Experimental Glass Ionomer Cement Research Articles

Comparative Evaluation of Microleakage of Fiber-reinforced Glass Ionomer Cement and Conventional Glass Ionomer Cement Restorations Immersed in Three Different Beverages: In Vitro Study.

The aim of the study was to compare and evaluate the microleakage of fiber-reinforced glass ionomer cement (GIC) and conventional glass ionomer cement restorations immersed in three different beverages. A total of 96 human exfoliating deciduous molars were selected which were cleaned and disinfected. Standardized Class V cavity preparations were done and buccal surface were restored with experimental fiber-reinforced glass ionomer cement (Exp-FRGIC), lingual surface were restored with Type II conventional GIC. They were divided into four groups according to the test beverage. The samples were subjected to various immersion regimes and evaluated for microleakage under stereomicroscope. Intragroup comparison for (Exp-FRGIC) showed significant microleakage when immersed in fresh fruit juice at high immersion whereas intragroup comparison in conventional GIC, showed highest microleakage with soft drink. Intergroup comparison of (Exp-FRGIC) in high immersion regime, showed more microleakage with specimen immersed in soft drink followed by fresh fruit juice. It can thus be concluded that the three beverages used in the study affected the microleakage of both restorative materials significantly. Increasing usage of fruit juices in the pediatric diet has a definite impact on the progression of caries and it directly or indirectly affects the quality of restorations placed in the oral cavity. How to cite this article: George MA, Chandak SA, Khekade SH, et al. Comparative Evaluation of Microleakage of Fiber-reinforced Glass Ionomer Cement and Conventional Glass Ionomer Cement Restorations Immersed in Three Different Beverages: In Vitro Study. J Contemp Dent Pract 2024;25(4):346-353.

Using Functionalized Micron-Sized Glass Fibres for the Synergistic Effect of Glass Ionomer on Luting Material.

This laboratory experiment was conducted with the objective of augmenting the mechanical properties of glass ionomer cement (GIC) via altering the composition of GIC luting powder through the introduction of micron-sized silanized glass fibres (GFs). Experimental GICs were prepared through the addition of two concentrations of GFs (0.5% and 1.0% by weight) to the powder of commercially available GIC luting materials. The effect of GF in set GIC was internally evaluated using micro-CT while the mechanical attributes such as nano hardness (nH), elastic modulus (EM), compressive strength (CS), and diametral tensile strength (DTS) were gauged. Additionally, the physical properties such as water solubility and sorption, contact angle (CA), and film thickness were evaluated. Reinforced Ketac Cem Radiopaque (KCR) GIC with 0.5 wt.% GF achieved improved nH, EM, CS, and DTS without affecting the film thickness, CA or internal porosity of the set GIC cement. In contrast, both GF-GIC formulations of Medicem (MC) GIC showed the detrimental effect of the GF incorporation. Reinforcing KCR GIC with 0.5 wt.% silanized GFs could improve the physical and mechanical attributes of luting material. Silanized GF, with optimal concentration within the GIC powder, can be used as a functional additive in KCR GIC with promising results.

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.

Experimental Glass Ionomer Cement Containing Gallic acid: Antibacterial Effect and Fluoride Release an in vitro Study

Abstract:&#x0D; Aim: Assessment of antibacterial effect and fluoride release on glass ionomer cement (GIC) modified by different concentrations of gallic acid (GA) and their effect on working and setting time.&#x0D; Methodology: Four groups were tested, group I (control non modified group) and groups II-IV represent GIC modified by GA in three different concentrations (125mg/ml, 62.5mg/ml and 31.25mg/ml GA powder / GIC liquid respectively). Antibacterial effect against Streptococcus Mutans (S. Mutans) was determined after 24hr by broth dilution method. Fluoride release was evaluated after three time intervals 24, 48 and 96hr using spectrophotometer. Working and setting time were measured in all groups by indentation method.&#x0D; Results: Increasing the concentration of GA significantly increase the antibacterial effect. For all time intervals, the highest fluoride release were observed in group IV and the lowest were in group I. After 24hr groups II, III and IV were significant to group I, while after 48 and 96hr group IV was significant to group I. In addition, working and setting time significantly increased with increasing the GA concentration.&#x0D; Conclusion: Gallic acid improve the antibacterial effect of GIC against S. Mutans and also improve the fluoride release. The increase in working and setting time of GA modified groups were still within the limit given by ISO 9917–1:2007 specifications.

