Glass-ionomer Dental Cements Research Articles

MODIFICATION OF GLASS IONOMER FILLING MATERIAL BY METAL NANOPARTICLES AND THEIR COMPOUNDS: EFFECT ON ANTI-MICROBIAL ACTIVITY

Background: Glass ionomer filling materials are widely used in stomatology, but do not have an antimicrobial effect that effectively prevents the development of secondary and recurrent dental caries. Researchers are attempting to modify these materials by introducing various biologically active additives into them. The aim of the study was to evaluate the antimicrobial properties of a dental ionomer filling material modified withadditives based on high–energy nanoparticles of silver, copper, titanium and their compounds. Material and methods: Colloidal aqueous and alcoholic solutions of metals and their oxides with stabilizers were obtained by the electroerosion method. Citric acid, cetylpyridinium chloride and Trilon B were used as stabilizers. The zeta potential and the distribution of particles of the dispersed phase in solutions were measured. Samples of dental glass ionomer cement "Cemion-Aqua" were impregnated with colloidal solutions of nanoparticles. The microbiological activity of glass ionomer fillings samples in relation to plaque was determined by disc diffusion and suspension methods. Results: The results showed that modification of glass ionomer cement samples with silver hydrosols in citric acid solutions with concentrations of 0.04% and 0.0025% increases the zone of radial lysis of microbial plaque colonies around the cement samples by 1.5 and 2.5 times compared with the control. By the suspension method, it was determined that silver hydrosols in a solution of citric acid and without it reduce the formation of colonies of microorganisms to several units up to 72 hours of exposure compared with the control. And copper hydrosols in solutions of cetylpyridinium chloride prevent an increase in the number of colonies of microorganisms after 24 hours of exposure compared with the control. Silver hydrosol in a solution of citric acid with a concentration of 0.0025% and silver alcohol sol reduce the number of colonies of microorganisms to several units after 3 hours of exposure.

BIOCHEMICAL PARAMETERS OF BLOOD OF LABORATORY ANIMALS IN CASE OF PROLONGED CONTACT WITH THE RESEARCH MATERIAL

The purpose of this study was to determine the biochemical parameters of blood of laboratory animals in prolonged contact with the experimental material
 Materials and methods. An experimental study was conducted in the laboratories and vivarium of the State Institution "Institute of Spine and Joint Pathology named after Prof. M.I. Sitenko" on 28 white laboratory rats aged 6 months with a body weight of 200 to 250 grams. The animals were randomly divided into two groups: a control group (14 rats) and an experimental group (14 rats), which were exposed to dental glass ionomer cement at a dose of 1.0 mg/kg. Toxic effects were evaluated for 1 month. The blood sampling procedure included tail vein dilation, disinfection, tail fixation, and blood collection. The study was conducted in special conditions with full feeding.
 Results. The study found no significant negative effects of prolonged use of dental glass ionomer cement (GIC) on kidney function. Analysis of diuresis, urea and creatinine levels in urine and blood serum showed no statistically significant differences between males and females. No sugar, ketones, or protein were detected in the animals' urine. Serum creatinine levels were (65.47±4.6) μmol/l in males and (63.38±7.1) μmol/l in females, while serum urea levels were (4.84±0.47) μmol/l in males and (4.67±0.42) μmol/l in females. Urinary urea levels were (374.35±20.7) mmol/l in males and (371.15±22.3) mmol/l in females.
 Conclusions. The obtained results of the study indicate statistically significant deviations in the studied indicators of the functional state of the kidneys both in males and females after prolonged use of dental glass-inomer cement based on polyacrylate carboxylate. The presence of sugar, ketones and protein was not detected in the urine of the animals. The analysis of serum creatinine levels showed no statistically significant differences between the conditions, and serum urea levels did not differ between them either. Thus, it can be concluded that the use of glass-inomer cement has no negative effect on the functional state of the kidneys in the studied animals.

