Polymeric composites for dentistry. II. Physical investigations on new dental composites (original) (raw)
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2012
A photo-polymerizable Bisphenol-A diglycidylether methacrylate resin was characterized by Fourier transform infrared spectroscopy after its irradiation under different conditions to identify the best curing. Bonding-agent free composites with particles of ball-milled glass, silica and titania at loading of 10 and 50% wt were prepared, and their viscoelastic properties investigated by dynamic mechanical analysis, in experimental conditions close to the working environment in the mouth.
Synthesis and Characterization of New Dental Composites Using Calcium Fluoroaluminosilicate Glass
2018
New dental composites prepared from Bis_GMA/TEGDMA with different ratios of Calcium fluoroaluminosilicate glass used as filler. The particle size of Calcium fluoroaluminosilicate glass was within (1-10) µm. visible light with 480nm wavelength and duration time of 40sec.was used in the polymerization process. Physical and mechanical properties of the dental material prepared were studied. These properties including, shrinkage; depth of cure, thermal expansion coefficient, Degree of conversion and diametral tensile strength (DTS). The static flexural strength and flexural modulus were measured using a three-point bending set up according to the ISO-4049 specification. The volumetric shrinkage values was found ranging between 2.6% to 2.9%, The degree of conversion was found between 79.57% to 68.27%, The depth of cure is 2.6 to 3.3mm, thermal expansion coefficient was also between 46.7 and 58.4×10-6 °C-1. While the mechanical properties such as the highest flexural strength was found ab...
Dental polymer composites were introduced commercially in the mid-1960s for the restoration of anterior teeth. Since their advent their characteristics such as physical properties, manipulative qualities, durability and wear resistance have improved remarkably. As a result they are widely used instead of amalgam. Composites make up for the weak points of amalgam, such toxicity from mercury content, corrosion and low adhesive property. In addition dental polymer composites have a better aesthetic property than amalgam. Today are possibly the most ubiquitous materials available in dentistry as they are used in a huge variety of clinical applications, ranging from filling materials, luting agents, indirect restorations and metal facings to endodontic posts and cores. Dental polymer composites mainly have three major components: an organic polymer matrix, inorganic filler and a coupling agent. The polymer forms the matrix of the composite material binding the individual filler particles together through the coupling agent. The polymer is a rigid solid which is prepared by the freeradical polymerization of a liquid monomer or mixture of monomers. It is this ability to convert from a plastic mass into a rigid solid that allows this material to be used for the restoration of dentition. The most common monomers in modern dental polymer composites are cross-linking dimethacrylates, e.g. 2,2-bis[4-(2-hydroxy-3methacryloxypropyl)phenyl]propane (Bis-GMA), 1,6-bis-[2-methacryloxyethoxycarbonylamino]-2,2,4-trimethylhexane (UDMA), decanediol dimethacrylate (D 3 MA) or triethyleneglycole dimethacrylate (TEGDMA). The radical polymerization of the matrix monomers results in a three dimensional network, in which the filler particles are dispersed. The selection of appropriate monomers for the formulation of a composite strongly influences the reactivity, viscosity and polymerization shrinkage of the composite paste, as well as the mechanical properties, water uptake and swelling of the cured composite. To ensure an adequate long shelf life for the composite it is essential that premature polymerization is prevented. To this end an inhibitor such as hydroquinone (0.1%) is included. Most dental polymer composites are light curing composites, which harden by irradiation with visible light 400-500nm.The properties of polymer composites are considerably influenced by the fillers employed. According to the nature and the particle size of the filler the dental composites have been classified into four main groups, traditional composites, microfilled composites, hybrid or blended composites and small particle hybrid composites.
Synthesis and characterizations of new dental composites using calciumfluoro aluminosilicate glass
Open Access Journal of Science
New dental composites prepared from Bis GMA/TEGDMA with different ratios of Calcium fluoroaluminosilicate glass used as filler. The particle size of Calcium fluoroaluminosilicate glass is (1¬10)µm. The visible light of 480 nm and duration time 40s was used in polymerization method. The physical and mechanical properties of the dental material were studied. These properties included, shrinkage; depth of cure, thermal expansion coefficient, Degree of conversion and diametral tensile strength (DTS). The static flexural strength and flexural modulus were also measured using a three-point bending set up according to the ISO-4049 specification. The volumetric shrinkage values was found between 2.6% to 2.9%,The degree of conversion was found to be 79.57% to 68.27%, the depth of cure is 2.6to3.3mm, and thermal expansion coefficient between 45.5 and 54.6×10-6 ºC. For the mechanical properties, the highest flexural strength 90.35 MPa, flexural modulus (11.29 GPa), and DTS (54.27 MPa). All tested composites complied with the requirement of ISO 4904: 2008 for all tested samples and coplied with ANSI/ADA specification No. 27 for cure resins.
