A comparative study of color stability and fluoride release from glass ionomer cements combined with chlorhexidine

Comparative Analysis of Color Stability and Its Impact on Artificial Aging: An In Vitro Study of Bioactive Chitosan, Titanium, Zirconia, and Hydroxyapatite Nanoparticle-Reinforced Glass Ionomer Cement Compared With Conventional Glass Ionomer Cement

Background Discoloration affects glass ionomer cement (GIC) color stability due to its brittle nature and microporosity. To counter this, incorporating alternative materials is essential for maintaining color stability. Aim This study aims to determine the color stability and gloss of GIC modified with bioactive chitosan, titanium, zirconia, and hydroxyapatite nanoparticles before and after artificial aging. Materials and methods  The study was conducted at Saveetha Research Centre, Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, located in Chennai, India. Green-mediated chitosan, titanium, zirconia, and hydroxyapatite (Ch-Ti-Zr-HA) nanoparticles were synthesized using the one-pot synthesis technique. Forty-eight disc-shaped specimens were prepared by incorporating the obtained nanoparticles (nanocomposite) into the GIC, with a diameter of 5 mm and thickness of 2 mm. The specimens were prepared in different concentrations (3%, 5%, and 10%) designated as group I, group II, and group III, respectively. Group IV, serving as the control, consisted of conventional GIC without any modifications. Following preparation, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis confirmed sample elements, and the specimens were submerged in distilled water for a duration of 24 hours prior to the commencement of testing. Subsequently, the specimens underwent artificial aging (thermocycling), between temperatures of 5°C and 55°C, for a total of 30,000 cycles, with a 30-second dwell time. Color change and gloss characteristics were assessed both after 24 hours and following thermocycling using a spectrophotometer and glossometer, respectively. The average color change parameter (ΔE) was measured using Adobe Photoshop. The data obtained were subjected to statistical analysis using an unpaired t-test. Results Significant color stability variations were observed post thermocycling (P = 0.001). Group 2 (5%) exhibited minimal delta E difference (0.508 ± 0.105), indicating superior color stability, while group 4 (control) had maximum difference (1.15 ± 0.187), indicating lower stability. Gloss tests confirmed GIC's polishability, where there were significant differences among all the groups. Conclusion It can be concluded that 5% nanoparticle-modified GIC has better color stability and gloss than conventional GIC. Further studies are needed to analyze the color stability and gloss through dentifrices and other beverages.

Evaluation of Fracture Toughness, Color Stability, and Sorption Solubility of a Fabricated Novel Glass Ionomer Nano Zirconia-Silica-Hydroxyapatite Hybrid Composite Material

The aim of this study was to investigate the effects of adding a nano zirconia-silica-hydroxyapatite (nanoZrO2-SiO2-HA) composite synthesized using a one-pot sol-gel technique to a conventional glass ionomer cement (GIC), which was then characterized using X-ray diffraction (XRD). Following the characterization studies, further investigations were carried out after the addition of nanoZrO2-SiO2-HA to cGIC (GIC nanoZrO2-SiO2-HA) at various percentages (~5% to 9%) to compare their fracture toughness, color stability, and sorption- solubility in relation to cGIC (Fuji IX). The XRD diffractogram indicated the presence of peaks for ZrO2, SiO2, and HA. The fracture toughness of GIC 5%nanoZrO2-SiO2-HA was statistically higher than that of other percentages of GIC nanoZrO2-SiO2-HA and cGIC. The highest values recorded were fracture toughness ( $1.35\pm 0.15\text{MPa}.{\text{m}}^{1/2}$ ), leading to an increase of ∼57%, as compared to cGIC. Overall, the color change ( $\Delta E$ ) values for GIC 5% nano Zr-Si-HA group were lower than those of cGIC over a one-month period and were between slight and perceptible. In addition, GIC 5%nanoZrO2-SiO2-HA recorded lower sorption values ( $23.64\pm 2.3\mu \text{gm}{\text{m}}^{-3}$ ) as compared to cGIC ( $36.28\pm 2.6\mu \text{gm}{\text{m}}^{-3}$ ) and higher solubility ( $66.46\pm 2.4\mu \text{gm}{\text{m}}^{-3}$ ) as compared to cGIC ( $56.76\pm 1.6\mu \text{gm}{\text{m}}^{-3}$ ). The addition of nanoZrO2-SiO2-HA to cGIC significantly enhanced its physicomechanical properties. Based on the results of our study, GIC nanoZrO2-SiO2-HA has the potential to be suggested as a restorative dental material with diverse applications ranging from cavity restoration, core build-up, and as a luting material.