Evaluation of compressive strength, surface microhardness, solubility and antimicrobial effect of glass ionomer dental cement reinforced with silver doped carbon nanotube fillers

BackgroundConventional glass ionomer cements (GICs) are currently the most widely used dental cements due to their chemical bonding into tooth structure, release of fluoride, and ease of manipulation and usage. One of their drawbacks is their low mechanical properties and high solubility. Carbon nanotubes (CNTs) could be utilized in dentistry due to their several potential applications. CNTs can be used as fillers to reinforce polymers or other materials. Additionally, silver (Ag) nanoparticles are highly effective at preventing dental biofilm and enhancing mechanical properties.ObjectivesThe aim of the present in vitro study is to evaluate the compressive strength, surface microhardness, solubility, and antimicrobial effect of the conventional GIC reinforced with manual blending of 0.01 wt.% Ag doped CNT fillers.MethodsThe control group was prepared by mixing dental GIC powder with their liquid. The innovatively reinforced dental GIC group was prepared by incorporating 0.01 wt.% Ag doped CNT fillers into the GIC powder prior to liquid mixing. Chemical characterization was performed by XRF. While, physical characterization was done by measuring film thickness and initial setting time.The compressive strength, surface microhardness, solubility, and antimicrobial effect against Streptococcus mutans bacteria using an agar diffusion test were measured. The data was statistically analyzed using independent sample t-tests to compare mean values of compressive strength, surface microhardness, solubility, and antimicrobial activity (p ≤ 0.05).ResultsThe results revealed that innovative reinforced GIC with 0.01 wt.% Ag doped CNT fillers showed higher mean compressive strength, surface microhardness, and antimicrobial effect values than the conventional GIC control group; there was no significant difference between different groups in relation to the solubility test (P ≤ 0.05).ConclusionThe innovatively reinforced GIC with 0.01 wt.% Ag doped CNT fillers had the opportunity to be used as an alternative to conventional GIC dental cements.

Effect of Biosilicate® Addition on Physical–Mechanical and Biological Properties of Dental Glass Ionomer Cements

This study investigated the influence of incorporating Biosilicate® on the physico-mechanical and biological properties of glass ionomer cement (GIC). This bioactive glass ceramic (23.75% Na2O, 23.75% CaO, 48.5% SiO2, and 4% P2O5) was incorporated by weight (5%, 10%, or 15%) into commercially available GICs (Maxxion R and Fuji IX GP). Surface characterization was made by SEM (n = 3), EDS (n = 3), and FTIR (n = 1). The setting and working (S/W time) times (n = 3) and compressive strength (CS) were analyzed (n = 10) according to ISO 9917-1:2007. The ion release (n = 6) was determined and quantified by ICP OES and by UV-Vis for Ca, Na, Al, Si, P, and F. To verify cell cytotoxicity, stem cells from the apical papilla (SCAP) were exposed to eluates (n = 3, at a ratio of 1.8 cm2/mL) and analyzed 24 h post-exposure. Antimicrobial activity against Streptococcus mutans (ATCC 25175, NCTC 10449) was analyzed by direct contact for 2 h (n = 5). The data were submitted for normality and lognormality testing. One-way ANOVA and Tukey’s test were applied for the working and setting time, compressive strength, and ion release data. Data from cytotoxicity and antimicrobial activity were submitted for Kruskal–Wallis’ testing and Dunn’s post hoc test (α = 0.05). Among all experimental groups, only those with 5% (wt) of Biosilicate® showed better surface quality. Only M5% showed a comparable W/S time to the original material (p = 0.7254 and p = 0.5912). CS was maintained for all Maxxion R groups (p > 0.0001) and declined for Fuji IX experimental groups (p < 0.0001). The Na, Si, P, and F ions released were significantly increased for all Maxxion R and Fuji IX groups (p < 0.0001). Cytotoxicity was increased only for Maxxion R with 5% and 10% of Biosilicate®. A higher inhibition of S. mutans growth was observed for Maxxion R with 5% of Biosilicate® (less than 100 CFU/mL), followed by Maxxion R with 10% of Biosilicate® (p = 0.0053) and Maxxion R without the glass ceramic (p = 0.0093). Maxxion R and Fuji IX presented different behaviors regarding Biosilicate® incorporation. The impacts on physico-mechanical and biological properties were different depending on the GIC, but therapeutic ion release was increased for both materials.

