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Nanotechnology for dental composites
Abstract
In dentistry, composites consisting of inorganic fillers such as radiopaque glass, quartz or ceramic particles and an organic resin matrix based on a mixture of dimethacrylates, are used for the restoration of teeth. Important properties of the dental restorative materials can be improved by means of nanotechnology. Inorganic-organic hybrid materials can be used as monomer matrix in dental restoratives to diminish their polymerisation shrinkage and improve their wear resistance and biocompatibility. Inorganic-organic hybrids with tailor-made properties can be created by means of sol-gel processing of hydrolytically condensable, organically modified trialkoxysilanes, which contain radically polymerisable methacrylate groups or cyclic groups capable of ring-opening polymerisation. Furthermore, nanofillers can contribute to increasing the modulus of elasticity or improving the optical properties of the dental composites and are useful as starting compounds for the synthesis of new low temperature processable dental ceramics. Moreover, well designed nano- and microstructured sol-gel components can be used for producing protective and wear resistant coatings for teeth, metal alloys, and glass fillers of special compositions.
... However, teeth consist of enamel and dentin tissue, which are elastically different from each other. For this, two different restorative materials should be used, and one of them should be chosen as a standard [15][16][17][18]. The properties of restorative materials affect the stress distribution in dental tissues and thus the durability of the restoration. ...
... Ideally, the elastic properties of restorative materials should be similar to those of the tooth structure to provide a more uniform stress distribution. The finite element method (FEM) is recognized in the literature as a widely used and reliable tool for simulation and computational analyses [15][16][17][18]. ...
... Polymers 2023,15, 1637 ...
Objectives: the aim of this study was to examine the stress distribution of enamel, dentin, and restorative materials in sound first molar teeth with restored cavities with conventional resin composites and bulk–fill composites, as well as to determine their fracture lifetimes by using the three-dimensional finite element stress analysis method. Materials and Methods: an extracted sound number 26 tooth was scanned with a dental tomography device and recorded. Images were obtained as dicom files, and these files were transferred to the Mimics 12.00 program. In this program, different masks were created for each tooth tissue, and the density thresholds were adjusted manually to create a three-dimensional image of the tooth, and these were converted to a STL file. The obtained STL files were transferred to the Geomagic Design X program, and some necessary adjustments, such as smoothing, were made, and STP files were created. Cavity preparation and adhesive material layers were created by transferring STP files to the Solidworks program. Finally, a FE model was created in the ABAQUS program, and stress distributions were analyzed. Results: when the bulk–fill composite and conventional resin composite materials were used in the restoration of the cavity, the structures that were exposed to the most stress as a result of occlusal forces on the tooth were enamel, dentin, restorative material, and adhesive material. When the bulk–fill composite material was used in restoration, while the restorative material had the longest fracture life as a result of stresses, the enamel tissue had the shortest fracture life. When the conventional resin composite material was used as the restorative material, it had the longest fracture life, followed by dentin and enamel. Conclusion: when the bulk–fill composite material was used instead of the conventional resin composite material in the cavity, the stress values on enamel, dentin, and adhesive material increased as a result of occlusal forces, while the amount of stress on the restorative material decreased. In the fracture analysis, when the bulk–fill composite material was used instead of the conventional resin composite material, a decrease in the number of cycles required for the fracture of enamel, dentin, and restorative materials was observed as a result of the forces generated in the oral cavity.
... However, teeth consist of enamel and dentin tissue, which are elastically different from each other. For this, two different restorative materials should be used, and one of them should be chosen as a standard [15][16][17][18]. The properties of restorative materials affect the stress distribution in dental tissues and thus the durability of the restoration. ...
... Ideally, the elastic properties of restorative materials should be similar to those of the tooth structure to provide a more uniform stress distribution. The finite element method (FEM) is recognized in the literature as a widely used and reliable tool for simulation and computational analyses [15][16][17][18]. ...
... Polymers 2023,15, 1637 ...
... However, teeth consist of enamel and dentin tissue, which are elastically different from each other. For this, two different restorative materials should be used, and one of them should be chosen as a standard [15][16][17][18]. The properties of restorative materials affect the stress distribution in dental tissues and thus the durability of the restoration. ...
... Ideally, the elastic properties of restorative materials should be similar to those of the tooth structure to provide a more uniform stress distribution. The finite element method (FEM) is recognized in the literature as a widely used and reliable tool for simulation and computational analyses [15][16][17][18]. ...
... Polymers 2023,15, 1637 ...
... However, teeth consist of enamel and dentin tissue, which are elastically different from each other. For this, two different restorative materials should be used, and one of them should be chosen as a standard [15][16][17][18]. The properties of restorative materials affect the stress distribution in dental tissues and thus the durability of the restoration. ...
... Ideally, the elastic properties of restorative materials should be similar to those of the tooth structure to provide a more uniform stress distribution. The finite element method (FEM) is recognized in the literature as a widely used and reliable tool for simulation and computational analyses [15][16][17][18]. ...
... Polymers 2023,15, 1637 ...
Objectives: the aim of this study was to examine the stress distribution of enamel, dentin, and restorative materials in sound first molar teeth with restored cavities with conventional resin composites and bulk–fill composites, as well as to determine their fracture lifetimes by using the three-dimensional finite element stress analysis method. Materials and Methods: an extracted sound number 26 tooth was scanned with a dental tomography device and recorded. Images were obtained as dicom files, and these files were transferred to the Mimics 12.00 program. In this program, different masks were created for each tooth tissue, and the density thresholds were adjusted manually to create a three-dimensional image of the tooth, and these were converted to a STL file. The obtained STL files were transferred to the Geomagic Design X program, and some necessary adjustments, such as smoothing, were made, and STP files were created. Cavity preparation and adhesive material layers were created by transferring STP files to the Solidworks program. Finally, a FE model was created in the ABAQUS program, and stress distributions were analyzed. Results: when the bulk–fill composite and conventional resin composite materials were used in the restoration of the cavity, the structures that were exposed to the most stress as a result of occlusal forces on the tooth were enamel, dentin, restorative material, and adhesive material. When the bulk–fill composite material was used in restoration, while the restorative material had the longest fracture life as a result of stresses, the enamel tissue had the shortest fracture life. When the conventional resin composite material was used as the restorative material, it had the longest fracture life, followed by dentin and enamel. Conclusion: when the bulk–fill composite material was used instead of the conventional resin composite material in the cavity, the stress values on enamel, dentin, and adhesive material increased as a result of occlusal forces, while the amount of stress on the restorative material decreased. In the fracture analysis, when the bulk–fill composite material was used instead of the conventional resin composite material, a decrease in the number of cycles required for the fracture of enamel, dentin, and restorative materials was observed as a result of the forces generated in the oral cavity.
... However, teeth consist of enamel and dentin tissue, which are elastically different from each other. For this, two different restorative materials should be used, and one of them should be chosen as a standard [15][16][17][18]. The properties of restorative materials affect the stress distribution in dental tissues and thus the durability of the restoration. ...
... Ideally, the elastic properties of restorative materials should be similar to those of the tooth structure to provide a more uniform stress distribution. The finite element method (FEM) is recognized in the literature as a widely used and reliable tool for simulation and computational analyses [15][16][17][18]. ...
... Polymers 2023,15, 1637 ...
... Pigments crucially represent the shade and maintain the color for a long time that could affect the physical properties of composites [10] , but few data exist on the radiopacity levels of composites' different shades. Some studies found that radiopacity is material-dependent and had no significant change among various shades [23,24] , but a significant difference existed among the radiopacity of the various shades of tested composites, similar to studies by Dionysopoulos et al [1,2] . Although significant differences exist significance exists among shades of G-aenial Anterior (A2 and JE) and Aelite (Enamel and Body), the radiopacity values were too similar to make any clinical significance. ...
... Posterior composites have higher filler loadings, as shown in Table 1. Higher filler amounts mainly lead to higher radiopacity levels [24] , but the tested composites also have different filler sizes. Dionysopoulos et al (2017) [1] reported that there is no exact evidence of filler size affecting materials' radiopacity levels. ...
... One reason for G-aenial Posterior and Filtek Z550 is that their fillers had irregular shapes (glass frit and zirconia respectively) with strong radiopaque elements. Moszner showed that formulas with irregular shapes have higher radiopacity than spherical silicas [24] . The present study also proves that the lowest radiopaque composites Aelite Flo (3.11) and G-aenial Anterior A2 (3.16) mainly had silica as fillers. ...
Aim of the present in vitro study is to evaluate the radiopacity levels of composite resins with various shades and viscosity. 10 mm×2 mm discs were prepared from 7 condensable and 4 flowable composites (n=10). An aluminum step wedge ranging from 2.0 to 10.0 mm in thickness was placed on the occlusal film. Digital radiographs were taken using a dental X-ray device and radiographic densities of each step of the aluminum wedge and the samples were recorded to the computer. Five readings were taken and means were calculated. One-Way Anova and Tamhane post hoc tests were performed. While G-eanial Posterior has the highest radiopacity value followed by Filtek Z550, Aelite Flo has the lowest radiopacity value. Posterior composites show higher radiopacity and flowable composites with higher filler loadings have superior radiopacity levels to condensable composites. Enamel and body shades of the composite brands have also statistically significant differences in radiopacity scores. Eventually, radiopacity level of a composite resin material is not affected by the size of fillers; however, the composition, shape and loading of the fillers can specify the radiodensity.
... TEGDMA -triethylene glycol dimethacrylate; UDMA -urethane dimethacrylate, and others) 13 and inorganic-organic fillers of different sizes, generally in the micrometer range. 14 The treatment of the fillers' surface with silane allows the formation of covalent bonds between the inorganic filler particles and the organic resin matrix. 14 Typically, nanobased restorative composites contain 13-30 wt% of polymerizable organic matrix and 70-87 wt% mixture of different inorganic fillers, 13 in addition to a photoinitiator or other curing systems. ...
... 14 The treatment of the fillers' surface with silane allows the formation of covalent bonds between the inorganic filler particles and the organic resin matrix. 14 Typically, nanobased restorative composites contain 13-30 wt% of polymerizable organic matrix and 70-87 wt% mixture of different inorganic fillers, 13 in addition to a photoinitiator or other curing systems. Although the failure rate of resin composite restorations has decreased over the years, the requirements for a successful restoration are so many that manufacturers of resin-based materials can barely meet half of them with the traditional composition of dental composites. ...
... Although the failure rate of resin composite restorations has decreased over the years, the requirements for a successful restoration are so many that manufacturers of resin-based materials can barely meet half of them with the traditional composition of dental composites. 14 To improve the longterm clinical performance of resin composites, strategies have focused on minimizing the effects of polymerization shrinkage and viscosity of materials with high filler loading. 15 There are also promising outcomes to improve the performance of dental adhesives and enhance the stability of the tooth/composite restorative interface. ...
Objective
Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin‐based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin‐based restorative materials with nanoparticles.
Materials and Methods
A literature review was conducted using PubMed/Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin‐based restorative materials containing nanoparticles were included.
Results
A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti‐bacterial properties were described. The clinical performance of resin‐based restorative materials with nanoparticles was also reported.
Conclusions
The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future.
Clinical significance
In spite of the recent advancements of nanotechnology in resin‐based restorative materials, some challenges need to be overcome before new nano‐based restorative materials are considered permanent solutions to clinical problems.
... 16 Although composites are favourable restorative materials 17 Nanohybrid is a hybrid resin composite with improved distribution of fillers in the matrix by combining, Nanofiller in a pre-polymerized filler form together with submicron particles to achieve better mechanical, chemical, and optical properties. 3,18 The present study evaluated the effect of the addition of Graphene Nanoparticles on the Surface roughness, Microhardness, and Flexural strength of Nanohybrid composite resin (Tetric N Ceram) after subjecting the specimens to a thermomechanical loading cycle. The present study was strongly supported by previous studies in which improvements in mechanical properties were reported on the addition of various Nanoparticles. ...
