The Influence of Mixing Methods on the Compressive Strength and Fluoride Release of Conventional and Resin-Modified Glass Ionomer Cements

Sealing moderate caries lesions with bioactive glass-ionomer: A split-mouth clinical trial

Laboratory evidence has shown that 45S5 bioglass can help in dental remineralization, so its incorporation into resin-modified glass ionomer cement (RMGIC) has been studied. This randomized clinical trial aimed to determine the efficacy of RMGIC enriched with 10% 45S5 bioglass (RMGIC/45S5) in preventing the progression of moderate caries lesions. Sixty-six permanent molars with moderate caries lesions, were randomly sealed with RMGIC or RMGIC/45S5. After 1, 3-6 months, patients' oral health, material behavior, and caries evolution were evaluated. Chi-square and Fisher's exact test was employed. After one month, the RMGIC showed higher total retention and better clinical performance compared to RMGIC/45S5, both showed a predominance of sealed teeth or without caries progression. After 6 months, no materials retention, quality and caries progression difference was observed for both materials. Short-term clinical follow-up reveals worse retention and quality of RMGIC/45S5, only after 6 months no clinical/microscopic differences are observed between the materials.

A comparative evaluation of fluoride release and rechargeability in conventional GIC (type II), pediatric GIC (type IX), and Cention-N: an in vitro study

PURPOSE

A comparative evaluation of fluoride release and re-chargeability in conventional glass ionomer cement (GIC) (type II), Pediatric GIC (type IX), and Cention-N-an in vitro study at an interval of first, fourteenth, and twenty first days.

METHODS

Three groups of test materials, each with twenty samples, were prepared. Measurements of the cumulative fluoride release [parts per million (ppm)] and re-release measured on the first, fourteenth, and twenty first days. Analysis of variance (ANOVA) was used to compare the means for different readings, and Tukey's post hoc analysis was used to compare each group with each other.

RESULTS

Initial and subsequent fluoride release of Cention-N at days one, fourteen, and twenty-one were all noticeably higher than those of conventional and pediatric GIC.

CONCLUSION

Compared to the Conventional and Pediatric GIC restorative materials, Cention-N was more effective in the initial and fluoride re-release.

An Evaluation of Experimental Calcium Ion-Leachable Nanocomposite Glass Ionomer Cements

Glass ionomer cements (GICs) are among the main restorative dental materials used broadly in daily clinical practice. The incorporation of clay nanoparticles as reinforcing agents is one potential approach to improving GIC properties. This study aims to investigate whether the incorporation of calcium-modified clay (Ca-clay) nanoparticles in conventional GICs alters their structural characteristics, along with their physicochemical and mechanical properties. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were performed to assess the surface characterization of GIC nanocomposites, whereas a setting reaction was carried out via an attenuated total reflection Fourier transform infrared spectrometer (ATR-FTIR). A universal testing machine was used for compression tests, while calcium ion release was quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). GIC composite groups reinforced with Ca-clay were found to release a fine amount of calcium ions (5.06-9.91 ppm), with the setting reaction being unaffected for low Ca-clay loadings. The median compressive strength of 3 wt% in the Ca-clay group (68.97 MPa) was nearly doubled compared to that of the control group (33.65 MPa). The incorporation of Ca-clay nanoparticles in GICs offers a promising alternative among dental restorative materials regarding their chemical and mechanical properties.

Retrospective Clinical Evaluation of RMGIC/GIC Class V Restorations

The aim of this retrospective study was to evaluate the clinical performance of glass-ionomer cement (GIC) and resin-modified glass-ionomer cement (RMGIC) materials in Class V carious cervical lesions restored by dental students. Ninety-six (96) restorations performed with either GIC (Fuji IX) (n = 39) or RMGIC (Fuji II LC) (n = 57) were evaluated using the modified USPHS criteria by two independent investigators at two follow-up evaluations (two years apart). The Fisher statistical test was used to compare USPHS criteria and examine significant differences, with a significance level set at p < 0.05. The Kaplan-Meier algorithm was used to calculate the survival probability. The overall success rate of Class V restorations was 72.9% at the second follow-up evaluation, with restorations ranging in age from 2.5 to 3.5 years. The RMGIC (Fuji II LC) restorations exhibited a significantly higher overall success rate compared to the GIC (Fuji IX) restorations (p = 0.0104). Significant differences were observed in retention (p = 0.0034) and color match (p = 0.0023).