Development of a gum recession model in an experiment

Background: The article presents experimental studies conducted on Wistar rats in the amount of 50 individuals. An artificial gum recession defect was created.Aim: to evaluate the effectiveness of creating a gum recession model in the proposed way.Material and methods: Experimental animals at the beginning of the study had an intact oral mucosa: pale pink color, without pathological changes. An experimental model of gum recession was created by excision of V-shaped periodontal tissues from the vestibular surface in the area of the lower jaw incisors of a rat, then a DispodentPak No. 000 retraction thread was applied in the area of the lower central incisors in the circular ligament of the tooth to a depth of 1.5 mm, and Vitrebond dental glass ionomer cement was applied to the vestibular surface of the neck of the tooth of the lower incisors, with at the same time, prednisone is administered intramuscularly at the rate of 12 mg / kg of animal weight on the 1st, 3rd and 5th day. For the experiment, female white rats in the amount of 50 individuals were used as a model. All animals were divided into 2 groups depending on the method of creating a gum recession defect. In the control group of rats, the defect was created according to the standard procedure by conducting a V-shaped incision.Results: When creating the proposed model of experimental gum recession, the clinical and pathomorphological picture is achieved under the influence of local factors: V-shaped gum incision, retraction thread, dental glass ionomer cement. To suppress the processes of self-regeneration of the gums, the optimal dose of prednisone is administered.Conclusions: On the 3rd day of the experiment, a V-shaped defect was observed in animals. On the 10th day, clinical signs of gum recession are determined: a defect with a depth of 2 mm. The average depth of recession in animals was (2 ± 1.7 mm). A relatively short process of modeling a gum recession (no more than a month). In this case, a local lesion of the gum is created, not burdened by any other pathology in the animal, and having both local and general (stress) pathogenetic factors, against the background of changes in the reactivity of the organism, which corresponds to the modern theory of the occurrence of recession as a polyethological disease in humans.

A one-step facile process for extraction of cellulose from rice husk and its use for mechanical reinforcement of dental glass ionomer cement

The extraction of cellulose was optimized using only hypochlorite and characterized and then utilized as a filler in glass ionomer cement where its strength and elasticity were studied.

ИСЛЕДОВАНИЕ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ НА ОСНОВЕ АЛЮМОФТОРСИЛИКАТНОГО СТЕКЛА

The results of a comparative analysis of dental glass ionomer cements are compared: "AHfil +" (AHL, United Kingdom), "Ketac Molar Easymix" (3M ESPE, USA), "Fuji IX GP" (GC, Japan), "ProGlass Nine" (Silmet , Israel), "Polyacrylin" (TechnoDent, Russia), "Cemion" (VladMiVa, Russia), "Kemfil" (StomaDent, Russia) and "Glassin Rest" (Omega-Dent, Russia) in terms of working time, hardening time, strength compression, radiopacity, microstructure and chemical composition. It is shown that the main component of the powders of these GICs is crushed calcium ("Kemfil"), strontium ("AHfil +", "Cemion" and "Fuji IX GP"), calcium-strontium ("ProGlass Nine", "Polyacrylin" and "Glassin Rest") and lanthanum-calcium aluminofluorosilicate glass ("Ketac Molar Easymix"). All of them contain phosphorus. Differences in powder granulometric composition indicate a difference in the technology of glass grinding during their production. The working time of the studied GICs is from 1 to 3.5 minutes. The requirements of GOST 31578-2012 and ISO 9917-1:2007 do not correspond to "ProGlass Nine" (36 ± 3 MPa), "Kemfil" (68±6 MPa) and "Glassin Rest" in terms of strength, and "ProGlass Nine" in hardening time. "Fuji IX GP" has the highest strength (201 ± 33 MPa), the rest of the GIC - 142-169 MPa. All studied GICs, with the exception of the non-radiopacity "ProGlass Nine", have a radiopacity corresponding to 1 mm of aluminum. According to the results of the tests, "AHfil +", "Ketac Molar Easymix", "Fuji IX GP", "Polyacrylin" and "Cemion" are recommended for clinical use by dentists