... 20,27 The present study was in agreement with the previously reported by Ming Tian, Moszner N, Mohammad Atai, Gracia where incorporation of nanoparticles of TiO 2 , Zirconia, thermally sintered silica, Nano Fibrillar silicate to composite resin in lesser concentrations improved the FS of the resin and resins modified with higher concentrations of nanoparticles reduced the FS values. 6,18,21,26 However, the study was in disagreement with a study where the authors found a decreased flexural strength of acrylic resin with TiO 2 groups, regardless of the concentration. 29 However, the study has a few limitations, this is an in-vitro study in which all the factors which contribute to the success or failure of restorations in a clinical situation cannot be evaluated. ...
Composite restorative material is one of the most accomplished contemporary biomaterials because of its high aesthetic potential with satisfactory clinical durability. Although composites are favourable restorative material their polymerization shrinkage still remains a challenge. Recently, Science of Nanotechnology has invaded into the field of Dentistry in an attempt to offset the existing shortcomings of traditional dental composites and substantially improving its properties by adding nano sized filler particles like Silver, Titanium Dioxide, Zirconia and Silicone. Graphene Nanoparticles (GNP) are novel fillers that possess a high fracture strength, mechanical strength, chemical stability, flexibility, they are also biocompatible and non-cytotoxic. The objective of this study is to evaluate the Surface roughness, Microhardness and Flexural strength of Nano hybrid composite resin modified with Graphene nanoparticles after subjecting the specimens to Thermo Mechanical cyclic loading.
... Nanocomposites have developed mechanical properties i.e. superior compressive strength, good fracture resistance, diametrical tensile strength, lower polymerization shrinkage, well wear resistance, maximum polish retention, great translucency, and superior esthetics [4,5]. ...
The aims of this in vitro study is to evaluate and compare compressive strength of newer nanocomposites (FiltekZ350, Ceram X Mono,Herculite XRV Ultra) with microhybrid (FiltekZ250) and to assess difference in compressive strength of newer nanocomposites. Materials and Methods: Forty specimens of composite were made using plastic mold measuring 5mm x 5mm and were grouped with ten specimens in each ,Group I: Filtek Z 250, Group II: Filtek Z 350, Group III: Herculite XRV Ultra, Group IV: Ceram X Mono. Composite resins are placed in cylindrical plastic mold and covered with celluloid strip and were cured by light curing device. Compressive strength was recorded using universal testing machine. Results are statistically analyzed using one way ANOVA and LSD test. Results: Nanocomposites have better compressive strength value than microhybrid composite but they are not significantly different
Composite
Hybrid
Nanohybrid
Fracture resistance
... Imperceptible composite resin restorations can be achieved through natural incremental layering with various shades of enamel and dentine-like materials. 55 Reasons For Shade Mismatch: Ikeda et al. found that opaque-shade composite resins are less translucent than dentin or enamel shade composite resins, and 2 mm thick is preferable for shade matching. 56 The addition of Bis-GMA to TEGDMA increases the resin's refractive index, enhancing its optical match with the silica filler system. ...
Aesthetic dental restorations represent a substantial component of restorative, prosthodontic, and pedodontic dental practice. Composite resin restorations are clinically convenient but lack long-term durability in the oral cavity. Their capacity to replicate real teeth in comparison to dental ceramics is likewise contentious. Porcelain restorations may be customized in various hues of body, dentin, and enamel to resemble real teeth. Manufacturers have introduced multilayered composites as an alternative to dental porcelain restorations, asserting that they provide a range of hues from the VITA 3D master shade guide. This research review is intended to uncover recent evidence contributing to the shade selection process, the kinds of new shade guides, their advancements in composite shade guide systems, and the present condition of shade mismatch. Literature was examined in four prominent medical and dentistry databases from January 2010 to June 2024. Most researches related to multilayered or multishaded dental composites proclaim the shades to match various shades of VITA three D master, while many show evidence that they do not match.
... Silver NPs is the frequently, used in various products in different form, which is followed by carbon and ion oxides such as TiO 2 (Xiu, 2011;McIntyre, 2012). The nanoparticle can improve the quality of the products by adding many functional groups to it (Moszner and Klapdohr, 2004). ...
Tooth decay is one of the most common problems in the global world. Every age group directly or indirectly affected with tooth decay problem because of their life style and junk food. Zinc oxide (ZnO) powder widely used as filling material without any side effects but it degrades gradually as well as having no antimicrobial activity. Nowadays in the treatment of dental caries/cavity, periodontal diseases tooth decay etc. infected by microorganisms (such as bacteria or fungi) using conventional materials or drugs are insufficient. Thus, the researchers are looking for new material/powder which has both the properties and easily applicable with low cost. Nano material and Nanotechnology has played an important role as a filling agent. Recently it is found that ZnO antimicrobial nanoparticles (NPs) are used because of several advantages such as very small sizes, large surface to volume ratio and special physical and chemical properties
... In some nanohybrid pr oducts, pr epolymerized fillers containing NPs are employed. All these nanofillers, prepared chemically by sol-gel technology, are claimed to impr ov e c omposit e polishability, long-lasting gloss, low wear and enhance the mechanical properties of these highly aesthetic materials [13][14][15]. ...
Aim: Today, there is a lack of research studies concerning human acute exposure to nanoparticles (NPs). Our investigation aimed to simulate real-world acute inhalation exposure to NPs released
during work with dental nanocomposites in a dental office or technician laboratory. Methods: Blood samples from female volunteers were processed before and after inhalation exposure.
Transcriptomic mRNA and miRNA expression changes were analyzed. Results: We detected large interindividual variability, 90 significantly deregulated mRNAs, and 4 miRNAs when samples of
participants before and after dental nanocomposite grinding were compared. Conclusion: The results suggest that inhaled dental NPs may present an occupational hazard to human health, as
indicated by the changes in the processes related to oxidative stress, synthesis of eicosanoids, and cell division.
... These characteristics have also been studied by Marghalani [66], where spherical nanofiller particles, mainly silica-based and irregular particles of ground glass melts (Ba-Al-B-silicate glass) had their radiopacity tested. The irregular filler-based series formulations were more radiopaque than the spherical series, this was attributed to the incorporation of a higher atomic number element; in this case, barium [67][68][69]. The barium element is found mainly in irregular shape series allowing this higher opacity in comparison to the spherical series. ...
It's been a growing concern that many microbes are developing resistance against many antibiotics, lowering the effectiveness and progress expected from that treatment option. To overcome the re-sistance developed by microbes, metallic and non-metallic-based nanoparticle treatments are starting to present a very promising approach. Furthermore, polyurethanes are used in a wide range of biomedical applications due to their variety of physical-chemical, mechanical, and structural properties, and biotic and abiotic degradation. They are widely used in bio-imaging procedures when metallic-based filler particles are incorporated, making the final product radiopaque. It would be advantageous, however, if polyurethanes with intrinsic radiopacity could be produced in their synthesis, avoiding a series of disadvantages in the processing and final product and also presenting potential antimicrobial activities. This review’s objective was to study the radiopacifying charac-teristics of nanoparticles as well as the physical principles of radiopacity and the variety of medical applications of polyurethanes with nanoparticles. It was found in this study that the synthetization of radiopaque polyurethanes is not only possible but also that the efficiency of synthetization was improved when using atoms with high electron density as part of the back chainbone or grafted, making them great multipurpose materials.
... Determining the surface shell of a-SiO 2 NPs lacks a definitive rule, yet it can be identified based on atoms lacking complete coordination with all atomic pairs. These defects endow a-SiO 2 NPs with innovative value, leading to applications in chemical reactions [21,22], cosmetics [23], catalysis [24], and commercial fields like electronics, optoelectronics [25,26], microelectronic fabrication [27], varnishes [28], printers [29], and food [30]. Various methods exist for synthesizing and characterizing amorphous NPs, including diffraction techniques for structural insights. ...
This study focuses on the electronic structure and properties of amorphous SiO2 nanoparticle with a radius of 18 Å using Density Functional Theory and the Orthogonalized Linear Combination of Atomic Orbital method. Through employing appropriate statistical techniques, three distinct models (I, II, and III) of amorphous SiO2 nanoparticle with an 18 Å radius are generated based on the continuous random network structure incorporating periodic boundaries. The calculated Total Density of States and Partial Density of States reveal insights into the electronic interactions within the nanoparticle. The band gap values are assessed at both less accurate and more accurate potentials such that the band gap increases from 2 eV to 4.2 eV with higher potentials for Model I, where surface atoms has dangling bonds stabilized by hydrogen atoms. Model II, consisting of all surface silicon atoms bonded to four oxygen atoms, exhibits a band gap of 1 eV, increasing to 1.8 eV with higher potentials. Model III, saturated with hydrogen atoms, shows a band gap of 4 eV, decreasing to 3.75 eV at higher potentials. The introduction of the more accurate potential serves to minimize the gap states initially observed with the less accurate potential. The electronic structure calculations provide crucial information for understanding the electronic interactions within the amorphous SiO2 nanoparticle with implications for their applications in various fields such as biomedicine, catalysis, electronics, and nanotechnology.
... Because these filler sizes are below the wavelengths of visible light (380-780 nanometers), nanofilled composites provide positive translucency, polishability and surface gloss.[ 21,48 ] In addition, it has been reported that these materials show high translucency of nanomeric particles ranging from 20-75 nanometers on average, which is below the wavelengths of visible light.[ 49 ] Composites show a "chameleon" effect in small cavities with the help of surrounding and underlying dental tissues.[ ...
The aim of this study is to evaluate the color stability, translucency and hardness of eight different composite resins, after thermal cycling and immersion in beverages. Six light-cured dimethacrylate-based composite (Clearfil Majesty Esthetic, Clearfil Majesty Posterior, Grandio, Grandio Flow, Arabesk Top, Valux Plus), an ormocer (Admira) and a silorane-based composite (Filtek Silorane) were tested in this study. Fifteen samples (8x2 mm) from each composite were prepared. All samples were subjected to thermal cycling [(5.0 ± 0.5)~(55.0 ± 1.0) °C, 1000 cycles]. After thermal cycling, fifteen specimens in each group were divided into three subgroups (n = 5): distilled water (control), coffee, and red wine at 37°C for 30 days. With a spectrophotometer, the △E and Translucency Parameter (TP) were calculated against white and black backgrounds. Color, translucency and hardness of all samples were remeasured baseline, after thermal cycles and after immersion in beverages. The data were analyzed using repeated measured analysis of variance and Bonferroni multiple-comparison test (P3.3). The effect of thermal cycles on color and transluceny was not statistically significant (P>0.05). TP values generally decreased especially after immersion in red wine (P
... can improve the quality of the products by adding many functional groups to it (2) . Thus nano products are widely used in industry (3) , medicine and in the dental field (4) . ...
... These can be used to create high wearresistant composite coatings that are biocompatible. They are also used to develop bioactive materials, such as dental implant coatings and bioceramics [12]. Metallic nanostructures are the most promising agents for dental implant coatings owing to their remarkable anti-biofilm properties against infection-causing pathogens like Staphylococcus, Pseudomonas, and ...