Color Stability of Glass Ionomer Cement after Reinforced with Two Different Nanoparticles

Aim

This study aimed to compare the staining characteristics of a commercially available restorative glass ionomer cement to a formulation reinforced by the addition of carbon nanotubes and another formulation reinforced by the addition of silver nanoparticles to the powder of the same cement. Methodology. Twenty samples each of a control glass ionomer cement (PULPDENT® Glass Fill®, Pulpdent Corp. Watertown, MA, USA), control cement reinforced with 0.0006 gm (0.03% by weight) of carbon nanotubes (Sigma Aldrich, St Louis MO, USA), and control cement reinforced with 0.2 gm (10% by weight) of silver nanoparticles (Nanocyl™, Nanocyl SA, Sambreville, Belgium) were immersed in a staining solution. Color evaluations were carried out after 1 h, 24 h, and 1 week. Color change values were calculated.

Results

The results indicated that carbon nanotube reinforced specimens exhibited less color stability when compared to controlled glass ionomer cement specimens; however, both samples had significantly greater color stability than silver nanoparticle reinforced glass ionomer samples.

Conclusion

It can be concluded within the limitations of this study that carbon nanotube reinforced glass ionomer cements have better color stability than silver nanoparticle reinforced glass ionomer cements.

Mechanical and optical properties of conventional restorative glass-ionomer cements - a systematic review

Objectives

To perform a systematic review of test methodologies on conventional restorative glass-ionomer cement (GIC) materials for mechanical and optical properties to compare the results between different GICs.

Material and Methods

Screening of titles and abstracts, data extraction, and quality assessments of full-texts were conducted in search for in vitro studies on conventional GICs that follow the relevant specifications of ISO standards regarding the following mechanical and optical properties: compressive strength, flexural strength, color, opacity and radiopacity.

Sources

The Latin American and Caribbean Health Sciences (LILACS), Brazilian Bibliography of Dentistry (BBO) databases from Latin-American and Caribbean System on Health Sciences Information (BIREME) and PubMed/Medline (US National Library of Medicine - National Institutes of Health) databases were searched regardless of language. Altogether, 1146 in vitro studies were selected. Two reviewers independently selected and assessed the articles according to pre-established inclusion/exclusion criteria. Among all the properties investigated, only one study was classified as being of fair quality that tested compressive strength and was included. It was observed that many authors had not strictly followed ISO recommendations and that, for some properties (diametral tensile strength and microhardness), there are no guidelines provided.

Conclusions

It was not possible to compare the results for the mechanical and optical properties of conventional restorative GICs due to the lack of standardization of studies.

Effects of theobromine addition on chemical and mechanical properties of a conventional glass ionomer cement

In vitro effect of 1% theobromine addition on the physical and chemical properties of conventional glass ionomer (GIC) cement was investigated. Conventional GIC (GIC-C) and 1% theobromine added to GIC (GIC-THEO) specimens were compared regarding the microhardness (n = 10), sorption (n = 5), solubility (n = 5), color change (n = 10), fluoride release in saliva (n = 10) and the amount of biofilm deposition (n = 20). Compared against conventional GIC, adding 1% theobromine increased microhardness (p < 0.05), while its sorption, solubility, color and fluoride release to saliva (p > 0.05) remained unchanged. On the other hand, Streptococcus mutans biofilm amount deposited on its surface decreased statistically when theobromine was added to GIC (p < 0.05). Based on the results, it could be concluded that 1% theobromine addition to GIC can be a good strategy as it keeps some of its properties and improves microhardness and biofilm deposits strengthening its role in the preventive approach of dentistry.