Commercial Glass Ionomer Cement Research Articles

Experimental borosilicate bioactive glasses: Pulp cells cytocompatibility and mechanical characterization.

To assess in vitro the effect of two novel phase separated borosilicate glasses (PSBS) in the system SiO2 -B2 O3 -K2 O-CaO-Al2 O3 on dental pulp cells; and to compare their bioactivity and mechanical properties to a conventional fluoroaluminosilicate glass ionomer cement namely FUJI IX. The cytocompatibility assessment of the two novel borosilicate glasses, one without alumina (PSBS8) and one containing alumina (PSBS16), was performed on cultured primary human pulp cells. Alamar blue assay was used to assess cell metabolic activity and cell morphology was evaluated by confocal imaging. The bioactivity in Stimulated Body Fluid was also evaluated after 1 and 3 weeks of immersion using SEM-EDX analysis. Vickers microhardness and flexural strength were assessed after incorporating the glass particles into a commercial glass ionomer cement (GIC) liquid containing both polyacrylic and polybasic carboxylic acid. The data revealed that the two borosilicate glasses enhanced cell viability ratios at all-time points in both direct and indirect contact assays. After 3 days of contact, PSBS8 without alumina showed higher viability rate (152%) compared to the PSBS16 containing alumina (145%) and the conventional glass ionomer particles (117%). EDX analysis confirmed an initial Ca/P ratio of 2.1 for 45S5K and 2.08 for PSBS8 without alumina after 3 weeks of immersion. The cement prepared using PSBS8 showed significantly higher Vickers hardness values (p=.001) than that prepared using PSBS16 (46.6 vs. 36.7 MPa). After 24 h of maturation, PSBS8 (without alumina) exhibited a flexural strength of 12.9 MPa compared to a value of 16.4 MPa for the commercial control. PSBS8 without alumina had a higher strength than PSBS16 with alumina, after 1 and 7 days of maturation (p=.001). The present in vitro results demonstrated that the borosilicate bioactive glass without alumina enhanced pulp cell viability, spreading and acellular bioactivity better than the conventional GIC and the experimental borosilicate glass containing alumina.

Clinical and Microbiological Evaluation of a Chlorhexidine-Modified Glass Ionomer Cement (GIC-CHX) Restoration Placed Using the Atraumatic Restorative Treatment (ART) Technique.

The aims of this study were to investigate the clinical effectiveness and patient acceptability of a modified glass ionomer cement placed using the atraumatic restorative treatment (ART) technique to treat root caries, and to carry out microbiological analysis of the restored sites. Two clinically visible root surface carious lesions per participant were restored using ART. One was restored with commercial glass ionomer cement (GIC) (ChemFil® Superior, DENTSPLY, Konstonz, Germany) which acted as the control. The other carious root lesion was restored with the same GIC modified with 5% chlorhexidine digluconate (GIC-CHX; test). Patient acceptability and restoration survival rate were evaluated at baseline and after 6 months. Plaque and saliva samples around the test and control restorations were collected, and microbiological analysis for selected bacterial and fungal viability were completed at baseline, and after 1, 3, and 6 months. In total, 52 restorations were placed using GIC and GIC-CHX in 26 participants; 1 patient was lost to follow-up. After reviewing the restorations during their baseline appointments, participants indicated that they were satisfied with the appearance of the restorations (n = 25, 96%) and did not feel anxious during the procedure (n = 24, 92%). Forty-eight percent (n = 12) of the GIC-CHX restorations were continuous with the existing anatomic form as opposed to six for the GIC restorations (24%), a difference which was statistically significant (p = 0.036). There was no statistically significant reduction in the mean count of the tested microorganisms in plaque samples for either type of restorations after 1, 3, or 6 months. Restoration of carious root surfaces with GIC-CHX resulted in higher survival rates than the control GIC. ART using GIC-CHX may therefore be a viable approach for use in outreach dental services to restore root surface carious lesions where dental services are not readily available, and for older people and special needs groups.

