Calcium-fluoroaluminosilicate Glass Research Articles

Fabrication and characterization of remineralizing dental composites containing calcium type pre-reacted glass-ionomer (PRG-Ca) fillers

ObjectiveTo fabricate and characterize dental composites with calcium type pre-reacted glass-ionomer (PRG-Ca) fillers. MethodsPRG-Ca fillers were prepared by the reaction of calcium fluoroaluminosilicate glass with polyacrylic acid. Seven dental composites were produced from the same organic matrix (70/30wt% Bis-GMA/TEGDMA), with partial replacement of barium borosilicate (BaBSi) fillers (60wt%) by PRG-Ca fillers (wt%): E0 (0) – control, E1 (10), E2 (20), E3 (30), E4 (40), E5 (50) and E6 (60). Enamel remineralization was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), roughness (Ra), Knoop hardness (KHN), flexural strength (FS), flexural modulus (FM), water sorption (Wsp), water solubility (Wsl), and translucency (TP). Data were analyzed to one-way ANOVA and Tukey’s HSD test (α=0.05). ResultsAll composites with PRG-Ca induced enamel remineralization. E0 and E1 presented similar and highest DC% than E2=E3=E4=E5=E6. Ra and KHN were not influenced by PRG-Ca fillers (p<0.05). The higher the content of PRG-Ca, the lower FS, FM and TP (p<0.05). Wsp increased linearly with the content of PRG-Ca fillers (p<0.05). E6 presented the highest Wsl (p<0.05), while the Wsl of the other composites were not different from each other (p>0.05). SignificanceIncorporation of 10–40wt.% of PRG-Ca fillers endowed remineralizing potential to dental composites without jeopardizing the overall behavior of their physicochemical properties. Dental composites with PRG-Ca fillers seems to be a good alternative for reinforcing the enamel against caries development.

Evaluation of antibacterial and cytocompatible properties of multiple-ion releasing zinc-fluoride glass nanoparticles.

Zinc-fluoride glass nanoparticles (Zinc-F) release several ions, such as fluoride, zinc and calcium ions, through acid-base reactions. The aim of this study was to evaluate the antibacterial and cytotoxic properties of Zinc-F. Antibacterial tests showed that a Zinc-F eluting solution significantly reduced the turbidity and colony-forming units of Streptococcus mutans and Actinomyces naeslundii, compared to that of calcium-fluoroaluminosilicate glass nanoparticles without zinc ions. In live/dead staining, Zinc-F eluate significantly decreased green-stained bacterial cells, indicating live cells, compared with the control (no application). Human dentin coated with Zinc-F showed suppressed S. mutans and A. naeslundii biofilm formation. Additionally, Zinc-F eluate showed low cytotoxic effects in osteoblastic and fibroblastic cells. Therefore, our findings suggested that Zinc-F exhibits antibacterial and biocompatible properties through multiple-ion release.

Soda lime silicate glass and clam Shell act as precursor in synthesize calcium fluoroaluminosilicate glass to fabricate glass ionomer cement with different ageing time

Glass Ionomer Cement (GIC) is produced from an acid-base reaction between various type of alkaline glass powder and polymeric acid. In this research, calcium fluoro-alumino-silicate (CFAS) glass was derived from waste materials such as soda-lime-silica (SLS) glass and clam shell (CS) which are sources of silica and calcium oxide respectively. The polyacrylic acid (PAA) is used to produced mobile carboxyl group and then, react with metal ions on the surface of CFAS glass. To study the influence of ageing time on physical, structural and mechanical properties of GIC, deionized water was used as a soaking medium. The density results increase throughout the ageing time from 7–28 days. The density of GIC at 7 days shows 1.622 g/cm3 and increasing to 1.789 g/cm3 at 28 days. However, the molar volume shows the opposite action comparing with the density of GIC. The molar volume shows continue decreasing from 357.63–324.25 cm3 mol−1. From the XRD result, GIC was indicating amorphous structure during ageing range between 7–28 days. FTIR analysis shows this phenomenon occurs due to the deformation of Si−OH bonding and formation of Si-O-Si simultaneously in the presence of water which is influence the mechanical strength of GIC. The mechanical properties of GIC increase by ageing time through the compressive test from 42.23–50.28 MPa. Thus, the observed results in this study promise the GIC derived from waste materials have a high potential in dental application due to excellence structural and mechanical properties against ageing.

