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1.
Fluoride release from model glass ionomer cements 总被引:1,自引:0,他引:1
Guida A Hill RG Towler MR Eramo S 《Journal of materials science. Materials in medicine》2002,13(7):645-649
Glass ionomer cements (GICs) are an important class of biomedical material used extensively for color matched mercury free, dental restorations. GICs can release clinically beneficial amounts of fluoride and have acceptable handling properties which make them suitable as dental restoratives. The fluoride release of model GICs produced from specially synthesized fluoro-alumino-silicate glasses was studied. Nine glasses of varying fluoride content based on 4.5SiO2–3Al2O3–1.5P2O5–(5–Z)CaO–ZCaF2 were synthesized and cement disks were prepared from them. The glass transition temperature reduced with increasing fluorine content of the glass. Fluoride ion release was measured into distilled water as a function of time for up to 140 days using a fluoride ion selective electrode. The quantity of fluoride released was found to be proportional to the fluorine content of the glass at all intervals time. The cumulative fluoride release was proportional to square root time. Substituting strontium for calcium in the glass had little influence on the fluoride release behavior of the cements. 相似文献
2.
Jin Ik Lim Kook-Jin Lim Ho-Nam Lim Yong-Keun Lee 《Journal of Materials Science》2010,45(19):5211-5217
Glass ionomer cement (GIC) has been successfully used in dental field for more than 40 years. Despite numerous advantages
of GIC, low bond strength and slow setting rate limited conventional GICs for use only at low stress-bearing areas. To improve
bond strength to tooth, two kinds of cyanoacrylates such as ethyl 2-cyanoacrylate (EC) and allyl 2-cyanoacrylate (AC) were
added in a commercial GIC. Changes in setting time of cyanoacrylate-modified GICs (CMGICs) according to the concentration
of cyanoacrylates and/or p-toluene sulfonic acid (TSA) was investigated using a rheometer. Shear bond strength to human dentin was measured. Biocompatibility
was determined by the viability of fibroblasts. Optimal concentrations for EC and TSA were 5–10% of the GIC powder and 30%
of the GIC liquid, respectively. EC-based CMGIC showed twofold increase of initial bond strength compared with conventional
GIC. Also, AC-based CMGIC showed three times higher bond strength and similar biocompatibility compared with the GIC. Therefore,
CMGIC materials can be widely applied in dental adhesive restoration field because they showed improved bond strength and
proper setting time. 相似文献
3.
4.
A. Wren O. M. Clarkin F. R. Laffir C. Ohtsuki I. Y. Kim M. R. Towler 《Journal of materials science. Materials in medicine》2009,20(10):1991-1999
Glass ionomer cements (GICs) have potential orthopaedic applications. Solgel processing is reported as having advantages over
the traditional melt-quench route for synthesizing the glass phase of GICs, including far lower processing temperatures and
higher levels of glass purity and homogeneity. This work investigates a novel glass formulation, BT 101 (0.48 SiO2–0.36 ZnO–0.12 CaO–0.04 SrO) produced by both the melt-quench and the solgel route. The glass phase was characterised by X-ray
diffraction (XRD) to determine whether the material was amorphous and differential thermal analysis (DTA) to measure the glass
transition temperature (T
g). Particle size analysis (PSA) was used to determine the mean particle size and X-ray photoelectron spectroscopy (XPS) was
used to investigate the structure and composition of the glass. Both glasses, the melt-quench BT 101 and the solgel BT 101,
were mixed with 50 wt% polyacrylic acid (M
w, 80,800) and water to form a GIC and the working time (T
w) and the setting time (T
s) of the resultant cements were then determined. The cement based on the solgel glass had a longer T
w (78 s) as compared to the cement based on the melt derived glass (19 s). T
s was also much longer for the cement based on the solgel (1,644 s) glass than for the cement based on the melt-derived glass
(25 s). The cements based on the melt derived glass produced higher strengths in both compression (σc) and biaxial flexure (σf), where the highest strength was found to be 63 MPa in compression, at both 1 and 7 days. The differences in setting and
mechanical properties can be associated to structural differences within the glass as determined by XPS which revealed the
absence of Ca in the solgel system and a much greater concentration of bridging oxygens (BO) as compared to the melt-derived
system. 相似文献
5.
Shahid S Billington RW Hill RG 《Journal of materials science. Materials in medicine》2011,22(2):247-251
Ultrasound has been shown to improve the set of glass ionomer cements (GICs) and also other cement properties. In particular,
the release of fluoride is enhanced. These cements also can take up fluoride ion from liquids. The aim of this study is to
investigate the effect of ultrasound on this cement property. Two commercial dental restorative GICs were used together with
a modified commercial material and an experimental material based on a F-free glass. All three commercial materials came in
capsules which were mixed as makers directed, the experimental material was mixed as in previous papers. Mixed cement was
placed polyethylene moulds to create 3 × 2 mm thick discs. These were either allowed to standard set for 6 min or set with
ultrasound for 55 s. 18 samples were made for each material/set. Three samples were placed in 4 ml of 0.2% NaF solution for
24 h at 37°C. The cylinders were removed and the F concentration of the solutions measured by ISE using TISAB decomplexant.