Diatomaceous earth as a drug-loaded carrier in a glass-ionomer cement

The effect of a natural filler (diatomaceous earth [DE], a promising drug-delivery agent) and its content was investigated on the performance of a model glass-ionomer cement (GIC). Three sample series, differing in DE content (0, 2.5 and 5 wt%), were prepared using a commercial GIC as a matrix (3M Ketac Molar Easymix). The resultant surface microhardness and roughness, wear performance, and compressive strength of the samples were measured after the samples had been stored in deionized water at 37°C for a fixed time. Moreover, the film thickness was tested for the freshly mixed samples. The numerical data was subjected to statistical analysis, in order to test the null hypotheses of the equality of the measured properties between the reference and the DE-modified samples. According to the results, diatomaceous earth particles are uniformly distributed in the GIC matrix, and the cavities of frustules tend to be filled with the GIC. This translates into the observed performance of the DE-loaded GIC. Compared with the reference material (0 wt% DE), the surface microhardness (2.5 wt% DE, p = 0.014; 5 wt% DE, p = 0.005) and roughness (e.g. Ra; 2.5 wt% DE, p = 0.003; 5 wt% DE, p < 0.001) are increased. No effect on the wear performance (p = 0.530 and 0.256, respectively) or compressive strength (p = 0.514) was noticed in the case of DE partially substituting the glass phase. Based on the study results, it is evidenced that diatom frustules are a suitable filler for application in conventional glass-ionomer cements as the glass-substituting drug-loaded carrier. Notably, however, the surface finish method of the DE-filled materials needs development.

Effect of Nanofilled Resin-Based Coating on the Compressive Strength of Glass Ionomer Cement – in vitro

Glass ionomer cement as one of the restoration materials requires high compressive strength so it can last during functional activity. The latest glass ionomer cement comes with glass hybrid technology and a nanofilled resin-based protective coating which is said to increase the compressive strength of glass ionomer cement. The aim of this study was to analyze the effect of nanofilled resin-based coating and the types of glass ionomer cement materials on their compressive strength. Two types of commercial glass ionomer cement material were used; conventional (Fuji IX GP Extra), and hybrid (EQUIA Forte Fill) glass ionomer cement. Forty cylindrical (4 x 6 mm) samples were prepared in each group. The main group was divided into 4 subgroups (n=10) based on the protective coating used (EQUIA Forte Coat, Varnish, Control, Water + EQUIA Forte Coat). Eight subgroups were immersed in 37 °C distilled water for 7 days, then a compressive strength test was performed using a universal testing machine. The data analysis showed no significant difference in the compressive strength between the two types of glass ionomer cement materials (p&gt;0.05). The use of a protective coating was associated with a significant decrease in the compressive strength (p&lt;0.05). The use of glass ionomer cement without the application of a protective coating was considered to be quite good because the compressive strength value of the restoration still met the standards of the American Dental Association.

Improving the Mechanical Properties of Conventional Glass Ionomer Cement Through Using 4-Pentenoic Acid Modified Polycarboxylic Acid (PCA)

With the aim to enhance the mechanical properties of conversional glass ionomer cements (GICs), 4-pentenoic acid (PA) was used as a co-monomer to synthesize a new kind of polycarboxylic acid (PCA) through free radical polymerization with acrylic acid (AA) and itaconic acid (IA). The chemical structures of the PCA were confirmed by 1H-NMR and FT-IR. Number average molecular weights (Mn) and glass transition temperatures (Tg) of the synthesized PCA were investigated and the results showed that the Mn and Tg were in a trend of decreasing with increasing of the PA content in the raw materials. The synthesized PCA was dissolved in water with a mass ratio of 50 wt.% to prepare the liquid part of the GIC, and then mixed with glass powders of commercial GIC Fuji IX to prepare the GICs samples. The results of mechanical tests showed that the PCA with 5 wt% of 4-pentenoic acid as a comonomer showed the best comprehensive mechanical properties.