Purpose: Nanomaterials have a plethora of applications in the field of dental sciences. Due to their peculiar properties and distinguishing characteristics, nanomaterials are used as candidates for coating titanium, acrylic, and PLA/PCL-based dental implants. This article reviews various nanomaterials that can impart antibacterial properties and be used as implant coating materials. Methods: Research articles published between 1992 and 2021, based on nanomaterial coatings for dental applications, were retrieved from Google Scholar and were thoroughly studied. Results: The research articles reviewed indicated that a substantial amount of progress had been made in the area of antibacterial resistance of nanomaterial-based coatings for dental implants. This work’s main contribution lies in a comprehensive review of the various nanostructures that inhibit the nurturing of bacterial biofilms on implants, thus diminishing the probability of any infection. Significance: Given the reported results, additional clinical research and investigation on nanostructure-coated implants aids in efficient implementation.
... These can be used to create high wearresistant composite coatings that are biocompatible. They are also used to develop bioactive materials, such as dental implant coatings and bioceramics [12]. Metallic nanostructures are the most promising agents for dental implant coatings owing to their remarkable anti-biofilm properties against infection-causing pathogens like Staphylococcus, Pseudomonas, and ...
Purpose: Nanomaterials have a plethora of applications in the field of dental sciences. Due to their peculiar properties and distinguishing characteristics, nanomaterials are used as candidates for coating titanium, acrylic, and PLA/PCL-based dental implants. This article reviews various nanomaterials that can impart antibacterial properties and be used as implant coating materials. Methods: Research articles published between 1992 and 2021, based on nanomaterial coatings for dental applications, were retrieved from Google Scholar and were thoroughly studied. Results: The research articles reviewed indicated that a substantial amount of progress had been made in the area of antibacterial resistance of nanomaterial-based coatings for dental implants. This work’s main contribution lies in a comprehensive review of the various nanostructures that inhibit the nurturing of bacterial biofilms on implants, thus diminishing the probability of any infection. Significance: Given the reported results, additional clinical research and investigation on nanostructure-coated implants aids in efficient implementation.
... Much research has been a growing interest to upgrade of tribological and mechanical properties of composites. Many attempts focused on using various techniques to overcome these drawbacks through the dispersion of nanoparticles in the polymer resin [12][13][14][15][16][17]. Several nano-scale materials such as organic nanofiller, carbon nanotubes (CNT), carbon nanofibers (CNF), graphene, and nano-metals are used as filler materials to enhance the mechanical characterizes of polymers and to extend the lifespan of composites [18][19][20][21][22]. Multi-walled carbon nanotubes MWCNTs were successfully inserted into the nylon-6 fibers as fillers to dental resin PMMA. ...
Although dental raw PMMA has unique features such as its ease and aesthetic fabrication, low cost, and a favorable physical and mechanical properties. Nonetheless, these are insufficient to provide the necessary wear resistance, hardness, and mechanical strength. Wherefore, dental applications are less suited to pure PMMA. The present article focuses on using hybrid filler of Al2O3 and TiO2 NPs with various loading content to evaluate and minimize the wear rate. The tribological characteristics of the nanocomposites were evaluated by a reciprocating tribometer. And the wear resistance was assessed with 3D microscopic images and SEM. The PMMA nanocomposite samples containing 0.4%, 0.8%, 1.2%, 1.6%, and 2.0 wt% filling content of hybrid Al2O3 and TiO2 NPs to compared to an unfilled sample, were fabricated. The hardness of the nanocomposites was found using Shore D durometer. The XRD, density, modulus of elasticity, compressive yield strength, and fracture toughness were performed experimentally. Results showed that the incorporation of hybrid of Al2O3 and TiO2 NPs showed a good enhancement in the mechanical and tribological properties of PMMA composites. Experimental results illustrated that, the nanocomposites with 0.8 wt.% of filler content recorded a distinct performance among other filler amounts. COF and Wear rate are reduced up to 20% and 28%, respectively.
... Due to the defects, a-SiO2 NPs have more innovative significance with well-defined applications such as catalysis [20], chemical reaction [21] and micro-electronic fabrication [22]. Because of emerging commercialization in the realm of nanotechnology, they are used in electronic and optoelectronic devices [23,24], as additives to cosmetics [25], printers [26], varnishes [27] and food [28]. Moreover, a-SiO2 NPs have been used for the host of biomedical and biotechnological application such as cancer therapy [29], DNA transfection, enzyme mobilization [30], gene delivery, drug release control, photoluminescence [31] and as carriers for indomethacin in solid state dispersion. ...
The spherical amorphous silica (a-SiO2) nanoparticles (NPs) are constructed from a previous continuous random network (CRN) model of a-SiO2 with the periodic boundary. The models of radii 12 Å, 15 Å, 18 Å, 20 Å, 22 Å, 24 Å, and 25 Å are built from the CRN structure. Then, three types of models are constructed. Type I has the surface dangling bonds not pacified. In type II models, the dangling bonds are pacified by hydrogen atoms. In type III models, the dangling bonds are pacified by the OH groups. These large models are used to perform the electronic structure calculation of NPs by using the orthogonalized linear combination of atomic orbital (OLCAO) method. The results show some trends in band gap variation for Type I models. The trends in band gap variation for other two types are less clear. A series of NP models with a spherical pore in the middle of a solid NP model are constructed and studied. Spherical pores of radii of 6 Å, 8 Å, 10 Å, 12 Å, 14 Å, 16 Å and 18 Å are introduced within the spherical model of radius 20 Å. After OLCAO calculation, it is found that the band gap values remain constant (5 eV) up to 21.6% porosity and then decreases with increased in porosity. The relation with thickness of the porous NP shell and the surface to volume ratio (S/V) with the calculated band gap are studied in the same manner and will be discussed.
... can improve the quality of the products by adding many functional groups to it (2) . Thus nano products are widely used in industry (3) , medicine and in the dental field (4) . ...
... Les composites dentaires comme matériaux de restaurations dentaires ont remplacé l'amalgame, déjà banni en Norvège depuis 2008, à cause du mercure qu'il contient, connu pour être toxique et pouvant ainsi causer des problèmes de santé [1]. Ces nouveaux matériaux de restauration dentaire présentent donc des avantages tels que l'absence de mercure, résistance à la corrosion, et la non-conductivité thermique [2,3]. ...
... Surface roughening is one of these treatment methods. [9] Surface roughening methods stated as; roughening with diamond bur, and grinding with silicon paper, sandblasting, roughening with discs, air abrasion with aluminum oxide or silica particles and chemical applications with phosphoric acid or hydrofluoric acid. [10,11] In light of the general information given above, this study aims to evaluate the effect of surface roughening with coarse diamond bur and discs on the bond strength of two different aged composite resins. ...
Background: There are controversies regarding the most effective surface treatment method to be applied for the effective repair of resin composites. Aims: This study aimed to compare the effects of surface roughening processes on repair bond strength of different types of aged composites. Water aging was applied to 60 nanohybrid and 60 micro-hybrid resin composite samples for 1 year. Samples were randomly divided into five groups and four types of roughening processes. Bur, OPTIDISC, SUPERSNAP, and BISCO were applied to the water-aged resin composite samples. Micro-shear test method was used to measure the repair bond strength. Materials and Methods: Data were analyzed with IBM SPSS V23. Compliance with normal distribution was examined by Kolmogorov-Smirnov test. Two-way analysis of variance (ANOVA) and Tukey HSD test for multiple comparisons were used. Results: The main effect of the type of resin composites and surface roughening methods were found to be significantly different. The MPa values of surface roughening groups were similar while the lowest mean value was obtained for the untreated group of the nanohybrid resin composite (P < 0.001). The bond strength for both resin composites was generally considered within acceptable limits except for no treatment group of nanohybrid resin composite. Conclusions: This study showed that surface roughening method is mandatory for effective bond strength and the type of fillers in resin composite affects the micro-shear bond strength.
... Surface roughening is one of these treatment methods. [9] Surface roughening methods stated as; roughening with diamond bur, and grinding with silicon paper, sandblasting, roughening with discs, air abrasion with aluminum oxide or silica particles and chemical applications with phosphoric acid or hydrofluoric acid. [10,11] In light of the general information given above, this study aims to evaluate the effect of surface roughening with coarse diamond bur and discs on the bond strength of two different aged composite resins. ...
Background:
There are controversies regarding the most effective surface treatment method to be applied for the effective repair of resin composites.
Aims:
This study aimed to compare the effects of surface roughening processes on repair bond strength of different types of aged composites. Water aging was applied to 60 nanohybrid and 60 micro-hybrid resin composite samples for 1 year. Samples were randomly divided into five groups and four types of roughening processes. Bur, OPTIDISC, SUPERSNAP, and BISCO were applied to the water-aged resin composite samples. Micro-shear test method was used to measure the repair bond strength.
Materials and methods:
Data were analyzed with IBM SPSS V23. Compliance with normal distribution was examined by Kolmogorov-Smirnov test. Two-way analysis of variance (ANOVA) and Tukey HSD test for multiple comparisons were used.
Results:
The main effect of the type of resin composites and surface roughening methods were found to be significantly different. The MPa values of surface roughening groups were similar while the lowest mean value was obtained for the untreated group of the nanohybrid resin composite (P < 0.001). The bond strength for both resin composites was generally considered within acceptable limits except for no treatment group of nanohybrid resin composite.
Conclusions:
This study showed that surface roughening method is mandatory for effective bond strength and the type of fillers in resin composite affects the micro-shear bond strength.
... Thus, PMMA should be enhanced to achieve suitable mechanical characteristics. 2 In recent years, there has been a growing interest in the improvement of the mechanical properties of composites. One of the strategies that have been used to overcome this drawback is nanoparticle incorporation in the polymer matrix [5][6][7][8]. The addition of fillers to the polymer matrix is a common approach to improve the mechanical properties of PMMA-based resins. ...
In this study, the mechanical and tribological properties of polymethyl methacrylate (PMMA)-based dentures strengthened by a low content of alumina (Al2O3) nanoparticles were evaluated. PMMA nanocomposites with different weight fractions (0.2, 0.4, 0.6, 0.8, and 1 wt%) of Al2O3 were fabricated, and a sample of pure PMMA was used as a control. Compression, hardness, and wear tests were conducted to investigate the effect of a low Al2O3 filler content on the mechanical and tribological properties of PMMA. The addition of Al2O3 filler improved the mechanical and tribological characteristics of PMMA. The highest elastic modulus and compressive yield strength (3.56 GPa and 138.21 MPa, respectively) were obtained using the PMMA sample with 0.6 wt% of nanoalumina, which represent an increase of 20.27% and 14.7%, respectively, compared with those of the pure PMMA. The fracture toughness and hardness were improved with the increase in the filler content until it reached 0.8 and 1.00 wt%, respectively. The tribological characteristics of PMMA also improved with the addition of Al2O3 nanoparticles. The least coefficient of friction (COF) and wear rate were obtained at a filler content of 0.6 wt%. Therefore, the addition of low amounts of Al2O3 to PMMA-based resins can improve their mechanical and tribological properties such as hardness, elastic modulus, fracture toughness, COF, and wear resistance.
... Composites et nanotechnologie [51] . L'introduction de la nanotechnologie dans le monde dentaire a fait beaucoup de bruit ces dernières années. ...
... Organically modified ceramics were introduced as reinforced materials to solve the failure problems of composites [5]. Because of distinct characteristics of nanocomposites have been proven to exhibit, superior compressive strength, wear resistance, fracture resistance, low polymerization shrinkage, high polish retention, good translucency, and good esthetics [6]. So, the insert of particles in nanometer size has been one of the most recentmeans to developments in this field [7]. ...