F uptake was determined by difference from the original NaF concentration. The two conventional GICs showed reductions of
17.4 and 8.5% for ultrasound compared to standard set whereas the modified material increased by 32.3% and the experimental
one by 20.6%. It is suggested that the effect of ultrasound may increase the surface area of the residual glass particles
in the GIC which would increase F uptake. In GICs where considerable F ion is released into the cement matrix by the enhanced
reaction caused by ultrasound this may be sufficient to reverse the former effect producing the reduced uptake observed. 相似文献
6.
Crowley CM Doyle J Towler MR Rushe N Hampshire S 《Journal of materials science. Materials in medicine》2007,18(8):1497-1506
Acid washing is known to influence the handling properties of ionomer glasses used in glass ionomer cements due to the production
of an ion depleted-zone on the surface of the glass particles. The influence of acid washing on the particle size distribution
and surface area of four glasses was examined by scanning electron microscopy (SEM), particle size analysis (PSA) and accelerated
surface area porosimetry (ASAP) and the working and setting times of cements, produced from the glasses, correlated to changes
in surface morphology. A linear relationship was found between the specific surface area of acid-washed SiO2–Al2O3–XF2–P2O5 glasses (X being either calcium or strontium) and their cement working and setting times. These changes directly correlated
with increases in the mesopore volume. However, the influence of acid washing on the surface morphology was also found to
be glass composition-dependant with the addition of sodium into the glass network resulting in no significant change in the
surface area or mesopore volume despite changes in the working and setting time. Through examination of the influence of acid
washing and glass composition on the specific surface area improvements in the control of the working and setting times of
glass ionomer cements may be achieved. 相似文献
7.
da Silva RC Zuanon AC Spolidorio DM Campos JA 《Journal of materials science. Materials in medicine》2007,18(9):1859-1862
The in vitro antibacterial activity of four glass ionomer cements (Fuji IX, Ketac Molar, Vidrion R and Vitromolar) indicated
for Atraumatic Restorative Treatment (ART) was studied against strains of bacteria involved in the development of oral diseases,
Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The agar plate diffusion test was used for the cultures, which included chlorhexidine as a positive control. The results
demonstrated that all the cements evaluated presented antibacterial activity. Based on the results of this study, it can be
concluded that Fuji IX and Ketac Molar presented the most effective antibacterial activity considering the ART approach. 相似文献
8.
Wilde MG Delfino CS Sassi JF Garcia PP Palma-Dibb RG 《Journal of materials science. Materials in medicine》2006,17(9):869-873
This study aimed to evaluate the influence of fluoride-containing mouthrinse solutions (Fluorgard and Oral B) on the superficial microhardness of two resin-modified glass ionomer cements (Vitremer and Fuji II LC). Fifteen discs-shaped specimens of each glass ionomer cement (Ø10 mm; 2 mm thick) were prepared, thereby forming two groups. After 24-hour storage in artificial saliva, the microhardness was measure and the data were recorded. Next, each group was divided into three subgroups (n = 5), according to the solution to be immersed in. Control specimens were kept in artificial saliva along the whole experiment. The test specimens were kept in mouthrinse solution for 30 days. Vickers surface microhardness was analyzed at predetermined evaluation periods: 24 h, 48 h, 7, 14, 21 and 30 days after specimens’ preparation. Data were subjected to three-way ANOVA and to Tukey test (p<0.05). A better behavior of Fuji II LC was observed and Fluorgard affected most the characteristics of the tested materials. It may be concluded that fluoride-containing solutions influenced the tested characteristics of materials, mainly of Vitremer. 相似文献
9.
Yap AU 《Journal of materials science. Materials in medicine》1997,8(7):413-416
This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37°C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. 相似文献
10.
11.
The processing,mechanical properties and bioactivity of zinc based glass ionomer cements 总被引:2,自引:0,他引:2
The suitability of Glass Ionomer Cements (GICs) for use in orthopaedics is retarded by the presence in the glass phase of aluminium, a neurotoxin. Unfortunately, the aluminium ion plays an integral role in the setting process of a GIC and its absence is likely to hinder cement formation. However, zinc oxide, a bacteriocide, can act both as a network modifying oxide and an intermediate oxide in a similar fashion to alumina and so ternary systems based on zinc silicates often have extensive regions of glass formation. The purpose of this research was to produce novel GICs based on calcium zinc silicate glasses and to evaluate their rheological, mechanical and biocompatible properties with the ultimate objective of developing a new range of cements for skeletal applications. The work reported shows that GICs based on two different glasses, A and B (0.05CaO ⋅ 0.53ZnO ⋅ 0.42SiO2 and 0.14CaO ⋅ 0.29ZnO ⋅ 0.57SiO2, respectively), exhibited handling properties and flexural strengths comparable to conventional GICs. Upon immersion in simulated body fluid of a GIC based on glass B, an amorphous calcium phosphate layer nucleated on the surface of the cement indicating that these cements are bioactive in nature. 相似文献
12.
