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At least 19 recordsLinked to original sources

PubMed1990

Effect of water isolation and early finishing on hardness of glass ionomer cements.

Glass ionomer cements have the disadvantage of being vulnerable to moisture. We would like to overcome this problem by clinical procedures. Three glass ionomer cements were tested in vitro with the goal of protecting these materials from moisture during clinical operations. To observe the effectiveness of various surface protective measures, we divided each cement sample into six groups, each of which underwent 24-hour surface treatment. The first group was a control where the cement was covered with a glass slab for 24 hours. The remaining five groups were subjected to no treatment or treatment with varnish, cocoa butter, Teethmate-A, or Ketac-Glaze. Two additional groups were prepared for comparison of early finishing with and without water spray. When the Vickers hardness number (HVN) for each sample was measured at 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, and 40 days, it tended to increase after 24 hours, reaching a maximum value at different times with different cements. Analysis of variance revealed that during the first few days the hardness of the control was significantly different from that without treatment or with treatment by varnish or cocoa butter. However, treatment with Teethmate-A or Ketac-Glaze produced results close to those for the control. Significant differences in hardness during the first few days were noted when early finishing was carried out under wet and dry conditions. These findings indicate that a light-cured unfilled resin should be applied to the surface of glass ionomer cement immediately after the initial set to allow complete setting without interference by oral fluids. Also, water spray should be avoided during contouring of the cements if they have not fully hardened.

Glass Ionomer Cements↗

PubMed2005

[Development of study on modified glass ionomer cement].

Glass ionomer Cement (GIC) is a kind of new dental restorative material. At present, GIC is finding wider use in dental clinical practice such as restoration, adhesion, cavity liner, cure of dental sensitivity and temporary restoration of cavity, because it has several excellent advantages of strong adhesive strength, low stimulation, inhibition of carious teeth. In this paper, the history of glass ionomer cement is introduced and the researching development and perspective of modified glass ionomer cement is elaborated.

Dental Bonding↗

PubMed1990

Composition and characteristics of glass ionomer cements.

Glass ionomer cement materials are currently available for restoration, cavity lining and basing, luting, and preventive applications. The in vitro performance is a function of composition, manipulation, and placement. In general, the cements may be characterized as strong, stiff, hard materials that are adhesive to calcified tissue, have low toxicity, and are potentially anticariogenic through fluoride leaching.

Chemical Phenomena↗

PubMedDate not supplied

Modification of glass ionomer cements.

Glass Ionomer cement (the term was coined by B.E. Kent) has been described as a hybrid of silicate cements and zinc polycarboxylates. Scientific efforts were devoted to improving properties to make it a fully practical material for anterior and posterior restorations and secondarily properties were modified to extend its range of application. First half of 90's witnessed modifications that replace part or most of the original formulation with alternative filler particles or matrix setting reactions to make these materials more composite like. This article focuses on the various modifications of the basic Glass ionomer cement.

Acrylic Resins↗

PubMedDate not supplied

Glass ionomer cements.

Glass ionomer cements have been used in pediatric restorative dentistry for 20 years. Their usefulness in pediatric restorative dentistry is preferential relative to other materials because of their fluoride release, chemical adhesion to tooth structure, and availability to use in a variety of clinical scenarios. This paper reviews the use of glass ionomer materials in pediatric restorative dentistry. The paper provides a look at glass ionomer cements' use as sealants and restorative materials and examines glass ionomers as adhesives, as a stand-alone material and in the sandwich technique. This paper also provides a useful guide to connecting to other references regarding specific aspects of glass ionomers in children.

Cementation↗

PubMed1998

In vitro Characteristics of a Glass Ionomer Cement.