This study aims to evaluate the diametral tensile strength (DTS) and compressive strength (CS) of restorative composite resins that applied as restorative materials in the field of dentistry. The composites were prepared from different sets of monomers which divided into six groups (A, B, C, D, E, and F) according to the type and ratios of monomers used in preparing the matrix materials, excepted the basic monomer (2, 2 propyl bisphenol glycidyl dimethacrylate (Bis-GMA)) that added at constant ratio (40 wt%), in addition tothe nano-inorganic fillers [SiO2, ZrO2, HA, and Al2O3] which adding individually. Ninety specimens were prepared for diametral tensile strength test, which divided into six groups according to the prepared resin matrix and five sub-divided groups according to types of fillers of prepared composites, and for compressive strength test, the same numbers of specimens were prepared. In the beginning, the diametral tensile strength (DTS) and compressive strength of the prepared matrices were determined and then study the effect of adding the nano-inorganic fillers on the results of these properties for the prepared dental restorations nanocomposites materials. The results show that the composites based on resin matrix of group (D) having the selected monomers (BIS-GMA, meth acrylamide, methacrylic acid, and 1–6 hexanediol methacrylate) that reinforced with silica nanoparticle have higher properties as compared with other types of the prepared nanocomposite, where these values reached to (54 MPa and 174 MPa) for diametral tensile strength and compressive strength, respectively.
... Through filling or combining inorganic rigid particles in the organic network, functional improvement can be achieved. With nanotechnology, the diameter of the filler can be reduced and its content and gradient distribution range increased, thereby reducing polymerization shrinkage and improving the mechanical and optical properties of the composite resin (Moszner and Klapdohr, 2004). ...
Objective: This study aimed to investigate the impact of artificial aging on the color stability and hardness of nanocomposite resin.
Methods: Four nanocomposite resin materials were used: Filtek Z350 XT (FZ), Synergy D6 (SD), Grandio (GD), and Clearfil Majesty Esthetic (CM). Thirty specimens were created from each material, which were divided into three (A,B,C) groups of 10 specimens each. For each material, the values of visual lightness (L*), degree of redness and greenness (a*), and degree of yellowness and blueness (b*) of the specimens in group A before and after aging, as well as the hardness of the specimens in group B before aging and in group C after aging, were measured. The American Society for Testing and Materials (ASTM) G155 Cycle 1 standard was adopted to test the aging of the specimens. The color difference (ΔE00) value and hardness difference (ΔH) value of the specimens before and after aging were calculated.
Results: Aging was found to have an impact on the ΔE00 values of the resin materials in each group ( H = 17.6, p = 0.001), and the hardness of the specimens in each group after artificial aging was significantly higher than before aging ( p < 0.05). The difference in ΔE00 between the FZ group and the SD, GD, and CM groups was statistically significant ( p < 0.05). The FZ group had the highest ΔE00 values. There was no correlation between ΔE00 and the hardness change percentage after aging ( r = 0.114).
Conclusion: Among the four nanocomposite resins tested in this study, except for Filtek Z350 XT’s ΔE00 values (>1.8) in the clinically unacceptable range, the remaining three kinds of resin ΔE00 values (<1.8) were all in the clinically acceptable range. The hardness of the four nanocomposite resins increased after aging. The results of the present study revealed that there was no correlation between ΔE00 and hardness change percentage in the four nanocomposite resin materials after aging.
... In our study, color differences were evaluated visually directly because human eye can detect verges of color changes so our result is in accordance with other studies [30][31][32]. ...
The aim of our study is to estimate the effects of three commercially available mouth-rinses with three different concentrations (0.2%, 0.12%, 0.02%) with three different intensities light cures which are (100, 300, 600 nm) to assess correlation between the effects of different CHX. Concentration and different intensities of light cure on composite discoloration.
... Son yıllarda sağlanan teknolojik ilerlemelerle partikül büyüklükleri 0,001 mikrona kadar düşürülmüştür. Bu büyüklükteki partiküller de nano-dolduruculu kompozitlerin üretilmesini sağlamıştır 5,6 . Bu alanda ilk üretilen kompozitler daha çok yapısal özelliklerinden dolayı, üretici firma tarafından ön bölge restorasyonları için önerilirken, nano-hibrit yapıda yeni üretilen kompozitler, hem ön hem de arka grup restorasyonlarda kullanılabilme endikasyonuna sahip oldukları bildirilmiştir 7 . ...
Amaç: Mine-sement sınırının altında hazırlanan kavitelerde mikrosızıntı ile mücadele edebilmek oldukça güçtür. Bu nedenle çalışmanın amacı derin class II kavitelerdeki stres ve marginal bölgedeki kapanma problemlerinin çözümüne yönelik son yıllarda sağlanan teknolojik ilerlemelerle geliştirilen nano dolduruculu kompozitlerin akışkan formlarının açık sandviç tekniği ile restore edilen derin kavitelerdeki etkinliğinin incelenmesidir. Yöntem: 60 adet dişe standart meziyo-okluzal (MO), aproksimal kutu (box) şeklinde kaviteler, oklüzo-gingival derinliği mine-sement sınırının 1 mm altında olacak şekilde ve aproksimal kutunun ebatları 2x4x6 mm olacak şekilde açılmıştır. Restorasyonları bitirilen dişler rastgele seçilerek 3 gruba ayrılmıştır (n=20). Grup 1 kontrol grubudur ve kaviteler direkt kompozit (Filtek Z250) uygulaması ile bitirilmiştir. Grup 2 de basamakta Supreme XT Flow, Grup 3 te basamakta Grandio Flow kullanılmış olup, her 3 grubun üst yapıları mikrohibrit kompozit rezin (Filtek Z250) ile restore edilmiştir. Tüm örnekler termo-mekanik yüklemeye maruz bırakılarak yaşlandırılmıştır. Mikrosızıntı tayini bazik fuksin boyasının penetrasyon miktarının stereomikroskop (X40) altında incelenmesi ile yapılarak istatistiksel analize tabi tutulmuştur. Bulgular: Sonuçların değerlendirilmesinde Mann Whitney U Test kullanılmıştır. Her iki nano dolduruculu akışkan kompozitler Supreme XT Flow ve Grandio Flow kontrol grubunda yer alan mikrohibrit rezine istatistiksel olarak anlamlı bir üstünlük sağlayamamışlardır (p>0,05). Ayrıca Supreme ve Grandio materyallerinin mikrosızıntı dereceleri arasında istatistiksel olarak anlamlı bir farklılık bulunamamıştır (p>0,05). Sonuç: Nanohibrit akışkan kompozitler kendilerinden beklenen derin class II kavitelerdeki mikrosızıntıyı azaltma konusunda daha üstün özellikler sergileyememiştir.
Cerium oxide nanoparticles are known for their antibacterial effects resulting from Ce³⁺ to Ce⁴⁺ conversion. Application of such cerium oxide nanoparticles in dentistry has been previously considered but limited due to deterioration of mechanical properties. Hence, this study aimed to examine mesoporous silica (MCM-41) coated with cerium oxide nanoparticles and evaluate the antibacterial effects and mechanical properties when applied to dental composite resin. Cerium oxide nanoparticles were coated on the MCM-41 surface using the sol–gel method by adding cerium oxide nanoparticle precursor to the MCM-41 dispersion. The samples were tested for antibacterial activity against Streptococcus mutans via CFU and MTT assays. The mechanical properties were assessed by flexural strength and depth of cure according to ISO 4049. Data were analyzed using a t-test, one-way ANOVA, and Tukey’s post-hoc test (p = 0.05). The experimental group showed significantly increased antibacterial properties compared to the control groups (p < 0.005). The flexural strength exhibited a decreasing trend as the amount of cerium oxide nanoparticle-coated MCM-41 increased. However, the flexural strength and depth of cure values of the silane group met the ISO 4049 standard. Antibacterial properties increased with increasing amounts of cerium oxide nanoparticles. Although the mechanical properties decreased, silane treatment overcame this drawback. Hence, the cerium oxide nanoparticles coated on MCM-41 may be used for dental resin composite.
Cerium oxide nanoparticles are known for their antibacterial effects resulting from Ce ³⁺ to Ce ⁴⁺ conversion. Application of such cerium oxide nanoparticles in dentistry has been previously considered but limited due to deterioration of mechanical properties. Hence, this study aimed to examine mesoporous silica (MCM-41) coated with cerium oxide nanoparticles and evaluate the antibacterial effects and mechanical properties when applied to dental composite resin. Cerium oxide nanoparticles were coated on the MCM-41 surface using the sol-gel method by adding cerium oxide nanoparticle precursor to the MCM-41 dispersion. The samples were tested for antibacterial activity against Streptococcus mutans via CFU and MTT assays. The mechanical properties were assessed by flexural strength and depth of cure according to ISO 4049. Data were analyzed using a t-test, one-way ANOVA, and Tukey’s post-hoc test ( p = 0.05 ). The experimental group showed significantly increased antibacterial properties compared to the control groups ( p < 0.005 ). The flexural strength exhibited a decreasing trend as the amount of cerium oxide nanoparticle-coated MCM-41 increased. However, the flexural strength and depth of cure values of the silane group met the ISO 4049 standard. Antibacterial properties increased with increasing amounts of cerium oxide nanoparticles. Although the mechanical properties decreased, silane treatment overcame this drawback. Hence, the cerium oxide nanoparticles coated on MCM-41 may be used for dental resin composite.
To investigate the reinforcing effect of nanoflower‐like hydroxyapatite (NFHA) in resin‐based dental composites, we synthesized a novel NFHA using microwave irradiation (MW), hydrothermal treatment (HT), and sonochemical synthesis (SS). Silanized NFHA was then used as the reinforcing filler in dental resin composites. We characterized the structure and morphology of various HA nanostructures using x‐ray diffraction, scanning electron microscope, and TEM. The mechanical performance of dental resin composites reinforced with silanized NFHA was measured using a universal testing machine. Spherical HA, synthesized through chemical precipitation (CP), served as the control group. One‐way analysis of variance was employed for the statistical analysis of the acquired data. The results demonstrate that the nanoflower morphology significantly was improved mechanical and physical properties. After conducting trials, the NFHA synthesized using MW and HT showed a substantial enhancement in mechanical and physical properties compared to the other structures. Therefore, it can be concluded that NFHA can serve as a novel reinforcing HA filler, providing regenerative properties to resin composites with sufficient mechanical strength.
Background
The effects of whitening toothpastes containing nanohydroxyapatite on the surfaces of restorative materials are not well known. This study evaluated the changes in surface roughness and color of coffee-stained restorative materials after brushing with nanohydroxyapatite and other whitening toothpastes.
Methods
Disc-shaped specimens were formed using microhybrid, nanohybrid, and supra-nano-filled composite ( n = 30) and stained with a coffee solution. A brushing simulation was applied with toothpastes containing nanohydroxyapatite (Dentiste Plus White), perlite (Signal White System) and hydrogen peroxide (Colgate Optic White) for 7, 15, and 30 days. Color and surface roughness measurements were taken before and after brushing. Color change (∆E 00 ) was calculated using the CIEDE2000 system.
Results
Supra-nano-filled composite-Dentiste Plus White, supra-nano-filled composite-Colgate Optic White, and nanohybrid composite-Signal White System were the groups with the greatest color change observed on the 7th, 15th, and 30th days, respectively. The smallest color change was seen in the microhybrid composite-Signal White System, microhybrid composite-Dentiste Plus White, and nanohybrid composite-Dentiste Plus White groups on the 7th, 15th, and 30th days, respectively. No significant surface roughness changes were observed in the nanohybrid composite-Dentiste Plus White, supra-nano-filled composite-Colgate Optic White, supra-nano-filled composite-Dentiste Plus White, or supra-nano-filled composite-Signal White System groups.
Conclusions
Whitening toothpaste containing nanohydroxyapatite provided a high degree of color change in the short term and did not create significant surface roughness in nanohybrid or supra-nano-filled composites.