A new hydrolytic route to an experimental glass for use in bioactive glass-ionomer cement

Routes to glass-ionomer cements (GICs) have been previously explored through traditional silica-precursors, however, economic routes have not been fully reported. Herein, glass-ionomer powder was prepared through a new hydrolytic- and economic-route. The mechanical properties and bioactivity of the prepared GIC relative to a commercial GIC were investigated. Silica was derived from sodium metasilicate rather than conventional alkoxysilanes. Sodium metasilicate was hydrolysed with hydrochloric acid to form a gel, which was washed until residual impurity was removed, then aged and dried to obtain silica. Silica was thereafter dissolved in citric acid to form a complex used for encapsulating other precursors. Afterwards, a burnout procedure was performed on the silica-citric acid-precursor moiety to obtain glass-ionomer powder. Cements were formed from the as-prepared powder and commercial powder using a similar polymer solution. The cements were subjected to mechanical testing and bioactivity tests in simulated body fluid (SBF). The samples were characterised using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and Fourier transform infrared spectroscopy. The experimental GIC exhibited compressive, flexural strength and microhardness of 103.65 (± 4.53) MPa, 17.41 (± 1.69) MPa and 64.10 (± 3.84) KHN, respectively; while those for the commercial GIC were 118.86 (± 1.67) MPa, 21.63 (± 2.36) MPa and 72.45 (± 3.30) KHN, respectively. The obtained GIC upon immersion in SBF over a 28-day period compared with commercial GIC by showing good level of stability while nucleating a layer of apatite-like deposits on its surface. GIC obtained via this new hydrolytic method could serve as a candidate dental restorative material.

Fatigue performance of endodontically treated molars restored with different dentin replacement materials

ObjectivesThe aim was to investigate the fatigue performance of endodontically treated (ET) molars restored by various dentin-replacing materials and material configurations. Moreover, the impact of additional adhesive treatment with glass-ionomer cement (GIC) was evaluated. Methods250 intact molars were collected and randomly distributed into ten groups (n = 25). After endodontic procedure standard Class I cavities were prepared and restored with different direct restorative techniques and dentin-replacing materials. Two-group were restored with either packable or flowable short fiber-reinforced composites (SFRCs). Two-group were restored by experimental fiber-reinforced GIC with and without adhesive treatment. Four-group were restored by conventional and resin-modified GICs with or without adhesive treatment. One-group was restored with a dual-cure composite resin and last group was restored with only conventional composite resin (control). Fatigue-survival was measured for all specimens using a cyclic-loading machine until fracture occurred or a number of 40.000 cycles were achieved. Kaplan-Meyer survival analysis was conducted, followed by pairwise log-rank post hoc comparisons. Fracture mode was then examined by means of optical microscopy and SEM. ResultsGroup restored with flowable SFRC showed significantly higher survival (p < 0.05) compared to all of the groups, except for group restored with packable SFRC (p > 0.05). Group restored with fiber-reinforced GIC had significantly (p < 0.05) higher survival rates compared to other commercial GICs. SEM demonstrated change of the fracture line when fracture reached the SFRC layer. SignificanceDirect restoration of Class I in ET molars with the use of SFRCs as dentin-replacing materials demonstrated its ability to reinforce the dental structures and to increase the fatigue resistance in this specific clinical situation.

Biocompatible orthodontic cement with antibacterial capability and protein repellency

BackgroundWhite spot lesions (WSLs) often occur in orthodontic treatments. The objectives of this study were to develop a novel orthodontic cement using particles of nano silver (NAg), N-acetylcysteine (NAC) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and to investigate the effects on bonding strength, biofilms and biocompatibility.MethodsA commercial resin-modified glass ionomer cement (RMGIC) was modified by adding NAg, NAC and MPC. The unmodified RMGIC served as the control. Enamel bond strength and cytotoxicity of the cements were investigated. The protein repellent behavior of cements was also evaluated. The metabolic assay, lactic acid production assay and colony-forming unit assay of biofilms were used to determine the antibacterial capability of cements.ResultsThe new bioactive cement with NAg, NAC and MPC had clinically acceptable bond strength and biocompatibility. Compared to commercial control, the new cement suppressed metabolic activity and lactic acid production of biofilms by 59.03% and 70.02% respectively (p < 0.05), reduced biofilm CFU by 2 logs (p < 0.05) and reduced protein adsorption by 76.87% (p < 0.05).ConclusionsThe new cement with NAg, NAC and MPC had strong antibacterial capability, protein-repellent ability and acceptable biocompatibility. The new cement is promising to protect enamel from demineralization during orthodontic treatments.