Glass ionomer cements were first described by Wilson and Kent and have been used in dentistry since 1969. It has been recommended for bridging ossicular chain defects, fixation of ossicular chain prosthesis, anchoring of cochlear implants, mastoid obliteration, and repair of tegmen and posterior canal wall defects. The biocompatability and stability of this material over time is vital to its usefulness in neurotologic surgery. The purpose of this study was to assess the stability of a glass ionomer cement in the presence of bacteria and in different pH environments. We demonstrated that bacteria readily adhere to the surface and their presence is associated with accelerated loss of matrix. We found the cement to be susceptible to low pH and to release a visible cloud of debris upon contact with fluid. Calcium concentration in the solution was elevated at all pH levels. Although we are able to demonstrate these findings in vitro the clinical relevance is unclear. There have been several cases of aseptic meningitis possibly due to intracranial release of components of the cement. Until further studies are done use of the cement in contact with cerebral spinal fluid should be avoided. This cement, or a similar material, would be useful in neurotologic surgery but prior to widespread use further testing should be done to assess safety.

Journal Article↗

PubMed2004

Chlorhexidine release from an experimental glass ionomer cement.

Glass ionomer cements (GIC) can potentially be used as matrices for the slow release of active species, as has been shown previously for fluoride ions. This study investigated the use of an experimental GIC as a carrier for the release of chlorhexidine acetate (CHA) at included concentrations ranging from 0.5% to 13.0% of CHA by weight. Release into water was examined using high-performance liquid chromatography. All measurable chlorhexidine was released within 22 h1/2, however this was less than 10% of the total mass incorporated in the specimens. An increased percentage of CHA incorporated into the powder gave an increased release into the surrounding water. The bulk of the CHA was retained within the cement. For comparison, the surface chemistry of a CHA-containing GIC was examined using X-ray photoelectron spectroscopy before and after prolonged immersion in water. This confirmed retention of a large amount of CHA. Spectra after leaching appeared very similar to those from a CHA-free GIC after immersion in a CHA solution. In order to explore the effect of CHA-inclusion on the cement properties, compressive strengths, working and setting times were also measured. In general, compressive strengths were found to be decreased in direct proportion to the quantity of CHA added, while working and setting times increased.

Anti-Infective Agents, Local↗

PubMed1993

Biocompatibility of glass ionomer cements.

Glass ionomer cements (GICs) are widely used in the dental field and are increasingly being considered as materials with potentially good osteogenic properties. This paper details a comprehensive biocompatibility evaluation of a number of GICs. These include conventional, commercially available materials, novel formulations and a new light cured material. The experimental programme entailed in vitro cell culture studies using direct contact and extraction tests and an in vitro rat model in which the GICs were in intimate contact with bone for periods up to 8 wk. The results demonstrate clear differences between the materials and in particular highlight the poor cellular response to the light cured material. Methylthiazolyldiphenyl tetrazolium assay demonstrates stimulation of cell growth by some GIC formulations and indicates that cytotoxic leachable agents can be removed from others. The results obtained following implantation into bone are comprehensively presented using photomicrographs. New bone formation with time is demonstrated with a number of formulations.

Animals↗

PubMed2002

Fluoride release from model glass ionomer cements.

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 4.5SiO(2)-3Al(2)O(3)-1.5P(2)O(5)-(5-Z)CaO-ZCaF(2) 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.

Journal Article↗

PubMed1997

Microleakage of glass ionomer cement composite resin and glass ionomer resin cement.

An in vitro dye leakage study was performed to compare the sealing ability of glass ionomer, composite resin and glass ionomer/resin cement when used as restorative materials for G.V. Black class V cavities. In this research, standard Class V cavities were prepared in sound premolar teeth extracted for orthodontic reasons. The cavities were randomly divided into 3 groups. After filling the cavities with glass ionomer cement, composite resin and light curing glass ionomer/resin cement, the specimens were immersed in silver nitrate solution. Marginal microleakage at the interface between the cavity wall and restoration was evaluated. The results were analyzed by using Kruskal-Wallis and Mann Whitney U tests. Result of this in vitro study indicate that composite resin and glass ionomer/resin cement provide a better seal than glass ionomer cement.