Two-body wear and fracture behaviour of an experimental paediatric composite crown in comparison to zirconia and stainless steel crowns dependent on the cementation mode

ObjectivesThe purpose of this in vitro study was to assess the two-body wear and fracture behaviour of an experimental additive manufactured composite crown in comparison to zirconia and stainless steel crowns and its cementation protocol for primary molars. Material and methodsThree different paediatric crowns – experimental composite crowns (CCs, 3M), zirconia crowns (ZCs, NuSmile), and stainless steel crowns (SSCs, 3M)–were cemented with an experimental resin-modified glass ionomer cement (RMGIC, 3M) and two self-adhesive cements (SACs; RelyX Unicem Automix 2, 3M; BioCem, NuSmile). Seven groups, each with eight specimens, were thermally cycled (55 °C/50 °C) and dynamically loaded (50N/ 1.2Hz) in a masticatory simulator with steatite antagonists. The areal and volumetric material loss of all specimens before and after 1,200,000 masticatory cycles was evaluated with a 3D profilometer. Light and scanning electron microscopy were used for qualitative analysis. Pairwise comparisons between all the groups were performed using the Mann–Whitney U test (p < 0.05). ResultsMicroscopic imaging revealed different wear patterns for each material. Lowest fracture rates were documented for the CCs. In contrast, all the SSCs showed perforations. The CCs cemented with RMGIC showed the highest significant volumetric wear (6.3 ± 0.72 mm³), followed by the SSCs cemented with RMGIC (3.6 ± 1.79 mm³) and CCs cemented with SAC (3.5 ± 1.92 mm³). No significant differences were found in terms of the wear among all the other groups, ranging between 0.4 ± 0.25 and 0.6 ± 0.32 mm³. ConclusionThe volume loss of the tested crowns differed for each material and was dependent on the type of cementation. With regard to in vitro wear and fracture patterns, cementation with SAC may increase the clinical performance of CC paediatric crowns.

Effect of adding micro and nano-carbon particles on conventional glass ionomer cement mechanical properties

Abstract The aim of the work is to characterize the mechanical properties of glass dental materials Glass Ionomer Cement (GIC) after adding Carbon micro and nano particles with (3, 5 and 7) wt% of the additives into the powder component of (Riva self-cure from SDI limited Australia, shade A1). Compressive strength (Cs), Biaxial Flexural Strength (BFS), Vickers Microhardness Numbers (VHN) and wear rate losses (WR) were evaluated. The maximum compression strength was 120.347 MPa with 7 wt% Carbon micro particle, while maximum VHN and BFS was 72.04 VHN and 41.331 MPa were achieved with 7 wt% CNPs. On other hand minimum wear rate losses was 1.3216 µg/m at 7 wt% Carbon micro particle. GIC-containing Carbon micro and nanoparticles is a promising restorative material with improved mechanical properties. This novel experimental GIC may be potentially used for higher stress-bearing site restorations.

Antimicrobial Effect of an Experimental Glass Ionomer Cement against Pathogens associated with Deep Carious Lesions

To study the antimicrobial effect of chlorhexidine diacetate (CHX-D)-modified type II glass ionomer cement (GIC) against the two predominant deep caries microorganisms, namely Lactobacillus casei and Actinomyces viscosus. An experimental GIC (ex-GIC) was prepared by mixing CHX-D powder with the powder of type II GIC to obtain 1% (w/w) concentration of CHX-D in the GIC. Antibacterial activity of this ex-GIC was tested against L. casei and A. viscosus using the agar diffusion method. The ex-GIC specimens were tested in their unset and set forms for each bacterium. For the unset group, specimens were placed in each agar plate immediately after manipulation and for the set group, specimens were placed in each agar plate, 1 hour after manipulation. The inhibition zones on the agar plate were recorded in millimeters immediately on placement of the specimen in the agar plate and after 48 hours. The reading was recorded and statistically analyzed for significant difference. Mann-Whitney U test showed statistically significant difference in the inhibition zones produced by ex-GIC against L. casei and A. viscosus when both were compared in unset (p-value = 0.002) and set (p-value = 0.031) groups. For both the groups, the zone of inhibition against L. casei was greater. Though the unset group recorded wider zone of inhibition, the difference was not significant when compared with the respective set group. This was true for both the bacterial groups. The 1% CHX-D-modified type II GIC showed antibacterial property against L. casei and A. viscosus and significantly higher activity against L. casei. Addition of 1% CHX-D to type II GIC showed evidence of antibacterial activity against organisms found in deep carious lesion and therefore may exhibit superior antimicrobial efficiency when used as an intermediate therapeutic restoration in deep cavities.