Preparation of basalt fibers grafted with amine terminated urea-based oligomer and its application in reinforcing conventional glass ionomer cement

The purpose of this study was to improve interfacial interaction between basalt fibers (BF) and glass ionomer cement (GIC) matrix with grafting amine terminated urea-based oligomer (DIEDA) onto the surface of BF. The DIEDA-BF was prepared by the reaction between 3-aminopropyl- triethoxysilane (APS) modified BF with Isophorone diisocyanate (IPDI) and followed with ethylenediamine (EDA). The reaction was repeated to obtain three generations of DIEDA-BF which were marked as DIEDA-BF-G1, DIEDA-BF-G2, and DIEDA-BF-G3, respectively. X-ray photoelectron spectroscopy (XPS) was used to characterize DIEDA-BF. 3D morphology analysis was taken to investigate the variation of BF after being treated with EDA. Three-point bending-test, compressive strength (CS) test, and fracture toughness (FT) were used to evaluate the reinforcement effect of DIEDA-BF on commercial GIC (GC Fuji IX). Water sorption (WS) and solubility (SL) were measured according to the mass variation at fixed time intervals. The changes of flexural strength (FS) and modulus (FM) after water immersion were used to evaluate the water-aging resistance of DIEDA-BF reinforced GIC. Pure GIC and APS reinforced GIC (APS-GIC) were used as double control groups. The XPS analysis indicated that DIEDA was successfully grafted onto the surface of BF. 3D morphology analysis revealed that BF could be corroded in EDA, thus DIEDA-BF-G3 had lower N content on the surface than DIEDA-BF-G2. The results of mechanical tests showed that DIEDA-BF-G1 and DIEDA-BF-G2 had the best reinforcement effect. The DIEDA-BF-G1 reinforcement GIC (DIEDA-BF-G1-GIC) was chosen for WS, SL, and water aging resistance test further. The results showed that all fiber reinforced GICs had higher WS than pure GIC, and the relationship in SL between fiber reinforced GICs and pure GIC varied with immersion time. The FS of DIEDA-BF-G1-GIC decreased after one week of water immersion, and had no variation after prolonging the immersion time. After three months of water immersion, DIEDA-BF-G1-GIC still had much higher FS than pure GIC and APS-BF-GIC. DIEDA could improve the interfacial interaction between BF and GIC matrix. After long term of water immersion, DIEDA-BF reinforced GIC still had FS higher than 50 MPa, which even met the ISO requirement in FS for dental resin composite. Therefore, GIC/DIEDA modified BF composite had potential to be used in stress bearing areas in dentistry.

Glass ionomer cement modified by a imidazolium salt: adding antifungal properties to a biomaterial.

We present the structural modification of a commercially available glass ionomer cement by inserting the imidazolium salt 1-n-hexadecyl-3-methylimidazolium chloride (C16MImCl), composing a new biomaterial with antifungal biofilm activity. Test specimens were prepared using a commercial glass ionomer cement to which 10ppm of cetylpyridinium chloride (reference ionic antifungal agent) or C16MImCl were added. The feasibility and hypoallergenicity of the new biomaterial were assessed by microhardness plastic deformation and chorioallantoic membrane assays. Colony counting and scanning electron microscopy were used to evaluate the modified specimens' antibiofilm activity against three multidrug-resistant Candida species. The modified glass ionomer cement presented a strong antibiofilm activity against Candida spp., without losing its original micromechanical and hypoallergenic properties, rendering it a promising candidate for further application in dentistry.