Aluminum Silicates↗

PubMed1992

Sealing effectiveness of light-cured glass ionomer cement liners.

Glass ionomer materials have been used as liners or bases beneath restorations, but light-cured varieties have recently been introduced. Microleakage at the restoration/tooth interface in cervical cavities was used to test the adhesion to dentin of two new light-cured glass ionomer cement lining materials, XR-Ionomer and Fuji Lining LC. Wedge-shaped cervical cavities were prepared on extracted teeth with a gingival cavosurface margin involving dentin, and the specimens were assigned randomly to three groups. The experimental groups were restored with two light-cured glass ionomer cements, the controls were restored with a chemically cured glass ionomer cement; and marginal leakage was assessed by dye penetration. The two light-cured glass ionomer cements displayed some adhesion to dentin in class V test cavities, but there was no significant difference between the two materials.

Dental Bonding↗

PubMed1995

In vitro enamel remineralization at orthodontic band margins cemented with glass ionomer cement.

Demineralization adjacent to orthodontic bands remains a clinical concern. The release of fluoride from glass ionomer cement has been shown to inhibit demineralization. The purpose of this study was to examine the remineralization effects of a glass ionomer cement adjacent to orthodontic bands. Forty extracted molars were painted with an acid-protective varnish, excluding a 2 x 6 mm window on the buccal surfaces. Artificial caries-like lesions were created in the exposed enamel with an acidified gel. Half the lesion on each tooth was then painted with an acid-protective varnish. An orthodontic band was cemented with a glass ionomer cement or zinc phosphate cement, the gingival margin of the band located at the level of the artificial carious lesion. The teeth were placed in separate closed environments of a nonfluoridated artificial saliva for 3 months. The teeth were then sectioned and photographed with polarized light microscopy in imbibition medias of water and Thoulet's (R.I.: 1.41, 1.47), representing a minimum of 5%, 10%, and 25% pore volume, respectively. With a sonic digitizer, the area of the body of the lesion was measured in each imbibition media, comparing the maintained varnished out lesions to the lesions exposed to the cement. Results demonstrated a statistically significant reduction in the body of the lesions (p < 0.005) for those exposed to the glass ionomer cement.

Dental Caries↗

PubMed2003

Two-body and three-body wear of glass ionomer cements.

OBJECTIVES: Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two-body and three-body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi-Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material. METHODS: Two-body wear tests were carried out in the computer controlled 'artificial mouth' of the Munich Dental School, three-body wear was tested with the ACTA wear machine. RESULTS: The resulting average two-body wear rates (in microm) were: Fuji IX 327 (SD +/- 82) < Ketac Molar 379 (SD +/- 94) < Hi-Fi 376 (SD +/- 90) < Ketac silver 449 (SD +/- 127). The differences between the materials were significant (P < 0.05, ANOVA, modified LSD-test) with the exception of Ketac Molar and Hi-Fi. The average three-body wear rates (in microm) were: Hi-Fi 30 (SD +/- 10) < Ketac Molar +/- 42 (SD +/- 12) < Fuji IX 49 (SD +/- 14) < Ketac silver 73 (SD +/- 23). The difference between Ketac silver and the three other materials was significant (P < 0.05, ANOVA, modified LSD-test). No significant difference was calculated between Hi-Fi, Ketac Molar and Fuji IX. CONCLUSIONS: As Ketac Molar, Hi-Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal-contact and contact-free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder: liquid ratio than by incorporating silver particles into the glass powder.

Analysis of Variance↗

PubMed1996

Response of oral mucosal cells to glass ionomer cements.