Comparison of capsule-mixed versus hand-mixed glass ionomer cements Part II: Porosity

Glass ionomer restorative cements (GIC) are routinely used in dental practice. During mixing, air incorporation may lead to higher porosity with subsequent weakening of the cement. The degree of porosity will determine whether capsule-mixed or hand-mixed GIC are mechanically stronger for clinical use. To compare the porosity of four commercially available dental glass ionomer cements, supplied in both hand mix and capsule-mix formulations, by evaluating number of voids (%), total volume of voids (mm3 ) and volume percentage of voids (%). Eighty samples were manufactured from hand-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal, Ketac Molar Easymix, and equivalent capsule-mixed GIC: Riva Self Cure; Fuji IX GP ; Ketac Universal Aplicap and Ketac Molar Aplicap. Micro-CT scanning was used to evaluate porosity. The number of voids (mm3 ), total volume of voids (mm3 ) and the volume percentage of voids (%) were calculated.

Determination of the toxicity glass ionomer cements for permanent fixa-tion of non-removable constructions of dentures

The experiment was carried out on groups of laboratory rats with a detailed study of the injected material, hematological, biochemical parameters of blood, behavioral reactions of animals and kidney function of experimental animals. The aim of the study was to determine the toxic effect of the new glass ionomer cement for permanent fixation of fixed structures of dentures on organs and tissues of laboratory animals. The keeping of animals and experiments were carried out in accordance with the "European Convention for the Protection of Vertebrate Animals used for Experimental and Other Scientific Purposes" (Strasbourg, 1986), Law of Ukraine No. 3447-IV on 21 Feb 2006 "On protection of animals from cruel treatment". Observations of the state and behavior of the animals showed that they tolerate daily contact with glass ionomer cement for one month satisfactorily. Indicators of liver weight in females (5.135±0.233) g and in males (6.234±0.342) g. In the experimental groups in contact with glass ionomer material, there were no significant differences in the number of erythrocytes [females – (4.86±0.26)·1012/l and in males – (4.53±0.14)·1012/l], hemoglobin [in females – (79.62±2.37) g/l, in males – (81.21±5.48) g/l], leukocytes [in males – (10.27±0.94)·109, in females – (9.81±0.68)·109/l]. The data obtained indicate the absence of toxic the effect of dental glass ionomer cement on peripheral blood. So the studied glass ionomer cement had no cytolyses effect on the liver. Changes in the composition of total protein [in males – (69.79±2.36) mmol/l, while in females – (67.35±2.47) mmol/l], albumin [in males – (28.56±1.87) mmol/l, in females – (28.49±2.36) mmol/l] in blood serum correspond to disorders of protein synthesis associated with damage to the liver parenchyma. The obtained results indicate that glass ionomer cement for permanent fixation of non-removable orthopedic prostheses did not have a toxic effect on the organs and tissues of experimental animals with prolonged use. Keywords: glass ionomer cement, permanent fixation, fixed structures of dentures, toxicity, experiment.

An overview of advances in glass ionomer cements

Glass-ionomer dental cements (GICs) are aesthetic direct restorative materials with anticariogenic activity. Glass-ionomers are composed of alumino-silicate glass powder and poly acrylic acid liquid. The significant characteristics of GICs among restorative materials are their ability to bond to moist tooth structure without any pre-treatment and to provide a prolonged period of fluoride release, which prevents subsequent tooth decay (caries). These characteristics, along with the materials' acceptable aesthetics and biocompatibility, make them popular and desirable for use in medical and dental applications. However, GICs exhibit poor mechanical qualities and moisture sensitivity. To improve their mechanical and physical qualities, the GIC powders have undergone extensive formulation and modification. This paper provides an overview of various fillers used to enhance the mechanical and physical properties of GICs.