Flowable restorative composites that are unique for clinical application performances, both in mechanical and physico-chemical properties as well as flowability, were developed through the modification of A200 and M8000 silica particle surfaces with various silane-based coupling agents. The presence of the coupling agent used in particle surface modification for matrix-particle interface formation was specified with thermogravimetric analysis and Brunauer–Emmett–Teller surface area analysis while the bonding was specified with Fourier Transform Infrared and X-Ray Photoelectron spectroscopy analysis. Flexural strength, compressive strength and water sorption, which are considered to be important tests in this field, were conducted and studied. Flowability was examined keeping clinical application performances in mind. The increase in silanization activity that is dependent on the length and volume of the active unit belonging to the coupling agent decided by the dispersion of modified silica particles in the matrix is linearly related to the active unit quantity of the coupling agent. Active unit quantity, which is also linearly related to the flowability of the composite, affects mechanical and physico-chemical properties of the composites. The flow distances and rates of the produced composites are in the range of 0.63–3.43 cm and 0.11–0.57 mm/s, respectively. different composites in the flowable composites class, which are generally adopted in the area of dental composites, have been produced. The created interface changed the rheologies of the composites, resulting in a change in flow distances and rates, and composites exhibiting similar flow behavior as commercial flowable composites were obtained.
Statement of problem
Microleakage and loss of the composite resin sealing the screw-access channel are frequent complications of screw-retained implant-supported prostheses. How the screw-access channel should be best restored to reduce such complications is unclear.
Purpose
The purpose of this in vitro study was to evaluate the microleakage and bond strength of 3 types of composite resins (flowable, packable, and bulk-fill) with or without a bonding agent treatment to seal the screw-access channel of 2 types of restorative materials (zirconia and Co-Cr alloy) with or without thermocycling.
Material and methods
In total, 240 yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) specimens (IPS e.max ZirCAD) and 240 Co-Cr alloy (Vera PDS) specimens were prepared with a Ø3×3-mm cylindrical cavity at the center to simulate the screw-access channel. Three types of composite resins (flowable, packable, and bulk-fill resin) (Filtek Z350 XT Flowable Restorative, Filtek Z350 XT Universal Restorative, and Filtek One Bulk Fill Restorative) were applied to restore the access channel of the zirconia and Co-Cr specimens with or without a bonding agent (Single Bond Universal Adhesive). Microleakage and push-out bond strength were determined and compared by dividing the specimens into experimental groups with or without thermocycling (1000 times with 30 seconds at 5 ±2 °C and 55 ±2 °C). The results were analyzed by using a 1-way ANOVA and 4-way ANOVA. Adjustment for multiple comparisons was made with the Tukey Honestly Significant Difference (HSD) test.
Results
The specimens subjected to thermocycling showed a lower bond strength (P<.001) and higher microleakage (P<.001) than specimens stored in a constant-temperature water bath. Specimens treated with bonding agents showed a higher bond strength (P<.001) and lower microleakage (P<.001) than specimens not treated with a bonding agent. Higher bond strengths were observed in the order of bulk-fill resin, packable resin, and flowable resin (P<.001). Packable resin showed higher microleakage than flowable resin and bulk-fill resin (P<.05). No significant difference in microleakage was found between the flowable resin and bulk-fill resin (P>.05).
Conclusions
Higher bond strengths were observed in the order of bulk-fill resin, packable resin, and flowable resin. Less microleakage was observed in the flowable resin and bulk-fill resin than in the packable composite resin. Bonding agent treatment was effective in increasing bond strength and decreasing microleakage. Zirconia and Co-Cr showed a bond strength similar to that of composite resins, but zirconia showed higher microleakage than Co-Cr. Restoring the screw-access channel with the bulk-fill resin should increase bond strength and reduce microleakage.
Polymeric dental filling (light-cured dental filling) has many problems like polymerization shrinkage and weakness in mechanical properties. Recently, scientists found that nanoparticles have good solutions to many problems in dentistry. Nanoparticles were prepared from ZnO, by sol-gel, laser ablation, chemical, and sol-gel methods according to papers published earlier. These nanoparticles were then added to the light-cured dental filling as filler. The polymeric dental filling containing the nanoparticles prepared were then examined by X-ray diffraction, depth of cure, compression strength, hardness (lower and upper surfaces), degree of cure, the relation between the depth of cure and degree of cure, the diameter of samples, and polymerization shrinkage. The examinations and results showed that polymeric dental filling containing silver nanoparticles has maximum compression strength and hardness and no polymerization shrinkage. The most important result was that ZnO nanoparticles filler canceled polymerization
Aims and background:
The aim of this study is to evaluate the surface microhardness and roughness of composites treated with three different polishing systems exposed to two different corrosive beverages.
Material and methods:
Ninety-six composite resin disks were randomly divided into four groups, one of which was the control group. The surface roughness and microhardness values were measured after 24 h in the polishing process. The samples were divided into three subgroups and kept in distilled water, cola, and ice tea for 20 min a day for 14 days. Then, the roughness and microhardness measurements of the samples were taken again. Two samples randomly selected from each group were examined using a scanning electron microscope (SEM) and analyzed statistically using the two way anova (ANOVA) and Duncan tests.
Results:
A statistically significant difference was found between the roughness and hardness values at the end of 24 h and 14 days. Onegloss (OG), Dentoflex (DF), and Super-snap (SNP) polish systems showed the highest roughness in the cola group, respectively. Microhardness values: The unpolished group had the lowest significant microhardness in the coke group (P < 0.05).
Conclusion:
In this study, it was seen that the lowest success rate was the OG polishing system.
Polymeric dental filling (light-cured dental filling) have many problems like polymerization shrinkage and weakness in mechanical properties. Recently, scientists found that nanoparticles are good solutions for many problems in dentistry. Four nanoparticles were prepared ZnO, silver, ZrO2, and TiO2 by sol-gel, laser ablation, chemical, and sol-gel methods. These nanoparticles were then added to light-cured dental filling as fillers. The polymeric dental filling containing the nanoparticles prepared were then examined by X-ray diffraction, depth of cure, compression strength, hardness (lower and upper surfaces), degree of cure, relation between depth of cure and degree of cure, diameter of samples, and polymerization shrinkage. The results showed that polymeric dental filling containing silver nanoparticles had the maximum values of compression strength and hardness with improved mechanical strength with no polymerization shrinkage of the dental filling.
The purpose of this study was to evaluate the surface roughness, microhardness, color change, and translucency of a newly marketed universal nanohybrid composite resin (CR) (G‐aenial A'CHORD) comparing with four contemporary universal CRs including two nanofilled (Filtek and Estelite Asteria) and two nanohybrid CRs (Charisma Dimond and Neo Spectra ST HV in vitro). Sixty‐five specimens (8.0 mm × 2.0 mm) were fabricated (n = 13, per group). After finishing and polishing, specimens were subjected to surface roughness and microhardness tests. Color and translucency of the specimens were evaluated at baseline and after darkening with coffee solution at day 1 and day 7. A representative specimen from each group was investigated under scanning electron microscopy (SEM). Data was analyzed statistically (p < .05). There were significant differences among the groups in terms of surface roughness, microhardness, color, and translucency. The surface roughness was recorded as: Charisma Diamond > Neo Spectra ST HV, Filtek > Estelite Asteria, G‐aenial A'CHORD, whereas Vickers Hardness number was as: Filtek, Charisma Diamond > Neo Spectra ST HV > G‐aenial A'CHORD, Estelite Asteria. Color change was as: Charisma Diamond > Neo Spectra ST HV, Filtek, G‐aenial A'CHORD > Estelite Asteria and the translucency was as: Neo Spectra ST HV > G‐aenial A'CHORD, Filtek > Estelite Asteria, Charisma Diamond. SEM examinations revealed smooth surfaces for G‐aenial A'CHORD, Neo Spectra ST HV and Estelite Asteria. Mechanical and optical properties of universal composite resins with different compositions show variations.
This chapter focuses on metal oxides as nano building blocks relevant in industrial applications. Metal oxide nanoparticles have been used as colloids and powders for quite some time. In the last 20 years, there has been a tremendous increase in the scientific field as well as in the technological exploitation of metal oxide nanoparticles as reflected by the number of patent applications in the field. The chapter describes selected metal oxide materials, their basic properties, and specific application fields. An enabling nanomaterial will make new products possible, where there is no alternative from conventional materials. In this case the price tags for products can be higher since there is no competition with alternative solutions. From an economical perspective the enabling aspect is the most interesting. Concerning operating profits also the production volume does not necessarily equate with economical value. In cosmetics, pharmaceutical, and medical applications the profit margins are much higher than for industrial applications.
This study aims to evaluate the effects of different finishing and polishing (F/P) systems on gloss and surface morphology of a new nanocomposite. Thirty discs of Filtek Universal Restorative material (3 M, ESPE) were prepared and divided into six groups (n = 5). Group A and B followed F/P protocols for anterior restorations, whereas Group C and D for posterior ones. Group E represented the control (covered by Mylar strip) and Group F represented the nanocomposite placement by means of clinical hand instruments; Groups E and F did not undergo F/P procedures. Among the polished groups, Group B showed the highest values (68.54 ± 7.54 GU), followed by Group A and D (46.87 ± 5.52 GU; 53.76 ± 2.65 GU). Finally, Group C (37.38 ± 4.93 GU) displayed the lowest results. Overall, Group E showed the highest gloss values (93.45 ± 8.27 GU), while Group F presented the lowest ones (1.74 ± 0.64 GU). Surface analysis revealed that Group A, C, and D displayed a smooth surface. Group B showed the lowest irregularities. Group E exhibited the most uniform superficial morphology. On the other hand, Group F displayed the most irregular one. In conclusion, using the tested material, only two protocols achieved appropriate gloss values. Then, clinicians might use the protocols of Group B and Group D, for anterior and posterior restorations, respectively.
Aim
To examine the effects of fluoride, hydroxyapatite, and bromelain-containing toothpaste types on the surface roughness of nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers.
Materials and Methods
A total of 160 specimens were fabricated using nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers. Each material group was divided into four subgroups ( n = 5) as follows: Control (C), fluoride toothpaste (FT), bromelain toothpaste (BT), and hydroxyapatite toothpaste (HT). Surface roughness values of all specimens were examined using an optical profilometer and a scanning electron microscope at 500, 1,000, and 3,500 magnifications.
Results
The highest average roughness value (Ra; µm) was obtained from the conventional glass ionomer material ( P < .001). While the mean Ra value was 0.155±0.116 µm at baseline, it was 0.262±0.203 µm in the fluoride group, 0.237±0.192 µm in the hydroxyapatite group, 0.260±0.293 µm in the bromelain group, and 0.198± 0.187 µm in the control group ( P < .001).
Conclusion
We have found that brushing with various types of toothpaste containing fluoride, bromelain, and hydroxyapatite may not result in obtaining different surface roughness values from different types of restorative materials. Differences in surface roughness values of restorative materials may be found at different magnifications under scanning electron microscope.
Silicon oxide or metal oxide clusters or small particles with polymerizable organic groups covalently bonded to their surface
can be copolymerized with organic monomers by various polymerization techniques. Whereas the preparation and properties of
the polymers reinforced by R
8Si8O12 have already been well investigated, analogous materials with incorporated transition metal oxide clusters are only beginning
to show their potential as an interesting new class of inorganic-organic hybrid polymers. In the second part of the article,
approaches are reviewed in which the inorganic building block serves as an initiator for polymerization reactions. This results
in materials in which the organic polymer is grafted from an inorganic core. Most work has been done with surface-modified
silica particles. Free radical polymerizations and atom transfer radical polymerizations with macroinitiators are summarized.