Although glass ionomer cements are generally considered to be tissue-compatible, it has been suggested that unreacted components or setting reaction by-products can affect cell metabolism. The current study examined the effects of constituents leached out of three glass ionomer cements on growth and metabolism of oral epithelial cells. Aseptically prepared discs of Ketac-Cem Radiopaque (KCR), Ketac-Cem Maxicap (KCM) and Fuji I were incubated in Dulbecco's medium for 10 d, with daily medium changes. Cultures of hamster cheek pouch (HCP) cells, a line of hamster buccal pouch epithelial cells, were incubated in control or eluate-containing media for 24 h. Viable cell numbers were determined by the colorimetric MTS assay, and DNA and RNA syntheses were assessed using [3H]thymidine and [3H]uridine incorporation, respectively. Responses to materials were determined by comparison of cell numbers and radioisotope incorporation (counts per minute (cpm) per 1000 cells). Results were analysed by ANOVA and Duncan's multiple range test, then converted to percent control for comparison. The eluates of all three materials from the first 24 h of soaking inhibited HCP cell growth. The number of cells in cultures exposed to Fuji were 88% of control cultures, while those exposed to KCR and KCM were 58% and 59% of control, respectively. The difference between Fuji-exposed and control cultures was significant (P < 0.05). The two Ketac cements were different from Fuji-exposed and control cultures (P < 0.05) but not from each other. All of the materials caused significant increases in labelling of DNA compared to control cultures (P < 0.05) when calculated on a per cell basis, but the materials did not differ from each other. Both Ketac cements also significantly stimulated labelling of RNA per cell compared to control cultures (P < 0.05). All effects of the material decreased over time. Results suggest that leachable components of the materials may affect the rate of progression of HCP cells through the cell cycle, rather than overt toxicity that results in cell death.

Animals↗

PubMed1990

[Glass-ionomer cements].

Glass-ionomer cements represent a new type of dental materials widely clinically applied owing to their good adhesion to dental tissue, caries-protective effects, biocompatibility and simple handling. They are two-component materials commercially available in forms of powder or liquid. The two components are mixed manually or automatically in a vibrator to produce a compact mixture. In addition to chemical, light-polymerizing hybrid glass-ionomer cements are also available. A description is given of physical and chemical features of these materials, their classification and use in particular clinical cases.

Glass Ionomer Cements↗

PubMed1989

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.

Dental Bonding↗

PubMed1996

Enamel fluoride levels after orthodontic band cementation with glass ionomer cement.

The aim of this investigation was to examine the fluoride uptake by enamel after application of glass ionomer cement for orthodontic band cementation compared with zinc phosphate cement. The study was conducted on 21 children whose mean age was 14 years. All the children were reared in the Middle Anatolian cities where the water fluoride concentration was below the level of 0.50 ppm. The subjects were randomly divided into three groups. The first experimental group, had seven subjects whose teeth were topically fluoridated with 2 per cent NaF solution, before orthodontic band cementation with zinc phosphate cement. The second experimental group also had seven subjects whose orthodontic bands were cemented with glass ionomer cement. The third group, consisted of seven control subjects and no dental procedures were performed in this group. All the participants were followed for 3 months and at the end of this period maxillary first premolars, which were in the ninth developmental stage according to Nolla (1960), were extracted for orthodontic purposes. The enamel fluoride concentrations were determined on the left maxillary first premolars at three successive etch depths by means of a fluor ion electrode, whereas the calcium concentrations were determined with an atomic absorption spectrophotometer. The results of this investigation showed that in both cementation groups enamel fluoride concentrations at three successive etch depths were highly increased compared with the control group. However, the difference between the cementation groups was not statistically significant.

Adolescent↗

PubMed1991

Microleakage of crowns cemented with glass ionomer cement: effects of preparation finish and conditioning with polyacrylic acid.

This study compared the marginal leakage of cast gold complete crowns cemented with glass ionomer and with zinc phosphate cement. The effect of polishing the preparations and conditioning with polyacrylic acid was also evaluated for glass ionomer cement. The cast gold crowns cemented with glass ionomer cement demonstrated significantly lower marginal leakage than did those with zinc phosphate cement. The extent of microleakage was not substantially different between crowns when the preparations were polished and conditioned with polyacrylic acid.

Acrylic Resins↗