The effect of boron substitution for aluminium on the microstructure of calcium fluoro-aluminosilicate glasses and glass-ceramics

Calcium fluoro-aluminosilicate (4.5SiO2-3Al2O3-1.5P2O5-3CaO-2CaF2) glasses have significant applications in the medical and dental fields. However, due to the biological hazard of aluminium in the human body, this study focused on the influence of boron substitution for aluminium on the structure and properties of a series of substituted glasses and their correlated glass-ceramics. The results indicated that by increasing the amount of boron, the density of glasses and their glass-ceramics both decreased, whereas the number of bridging oxygens in the glasses increased. The glass transition temperature and the crystallization temperature remained almost unchanged for the glasses with a boron substitution of less than 25 mol%. Boron formed oxygen bridges in all glasses in the form of BO3 triangles and BO4 tetrahedra. Reducing the Al content in glasses, had an effect on the morphology and orientation of the fluorapatite crystal phase formed.

The microstructure and spectroscopic properties of calcium fluoro-aluminosilicate glasses and glass-ceramics by boron substitution

The calcium fluoro-aluminosilicate (4.5SiO2-3Al2O3-1.5P2O5-3CaO-2CaF2) glasses have significant applications in medical and dental fields. However, due to the biological hazard of aluminium element in human body, this study focus on the influence structure and properties of a series of resultant glasses and their correlated glass-ceramics after boron substitution for aluminum at different amounts. The results indicates that by increasing addition amount of boron, the density of the glasses and its glass-ceramics both decrease with the increase amount of bridging oxygens. And the glass transition temperature (Tg) and crystallization temperature (Tp) almost unchange for glasses but for the glass-ceramics, a decrease of both Tg and Tp are observed. Boron atoms only bridges with oxygen in glasses and its glass-ceramics as the form of BO3 and BO4 groups. By reduction of Al in glass, some non-Al containing needle-like calcium phosphate become the main crystalized phase.

Evaluation of Calcium Fluoroaluminosilicate Based Glass Ionomer Luting Cements Processed Both by Conventional and Microwave Assisted Methods

Calcium fluoroaluminosilicate glasses (CAS) are used in the formulation of glass ionomer cements for dental applications. However, the cements obtained from CAS glasses were found to be radiolucent. In this study, the influence of substituting Zn, Sr and Mg for Ca of CAS glasses was investigated with respect to the structure and setting characteristics, mechanical properties, and radiopacity of cements designed for luting applications. Three glass compositions based on substitution of Zn, Sr and Mg for Ca at 1:1 molar ratio was synthesized. They were coded as the G 021 (Ca: Zn), G 022 (Ca: Sr), G 023 (Ca: Mg). G 021 and G 022 glasses were processed by conventional melt quench route, whereas G 023 was processed by microwave melt–quench route. Each glass was then mixed with Fuji Type I GIC liquid in order to evaluate the properties of novel cements at different powder/liquid ratios. X-ray diffraction and Fourier Transform-Infrared spectroscopy analysis confirmed the structure of the processed glasses. The average particle size of the processed glass powders was within specification limits for luting applications (&lt;15 μm). The substitution of Zn, Sr and Mg for Ca at 1:1 molar ratio increased the reactivity of the respective glasses. This has been reflected in their respective setting characteristics and mechanical properties. The optimal combination of setting time, strength and radiopacity for the cements examined here was shown by G 022 cements. The microwave melting can be utilized for processing ionomer glasses as it did not alter the structure and properties of G 023 cement.

Studies on the Potential of Waste Soda Lime Silica Glass in Glass Ionomer Cement Production

Glass ionomer cements (GIC) are produced through acid base reaction between calcium-fluoroaluminosilicate glass powder and polyacrylic acid (PAA). Soda lime silica glasses (SLS), mainly composed of silica (SiO2), have been utilized in this study as the source of SiO2for synthesis of Ca-fluoroaluminosilicate glass. Therefore, the main objective of this study was to investigate the potential of SLS waste glass in producing GIC. Two glasses, GWX 1 (analytical grade SiO2) and GWX 2 (replacing SiO2with waste SLS), were synthesized and then characterized using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). Synthesized glasses were then used to produce GIC, in which the properties were characterized using Fourier transform infrared spectroscopy (FT-IR) and compressive test (from 1 to 28 days). XRD results showed that amorphous glass was produced by using SLS waste glass (GWX 2), which is similar to glass produced using analytical grade SiO2(GWX 1). Results from FT-IR showed that the setting reaction of GWX 2 cements is slower compared to cement GWX 1. Compressive strengths for GWX 1 cements reached up to 76 MPa at 28 days, whereas GWX 2 cements showed a slightly higher value, which is 80 MPa.