The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study

The Electrical Conductivity and Dielectric Properties of Dental Glass Ionomer Cements: In Vitro Study

Glass-ionomer dental cements as novel solid-state buffers

This study examined the possible buffering effect of acid-base glass-ionomer cements. Commercial capsulated materials were used, namely: Riva Self Cure, Ketac Molar, Equia Forte and Chemfil Rock. Cements were prepared by vibratory mixing then cylinders (4 mm diameter, 6 mm height) prepared from them using metal moulds. They were cured in the moulds at 37 °C for one hour, then placed in 8 ml deionised water at 22 °C and stored for 24 h or 4 weeks. Then they were crushed to powders with a pestle and mortar. Ten samples per powder (0.05 g) were placed in individual 10 ml volumes of deionised water. For two sets of ten (24 h or 4 weeks old), 1.0 ml of 0.01 M HCl was added, equilibrated and the pH measured by calibrated electrode. For another two sets of ten (24 h or 4 weeks old), 1.0 ml of 0.01 M NaOH was added, equilibrated, and the pH measured. The pH of a control set of solutions (no cement powder) was also measured. Data were tested using 1-way ANOVA and Tukey HSD test. The original acid solution pH was 3.2, which rose to 4.4–5.5 depending on brand and age of cement. The original alkali solution pH was 11.3, which fell to 6.7–8.3 depending on the details of the cement. Differences from initial pH had Tukey HSD p values of 0.001 in all cases. It was concluded that acid-base glass-ionomers can act as solid-state buffers, a finding attributed to the carboxylic acid/carboxylate conjugate pairs within them.

Surface Studies on Glass Powders Used in Commercial Glass-Ionomer Dental Cements.

The surface properties of three commercial ionomer glass powders, i.e., Fuji IX, Kavitan Plus and Chemadent G-J-W were studied. Samples were analyzed by X-ray fluorescence spectroscopy (XRF), and the density was determined by gas pycnometry. Morphology was studied using scanning electron microscopy (SEM) and laser diffraction (LD) technique, whereas low-temperature nitrogen sorption measurements determined textural parameters like specific surface area and pore volume. Thermal transformations in the materials studied were evaluated by thermogravimetric analysis (TGA), which was carried out in an inert atmosphere between 30 °C and 900 °C. XRF showed that Fuji IX and Kavitan Plus powders were strontium-based, whereas Chemadent G-J-W powder was calcium-based. Powders all had a wide range of particle sizes under SEM and LD measurements. Specific surface areas and pore volumes were in the range 1.42–2.73 m2/g and 0.0029 to 0.0083 cm3/g, respectively, whereas densities were in the range 2.6428–2.8362 g/cm3. Thermogravimetric analysis showed that the glass powders lost mass in a series of steps, with Fuji IX powder showing the highest number, some of which are attributed to the dehydration and decomposition of the polyacrylic acid present in this powder. Mass losses were more straightforward for the other two glasses. All three powders showed distinct losses at around 780 °C and 835 °C, suggesting that similar dehydration steps occur in all these glasses. Other steps, which differed between glass powders, are attributed to variations in states of water-binding on their surfaces.

Influence of Al2O3 and P2O5 contents in sol-gel ionomer glass system on the structure and their cement properties

Glass ionomer dental cement (GIC) is commonly used as a restorative material. The sol-gel synthesis of the ionomer glass is an alternative method, which can produce higher purity and homogeneous at low temperature compared with the traditional melt-quench method. This study synthesized the ionomer glass with the variation of Al2O3 and P2O5 contents in the glass formula by the sol-gel route. The term of Al/(Si+P) ratio was evaluated by XRD and XPS to understand the structural change in the sol-gel glasses. The relationship of the chemical structure of the sol-gel glass, the ions releasing behavior, setting time, and compressive strength of the sol-gel GIC were determined. This study demonstrated that the increase of Al2O3 content in glass formula increased [AlO6] octahedron and bridging oxygen (BO) in the glass structure, while the increase of P2O5 content in glass formula led to the increasing of the [AlO4] tetrahedron and BO. The sol-gel GIC composition met the maximum compressive strength at Al/(Si+P) = 1.57, whereas the general GIC composition required at Al/(Si+P) nearby 1. Moreover, in vitro cell viability of NIH/3T3 fibroblast cells also showed promising result after 2 days culture. This study provided the knowledge for adjusting the sol-gel glass composition for the appropriate properties of GIC.