Neutral Sodium Fluoride Gel Uptake of Newly Placed Nanodiamond-modified Glass Ionomers.

Three commercial restorative glass-ionomer cements (GICs) were modified with 5% and 10 wt/wt% nanodiamond (ND) particles incorporated into the powder of the GICs. The aim of the study was to assess the percentage of surface fluoride increase on different materials, following 2% neutral sodium fluoride gel application (2% NSF). Materials and Methods: The commercial GICs were: FN, Fuji IX GP (GC); KU, Ketac Universal (3M Oral Care); and RSC: Riva Self Cure (SDI). Grade 1 (Plasmachem) nanodiamond was used. Six specimens of each material were prepared using precise powder:liquid ratios. After a 10-min setting time, the GICs were polished. The specimens were randomly divided into two groups: control (group A) and test (group B). The samples were blot dried and group B received the 2% NSF gel for 2 min. The excess was wiped off with gauze and both groups were analyzed with SEM-EDS. Results: Data analysis revealed that all the GICs and their respective ND modifications had a statistically significant surface fluoride percentage increase (p < 0.0001) on the GICs in group B. The addition of ND10% w/w to FN (p < 0.001) and RSC (p = 0.029) resulted in statistically significant increase of surface fluoride percentage. KU remained consistent with no statistically significant increase noted between ND-modified KU and KU in group A or B. Conclusion: The ability of GICs to absorb the 2% NSF gel immediately after finishing of the restoration statistically significantly increases the fluoride percentage of the surface layer.

Single speckle image analysis for monitoring the hardening kinetics of glass ionomer cements.

In this paper, we monitor the setting reaction of commercial glass ionomer cements using a laser speckle technique and adopting a spatial approach in the analysis of recorded speckle images. Experimental results showed that spatial contrast and speckle grain size increased as two studied cements underwent their setting reactions. After combining two geometrical configurations to measure the intensities of backscattered and transmitted light, we concluded that the increase in speckle grain size was caused by an increase in size of the scattering centers, since cement components aggregate and hence transition from a Rayleigh to a Mie scattering regime. Finally, two main phases were distinguished in the hardening process, as reported in the literature; however, the technique we propose has the advantage of easily identifying these two phases. The analysis of a single speckle image offers multiple advantages over the temporal analysis of a series of speckle images, in particular due to the low number of images recorded and a far shorter image processing time.

Physical Properties of Glass Ionomer Cement Containing Pre-Reacted Spherical Glass Fillers.

The aim of this study was to assess the effect of different commercial liquid phases (Ketac, Riva, and Fuji IX) and the use of spherical pre-reacted glass (SPG) fillers on cement maturation, fluoride release, compressive (CS) and biaxial flexural strength (BFS) of experimental glass ionomer cements (GICs). The experimental GICs (Ketac_M, Riva_M, FujiIX_M) were prepared by mixing SPG fillers with commercial liquid phases using the powder to liquid mass ratio of 2.5:1. FTIR-ATR was used to assess the maturation of GICs. Diffusion coefficient of fluoride (DF) and cumulative fluoride release (CF) in deionized water was determined using the fluoride ion specific electrode (n=3). CS and BFS at 24 h were also tested (n=6). Commercial GICs were used as comparisons. Riva and Riva_M exhibited rapid polyacrylate salt formation. The highest DF and CF were observed with Riva_M (1.65x10-9 cm2/s) and Riva (77 ppm) respectively. Using SPG fillers enhanced DF of GICs on average from ~2.5x10-9 cm2/s to ~3.0x10-9 cm2/s but reduced CF of the materials on average from ~51 ppm to ~42 ppm. The CS and BFS of Ketac_M (144 and 22 MPa) and Fuji IX_M (123 and 30 MPa) were comparable to commercial materials. Using SPG with Riva significantly reduced CS and BFS from 123 MPa to 55 MPa and 42 MPa to 28 MPa respectively. The use of SPG fillers enhanced DF but reduced CF of GICs. Using SPG with Ketac or Fuji IX liquids provided comparable strength to the commercial materials.