Characterization of the calcium-fluoroaluminosilicate glass prepared by a non-hydrolytic sol-gel route for future dental application as glass ionomer cement

Glass ionomer cements are widely employed in dentistry due to their physical, biological and mainly anti-caries properties. Glass ionomers consist of an aluminosilicate glass matrix modified with other elements, and they contain large quantities of fluorine. In this study, we report on the preparation of calcium-fluoroaluminosilicate glasses by a nonhydrolytic sol-gel route as an alternative approach to obtaining alumina-silica matrices. The glass powders were prepared via the non-hydrolytic sol-gel method, by mixing AlCl3, SiCl4, CaF2, AlF3, NaF, and AlPO4. The powders were studied by thermal analysis (TG/DTA/DSC), photoluminescence (PL), nuclear magnetic resonance (NMR27Al-29Si), and X ray diffraction (XRD). TG/DTA/DSC analyses revealed a constant mass loss due to structural changes during the heating process, which was confirmed by NMR and PL. A stable aluminosilicate matrix with potential future application as a glass ionomer base was obtained.

Preparation of calcium fluoroaluminosilicate glasses containing sodium and phosphorus by the nonhydrolytic sol–gel method

Aluminum and silicon oxide-based inorganic matrices have been extensively studied because of their countless applications. Dental cements consist of aluminum and silicon-based amorphous polymeric materials containing fluoride, sodium, phosphorus and calcium, which are also good candidates for bone replacement. The nonhydrolytic sol–gel method has emerged as an alternative route for the preparation of these materials under milder conditions than those employed in traditional methods, such as oxide fusion. The main advantages of the nonhydrolytic sol–gel method include the use of low temperatures and the ready availability and easy purification of the precursors. Together, these factors have contributed to the production of highly pure materials with controlled porosity and nanometric particles. Dental restorations based on aluminosilicate matrices are known as glass ionomer cements. These materials have interesting physical and dental properties, mainly because they display anticariogenic activity and exhibit prolonged adhesiveness to the dental structure. The base of the ionomer is an aluminosilicate that is industrially synthesized by the fusion of SiO 2, Al 2O 3, AlF 3, CaF 2, NaF and AlPO 4, in various concentrations. The characterizations conducted in this study reveal that this ionomer displays interesting properties, so its use as a precursor of dental cement and a biomaterial for bone replacement is highly recommended.

Dissolution behavior and fluoride release from new glass composition used in glass ionomer cements

The degradability in an acidic environment and the release of different ions, such as Na +, Ca 2+, Al 3+ and F − from a calcium fluoro-aluminosilicate glass (used in glass ionomer cements) during different exposure times at 37 °C has been the object of this study. The formation of a leached layer on the surface of the glass has proved to be an important factor in the ionic release from the glass. The structural change in the silicate network of the glass during the dissolution and formation of the leached layer on the surface of the glass has been analyzed by Fourier transform infrared (FTIR) spectrometer. The present study has investigated topographic profiles as a function of time through atomic force microscope (AFM). Also, the formation of the leached layer on the surface of the glass has been described with AFM by measuring the corrosion depth for different times of acidic treatment.

Characterization of the structure of calcium alumino-silicate and calcium fluoro-alumino-silicate glasses by magic angle spinning nuclear magnetic resonance (MAS-NMR)

Calcium aluminosilicate and calcium fluoro-aluminosilicate glasses have been characterized by 29Si, 27Al and 19F MAS-NMR. The two calcium aluminosilicate glasses examined were based on the composition 2SiO 2 · Al 2O 3 · 2CaO (ART1) and the mineral anorthite 2SiO 2 · Al 2O 3 · CaO (ART2). The observed chemical shifts for 29Si and 27Al agreed with previous studies. The fluorine containing glasses were based on 2SiO 2 · Al 2O 3 · (2− X)CaO · XCaF 2. The 29Si chemical shift moved in a negative direction with increase fluorine content indicating a progressive reduction in the average number of non-bridging oxygens, NBO, attached to a silicon. The 27Al spectra indicated the presence of four coordinate aluminium in the glasses with X=0.0–0.75, but aluminium was present in Al(IV), Al(V) and Al(VI) coordination states in the highest fluorine content glass with X=1.0. The 19F spectra indicated the presence of F–Ca( n) in low fluorine content glasses and both F–Ca( n) and Al–F–Ca( n) in high fluorine content glasses. We speculate here that the Al–F–Ca( n) species are oxyfluorides [AlO x F y ] n− , where x=1–6, y=1–6 and n is the charge on the total complex when aluminium is in Al(IV), Al(V) and Al(VI) coordinate states. The reduction in the average number of NBO per silicon with increasing fluorine content is explained by fluorine converting Ca 2+ to F–Ca( n).