Sol–gel-derived bioactive glass nanoparticle-incorporated glass ionomer cement with or without chitosan for enhanced mechanical and biomineralization properties

ObjectiveThis study investigated the mechanical and in vitro biological properties (in immortalized human dental pulp stem cells (ihDPSCs)) of bioactive glass nanoparticle (BGN)-incorporated glass ionomer cement (GIC) with or without chitosan as a binder. MethodsAfter the BGNs were synthesized and characterized, three experimental GICs and a control (conventional GIC) that differed in the additive incorporated into a commercial GIC liquid (Hy-bond, Shofu, Japan) were produced: BG5 (5wt% of BGNs), CL0.5 (0.5wt% of chitosan), and BG5+CL0.5 (5wt% of BGNs and 0.5wt% of chitosan). After the net setting time was determined, weight change and bioactivity were analyzed in simulated body fluid (SBF) at 37°C. Mechanical properties (compressive strength, diametral tensile strength, flexural strength and modulus) were measured according to the incubation time (up to 28 days) in SBF. Cytotoxicity (1day) and biomineralization (14 days), assessed by alizarin red staining, were investigated using an extract from GIC and ihDPSCs. Data were analyzed using one-way analysis of variance (ANOVA) followed by Tukey’s post hoc test; p<0.05. ResultsBGNs were sol–gel synthesized to be approximately 42nm in diameter with a spherical morphology and amorphous structure. After the bioactivity and suspension ability of the BGNs were confirmed, all the experimental GIC groups had setting times of less than 6min and approximately 1% weight loss after 28days of incubation. In addition, BGNs incorporated into GIC (BG5 and BG5+CL0.5) exhibited surface bioactivity. The mechanical properties were increased in the BGN-incorporated GICs compared to those in the control (p<0.05). Without cytotoxicity, the biomineralization capacity was ranked in the order BG5, BG5+CL0.5, control, and CL0.5 (p<0.05). SignificanceBGN-incorporated GIC showed enhanced mechanical properties such as compressive, diametral tensile and flexural strength as well as in vitro biomineralization properties in ihDPSCs without cytotoxicity. Therefore, the developed BGN-incorporated GIC is a promising restorative dental material, although further in vivo investigation is needed before clinical application.

The addition of synthesized hydroxyapatite and fluorapatite nanoparticles to a glass-ionomer cement for dental restoration and its effects on mechanical properties

The objective of this study was to evaluate the effect of the addition of synthesized hydroxyapatite (HA) and fluorapatite (FA) nanoparticles to a glass-ionomer cement (GIC) on the mechanical properties, while preserving their unique and potent clinical properties. Bioceramics, such as HA and FA, have been recognized as restorative materials (e.g. GICs) in dentistry due to their chemical and biological compatibility with human hard tissues, which are considered calcium phosphate complexes. In this study, both of these inorganic nanoparticles (HA and FA) were synthesized via a wet-chemical precipitation method. The obtained nanoparticles were characterized with X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) Theory. Then, HA and FA were incorporated into the powder component of the resin-modified cement (Fuji II, GC gold label, GC international, Tokyo, Japan) at 5% and 8wt%, and unblended powder was employed as control. Compressive strength (CS) and diametral tensile strength (DTA) before and after 1, 7 and 28 days of storage in distilled water were evaluated using a universal testing machine. Surface microhardness after 1 and 7 days of storage in distilled water was determined using Vickers microhardness tester. Setting and working time was measured as specified in the ASTM standard. The surface morphology of the modified GICs was examined using SEM observations. The morphology of the synthesized HA and FA nanoparticles was hexagonal, and their average sizes were about 25nm and 30nm, respectively. The mechanical results of the modified GICs ascertained addition of HA and FA (5 and 8wt%) into the glass ionomer cement after 7 days of storage in distilled water exhibited statistically higher CS of about 107–113.6MPa and 111–117.8MPa, respectively, and also higher DTS, 13–16MPa and 14–19MPa, respectively. The hardness of the glass ionomers containing HA and FA nanoparticles (5wt%) were increased by 2.21% and 11.77%, respectively. In addition, working time and setting time by adding the 5% nanoparticles were reduced about 8.5% and 13.23% for HA and 10.63% and 19.11% for FA, respectively. It was concluded that glass ionomer cements containing nanobioceramics (HA and FA) are promising restorative dental materials with improved mechanical properties. These experimental GICs may be potentially employed for higher stress-bearing site restorations, such as Class I and II restorations.