Antibacterial activity of a glass ionomer cement doped with copper nanoparticles.

Copper nanoparticles (NCu) were synthetized and added to commercial glass ionomer cement, to evaluate in vitro its antibacterial activity against oral cavity strains. The NCu were synthesized by copper acetate reduction with L-ascorbic acid and characterized by FTIR, Raman, XPS, XRD and TEM. Then, commercial glass ionomer cement (GIC) was modified (MGIC) with various concentrations of NCu and physicochemically characterized. Cell viability was tested against human dental pulp fibroblasts (HDPFs) by Alamar-Blue assay and antibacterial test was performed against S. mutans and S. sanguinis by colony forming unit (CFU) growth method. Synthesized NCu rendered a mixture of both metallic copper and cuprous oxide (Cu2O). HDPF viability reduces with exposure time to the extracts (68-72% viability) and MGIC with 2-4 wt% NCu showed antimicrobial activity against the two tested strains.

Effects of N-Vinylcaprolactam Containing Polyacids and Zirconia on Mechanical Properties of Commercial Glass Ionomer Cements

This study aimed to investigate the impact of N-vinylcaprolactam (NVC) and Nano-sized yttria-stabilized zirconia (YSZ), separately and simultaneously, on the mechanical properties of the commercial glass ionomer cements (GICs). Methods: The NVC is able to ameliorate the mechanical and surface properties of glass ionomers; however, its effect hasn’t been investigated in conjunction with zirconia yet. In order to perform the current research, the liquid of glass ionomer was synthesized by adding the NVC to its copolymer and then was characterized by proton nuclear magnetic resonance and Fourier transforms infrared. In addition, Nano-sized YSZ was added to the powder of glass ionomer and then was characterized by scanning electron microscopy. Afterward, the specimens for both flexural strength (FS) and microhardness were prepared by mixing the powder and liquid of the modified glass ionomer. Eventually, the aforementioned properties were evaluated after 24 h and 1 week of immersion in distilled water in an incubator. Furthermore, the one-way analysis of variance was used to study the statistical significance of FS. Results: The obtained results demonstrated that microhardness andFS properties of the glass ionomer were clearly improved as zirconia and NVC were added to the powder and liquid of the glass ionomer, respectively (P<0.05). Moreover, the best result was achieved for the group in which the modification of powder and liquid of glass ionomer occurred concurrently. Conclusion: Based on the findings of the present study, it was deduced that the modified GIC is a promising dental material with improved mechanical properties.

Preparation and Characterization of Glass Ionomer Cements with Added Carboxymethyl Chitosan

Because of their low fracture strength, glass ionomer cements (GICs) can not be applied to the high stress loading areas in dentistry. With the aim to improve the fracture properties of GICs, carboxymethyl chitosan (CMCS) was dissolved in the liquid part of a commercial GIC, Fuji IX, and then mixed with inorganic particles to prepare GICs containing CMCS. The mechanical performance of the GICs containing CMCS showed that the CMCS could enhance the fracture properties of GICs when its concentration in the GICs was in a certain range; 0.0125 wt.% of CMCS in the liquid part of GIC improved both the flexural strength and the fracture toughness. The flexural strength, flexural modulus, and compressive strength results of the GICs containing CMCS after water aging showed that they also had good water aging-resistance.

