be achieved in normal conditions and produce corroded debris which could be cytotoxic and cause tattooing in the soft tissues.
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Imataki, Rie, Yukari Shinonaga, Takako Nishimura, Yoko Abe e Kenji Arita. "Mechanical and Functional Properties of a Novel Apatite-Ionomer Cement for Prevention and Remineralization of Dental Caries". Materials 12, n. 23 (2 dicembre 2019): 3998. http://dx.doi.org/10.3390/ma12233998.
Testo completoAbstract (sommario):
Especially in pediatric dentistry, prevention by the control of initial lesions prior to cavitation is very important, and application of a pit and fissure sealant is essential to achieve this. Numerous reports have suggested that resin-based sealants are inferior to sealants based on glass-ionomer cement (GIC), because of GIC’s many advantages, such as fluoride ion release properties and its good adhesion to tooth structures. However, the use of GIC is impeded due to its low flexural strength and fracture toughness. In this paper, we developed and characterized an apatite-ionomer cement (AIC) that incorporates hydroxyapatite (HAp) into the GIC; this development was aimed at not only reinforcing the flexural and compressive strength but also improving some functional properties for the creation of the material suitable for sealant. We examined the influence of differences in the compounding conditions of GIC powder, liquid, and HAp on flexural and compressive strengths, fracture toughness, fluoride ion release property, shear bond strength to bovine enamel, surface pH of setting cements, and acid buffer capability. These methods were aimed at elucidating the reaction mechanism of porous spherical-shaped HAp (HApS) in AIC. The following observations were deduced. (1) HAp can improve the mechanical strengths of AIC by strengthening the cement matrix. (2) The functional properties of AIC, such as acid buffer capability, improved by increasing the releasing amounts of various ions including fluoride ions. The novel AIC developed in this study is a clinically effective dental material for prevention and remineralization of tooth and initial carious lesion.
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Moldovan, Marioara, Robert Balazsi, Andrada Soanca, Alexandra Roman, Codruta Sarosi, Doina Prodan, Mihaela Vlassa, Ileana Cojocaru, Vicentiu Saceleanu e Ioan Cristescu. "Evaluation of the Degree of Conversion, Residual Monomers and Mechanical Properties of Some Light-Cured Dental Resin Composites". Materials 12, n. 13 (30 giugno 2019): 2109. http://dx.doi.org/10.3390/ma12132109.
Testo completoAbstract (sommario):
The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-ænial Anterior® - Ge, (GC Europe N.V., Leuven, Belgium), Charisma® - Ch (Heraeus Kulzer, Berkshire, UK). The physio-chemical properties were studied, like the degree of conversion and the residual monomers in cured samples using FTIR-ATR (attenuated total reflectance) and HPLC-UV (ultraviolet detection), as well as the evaluation of the mechanical properties of the materials. The null hypothesis was that there would be no differences between experimental and commercial resin composites regarding the evaluated parameters. Statistical analysis revealed that water and saliva storage induced significant modifications of all mechanical parameters after three months for all tested materials, except for a few comparisons for each type of material. Storage medium seemed not to alter the values of mechanical parameters in comparison with the initial ones for: diametral tensile strength (DTS-saliva for Ge and PM, compressive strength (CS)-water for Ch, DTS-water and Young’s modulus YM-saliva for P14M and YM-water/ saliva for P2S (p > 0.05). Two of the experimental materials showed less than 1% residual monomers, which sustains good polymerization efficiency. Experimental resin composites have good mechanical properties, which makes them recommendable for the successful use in load-bearing surfaces of posterior teeth.
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Seredin, Pavel, Dmitry Goloshchapov, Vladimir Kashkarov, Yuri Ippolitov e Jitraporn Vongsvivut. "The Molecular and Mechanical Characteristics of Biomimetic Composite Dental Materials Composed of Nanocrystalline Hydroxyapatite and Light-Cured Adhesive". Biomimetics 7, n. 2 (30 marzo 2022): 35. http://dx.doi.org/10.3390/biomimetics7020035.
Testo completoAbstract (sommario):
The application of biomimetic strategies and nanotechnologies (nanodentology) has led to numerous innovations and provided a considerable impetus by creating a new class of modern adhesion restoration materials, including different nanofillers. An analysis of the molecular properties of biomimetic adhesives was performed in this work to find the optimal composition that provides high polymerisation and mechanical hardness. Nanocrystalline carbonate-substituted calcium hydroxyapatite (nano-cHAp) was used as the filler of the light-cured adhesive Bis-GMA (bisphenol A-glycidyl methacrylate). The characteristics of this substance correspond to the apatite of human enamel and dentin, as well as to the biogenic source of calcium: avian eggshells. The introduction and distribution of nano-cHAp fillers in the adhesive matrix resulted in changes in chemical bonding, which were observed using Fourier transform infrared (FTIR) spectroscopy. As a result of the chemical bonding, the Vickers hardness (VH) and the degree of conversion under photopolymerisation of the nano-cHAp/Bis-GMA adhesive increased for the specified concentration of nanofiller. This result could contribute to the application of the developed biomimetic adhesives and the clinical success of restorations.