Journal of Materials Science Research, 2013
Bis-GMA (Bisphenol A glycidyl methacrylate) based resin composites in dentistry require UV induced light polymerization to be used as restorative materials. This polymerization induces shrinkage stresses on command light polymerization, which can be clinically significant. To resolve this issue inhibitors such as Bisphenol-A-glycidyl dimethacrylate (BHT) have been introduced as an alternative method to try to decrease this polymerization shrinkage. However increases in inhibitor concentration whilst reducing polymerization shrinkage might induce an effect on the mechanical properties of the resin composite. In addition, the oral cavity is a fluid environment and can induce changes in the resin composite. The aim of this study was to try to determine if an increase in inhibitor concentration had an effect on the flexural strength and elastic modulus of resin composites after short and medium term aging immersion. These assessments were accomplished by looking at Flexural Strength and Elastic Modulus after short and medium term aging immersion. An experimental composite was prepared using a blend of Bisphenol A glycidyl dimethacrylate (Bis-GMA): Urethane Dimethacrylate (UDMA): Triethylene glycol dimethacrylate (TEGDMA) (1:1:1 weight ratio) with 70 wt% silanized glass fillers. Four group concentrations of BHT were tested mechanically using flexural strength and elastic modulus. Based on this laboratory study, changes in BHT concentrations can induce and maintain high strength in resin composites.
Journal of Prosthodontics, 2010
Purpose: Mechanical properties of dental composite resins need to be improved in order to enhance their performance for applications in direct restorations. Application of nanoparticles in this field is a recent development. The aim of this study was to investigate the mechanical properties of experimental composites containing various mass fractions of silica nanoparticles.Materials and Methods: Experimental composites were composed of a visible-light-curing monomer mixture (70 wt% Bis-GMA and 30 wt% TEGDMA) and silica nanoparticles of a size ranging from 20 nm to 50 nm modified with γ-methacryloxy propyl trimethoxy silane (γ-MPS) as reinforcing filler. The composites were classified into four groups according to their filler mass fractions ranging from 20% to 50%. Following the same preparation procedure, a conventional composite was also fabricated consisting of a mass percentage of 60% silica fillers having particle sizes ranging from 10 μm to 40 μm in the same organic matrix, which served as control. Ten specimens were prepared of each experimental group and also of the control. Fracture toughness was measured using single-edge notched bend (SENB) specimens. Specimen fracture surfaces were mounted on aluminum stubs with carbon cement, sputter-coated with gold and examined under scanning electron microscopy (SEM). Flexural strength was evaluated through a standard three-point bending test and Vickers microhardness test was performed to investigate the hardness of the samples.Results: Filler mass fraction had a significant effect on composite properties. Fracture toughness, flexural strength, and hardness of composites at filler mass fraction of 40% of silica nanoparticles were (mean ± SD) 1.43 ± 0.08 MPa.m1/2, 149.74 ± 8.14 MPa, and 62.12 ± 3.07 VHN, respectively; relevant values for composites at 50% mass fraction of silica nanoparticles were 1.38 ± 0.07 MPa.m1/2, 122.83 ± 6.13 MPa, and 70.69 ± 3.67 VHN, respectively, all of which were significantly higher than 1.07 ± 0.06 MPa.m1/2, 104.61 ± 8.73 MPa, and 52.14 ± 4.02 VHN of the control, respectively (Tukey's multiple comparison test; family confidence coefficient = 0.95). Measured values for composites at 20% mass fraction of silica nanoparticles were 0.94 ± 0.06 MPa.m1/2, 103.41 ± 7.62 MPa, and 42.87 ± 2.61 VHN, respectively; relevant values for composites at 30% mass fraction of silica nanoparticles were 1.16 ± 0.07 MPa.m1/2, 127.91 ± 7.05 MPa, and 51.78 ± 3.41 VHN, respectively.Conclusions: Reinforcement of dental composite resins with silica nanoparticles resulted in a significant increase in the evaluated mechanical properties in comparison with the conventional composite. The filler mass fraction played a critical role in determining the composite's mechanical properties.
Synthesis and characterization of dental composites
AIP Conference Proceedings, 2018
During the last few decades, the increasing demands in esthetic dentistry have led to the development of dental composites material that provide similar appearance to the natural teeth. Recently, esthetic trend was an issue which increase the demand for teeth restorations that is similar with the origin. The esthetics of dental composite are more superior compared to amalgam, since its color look similar with natural teeth. Various dental composites have been developed using many type of fillers such as amorphous silica, quartz), borosilicate, Li-Sr-Ba-Al glass and oxide: zirconia and alumina. Researchers in Faculty of Dentistry Universitas Padjadjaran, have prepared dental composites using zirconia-alumina-silica (ZAS) system as the filler. The aim is to improve the mechanical properties and the esthetic of the dental composites. The ZAS was obtained from chemical grade purity chemicals and Indonesia's natural sand as precursors its characterization were also presented. This novel method covers the procedure to synthesis and characterize dental composites in Universitas Padjadjaran and some review about dental composites in global research.