Evaluation of the ability of glass-ionomer cement to bond to glass-ionomer cement

This study investigated the cohesive bond strengths of glass-ionomer cement at three setting and etching intervals and compared these bonds to the shear strength of the material itself. Bonded cylinders were created and then sheared using the Instron Universal Testing Machine. Analysis of bond values of glass ionomer added to glass ionomer indicate bond variability and low cohesive bond strength of the material. Bond values of unbonded glass-ionomer material indicate that the material itself is stronger than bonds established between bonded samples.     

Effects of water aging on the mechanical and anti-biofilm properties of glass-ionomer cement containing dimethylaminododecyl methacrylate

Objectives

The aims of this study were to investigate the effects of water aging for up to 6 months on the mechanical and anti-biofilm properties of a novel antibacterial glass ionomer cement (GIC) containing dimethylaminododecyl methacrylate (DMADDM).

The clinical development of the glass-ionomer cement. III. The erosion lesion.

A clinical trial of the glass-ionomer cement, ASPA IV, as a restorative material for erosion lesions is reported. The failure rate, in a three-year trial, was nine per cent; most failures occurring within the first few months after placement.     

Dowel retention with glass-ionomer cement.

The retentive capacity of the Whaledent Parapost system utilizing ASPA cement was compared at two lengths, three diameters, and with respect to the effect of both medication and citric acid pretreatment. The greatest single factor influencing retention was embedment depth into dentin. No significant differences were observed between the retention values for medicated and unmedicated teeth. Finally, no increase in retention was noted over previously reported values for zinc phosphate, carboxylate, and epoxy resin cements. The glass-ionomer cement tested offers no advantage for post retention.     

Modification of glass-ionomer cement properties by quaternized chitosan-coated nanoparticles

Odontology - Glass ionomers (GICs), because of their qualities, are in a good position to be modified to resist masticatory stresses as permanent posterior restoration and prevent recurrent caries....     

The structure of a glass-ionomer cement and its relationship to the setting process.

The G-200 glass of the glass-ionomer cement has two phases: a continuous calcium aluminosilicate matrix and partly crystalline calcium fluoride-rich droplets, the nature of which depend on the thermal history of the glass. The setting process of the cement takes place when the glass is mixed with poly(acrylic acid). It has two overlapping stages corresponding to the rapid leaching of calcium ions from the uncrystalline part of the droplets, followed by the slower release of aluminum (and some calcium) from the main glass phase. These processes are affected by the microstructure and microcomposition of the glass.     

The clinical use of glass-ionomer cements.

The use of glass-ionomer cements in clinical dentistry has expanded greatly over the last decade. Their use in treating early carious or erosion lesions has been investigated widely and established techniques include fissure filling, restoration of erosion lesions without cavity preparation, and the internal or tunnel restoration. Because of their adhesion to moist tooth structure, biologic compatibility, and fluoride release, increasing use also has been made of their anticariogenic properties in treating geriatric patients. Glass-ionomers have proved very successful as dentin substitutes for attaching composites to enamel without involving risk of pulpal damage in the deeper cavity. The deficiencies of glass-ionomer cements are well known, including lack of toughness, early water sensitivity, low abrasion resistance, and porosity, leading to poor surface polish. Solving these problems is formidable because inherently the strength of these cements is related to their water content. The clinician should be aware of these deficiencies and stay within the parameters of the techniques outlined in this article. In particular, clinical success depends on early protection of the cement from hydration or dehydration and the current use of light-cured bonding agents largely has solved this problem. The future probably lies in using laminate techniques in which materials that attach to dentin and form a biologic seal can be covered by tougher and harder enamel veneers, thus mimicking the structure of the tooth. It is possible that future materials will be developed on the lines of these polyelectrolyte cements in which higher molecular weight polymers are used in conjunction with polymers that contain photoinitiators to effect light curing and toughen the matrix. In addition, the possibility of developing laboratory-cured glass-ionomer inlays in which porosity can be reduced and tougher polymers used should be considered.     

Properties of improved glass-ionomer cement formulations.

The properties of variants of the ASPA cement are described. Improved manipulative and hardening properties are obtained by the incorporation of chelating co-monomers to the polyelectrolyte liquid and by replacing polyacrylic acid by alternative polyalkenoic acids.     