The latter method results in polymeric particles in which an inorganic core is surrounded by an organic polymer shell. A new
approach is the use of polyfunctional inorganic molecules or molecular clusters as initiators.
The sol-gel process is on interesting route to prepare inorganic and inorganic-organic sols. These sols, in general, consist of colloidal nanoparticles or oligomers and are stabilized by electrical charges or functional groupings in order to avoid uncontrolled agglomeration. By appropriate processing, many interesting materials such as coatings on glasses and plastics, ceramics or materials for optics, data storage and information technologies can be fabricated.
As a new frontier in particle and aerosol research, nanoparticle research has significant potential for scientific breakthrough and new technological innovations. In the past few years, atom clusters with average diameters in the range of 5 - 100 nm of a variety of materials, including metals and ceramics, have been synthesized. These new ultrafine-grained materials have properties that ore often significantly different and considerably improved relative to those of their bulk counterparts. The property changes result from their small grain size, the large percentage of their atoms in groin boundary environments, and the interactions between groins.
As a new frontier in particle and aerosol research, nanoparticle research has significant potential for scientific breakthrough and new technological innovations. In the past few years, atom clusters with average diameters in the range of 5-100 nm of a variety of materials, including metals and ceramics, have been synthesized. These new ultrafine-grained materials have properties that are often significantly different and considerably improved relative to those of their bulk counterparts. The property changes result from their small grain size, the large percentage of their atoms in grain boundery environments, and the interactions between grains.
To provide the filler for dental composite resins, pure silica-glass powder has been synthesized by the sol-gel process. The starting solution (sol) consisted of 1 mole tetraethoxysilane (TEOS), 10 moles of water, 20 moles of ethylalcohol and 0.02 moles of HCl catalyst. The hydrolysis and condensation of TEOS were studied by IR spectroscopy. It was observed that the resultant wet gel was the reaction intermediate containing siloxane bonds and abundant H2O. The sintering process was analysed by DTG thermal analysis. In order to obtain transparent glass particles without being contaminated by a black substance, it is hypothesised that organic side-chains should be thoroughly eliminated by fully drying and slowly heating the ground gel.
Powders of SiO2-BaO composition containing 5, 10, and 15 mol.-%BaO have been prepared by an aqueous sol-gel method for use in dental composite resins. Barium carbonate and tetraethoxysilane were used as starting materials, and aqueous formic acid solution was used as the reaction medium instead of conventionally used alcohol. The gels were calcined at 600, 800, and 7000°C and characterised by X-ray powder diffraction, infrared spectroscopy, differential thermal analysis, thermogravimetry, and transmission electron microscopy. The method is shown to provide homogeneous, reactive, amorphous powder at comparatively low temperatures and offers the potential of a simpler, more cost effective route than other reported methods.
The sol-gel process is an interesting route to prepare inorganic and inorganic-organic sols. These sols, in general, consist of colloidal nanoparticles or oligomers and are stabilized by electrical charges or functional groupings in order to avoid uncontrolled agglomeration. By appropriate processing, many interesting materials such as coatings on glasses and plastics, ceramics or materials for optics, data storage and information technologies can be fabricated.
Dental composite resins need a radiopacity exceeding that of human dental enamel to facilitate dental diagnostic observations. To provide the radiopaque fillers for dental composites, SiO2-BaO powders containing up to 15 mol.-%BaO have been prepared by heating to 1000°C ground gels made from a mixture of Si(OC2H5)4 and Ba(OC2H5)2. The sintering process was investigated by DTG thermal analysis and X-ray diffraction. The results suggested that, at temperatures greater than 450°C, Ba(OC2H5)2 was thermally decomposed, releasing Ba2+ ions into the SiO2 gel to glass conversion. It was also found that powders heated to 600°C were glassy, but that those heated at the temperatures greater than 800°C contained cristobalite crystals in the SiO2-based glass matrix. The results also showed that the radiopacity of powders, measured with a dental X-ray machine and a densitometer, increased with increase in BaO content and that the 95SiO2-5BaO (mol.-%) composition had a radiopacity slightly exceeding that of human dental enamel. It is concluded that SiO2-BaO powders prepared by sol-gel processing are suitable as radiopacity-adjustable fillers for dental composites.
IntroductionThe Silica Sol–Gel Process and Silica Sol–Gel MaterialsDirect Entrapment of Organic and Bioorganic Molecules in Sol–Gel Matrices General AspectsApplications in Analytical Chemistry: Sol–Gel SensorsCatalysis with Entrapped Organometallic Ion-pairs and ComplexesBiochemistry within Sol–Gel Matrices: The Entrapment of Enzymes and AntibodiesElectrochemistry with Organically Doped Sol–Gel ElectrodesCovalent Entrapment of Organic Functional Groups Trialkoxysilanes as Precursors for FunctionalizationAlkyl- and Aryl-substituted MaterialsMaterials Substituted by Polymerizable Organic Groups Cocondensation with E(OR′)nCocondensation of Different Organically Modified AlkoxidesCopolymerization with Organic MonomersMaterials Substituted by Aminoalkyl or Phosphinoalkyl GroupsMaterials Substituted by Miscellaneous GroupsOrganic/Inorganic Sol–Gel Copolymerizations Physical Hybrids (Class I)Sequential Organic/Inorganic Interpenetrating NetworksSimultaneous Organic/Inorganic Interpenetrating NetworksSilsesquioxane-containing Hybrids (Class II)Photochemistry, Photophysics and Optics of Doped Sol–Gel Materials Photoprobes for the Sol to Gel to Xerogel Transitions and for the Study of the Properties of the Sol–Gel CageOrganic Photochemistry within Sol–Gel MatricesSol–Gel Optics Photochromic Sol–Gel GlassesOptical and Photophysical Properties of Entrapped Organic MoleculesMaterials Substituted by ChromophoresConcluding RemarkAcknowledgmentsReferences General AspectsApplications in Analytical Chemistry: Sol–Gel SensorsCatalysis with Entrapped Organometallic Ion-pairs and ComplexesBiochemistry within Sol–Gel Matrices: The Entrapment of Enzymes and AntibodiesElectrochemistry with Organically Doped Sol–Gel Electrodes Trialkoxysilanes as Precursors for FunctionalizationAlkyl- and Aryl-substituted MaterialsMaterials Substituted by Polymerizable Organic Groups Cocondensation with E(OR′)nCocondensation of Different Organically Modified AlkoxidesCopolymerization with Organic MonomersMaterials Substituted by Aminoalkyl or Phosphinoalkyl GroupsMaterials Substituted by Miscellaneous Groups Cocondensation with E(OR′)nCocondensation of Different Organically Modified AlkoxidesCopolymerization with Organic Monomers Physical Hybrids (Class I)Sequential Organic/Inorganic Interpenetrating NetworksSimultaneous Organic/Inorganic Interpenetrating NetworksSilsesquioxane-containing Hybrids (Class II) Photoprobes for the Sol to Gel to Xerogel Transitions and for the Study of the Properties of the Sol–Gel CageOrganic Photochemistry within Sol–Gel MatricesSol–Gel Optics Photochromic Sol–Gel GlassesOptical and Photophysical Properties of Entrapped Organic MoleculesMaterials Substituted by Chromophores Photochromic Sol–Gel GlassesOptical and Photophysical Properties of Entrapped Organic MoleculesMaterials Substituted by Chromophores
The shrinkage of methacrylate-based dental resins can be reduced efficiently by incorporating 5 wt% of methacrylate-functionalized polyhedral oligomeric silsesquioxane (POSS) macromonomer into a mixture of oligomeric dimethacrylate/diluent mixture. The mechanical properties of the unfilled resins can also be improved. Methacrylate-functionalized POSS monomers can be expected more widespread and intense study in modification of multimethacrylate oligomer/diluent based dental materials if the miscibility between POSS monomer and the oligomer/diluent can be improved.
The flexural strength and the flexural modulus of inorganic-organic hybrid polymers obtained by sol-gel processing and subsequent light-induced polymerization of bis-[(methacryloyloxy)propoxycarbonylethyl)](3-triethoxysilyl)propylamine or (1,3(2)-bis-methacryloyloxypropyl)(3-triethoxysilylpropylaminocarbonyl)butyrate is enhanced by copolymerization with 10 wt % of the methacrylate-substituted oxozirconium cluster Zr4O2(OMC)(12). The mechanical properties of the cluster-cross-linked hybrid polymers do not deteriorate upon water storage at 37 degreesC.
The present paper will describe the preparation of monodispersed silica particles by a controlled growth process. This procedure has several advantages compared with the original Stöber (batch) process. A simple calculation allows seeds of a given size to be grown exactly to a pre-set final particle size. Spherical and exceptional monodispersed particles of up to 3·6 μm in diameter and a very high (particle) mass fraction of up to 10 vol.% silica could be prepared by this process. Moreover, a simple tube reactor is shown, which allows those particles to be produced on a continuous basis.ZusammenfassungIm Folgenden wird ein kontrollierter Wachstums-prozeß beschrieben, der verschiedene Vorzüge gegenüber dem ursprünglichen Batch-Prozeß von Stöber besitzt. Eine einfache Berechnung erlaubt es, eine vorgegebene Partikelgröße exakt herzustellen. Kugelförmige und außerordentlich einheitliche Partikel von bis zu 3·6 μm Durchmesser und sehr hohen Feststoffkonzentrationen von bis zu 10 vol.% SiO2 konnten hergestellt werden. Ferner wird ein einfacher Rohrreaktor vorgestellt, der die kontinuierliche Synthese solcher Pulver erlaubt.RésuméLe présent article décrit la préparation de particules de silice monodispersées par un procédé de croissance contrôlée. Cette dernière méthode présente plusieurs avantages en comparaison avec le procédé original en batch de Stöber. Un simple calcul permet de faire croître avec exactitude des grains d'ensemencement d'une taille donnée jusqu'à une taille finale de particules pré-déterminée. Des particules monodispersées sphériques jusqu'à 3·6 μm de diamètre et une fraction massique (en particules) très élevée jusqu'à 10 vol.% en silice pourraient être préparées par ce procédé. De plus, un simple réacteur tubulaire est décrit, lequel permet de produire ces particules de façon continue.
ORMOCER®s (ORMOCER® Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.) as inorganic-organic polymers synthesized by a two-step sol-gel processing method can be applied as thin transparent coatings on various substrates (polymers, metals, ceramics). The curing of ORMOCER®s is performed thermally (at temperatures below 200°C) or by UV-radiation. Their high abrasion resistance and good chemical stability led to several actual industrial applications. Beside mechanical protection functions (e.g. for sensitive polymer substrates) additional functionalities of ORMOCER® surfaces are investigated to find new application areas. This paper presents two additional surface functions of abrasion resistant ORMOCER® coatings: Antiadhesive and antistatic properties. Incorporation of perfluorinated alkoxysilane compounds via sol-gel processing decreases the surface energy of the cured layer. Water as well as non-polar substances lose their adhesion to the surface, wetting is reduced, solutions are drained off and particles can be removed easily.By addition of polar and/or ionic compounds bearing hydrolyzable alkoxysilyl groups a scratch resistant antistatic coating for polycarbonate was developed. Compared to the uncoated substrate, the specific surface resistance was decreased from 1015 to 108 Ω. Electrostatic charging is decreased and attraction of particles inhibited or reduced. The coatings are abrasion resistant and show very good adhesion even in a wet climate.
The thermal stability, density and hardness of new polyacrylate-SiO2 hybrid glasses, derived from poly [methyl methacrylate-co-3-(trimethoxysilyl) propyl methacrylate] or poly [3-(trimethoxysilyl) propyl methacrylate] and tetraethyl orthosilicate via the sol-gel approach, were found to depend greatly on the organic-inorganic composition and the thermal history of the materials but little on the copolymer composition. Higher stability, density and hardness can be achieved by increasing the content of SiO2 in the hybrid materials. Thermal treatment of the materials at 200°C increased the bulk density and hardness by ≈ 16% and by factor of 2–3, respectively, without decomposition of the polymer backbones.