Comparative Evaluation of Fluoride Release from Four Commercially Available Pediatric Dental Restorative Materials

Objectives

The aim of this study was to evaluate the fluoride-releasing abilities of commercially available restorative materials such as-Activa™ BioActive-restorative™ material, Zirconomer (Shofu Inc), Beautifil® II (Shofu Inc), GC Gold Label 9 high strength posterior restorative glass ionomer cement (GIC Corp).

Materials and methods

A total of 40 disk specimens (10 of each material) were placed into distilled/deionized (DI) water and the fluoride release was measured for 30 days. Fluoride ion measurement was performed at the end of the 1st, 3rd, 7th, 15th, and 30th day under normal atmospheric conditions by fluoride ion selective electrode (F-ISE) (Orion 9609 BNWP, Ionplus SureFlow fluoride electrode, Thermo Scientific, United States of America) coupled to a benchtop analyzer (Hachsen Ion+).

Results

All the materials included in the study exhibited fluoride release. Although there were differences in the amounts of fluoride released between Activa™, Zirconomer, and GC Gold Label 9 the mean difference between these three groups was not found to be statistically significant. Beautifil® II showed low amounts of fluoride released at all time intervals.

Conclusion

Among the above-compared materials Activa™ and Zirconomer exhibit both improved mechanical properties as well as they have fluoride-releasing ability so can be preferred over conventional glass ionomer restorations.

How to cite this article

Dhumal RS, Chauhan RS, Patil V, et al. Comparative Evaluation of Fluoride Release from Four Commercially Available Pediatric Dental Restorative Materials. Int J Clin Pediatr Dent 2023;16(S-1):S6-S12.

Effect of Bioactive Filler Addition on the Mechanical and Biological Properties of Resin-Modified Glass Ionomer

The maintenance of affected dentin can promote the greater conservation of tooth structure. The development of materials that have properties capable of reducing the demineralizing potential and/or even helping in dental remineralization is important for conservative dentistry. This study aimed to evaluate, in vitro, the alkalizing potential, fluoride as well as calcium ion release ability, antimicrobial activity, and dentin remineralization properties of resin-modified glass ionomer cement (RMGIC) incorporated with a bioactive filler (niobium phosphate (NbG) and bioglass (45S5)). The study samples were grouped into RMGIC, NbG, and 45S5. The materials' alkalizing potential, ability to release calcium as well as fluoride ions, and antimicrobial properties concerning Streptococcus mutans UA159 biofilms were analyzed. The remineralization potential was evaluated using the Knoop microhardness test, which was performed at different depths. The alkalizing and fluoride release potential was higher for the 45S5 group (p < 0.001) over time. An increase in the microhardness of demineralized dentin was observed in the 45S5 and NbG groups (p < 0.001). No differences in biofilm formation were observed between the bioactive materials, although 45S5 exhibited lower biofilm acidogenicity at different time points (p < 0.001) and greater calcium ion release in the microbial environment. A resin-modified glass ionomer cement enriched with bioactive glasses, particularly 45S5, is a promising alternative for the treatment of demineralized dentin.

Evaluation of the Mechanical Properties of Three Resin-Modified Glass-Ionomer Materials

This study is aimed at evaluating the flexural strength (FS), fracture toughness (FT), and diametral tensile strength (DTS) of three resin-modified glass-ionomer cements (RMGICs): Ketac Nano, Riva Light Cure, and Fuji II LC. One hundred twenty specimens were prepared from the RMGIC materials ( $n=10$ ). The cements were mixed and inserted into different mould sizes according to the test performed: FS: rectangular Teflon mould ( $32\text{mm}\times 3.15\text{mm}\times 2\text{mm}$ ); FT: notchless triangular prism (NTP) Teflon mould ( $6\text{mm}\times 6\text{mm}\times 6\text{mm}\times 12\text{mm}$ ); and DTS: ring road stainless steel mould ( $6\text{mm}\times 3\text{mm}$ ). Specimens were light cured for 20 seconds on each surface and stored in distilled water at ${37}^{°}\text{C}\pm 2^{°}\text{C}$ for seven days prior to tests. To evaluate the influence of storage in the mechanical properties of the RMGIs, specimens tested for DTS were stored in distilled water at ${37}^{°}\text{C}\pm 2^{°}\text{C}$ for 32 days prior to test. Data were analyzed by ANOVA and Tukey’s test ( $\alpha =0.05$ ). Fuji II LC presented significantly higher values for all tests employed when compared to Ketac Nano and Riva LC RMGIs. There was no significant difference on DTS before and after the 32-day storage for each material. Fuji II LC presented superior mechanical properties when compared to Ketac Nano, and Riva LC storage showed no influence on the mechanical properties of the RMGI materials tested.