Long-term clinical performance of experimental glass-ionomer cement with the bi-functional fluid

Long-term clinical performance of experimental glass-ionomer cement with the bi-functional fluid

Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO.

Some weaknesses of conventional glass ionomer cement (GIC) as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved. Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol%) of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitro rat dental pulp stem cells (rDPSCs) viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min) specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05) and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

Calcium polyphosphate as an additive to zinc-silicate glass ionomer cements.

Aluminum-free glass ionomer cements (GICs) are under development for orthopedic applications, but are limited by their insufficient handling properties. Here, the addition of calcium polyphosphate (CPP) was investigated as an additive to an experimental zinc-silicate glass ionomer cement. A 50% maximum increase in working time was observed with CPP addition, though this was not clinically significant due to the short working times of the starting zinc-silicate GIC. Surprisingly, CPP also improved the mechanical properties, especially the tensile strength which increased by ∼33% after 30 days in TRIS buffer solution upon CPP addition up to 37.5 wt%. This strengthening may have been due to the formation of ionic crosslinks between the polyphosphate chains and polyacrylic acid. Thus, CPP is a potential additive to future GIC compositions as it has been shown to improve handling and mechanical properties. In addition, CPP may stimulate new bone growth and provide the ability for drug delivery, which are desirable modifications for an orthopedic cement.

Comparative evaluation of the antibacterial and physical properties of conventional glass ionomer cement containing chlorhexidine and antibiotics.

Objective:To evaluate the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) containing chlorhexidine and antibiotics at varying concentrations.Materials and Methods:Chlorhexidine diacetate and antibiotics (ciprofloxacin, metronidazole, and minocycline) were incorporated into GIC Fuji IX at 1.5% and 3% w/w ratio to form the experimental groups. The experimental GIC specimens were placed on brain heart infusion agar plates inoculated with Streptococcus mutans, and the area of inhibition was measured after 48 h. The 24-h compressive strength of the set specimens was evaluated using a Universal Testing Machine.Results:The control group demonstrated no zone of inhibition. All experimental groups showed inhibition against S. mutans (P < 0.05), with larger zones of inhibition found in the higher concentration groups. Compressive strength at the end of 24 h decreased in the experimental groups as compared to the control group (P < 0.05), but no difference was found between the experimental groups (P > 0.05).Conclusion:The present study demonstrated that experimental GICs containing chlorhexidine diacetate and antibiotics were effective in inhibiting S. mutans, and incorporation of 1.5% ABX was optimal to give the appropriate antibacterial and physical properties.

Properties of a proline-containing glass ionomer dental cement

Proline-containing glass ionomers are promising fast-set dental restorative materials with superior mechanical properties; however, little information is available on other physical properties of this type of glass ionomer. The objectives of this study were to synthesize and characterize a polyacrylic acid terpolymer containing proline derivative (PD) and to investigate the physical properties of this glass ionomer cement (GIC) and its cytotoxicity invitro. A terpolymer of AA (acrylic acid), IA (itaconic acid), and proline derivative (MP) with an 8:1:1 molar ratio was synthesized and characterized. Experimental GIC specimens were made from the synthetized terpolymer with Fuji IX (GC America, Alsip, Ill) commercial glass ionomer powder as recommended by the manufacturer. Specimens were mixed and fabricated at room temperature and were conditioned in distilled water at 37°C for 1 day and 1 week. Vickers hardness was determined with a microhardness tester. The water sorption characteristics and fluoride releasing properties of the specimens were investigated. The invitro cytotoxicity of the experimental glass ionomer was assessed by evaluating the C2C12 cell metabolism with methyltetrazolium (MTT) assay. Commercial Fuji IX was used as a control for comparison. The data obtained for the experimental GIC (PD) were compared with the control group by using 1- and 2-way ANOVA and the Tukey multiple range test at α=.05. Proline-modified GIC (PD) exhibited significantly higher surface hardness values (Vickers hardness number [VHN] 58 ±6.1) in comparison to Fuji IX GIC (VHN 47 ±5.3) after 1 week of maturation. Statistical analysis of data showed that the water sorption properties of the experimental cement (PD) were significantly greater than those of the control group (P<.05). The experimental GIC showed a significant increase in the amounts of initial fluoride release (P<.05) with continued fluoride release from the bulk of the material. The experimental group showed slightly reduced cell metabolism and cell number in comparison to the control group. However, the results were not statistically different (P>.05). An amino acid-containing GIC had better surface hardness properties than commercial Fuji IX GIC. This formulation of fast-set glass ionomer showed increased water sorption without adversely affecting the amount of fluoride release. Considering its biocompatibility, this material shows promise not only as a dental restorative material but also as a bone cement with low cytotoxicity.