The many possibilities of modifying the precursor compounds and the microstructure and the other inherent advantages of the sol-gel process allow the deliberate tailoring of materials properties over a wide range, such as the physical and chemical properties of aerogels (see cover illustration).
Bicyclo[2.2.1]hept-2-ene-5-yl (norborn-2-ene-5-yl) derivatives of silic acid were synthesized by the Diels-Alder reaction, of the corresponding (meth)acryloxypropyl silanes with cyclopentadiene monomer. The norbornenyl silanes were characterized by elemental analyses, IR, 1H NMR, 13C NMR and 29Si NMR spectroscopy. The hydrolysis and condensation of norbornene-funktionalized silic acid esters yield polysiloxanes which can be crosslinked by the photoinitiated reaction with multifunctional thiols. The shrinking behaviour of the bulk materials which are obtained by this combination of the sol-gel process with the thiol-ene polymerization were investigated.
The mechanical properties of polyacrylate-silica hybrid sol-gel materials have been investigated in comparison with conventional resin composites. The hybrid materials with a wide range of silica content were synthesized via the sol–gel reactions of the silica precursor tetraethyl orthosilicate (TEOS) with acrylate copolymers of methyl methacrylate (MMA) with 3-(trimethoxysilyl)propyl methacrylate (MSMA). In these materials, the polymer chains are uniformly distributed in and covalently bonded to the inorganic silica host matrix at the molecular level without macroscopic organic–inorganic phase separation. The hybrid materials are transparent and non-porous. In the standard compression test, the hybrid materials exhibited strain hardening behavior which was absent in the conventional PMMA-silica composites. Their mechanical properties can be fine-tuned by varying the polyacrylate-silica composition in the synthesis and are superior over conventional composites at similar silica contents. These hybrid materials are promising for potential dental applications. Copyright © 2001 John Wiley & Sons, Ltd.
A critical challenge in the design of inorganic-organic composites is control over the mixing between the two chemically dissimilar phases. The sol-gel process has been utilized for the homogeneous incorporation of organic polymers into an inorganic matrix. One major limitation in the synthesis of sol-gel composites is the ubiquitous shrinkage that results from the evaporation of excess solvents and water. The authors have attempted to address this issue by developing in situ synchronous polymerization routes into these hybrid materials through the use of tetraalkoxysilanes possessing polymerizable alkoxides. Since their initial reports on the use of these new sol-gel precursors for the production of nonshrinking sol-gel composites, they have focused their efforts toward the synthesis and application of poly(silicic acid esters) bearing the same polymerizable alkoxides. This new approach allows for the synthesis of nonshrinking sol-gel composites with higher glass content than was previously possible with the tetraalkoxysilane derivatives. Furthermore, the use of poly(silicic acid esters) provides a new means for controlling composite morphology through the size and shape of the poly(silicic acid ester). Molecular weights for these poly(silicic acid esters) can be varied from 3,000 to 30,000 simply by increasing the reaction time of the silicic acid synthesis. Also, particle shape can be controlled by the pH of the reaction solution. A modified esterification process using THF or benzene for azeotropic removal of water has been developed for synthesizing poly(silicic acid esters) with thermally unstable unsaturated alcohols. These substituted poly(silicic esters) have been used to produce transparent nonshrinking composites with a wide range of glass/polymer ratios. 15 refs., 2 figs., 5 tabs.
The currently used commercial restorative composites contain a mixture of various cross-linking dimethacrylates, glass- and/or silicon dioxide fillers, and a photoinitiator system. They are cured by irradiation with visible light. New developments of polymeric composites for restorative filling materials are mainly focused on the reduction of polymerization shrinkage, and improvement of biocompatibility, wear resistance and processing properties. This can be partially achieved by using new tailor-made monomers and optimized filler particles.This review describes the polymeric chemical aspects of the application of new monomers, e.g. cyclic monomers, liquid-crystalline monomers, ormocers, branched monomers, compomers or Bis-GMA analogues or substitutes for restorative composites. In addition, the contribution of new filler-technologies for the improvement of restorative composites is discussed.
Composite coating films crack-free and with smooth surfaces have been prepared by the sol–gel technique using branched chain polyfluoroalkylsilane (triethoxy[4,4-bis(trifluoromethyl)-5,5,6,6,7,7,7-heptafluoroheptyl]silane) (D3Et) and tetraethoxysilane (TEOS) as starting materials. Surface properties of the fluorinated coating films heated at various temperatures were examined in comparison with films derived from methyltrimethoxysilane (MTM) and TEOS, based on the measurements of infra-red spectra, thermal gravimetric changes and X-ray photoelectron spectra and contact angle of water and diiodo methane. It was found that the fluorosilane-containing films had thermal stability and surface energies, γs, as small as polytetrafluoroethylene (PTFE) up to 400°C and a large contact angle of water comparable to the films derived from MTM and TEOS. Large hydrophobicity of fluorosilane-containing films seems to be due to the dispersion component of the surface energy compared with methyltrimethoxysilane and TEOS films. We conclude from X-ray photoelectron spectra measurements that the surface energy of the fluorinated coating film originate from polyfluorocarbon molecules at the topmost film surface.
Multicomponent oxide glasses can be produced not only by melting methods but also by hydrolysis and condensation of alkoxide complexes with several metals. This requires temperatures only up to the transformation range of the glass in question, usually 500–600 °C. The process does not pass through the molten phase. It is possible to obtain glasses or polycrystalline substances, depending on the composition. The method is particularly suitable for the production of thin, transparent multicomponent oxide layers of almost any composition on substrates. Some of these layers provide protection against climatic attack or against oxidation.
Inorg.-org. hybrid polymers were prepd. by radical polymn. of methacrylic acid or Me methacrylate with the (meth)acrylate-substituted oxozirconium and oxotitanium clusters Zr6(OH)4O4(OMc)12 (OMc = methacrylate), Zr4O2(OMc)12, Ti6O4(OEt)8(OMc)8 and Ti4O2(OPr1)6(OAcr)6 (OAcr = acrylate). A few mol% of cluster is sufficient for an efficient crosslinking of the polymer chains. Small-angle X-ray scattering data indicate that the cluster size is retained in the polymers and that the microstructure of the cluster cross-linked samples can be described by a dispersion of identical spherical or disk-shaped clusters in the polymer. The obtained hybrid polymers exhibit a higher thermal stability because depolymn. reactions are inhibited. Contrary to undoped poly(Me methacrylate), the cluster cross-linked polymers are insol. but swell in org. solvents. The solvent uptake upon swelling decreases with an increasing amt. of polymd. cluster. [on SciFinder(R)]
The use of atom transfer radical polymerization (ATRP) of methacrylate functional polyhedral oligomeric silsesquioxanes (POSS) monomers is described to synthesize hybrid homopolymers and block copolymers. From this approach, homopolymers, triblock copolymers, and star-block copolymers containing POSS was prepared. While polymers containing POSS were made by other methods, using ATRP, hybrid-POSS polymers with previously unattainable compositions and drastically lower polydispersities were synthesized.
A series of linear thermoplastic hybrid materials containing an organic polystyrene backbone and large inorganic silsesquioxane groups pendent to the polymer backbone have been synthesized and characterized. Our preliminary results indicate that the pendent inorganic groups drastically modify the thermal properties of the polystyrene and that interchain and/or intrachain oligomeric silsesquioxane interactions result in variations in solubility and thermal properties
We report here the synthesis and characterization of simple methacrylate/cube hybrids trhat can act as thermosets or photocurable monomers. These materials are easily manipulated, yet retain very high masked silica loadings
Bismethacrylate monomers and macromonomers bearing various alkoxysilyl units were prepared by convenient Michael addition of ethylene glycol acrylate methacrylate (EGAMA) and ethylene glycol bisacrylate (EGBA) to various α,ω-alkoxysilylamines. The resulting monomers and macromonomers have been characterized in detail by NMR spectroscopy, VPO measurements and FAB−MS. Average molecular weights Mn ranged between 530 and 1600 (VPO) in addition reactions with bisacrylates. FAB−MS evidenced the formation of a homologous macromonomer series. Viscosities of the liquid monomers are relatively low, ranging from 52 to 305 mPa·s. This renders these compounds interesting as reactive diluents in dental composite formulations. Polymerization of the monomers and macromonomers resulted in low volumetric shrinkage in the range of ΔV = 2.2−7.8% at high methacrylate conversion. Cross-linking was monitored by photo-DSC. Furthermore, composites were prepared by mixing Bis-GMA with the new hybrid monomers, initiator and glass filler. The composites showed compressive strengths of 190−329 MPa, flexural strengths from 23 to 53 MPa and Young's moduli between 2090 and 5060 MPa. Low volumetric shrinkage was observed also for the composites upon photopolymerization, ranging from only 0.8% to 2.2% in comparison to over 3% shrinkage of commercially available composites. Besides the viscosity reducing effect due to the branched structure, the pendant alkoxysilyl groups of the synthesized hybrid monomers can be polymerized to form nanoparticles with reactive acrylate surface, permitting the in situ preparation of nanocomposites.
The authors report the synthesis of optically transparent, interpenetrating composites through the synchronous formation of both the inorganic and the organic components.The synthesis was accomplished by the hydrolysis and condensation of tetraalkenyl orthosilicates to form an inorganic SiO2 matrix while simultaneously eliminating unsaturated alcohols which were polymerized in situ using free radical techniques.
Platinum-catalyzed hydrosilylation of allyl glycidyl ether (AGE) with octahydridosilsesquioxane ((HSiO1.5)(8), T-8(H)) and octakis(dimethylsiloxy)silsesquioxane ((HMe(2)SiOSiO(1.5))(8), Q(8)M(8)H) provides access to tetra- and octaepoxy-functionalized cubic silsesquioxanes (cubes). The resulting epoxy cubes offer ''masked'' silica contents of up to 65 wt %, are soluble in common solvents, and are viscous Liquids at room temperature, making them attractive for coating and nanocomposite applications. They polymerize on exposure to UV light in the presence of a cationic photoinitiator to produce insoluble, hybrid nanocomposites.
The homogeneous combination of inorganic and organic moieties in a single-phase material provides unique possibilities to tailor the mechanical, electrical, and optical properties with respect to numerous applications. The synthetic pathway follows the well-known sol−gel procedure. Nevertheless, the establishment of defined hybrid products necessitates a basic understanding of the underlying chemistry as well as of the parameters influencing the processing techniques. Modern spectroscopy provides versatile tools, e.g., multinuclear NMR experiments and Raman scattering to investigate the sol−gel processing of organo(alkoxy)silanes in their co-condensation reactions with main group or transition metal alkoxides as well as in their copolymerization reactions with each other or with organic molecules. This almost infinite modular design concept has led to the industrial application of coatings for transparent plastics, glasses, and metals to prevent these substrates from mechanical abrasion, permeation, or corrosion or to achieve decorative functions. Further passive optical properties can be realized by generating submicrometer surface patterns. By the integration of organic or inorganic dopants, like dyes or nanoparticles, highly sophisticated multifunctional hybrid polymers or nanocomposites are accessible and have become important to achieve active optical functions, e.g. switching, light harvesting, or storage media. Recently developed porous and dense bulk hybrid polymers have shown that the range of possible applications is not limited to surface refinement by coatings. This contribution reviews the present status as well as the perspectives of these types of advanced materials.