Kinetics of ion release from a conventional glass-ionomer cement

Release kinetics for sodium, silicon, aluminium, calcium and phosphorus from conventional glass-ionomer dental cement has been studied in neutral and acid conditions. Specimens (6 mm height × 4 mm diameter) were made from AquaCem (Dentsply, Konstanz, Germany), 6 per experiment. They were matured (37 °C, 1 h), then placed in 5 cm3 storage solution at 20–22 °C. In the first experiment, deionised water, changed daily for 28 days, was used. In the second, deionised water, changed monthly for 21 months, was used. In the third, lactic acid (20 mmol dm−3, pH: 2.7 ± 0.1), changed monthly for 21 months was used. After storage each solution was analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results showed that in neutral conditions, no calcium was released, but in acid, significant amounts were released. The other elements (Na, Al, Si and P) were released in neutral as well as acid conditions, with greater amounts in acid. More frequent changes of water gave greater release. In neutral conditions, release over 21 months followed the equation: [E]c = [E]1t/(t + t½) + β√t ([E]c is the cumulative release of the element). In acid conditions, this became: [E]c = [E]1t/(t + t½) + αt. Hence release of all elements was shown to occur in two steps, a rapid initial one (half-life: 12–18 h) and a longer second one. In neutral conditions, the longer step involves diffusion; in acid it involves erosion. These patterns influence the material’s bioactivity.

Computational Study of the Formation Reaction of Polyacid Precursors of Glass-Ionomer Materials

The formation of polyacids in a glass-ionomer cement was computationally modeled. The polyacid modelled is an oligomer made up of three molecules: acrylic acid, itaconic acid and an additional molecule that acts as a spacer group between the previous two. Acryloyl and meta-acryloyl derivatives of some amino acids and related molecules such as N-vinyl pyrrolidone and N-vinyl caprolactam were used as spacer groups. Some of these molecules have been previously used experimentally as spacer groups. In this work the spacer behaviour of 15 different molecules was investigated. To our knowledge, this is the first computational attempt to model some promising molecules to be incorporated into glass-ionomer dental cements. The results revealed the best structural arrangement for the investigated molecules.

Ultrasonic Inspection of the Setting Mechanism of Glass Ionomer Cement

Ultrasonic measurements were used to characterize the setting process of glass-ionomer dental cement (GIC) and to evaluate the effect of temperature on the setting time and mechanical properties. The ultrasonic method has the potential to be an ideal new tool for direct, real-time evaluation of the GIC setting reaction, providing detailed information on the evolution of their parameters as a function of setting time. The cement paste was prepared following the manufacturer’s instructions, from polycarboxylic acid and fluoroaluminosilicate glass, then inserted into cylindrical molds (8.0 mm in diameter and 3.0 mm in thickness). The cement mixing and the measurements of the acoustic properties were carried out at three different temperatures. The setting behavior was analyzed by monitoring changes in the ultrasonic velocity of the longitudinal wave. The results obtained show that the increase in temperature considerably accelerated the setting reaction. It was concluded that the proposed method is very effective in evaluating the setting reaction when an external energy source is applied and that the addition of heat energy to the setting almost sets GIC on command and improves their early mechanical properties.

Evaluation of the Flexural Strength, Water Sorption, and Solubility of a Glass Ionomer Dental Cement Modified Using Phytomedicine.