In vitro antibacterial effects of glassionomer cement containing ethanolic extract of propolis on Streptococcus mutans

The aim of this study was to evaluate the antibacterial property of glass-ionomer cement (GIC) containing propolis against Streptococcus mutans and its effect on the in vitro S. mutans biofilm formation. Ethanolic extract of propolis (EEP) was prepared at two concentrations as 25 and 50%. Three different experimental GIC disks were prepared using pure liquid and liquid solutions diluted with 25 and 50 percent of EEP concentrations. Minimum inhibitory concentration (MIC) of EEP on the growth of S. mutans ATCC 25175 was determined by using agar dilution method. Agar diffusion test and an in vitro S. mutans biofilm assay for GIC disks with and without EEP were performed. MIC values of Turkish propolis for S. mutans ATCC 25175 was found as 25 μg/mL. Experimental GICs containing propolis exhibited inhibition zones and their dry biofilm weights were less than the pure GIC. The bacterial density was lower in the GIC containing 50% EEP. A distinct antibacterial and antibiofilm efficacy of propolis containing GIC on S. mutans has been observed. Although further research is needed to show clinical results, antibacterial GIC containing propolis would be a promising material for restoration.

Ultrasonically set novel NVC-containing glass-ionomer cements for applications in restorative dentistry

The objective of this study is to investigate the effects of application of ultrasound on the physical properties of a novel NVC (N-vinylcaprolactam)-containing conventional glass-ionomer cement (GIC). Experimental GIC (EXP) samples were made from the acrylic acid (AA)-itaconic acid (IA)-NVC synthesized terpolymer with Fuji IX powder in a 3.6:1 P/L ratio as recommended by the manufacturer. Specimens were mixed and fabricated at room temperature and were conditioned in distilled water at 37°C for 1 day up to 4 week. Ultrasound (US) was applied 20 s after mixing by placing the dental scaler tip on the top of the cement and applying light hand pressure to ensure the tip remained in contact with cement without causing any deformation. Vickers hardness was determined using a microhardness tester. The working and setting times were determined using a Gillmore needle. Water sorption was also investigated. Commercial Fuji IX was used as control for comparison (CON). The data obtained for the EXP GIC set through conventional set (CS) and ultrasonically set (US) were compared with the CON group, using one-way ANOVA and the Tukey multiple range test at α = 0.05. Not only ultrasonic (US) application accelerated the curing process of both EXP cement and CON group but also improved the surface hardness of all the specimens. US set samples showed significantly lower water sorption values (P < 0.05) due to improved acid-base reaction within the GIC matrix and accelerated maturation process. According to the statistical analysis of data, significant increase was observed in the surface hardness properties of CS and US specimens both in EXP samples and the CON groups. It was concluded that it is possible to command set GICs by the application of ultrasound, leading to GICs with enhanced physical and handling properties. US application might be a potential way to broaden the clinical applications of conventional GICs in restorative dentistry for procedures such as class V cavity restorations.