In vitro compressive strength and edge stability testing of directly repaired glass-ionomer cements

ObjectiveTo study the repair potential of seven commercial glass-ionomer cements (GICs) using an in vitro edge compression test model.Materials and methodsA total of 448 normal and 192 repaired cylindrical specimens (6 × 4 mm) were produced from 6 GICs and one resin-modified GIC. Repaired samples consisted of a base aged for 1 month before repaired by an overlying layer. All samples were matured for 1 day, 1 week, 1 month or 3 months before compression, and edge tests were performed respectively on the whole surface (compressive strength, CS) or on the edge (edge stability, ES) using a universal testing machine.ResultsFor normal specimens, Ketac Universal (KU) illustrated a significantly higher CS than other groups at all time points (p < 0.001). ES of KU was weaker than EQUIA Forte (EQF), FIX (Fuji IX) and RSC (Riva Self Cure) after 1 day, increasing after 1 week. Repaired specimens showed CS comparable to normal specimens (p > 0.05). Repaired KU significantly improved CS compared to repaired EQF and Fuji II (FII) after 1 day. No statistical difference was found in ES among these groups (p > 0.05).ConclusionsKU provided the fastest maturation and greatest CS and ES in both normal and repair models after short-term ageing. Repair of GICs could potentially be achieved directly onto the fractured substrate and the subsequent improved mechanical performance could be maintained for at least 3 months.Clinical relevanceThis study provides a potential alternative in-vitro method to assess GIC restoration failure as well as provide insight into the mechanisms of GIC restoration repair.

Effects of Powdery Cellulose Nanofiber Addition on the Properties of Glass Ionomer Cement.

In this study, we aimed to evaluate the effect of the addition of powdery cellulose nanofibers (CNFs) on the mechanical properties of glass ionomer cement (GIC) without negatively affecting its chemical properties. Commercial GIC was reinforced with powdery CNFs (2–8 wt.%) and characterized in terms of flexural strength, compressive strength, diametral tensile strength, and fluoride-ion release properties. Powdery CNFs and samples subjected to flexural strength testing were observed via scanning electron microscopy. CNF incorporation was found to significantly improve the flexural, compressive, and diametral tensile strengths of GIC, and the corresponding composite was shown to contain fibrillar aggregates of nanofibers interspersed in the GIC matrix. No significant differences in fluoride-ion release properties were observed between the control GIC and the CNF-GIC composite. Thus, powdery CNFs were concluded to be a promising GIC reinforcement agent.

Properties of zirconia-containing glass-ionomer cement

Abstract Glass-ionomer cements (GICs) are used as restorative dental materials due to their capacity to chemically adhere to enamel and dentin, low thermal expansion coefficient, and compatibility with dental structures. However, these materials have low resistance to wear and fracture. In this work, zirconia-reinforced GICs were prepared to evaluate the influence of particle size as well as ZrO2 content on their properties. All evaluated composites presented compressive strength values above the pure GIC strength. The highest compressive strength values were obtained with the addition of 8.5 wt% ZrO2. The average roughness obtained was not significantly changed compared to commercial GIC and the lowest value was for the composite with 10 wt% ZrO2 (50 mesh). In the microhardness test, the highest values were obtained with the addition of 8.5 wt% of ZrO2. Therefore, the results indicated that the addition of ZrO2 to GIC is an effective alternative to improve the quality of dental restorations.

Mechanical properties and water sorption of two experimental glass ionomer cements with hydroxyapatite or calcium fluorapatite formulation.

In this study the mechanical behavior and water sorption (Ws) of experimental glass-ionomer-cements (GICs) with hydroxyapatite (HA) or calcium fluorapatite (CFA) prototype formulations were examined. Specimens from two experimental and one commercially available GIC were prepared in three protocols; (1) according to the manufacturer's instructions, (2) with coating and (3) with heat application. The specimens were stored in distilled water or artificial saliva at 37°C for 7- and 30-days. Flexural strength (FS), Vickers hardness (VHN) and Ws of GICs were evaluated. Experimental GICs showed higher FS values than commercial GIC (p<0.001). Higher FS and VHN values were observed when GICs were prepared according to manufacturer's recommendation. FS was affected only by GIC-type (η2=0.027), whereas VHN was affected by GIC-type (η2=0.331), treatment-protocols (η2=0.067), storage-medium (η2=0.100) and increased storage-duration (η2=0.317). The tested parameters did not significantly influence the Ws of all tested GICs (p>0.05). The GICs with HA or CFA formulations might represent a promising approach due to their FS, VHN and Ws characteristics.