In its most common form, the non-hydrolytic sol−gel (NHSG) process involves the reaction of a “metal” halide with an oxygen donor, leading to the formation of an inorganic oxide. The use of NHSG chemistry for the synthesis of organic−inorganic hybrids is in its infancy compared to progress on hybrid synthesis using hydrolytic sol−gel chemistry. To date, most work has been carried out on the synthesis of organically modified inorganic oxides such as ormosils, with very limited effort on oxide−polymer hybrids and no reported activity on incorporation of small organic molecules into oxide networks. In this paper, reports of the use of the NHSG route to synthesize hybrids are reviewed. The key features of the reaction chemistry are noted, along with a discussion of the scope and limitations of NHSG chemistry in comparison with the hydrolytic route. Promising areas for future study are proposed, together with potential applications of these hybrids.
Metal alkoxides of the type (R'O)(n)E-X-A, where A represents a functional organic group, and X is a hydrolytically stable spacer linking A and the metal alkoxide moiety E(OR')(n), are interesting precursors for the preparation of novel materials composed of both inorganic and organic entities. The basic chemistry behind the preparation and the sol-gel processing of these compounds is reviewed. The manifold options for chemical modification of both the inorganic and the organic groups allow the deliberate preparation of materials with special properties, Selected materials syntheses are discussed to demonstrate the scope of possible applications.
The use of nanoparticles in hybrid and polymeric matrices has been investigated. Different types of nanocomposites have been prepared. The ormosil type based on organoalkoxy silanes shows surprising properties with respect to solid content and relaxation. Thick films for coatings, embossed films for diffractive purposes, high temperature stable binders for glass fiber insulation materials and printing pastes have been prepared. The nanomer type with nanoparticles homogeneously dispersed in polymer matrices led to optical adhesives with improved properties with respect to Tg and thermal coefficient of expansion. The inverse nanomer type with the nanoparticles forming a percolating network was developed for photo curable optical interference layers on plastic, for example to AR coating by using simple wet chemical coating techniques.
Intramolecularly crosslinked poly(organosiloxane) particles are prepared by means of emulsion polycondensation or emulsion polymerization of alkoxysilanes or cyclic organic siloxanes. Starting from these intramolecularly crosslinked poly(organosiloxane) particles, graft copolymers are obtained by free-radical emulsion polymerization of unsaturated olefinic monomers (e.g. acrylates, styrene) in the presence of (functionalized) organosiloxanes. Intramolecularly crosslinked poly(siloxane) particles and their graft copolymers are characterized by means of light scattering (in dispersion), electron microscopy and thermal analyses (DSC, DMTA).
New methacryloyloxyalkylaminoalkylalkoxysilanes have been synthesised by Michael addition of the corresponding acryloyloxyalkyl methacrylates with (3-aminopropyl)triethoxysilane (APTES). Low-viscosity polycondensates have been formed by hydrolysis and condensation of these silanes in the presence of ammonium fluoride (NH4F). The reaction of APTES with the addition product of succinic or glutaric anhydride with glycerol dimethacrylate results in the formation of new dimethacrylate-functionalised 3-amidopropyltriethoxysilanes. The hydrolytic condensation of these silanes was carried out in the presence of 0.5 M HCl. The hydrolysis and condensation of the silanes have been studied by 29Si NMR spectroscopy. Cross-linked inorganic-organic materials have been obtained by free-radical photopolymerisation of the polycondensates and their mixtures in the presence of camphorquinone and ethyl 4-(dimethylamino)benzoate with visible light (VL). The synthesised polycondensates enable the preparation of diluent-free composites. The mechanical properties of VL-cured polycondensates and composites have been investigated.
Organic–inorganic hybrid materials were prepared by a convenient two-step curing procedure based on sol–gel condensation and subsequent photopolymerization. Novel bismethacrylate-based hybrid monomers with pendant, condensable alkoxysilane groups were prepared by Michael addition and possessed number-average molecular weights between 580 and 1600 g/mol. The formation of inorganic networks by sol–gel condensation of the alkoxysilane groups in the presence of aqueous methacrylic acid was monitored with rheological measurements. The condensation conversion was monitored with solid-state 29Si cross-polarization/magic-angle spinning NMR spectroscopy. Subsequent photopolymerization led to organic–inorganic hybrid networks and low volume shrinkage, ranging from 4.2 to 8.3%, depending on the molecular weight of the hybrid monomer applied. Highly filled composite materials with glass filler fractions greater than 75% showed attractive mechanical properties with Young's moduli of 2700–6200 MPa. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4274–4282, 2001
By incorporating poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(styrene-co-methyl methacrylate) (poly(St-co-MMA)) structure units covalently into the SiO2 glass network via a sol-gel approach, three organic-inorganic hybrid materials (PMMA-SiO2, PS—SiO2, and poly(St-co-MMA)—SiO2) have been prepared. The three hybrid sol-gel materials were used as filler (up to 60 wt.-%) for dental composite resins. The effect of the three filler materials on several mechanical properties of the dental composite resins was investigated. The hardness of the filled dental composites increased with increasing filler content, whereas the bending strength decreased. The compressive strength of the composites was improved, compared with the unfilled resin, but decreased with inreasing filler content.Drie organisch-anorganische Hybridmaterialien wurden nach dem Sol-Gel-Verfahren durch kovalenten Einbau von Poly(styrol-co-methylmethacrylat)(Poly(St-co-MMA))-, Polymethylmethacrylat(PMMA)- und Polystyrol(PS)-Struktureinheiten in ein SiO2-Netzwerk hergestellt und als Füllstoffe (bis zu 60 Gew.-%) in Dentalharzen verwendet. Der Einfluß der Füllstoffe auf einige mechanische Eigenschaften der Harze wurde untersucht. Die Härte der gefüllten Dentalharze nahm mit steigendem Füllstoffgehalt zu, wogegen die Biegefestigkeit abnahm. Die Druckfestigkeit der gefüllten Harze war besser als die des ungefüllten Harzes, nahm jedoch mit steigendem Füllstoffgehalt ab.
The elaboration of solids from the molecular scale by a kinetically controlled methodology is one of the main challenges of molecular chemistry. In the long term, this should permit the design of solids with desired properties. Here, some examples are given which show a few methods that have been used for the preparation of solids from molecular precursors. The one-pot synthesis of rheologically controlled SiC is described. Access to a new kind of ceramic is obtained by the same methodology using molecular precursors. Mixed ceramics with interpenetrating networks are not accessible by the chemical thermodynamic route. The chemistry of hybrid materials obtained from molecular precursors through inorganic polymerization is presented. This class of materials offers wide perspectives because of 1) the large possibilities opened by the organic unit, 2) the kinetic control, which permits any kind of texture for the solid, and 3) the aptitude of these solids to become nanostructured.
SiO2-Al2O3 binary glass powders with Al2O3 contents up to 50 wt% have been synthesized by the sol-gel process. The starting solution (sol) consisted of 1 mole of tetraethoxysilane, 50 moles of water containing aluminum nitrate, 10 moles of ethyl alcohol and 0.02 moles of HCl catalyst. The sol was converted into gel by heating at 85C and suction by running water. The sintering process was analysed by DTG thermal analysis. The fired powders were examined by XRD. It was confirmed that the gels were converted into the glass structure without crystallization. The measurements of refractive index and powder size of fired powders revealed that these powders could be used as refractive-index-adjustable fillers for dental composite resins. The other potential usage of the SiO2-Al2O3 powders obtained might be in the production of powders for dental cements.
We present a simple and fast method for the synthesis of polyacrylates-silica hybrid materials with significantly low volume shrinkages through the sol-gel reactions of tetraethyl orthosilicate and 2-hydroxyethyl methacrylate along with the free-radical polymerization of the acrylate monomer. The volume shrinkage from the processible sol to the final product was about 6–20% for the hybrid materials having the silica contents up to about 50 wt-%. As a result of the low shrinkage, crack-free, transparent and monolithic hybrid materials of relatively large sizes can be prepared within a short period of 6 to 12 hours. The formation of covalent bonding between the organic and the silica components in the hybrid materials was demonstrated. Thermal stability of the polyacrylate component in the hybrid materials were found to be higher than that of the bulk polymer. Other vinyl polymers such as poly(methyl methacrylate) and polyacrylonitrile have also been incorporated into the inorganic silica sol-gel matrix by using this method.
Bioactive glasses and glass ceramics need to be capable of growing a calcium phosphate layer at their surfaces in physiological environment in order to bond with living bone. Sol-gel prepared silica (silica gel) and titania (titania gel) are efficient calcium phosphate absorbents. Both gels extract calcium and phosphate from surrounding physiological and other calcium phosphate solutions and form a calcium phosphate at their surfaces in return. Thus, they can integrate with bone. Under the same condition, however, silica and titania, as both prepared through a conventional high temperature process, are unable to transfer calcium and phosphate from the solutions to obtain a calcium phosphate at their surfaces. Therefore, it is concluded that using inorganic or metal organic precursors, sol-gel process can yield bioactive materials with a high bioactivity.
Currently there are several models discussed to describe the formation of monodispersed silica particles by the controlled hydrolysis and condensation of tetraethylorthosilicate (TEOS) in mixtures of water/ammonia and ethanol. The present study will show results on an extended range of experimental conditions. Particle growth followed a first-order reaction kinetic with respect to TEOS concentration. Reaction orders for the ammonia and water content were 0.97 and 1.18, respectively. Only monomeric (approximate to 70-90%) and dimeric (approximate to 10-25%) silicate units were detected during the growth reaction and an activation energy of 27 kJ mol(-1) (6.5 kcal mol(-1)) was indicated Particles revealed an ultramicroporous internal structure. A narrower size distribution and a more spherical shape were observed at higher water concentrations. The results suggested an aggregation mechanism of nanometer-sized primary nuclei during the first stage of the reaction followed by a monomer addition growth mechanism thereafter.
A common characteristic of glasses, glass-ceramics and ceramics that bond to living tissues is the development of a bioactive hydroxyapatite (HA) in vivo at body temperature. Materials with the highest levels of bioactivity develop a silica gel layer that enhances formation of the HA layer. These sol-gel processes are now used to produce bioactive coatings, powders and substrates that offer molecular control over the incorporation and biological behaviour of proteins and cells with broad applications as implants and sensors.
A silane coupling agent, CF3(CF2)9CH2CH2Si(NCO)3, prepared by hydrosilylation of trichlorosilane with CF3(CF2)9 CHCH2 in the presence of hydrogen hexachloroplatinate(IV), followed by reaction with silver cyanate, was used for glass and bovine tooth surface modification. In ESCA of the modified glass surfaces, nitrogen atoms in the silane coupling agent bound to the surfaces were detected only at contamination levels. This ESCA revealed that neither urethane bonds nor NCO groups were present on the modified glass surfaces. Clear AFM images of the modified glass surfaces were also obtained. Though the contact angles of water on the modified glass surfaces were independent of the modification time (20 min or 4 h), the AFM images obtained show that the original glass-surface patterns of unevenness remained on the surfaces in the case of the short modification time (20 min), whereas they disappeared from the surfaces in the case of the long modification time (4 h). In the latter case (4 h), the silane coupling agent reacted sufficiently over the entire glass surface, and no region of unmodified glass surface was detected. The surfaces of bovine tooth specimens were modified with this silane coupling agent by spreading of the agent on the surfaces with a small brush followed by brief drying with a hair drier. The amounts of plaque adhering to the modified and unmodified bovine tooth surfaces after wearing of the specimens in a human oral cavity for five days were compared. The amounts of plaque adhering to these specimens in in vitro tests as determined from SEM images were also compared. It is expected that this silane coupling agent will be useful as a plaque-controlling surface modifier for enhancement of oral health.