The Effect of Incorporating Lithium Fluoride on the Compressive Strength and Diametric Tensile Strength of Glass Ionomer Cement

Experimental glass ionomer cement was prepared for the purpose of this study. Twenty disk specimens (16mm diameter x 10mm height) of test-GIC were prepared for the diametral tensile strength (DTS) test and twenty cylindrical specimens (6 mm diameter x 16mm height) were prepared for the compressive strength (CS) test. Specimens were stored in an artificial saliva at 37º C and (50±10%) of relative humidity in an incubator until testing. Five specimens of each GIC were submitted to CS and DTS test in each period, namely 1 hour, 24 hours, 7 days and 28 days. The specimens were tested in a Universal Testing Machine (Instron 1122, Instron corp., High Wycombe, U.K.) at a crosshead speed of 1.0mm/min for CS and 0.5mm/min for the DTS test until failure occurred. The results have revealed that incorporation of lithium fluoride in the formula of the test GIC might impart an increase in the mechanical properties of the GICs

Hydroxyapatite particle characteristics influence the enhancement of the mechanical and chemical properties of conventional restorative glassionomer cement

The aims of this study were to improve the mechanical and chemical properties of conventional restorative glass ionomer cement (GIC) by adding hydroxyapatite (HAp) preparations with different characteristics, and to investigate the underlying reaction mechanisms. Fuji IX GP® was used as the control GIC. The experimental GICs consisted of four HAp-particles with different characteristics added at 8 mass% to Fuji IX-powder. All cements were prepared by mixing with Fuji IX-liquid (P/L=3.6). Four HAp-particles were analyzed, and then the mechanical strengths and the fluoride-ion- release-recharge-behaviors of five GIC groups were evaluated. The results of this study demonstrate that the addition of HAp particles with highly reactive properties such as high specific surface area can enhance the flexural strength and fluoride ion release properties of conventional restorative GIC. Our results further indicate that HAp functions as an adsorbent and an ion exchangeable agent, resulting in improved mechanical and chemical properties of GIC.

Synthesis and biocompatibility of an experimental glass ionomer cement prepared by a non-hydrolytic sol-gel method

The aims of this study were to demonstrate the synthesis of an experimental glass ionomer cement (GIC) by the non-hydrolytic sol-gel method and to evaluate its biocompatibility in comparison to a conventional glass ionomer cement (Vidrion R). Four polyethylene tubes containing the tested cements were implanted in the dorsal region of 15 rats, as follows: GI - experimental GIC and GII - conventional GIC. The external tube walls was considered the control group (CG). The rats were sacrificed 7, 21 and 42 days after implant placement for histopathological analysis. A four-point (I-IV) scoring system was used to graduate the inflammatory reaction. Regarding the experimental GIC sintherization, thermogravimetric and x-ray diffraction analysis demonstrated vitreous material formation at 110oC by the sol-gel method. For biocompatibility test, results showed a moderate chronic inflammatory reaction for GI (III), severe for GII (IV) and mild for CG (II) at 7 days. After 21 days, GI presented a mild reaction (II); GII, moderate (III) and CG, mild (II). At 42 days, GI showed a mild/absent inflammatory reaction (II to I), similar to GII (II to I). CG presented absence of chronic inflammatory reaction (I). It was concluded that the experimental GIC presented mild/absent tissue reaction after 42 days, being biocompatible when tested in the connective tissue of rats.

Evaluation of the antibacterial and physical properties of glass ionomer cements containing chlorhexidine and cetrimide: An in-vitro study

Incorporation of antibacterial agents frequently results in changes in the physical properties of restorative materials. This in-vitro study investigated the antibacterial and physical properties of Glass ionomer cement (GIC) with chlorhexidine and cetrimide, to determine the optimal concentration, for incorporation of these agents to obtain antibacterial GICs for use with the Atraumatic restorative treatment approach. This was assessed using the agar diffusion test. Chlorhexidine diacetate and cetrimide were added to Glass ionomer cement type-IX (GIC-FUJI IX) at 1 and 2% W/W ratio. The experimental GIC specimens were placed on agar plates inoculated with Lactobacillus casei, and the area of inhibition was calculated after 48 hours. All the experimental GICs exhibited inhibition of bacteria, but the sizes were dependent on the concentration of the antibacterial agent. Incorporation of chlorhexidine diacetate and cetrimide, at 2%, significantly decreased the compressive strength, and the setting time was extended a little by the addition of any concentration of chlorhexidine and cetrimide. The present study demonstrated that experimental GICs containing chlorhexidine diacetate and cetrimide were effective in inhibiting bacteria associated with caries, and incorporation of 1% cetrimide was optimal to give the appropriate antibacterial and physical properties.