A novel comonomer-free light-cured glass-ionomer cement for reduced cytotoxicity and enhanced mechanical strength.

OBJECTIVE: The objective of this study was to develop a novel comonomer-free light-cured glass-ionomer system based on the 4-arm star-shape poly(acrylic acid). The mechanical strengths and in vitro cytotoxicity of the formed system were evaluated and compared with those of several representative commercial glass-ionomer cements. MATERIALS AND METHODS: The 4-arm poly(acrylic acid) was synthesized using ATRP and tethered with glycidyl methacrylate (GM). The GM-tethered polymer was formulated with water, photo-initiators, and Fuji II LC filler. Fuji II, Fuji II LC and Vitremer were used for comparison. Compressive strength (CS) and MTT assay were used as tools to evaluate the mechanical strengths and in vitro cytotoxicity of the cements, respectively. RESULTS: The experimental cement exhibited significantly high compressive, diametral tensile and flexural strengths as compared to commercial glass-ionomer cements, Fuji II, Fuji II LC and Vitremer. The effects of polymer/water (P/W) ratio, GM-grafting ratio, glass powder/polymer liquid (P/L) ratio and aging in water on strengths were significant. Similar to conventional glass-ionomer cement Fuji II, the eluates from the experimental cement showed little in vitro cytotoxicity to Balb/c mouse fibroblast cells, as compared to Fuji II LC and Vitremer that contain HEMA as a comonomer. CONCLUSIONS: It appears that this novel comonomer-free light-cured glass-ionomer cement will be a promising dental restorative because it demonstrated significantly improved mechanical strengths and almost no in vitro cytotoxicity as compared to current commercial light-cured glass-ionomer cements.     

Adhesion of glass-ionomer cement in the clinical environment.

This paper discusses the literature concerning the development of an ion-enriched layer between the glass-ionomer cement and tooth structure. Two restorations that had been in the oral cavity for considerable periods of time were used to confirm the existence of this layer. It is suggested that development of the layer is dependent on careful adherence to the recommendations for clinical placement, and recognition of the need to clean the surface of the cavity and to maintain the water balance of the cement. Having developed the ion-exchange layer, failure will be cohesive in the cement itself. Thus the strength of the union is dependent on the tensile strength of the cement.     

Mechanical and fluoride release properties of titanium tetrafluoride-added glass-ionomer cement

The aim of this study was to determine the fluoride-release and mechanical properties of a water-hardening glass-ionomer cement (GIC) (ChemFil Superior) when titanium tetrafluoride (TiF4) was added. Three experimental groups were prepared with TiF4 added to the liquid component of the material in concentrations of 0.5, 1, and 2%. The control group was the original form of the cement and free of TiF4. After the specimens (4 mm in diameter x 6 mm in length) were prepared, their compressive strength, microhardness, modulus of elasticity, and fluoride release were measured. Data were analyzed using one-way analysis of variance (ANOVA) and post-hoc test (Bonferroni/Dunn correction). The addition of TiF4 into GIC significantly reduced fluoride release from the material with the exception of 1% TiF4 (p < 0.0083). Compressive strengths of 0.5 and 1% TiF4-added GICs were higher than that of the original GIC, but it was not statistically significant (p > 0.05). The differences among modulus of elasticity values of experimental and control groups were not significant (p > 0.05). Similarly, microhardness of GIC was not affected with TiF4 addition (p > 0.05).     

Evaluation of the mechanical properties of dental adhesives and glass-ionomer cements

Adhesives and lining/base materials should relieve the stresses concentrated at the tooth/restoration interface. The study aimed at comparing the mechanical properties of eight adhesives and six glass-ionomer cements (GICs). The adhesives were applied on dentin disks, whereas 2 mm × 3 mm × 2 mm GICs specimens were prepared in a teflon mold. Vicker’s hardness (VH), elastic modulus (E), creep (Cr) and elastic work (We/Wtot) were measured with a micro hardness indenter. One-way ANOVA and Tukey’s test were used to compare the mechanical properties within each materials’ type and among the materials’ classes. Enamel and dentin were used as references. Significant differences were detected within each materials’ type and among the materials’ classes and enamel and dentin. GICs were superior to adhesives in VH and E and showed a VH similar to dentin. GICs presented mechanical properties more similar to enamel and dentin than adhesives.