Tian KV Nagy PM Chass GA Fejerdy P Nicholson JW Csizmadia IG Dobó-Nagy C 《Journal of materials science. Materials in medicine》2012,23(3):677-685
Discs of biocompatible glass ionomer cements were prepared for Hertzian indentation and subsequent fracture analyses. Specifically,
2 × 10 mm samples for reproducing bottom-initiated radial fracture, complemented by 0.2 × 1 mm samples for optimal resolution
with X-ray micro tomography (μCT), maintaining dimensional ratio. The latter allowed for accurate determination of volumetric-porosity
of the fully cured material, fracture-branching through three Cartesian axes and incomplete bottom-initiated cracking. Nanocomputed
tomography analyses supported the reliability of the μCT results. Complementary 2-dimensional fractographic investigation
was carried out by optical and scanning electron microscopies on the larger samples, identifying fracture characteristics.
The combined 3-D qualitative assessment of microstructure and fractures, complemented by 2-D methods, provided an increased
understanding of the mechanism of mechanical failure in these cements. Specifically, cracks grew to link pores while propagating
along glass-matrix interfaces. The methodological development herein is exploitable on related biomaterials and represents
a new tool for the rational characterisation, optimisation and design of novel materials for clinical service. 相似文献
13.
Ribeiro DA Marques ME Salvadori DM 《Journal of materials science. Materials in medicine》2006,17(6):495-500
Glass ionomer cements are widely used in dentistry as restorative materials and adhesives for composite restorations. However,
the results of genotoxicity studies using these materials are inconclusive in literature. The goal of this study was to examine
the genotoxic and cytotoxic potential of three different glass ionomer cements available commercially (Ketac Cem, Ketac Molar
and Vitrebond) by the single cell gel (comet) assay and trypan blue exclusion test, respectively. For this, such materials
were exposed to Chinese hamster ovary (CHO) cells in vitro for 1 h at 37∘C. Data were assessed by Kruskall-Wallis nonparametric test. The results showed that the powder from Ketac Molar displayed
genotoxicity only in the maximum concentration evaluated (100 μg/mL). In the same way, the liquid from Vitrebond at 0.1% dilution
caused an increase of DNA injury. Significant differences (P < 0.05) in cytotoxicity provoked by all powders tested of glass ionomer cements were observed for exposure at 1000 μg/mL
concentration. With respect to liquids of glass ionomer cements evaluated, the major toxic effect on cell viability was produced
at 10%, beginning at the dilution of 0.5% for Vitrebond. Taken together, we conclude that some components of glass ionomer
cements show both genotoxic and cytotoxic effects. 相似文献
14.
Pires RA Nunes TG Abrahams I Hawkes GE 《Journal of materials science. Materials in medicine》2008,19(4):1687-1692
A model of the setting chemistry of glass-ionomer cements (GICs) is proposed based on 27Al and 29Si solid state nuclear magnetic resonance spectroscopy data on three GICs. All the precursor glasses are found to contain
three aluminium species viz.: four, five and six-coordinate aluminium environments as well as four-bridging silicate tetrahedra.
Upon cement formation, Al3+ ions in the glass are leached out from the surface layer of the glass. On entering the cement matrix, these ions adopt six-coordination
and crosslink the polymer chains as part of the setting reaction. The remaining four-coordinate aluminium is distributed between
two species: one in the inert core of the glass particles; and a second, less concentrated, in the surface layer of the glass
particles, modified by the curing reactions. There is some evidence for residual five and six coordinate aluminium species
in the final cement in some of the systems. In the case of the silicate tetrahedra, the curing reactions result in a decrease
in the number of aluminium atoms in the second coordination sphere, with a subsequent recondensation of silicate network of
the glass. 相似文献
15.