Effect of zinc oxide nanoparticles on physical and antimicrobial properties of resin-modified glass ionomer cement

Background:

To improve the limitations, many modifications in the resin-modified glass ionomer (RMGI) composition have been proposed. In this study, we evaluated the effect of different concentrations of zinc oxide (ZnO) nanoparticles incorporated into RMGI cement on its physical and antimicrobial properties.

Materials and Methods:

In this in vitro study, ZnO nanoparticles with 0–4 wt.% concentrations were incorporated into RMGI. The following tests were carried out: (a) Antibacterial activity against Streptococcus mutans tested by disc diffusion method, (b) mechanical behavior assessment by measuring flexural strength (FS) and flexural modulus (FM), (c) micro-shear bond strength (μ-SBS), and (d) fluoride and zinc release. Data were analyzed using the statistical tests of ANOVA, t-test, and Tukey's HSD post hoc in SPSS V22. The level of significancy was 0.05.

Results:

In the disc diffusion method, specimens with 2 wt.% ZnO nanoparticles showed the highest antimicrobial efficacy (P < 0.05). After 1 month of water storage, no significant difference was observed in FS and FM of the samples (P > 0.05). In 2 wt.% ZnO nanoparticles group, μSBS increased in the first 7 days but decreased by 17% after one month, which showed a significant difference with that of the control group. The fluoride release did no change in the ZnO nanoparticle-containing group compared with the control group at all time intervals.

Conclusion:

Incorporation of 2 wt.% ZnO nanoparticles into the RMGI cement adds antimicrobial activity to the cement without sacrificing FS and fluoride release properties, while decreased μSBS.

Synergistic impact of cellulose nanocrystals with multiple resins on thermal and mechanical behavior

The cellulose nanocrystals (CNCs) surface modified with phenolic and acrylic resins were investigated for different properties such as thermally stability and adhesive property, the mechanical properties of CNCs and interactions of the resulting materials at a micro-level are very important. Phenolic resins are of great interest due to their smooth structure, low thermal conductivity and good thermal insulation. However, the high spray rates and poor mechanical properties limit its use for external insulation of buildings. Acrylic resins are used as a matrix resin for adhesives and composites due to their adhesion, mechanical properties, and their good chemical resistance. The brittleness of acrylic resins makes them less attractive than the structural materials, being much harder. For this reason, most of the resins are modified with suitable elastomers, which act as hardeners. Therefore, treatment of these compounds is necessary. In this research paper, the effect of CNCs surface on phenolic and acrylic resins were investigated to obtain an optimized surface using three different weight (wt%) ratios of CNCs. Scanning electronic microscopy (SEM), X-rays diffraction (XRD), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structure, and investigate different properties of CNCs. Furthermore, the Zwick/Roell Z020 model was used to investigate the adhesion properties of the phenolic and acrylic resins with CNCs.

Flexural strength and surface microhardness of materials used for temporary dental disocclusion submitted to thermal cycling: An in vitro study

OBJECTIVE

The objective of this study was to evaluate the effect of temperature variation on surface microhardness and resistance to flexion of different materials used for making a temporary dental disocclusion.

METHODS

One hundred specimens were made of the following materials (n=20): glass ionomer cement (GIC); compomer (CP); composite resin (CR); Blue colour resin composite for temporary dental disocclusion (BTDD); ultraviolet colour resin composite for temporary dental disocclusion (UVTDD). They were stored in distilled water for 24hours and, subsequently, half of the specimens in each group were subjected to thermal cycling (n=10). All samples were subjected to the microhardness test (HMV-2000) and the flexural strength analysis (INSTRON). The data were submitted to parametric statistical analysis (ANOVA) and Tukey's complementary test with a significance level of 5%. In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P<0.05) was responsible for the reduction of the values found, except for GIC.

RESULTS

In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P<0.05) was responsible for the reduction of the values found, except for GIC. For microhardness, the highest average was found for BTDD and UVTDD (P≤0.05). As for the resistance, the flexion was found that in the groups not submitted to thermal cycling there was no statistically significant difference for all materials, except for GIC, for the groups with thermal cycling the materials BTDD and UVTDD showed a statistically significant difference from GIC, however, they did not differ statistically from the CP and CR groups.

CONCLUSION

BTDD and UVTDD presented higher average results of surface microhardness and, in the resistance test, the flexion of these materials behaved similarly to the CP and the CR studied. The temperature variation has an effect on the properties of these materials.