Objectives: Various medicinal plant parts and extracts have been proven to be sources of biologically active compounds, many of which have been incorporated in the production of new pharmaceutical compounds. Thus, the aim of this study was to increase the antimicrobial properties of a glass ionomer cement (GIC) through its modification with a mixture of plant extracts, which were evaluated along with a 0.5% chlorohexidine-modified GIC (CHX-GIC) with regard to the water sorption, solubility, and flexural strength. Methods: Salvadora persica, Olea europaea, and Ficus carcia leaves were prepared for extraction with ethyll alcohol using a Soxhlet extractor for 12 h. The plant extract mixture (PE) was added in three different concentrations to the water used for preparation of a conventional freeze-dried GIC (groups 1:1, 2:1, and 1:2). Specimens were then mixed according to the manufacturer’s instructions and tested against the unmodified GIC (control) and a GIC modified with 0.5% chlorhexidine. Water sorption and solubility were evaluated after 7 days of immersion in distilled water. Flexural strength was evaluated in a three-point bending test after 24 h using a universal material testing machine at a crosshead speed of 1 mm/min. One-way analysis of variance (ANOVA) was used for comparison between the groups. Tukey’s post hoc test was used for pairwise comparison when the ANOVA test was significant. Results: There were no statistically significant differences between the control (M = 20.5%), CHX-GIC (M = 19.6%), 1:1 (M = 20.0%), 1:2 (M = 19.5%), and 2:1 (19.7%) groups with regard to the percentage of water sorption, while for water solubility the 2:1 (M = −0.39%) plant-modified group was significantly different from all of the other groups. Flexural strength test results showed that the 2:1 group (M = 26.1 MPa) recorded significantly higher mean values compared to all other tested groups. Conclusion and clinical relevance: The plant extracts did not negatively affect the water sorption and solubility of the GIC, while the flexural strength was improved by the addition of the plant extract at higher concentrations.

Novel multi-walled carbon nanotube reinforced glass-ionomer cements for dental restorations

Carbon nanostructures have been fascinating mankind since their discovery. Their excellent biocompatibility and toughening properties can virtually reinforce any material. Glass ionomer (GIC) dental cement is bestowed with numerous advantages like anti-caries action, adhesion to a tooth, etc. But, due to its low mechanical properties, it is not the material of choice to be used to fill the posterior teeth. In the present study, a composite of GIC and multi-walled carbon nanotubes (MWCNT) is studied to evaluate the potential use as posterior restorative types of cement. The MWCNT was mixed with GIC powder at 3 different proportions and cement pellets were formed by the usual mixing procedure followed in dentistry. The fabricated composites were characterized under XRD, Electron microscopy, FTIR, TGA and DSC. The setting time was evaluated. The composites were also analyzed for swelling and solubility properties. The pellets were placed in normal saline and were analyzed for compressive strength, hardness and wear. The results were statistically analyzed and the influence of MWCNT on the properties of composites were elucidated.

Dental glass ionomer cement consistency and film thickness

This comparative study is to evaluate consistency and film thickness for Iraqi made (Ashour) glass ionomer cement (GIC) and five different types glass ionomer cement and to compare these materials with each other and with British Standard Specification (BS Sp.) no.(6039) in (1981). In this study the following materials were used: 1.Ashour,Ketac, QD and Meron glass ionomer cements are type "1" (luting materials) according to manufacturer instructions. 2. Ionodent and Hybond glass ionomer cements are type "2" (filling materials) according to manufacturer instructions. The tests were done by using specimens of tested materials prepared by the aid of metal moulds, which are manufactured for each test according to specification. Electronic balance was used to calculate the amount of powder that must be mixed with (0.5) ml of liquid to provide consistency value within the range of specification. Glass slab, stainless steel mixing spatula and micrometer were used for measuring the film thickness,while vernier used instead of micrometer for measuring the consistency. Cabinet was made of wood and glass manufactured for providing (by using of atmospheric thermometer and hygrometer) the temperature and humidity necessary for each test. The results showed that there is a significant difference between different treatment groups. Further results showed that some tested materials exhibit a significant difference between each other and with specification. The comparative study found that the filling materials which are tested have physical properties of luting materials and there are some variations in these properties of all tested materials from those which are illustrated in the manufacturer leaflets and in the specification.