Talal A Tanner KE Billington R Pearson GJ 《Journal of materials science. Materials in medicine》2009,20(1):405-411
OBJECTIVE: To investigate the effect of ultrasound (US) application, US staring time and US duration on the setting of glass ionomer cement (GIC) by using Attenuated Total Reflectance Fourier Transform Infrared (ATR/FTIR) spectrometer. METHODS: Two conventional GICs, Fuji IX Fast and Ketac Molar were studied. US application was started at 30 s or 40 s after mixing and was applied for times between 15 and 55 s on samples of two different thicknesses. The samples were analysed using ATR/FTIR. RESULTS: US accelerated the curing process in both cements, US needed to be applied for more than 15 s. Both Fuji IX and Ketac Molar showed increased setting on increasing the US application duration from 15 s to 55 s. Increased setting of the GICs was produced when US application started 40 s after mixing rather than 30 s after mixing. CONCLUSIONS: The significant findings of the study include that US application accelerated the setting processes, by accelerating the formation of the acid salts. The salt formation increased with increase time of US application. The effect of application of US to setting GICs is influenced by time of the start of application of the US. The effects appear to material specific, with Ketac Molar showing a greater effect than Fuji IX. 相似文献
16.
Wren AW Coughlan A Placek L Towler MR 《Journal of materials science. Materials in medicine》2012,23(8):1823-1833
A gallium (Ga) glass series (0.48SiO(2)-0.40ZnO-0.12CaO, with 0.08 mol% substitution for ZnO) was developed to formulate a Ga-containing Glass Polyalkenoate Cement (GPC) series. Network connectivity (NC) and X-ray Photoelectron Spectroscopy (XPS) was employed to investigate the role of Ga(3+) in the glass, where it is assumed to act as a network modifier. Ga-GPC series was formulated with E9 and E11 polyacrylic acid (PAA) at 50, 55 and 60 wt% additions. E11 working times (T(w)) ranged from 68 to 96 s (Lcon.) and 106 s for the Ga-GPCs (LGa-1 and LGa-2). Setting times (T(s)) ranged from 104 to 226 s (Lcon.) and 211 s for LGa-1 and LGa-2. Compression (σc) and biaxial flexural (σf) testing were conducted where Lcon. increased from 62 to 68 MPa, LGa-1 from 14 to 42 MPa and LGa-2 from 20 to 47 MPa in σc over 1-30 days. σf testing revealed that Lcon. increased from 29 to 42 MPa, LGa-1 from 7 to 32 MPa and LGa-2 from 12 to 36 MPa over 1-30 days. 相似文献
17.
18.
N. K. Thanjal R. W. Billington S. Shahid J. Luo R. G. Hill G. J. Pearson 《Journal of materials science. Materials in medicine》2010,21(2):589-595
To compare the effect of ultrasonic setting with self curing on fluoride release from conventional and experimental dental
glass ionomer cements. To compare hand mixed and capsule mixing and the effect of replacing some of the reactive glass with
zirconia. In a novel material which advocated using radiant heat to cure it, to compare the effect of this with ultrasound.
To evaluate the effect of ultrasound on a glass ionomer with fluoride in the water but not in the glass. 10 samples of each
cement were ultrasonically set for 55 s; 10 controls self cured for 6 min. Each was placed in 10 ml of deionised water which
was changed at 1, 3, 7, 14, 21, 28 days. The solution fluoride content was measured using a selective ion electrode. All ultrasound
samples released more fluoride than the controls. Release patterns were similar; after a few days, cumulative fluoride was
linear with respect to t1/2. Slope and intercept of linear regression plots increased with ultrasound. With radiant heat the cement released less fluoride
than controls. The effect of ultrasound on cement with F in water increased only slope not intercept. Zirconia addition enhances
fluoride release although the cement fluorine content is reduced. Comparison of capsule and hand mixing showed no consistent
effect on fluoride release. Ultrasound enhances fluoride release from GICs. As heat has an opposite effect the heat from ultrasound
is not its only action. The lesser effect on cement with fluoride only in the water indicates that of ultrasound enhances
fluoride release from glass. 相似文献
19.
Song Chen Satwik Gururaj Wei Xia Håkan Engqvist 《Journal of materials science. Materials in medicine》2016,27(11):172
Developing dental restorations with enhanced antibacterial properties has been a constant quest for materials scientists. The aim of this study was to synthesize silver doped calcium phosphate particles and use them to improve antibacterial properties of conventional glass ionomer cement. The Ag doped monetite (Ag-DCPA) and hydroxyapatite (Ag-HA) were synthesized by precipitation method and characterized using X-ray diffraction, scanning electron microscope and X-ray fluorescence spectroscopy. The antibacterial properties of the cements aged for 1 day and 7 days were evaluated by direct contact measurement using staphylococcus epidermis Xen 43. Ion concentrations (F? and Ag+) and pH were measured to correlate to the results of the antibacterial study. The compressive strength of the cements was evaluated with a crosshead speed of 1?mm/min. The glass ionomer cements containing silver doped hydroxyapatite or monetite showed improved antibacterial properties. Addition of silver doped hydroxyapatite or monetite did not change the pH and ion release of F?. Concentration of Ag+ was under the detection limit (0.001?mg/L) for all samples. Silver doped hydroxyapatite or monetite had no effect on the compressive strength of glass ionomer cement. 相似文献