Effect of polyacid aqueous solutions on photocuring of polymerizable components of resin-modified glass ionomer cements

Objectives. Resin-modified glass ionomer cements (RMGI) are hybrid materials prepared by incorporation of polymerizable components (typically 2-hydroxyethyl methacrylate (HEMA) with possible addition of multifunctional methacrylates) into a conventional acid–base mixture (a polymeric acid with powdered calcium fluoro-aluminosilicate glasses). During setting, the photopolymerization process and the acid–base reaction affect each other. The aim of this work was to examine the effect of a 45% aqueous solution of poly(acrylic acid) (PAA) and the liquid component of a commercial glass ionomer cement on HEMA and triethyleneglycol dimethacrylate (TEGDMA) photopolymerization. Methods. The polymerization was initiated by 2,2-dimethoxy-2-phenylacetophenone (DMPA) and camphorquinone (CQ)/coinitiator system. The reaction course was monitored under Ar and air by isothermal differential scanning calorimetry. Results. The main effect of addition of polyacid solution (PAA and commercial) up to 10 wt% to HEMA on the polymerization initiated with DMPA was earlier onset of autoacceleration. For the process initiated by the CQ-based system, the addition of 5 wt% of PAA solution strongly accelerated the polymerization and increased the conversion, both in Ar atmosphere as well as in air. TEGDMA photopolymerization was not influenced or slightly retarded by the presence of 3 wt% of PAA solution (the upper limit of solubility), depending on the initiating system used. Significance. Under initiation conditions used in curing of commercial dental products (CQ-based two component initiating system), the presence of polyacid-aqueous solution in HEMA-based photocurable component increases markedly the polymerization rate and the conversion both in Ar atmosphere as well as in air. This result contributes to a characterization of the setting process of RMGIs.

PREPARATION AND EVALUATION OF ACRYLIC ACID, ITACONIC ACID, AND N-METHACRYLOYLGLUTAMIC ACID COPOLYMERS FOR USE IN GLASS-IONOMER TYPE DENTAL RESTORATIVES

A series of copolymers containing various molar ratios of acrylic acid, itaconic acid and N-methacryloylglutamic acid were prepared in aqueous solution, using standard free-radical polymerization conditions. Specimens for mechanical property studies were prepared by mixing water solutions of the copolymers (50:50, wt:wt) with a commercial, calcium-fluoroaluminosilicate glass powder, with curing or hardening achieved by salt-bridge formation. The glass powder used in the formulation(s) was the same as that used in Fuji II (GC America) glass-ionomer. The working and setting times of the various formulations were evaluated. The compressive strength was used as the basic screening property to find the optimum molar ratio of the three monomers. The diametral tensile strength, flexural strength and Knoop surface hardness of the cured materials were also determined. All mechanical properties were measured after the specimens were conditioned in distilled water for 7 days at 37°C. Based on the compressive strength (CS), poly (AA-co-IA-co-MGA) with a monomers ratio of 8:1:1, respectively, showed the highest CS (269.9 MPa). The 8:1:1 copolymer with different molecular weights were also prepared to evaluate the effect of MW on the compressive strength. The optimum MW copolymer gave a glass-ionomer having the compressive strength improved by 30%, compared to Fuji II (293.9 MPa vs. 224.9 MPa). The same polymer solution was also mixed with glass powders used in other commercial glass-ionomers, i. e., Ketac-Molar (ESPE, Seefeld, Germany), α-Fil and α-Silver (DMG, Hamburg, Germany) to produce conventional glass-ionomers test specimens. The mechanical properties of these materials were also obtained and compared to the Fuji II, Ketac-Molar, α-Fil and α-Silver controls.