Organic antibacterial modifications of high-viscosity glass ionomer cement for atraumatic restorative treatment: A review

High viscosity glass ionomer cement (HVGIC) has been employed as a restorative material for Atraumatic Restorative Treatment (ART). As residual caries persist after caries removal in ART, the antibacterial activity of HVGIC gains importance. Organic and inorganic substances with antibacterial properties have been incorporated into HVGIC over the years, and their effects on the antibacterial and physical properties have been studied. The objective of this paper is to review the various alterations made to HVGIC using organic compounds, their effect on the antibacterial activity, and the physical properties of the cement. Various in vitro investigations have been conducted by adding antiseptics, antibiotics, and naturally occurring antibacterial substances. Most of these compounds render superior antibacterial properties to HVGIC, but higher concentrations affect physical properties in a dose-dependent manner. However, some naturally occurring antibacterial substances, such as chitosan, improve the physical properties of HVGIC, as they enhance cross-linking and polysalt bridging. There is potential for clinical benefits to be gained from the addition of organic antibacterial compounds to HVGIC. In-depth research is required to determine the optimum concentration at which the antibacterial effect is maximum without affecting the physical properties of the cement.

Prevention of secondary caries using fluoride-loaded chitosan nanoparticle-modified glass-ionomer cement

OBJECTIVE

To study the effect of incorporating chitosan and fluoride-loaded chitosan nanoparticles into a glass-ionomer cement (GIC) to prevent secondary caries.

MATERIALS AND METHODS

A standard cervical cavity (mesio-distal width 6 mm, cervico-occlusal width 2 mm, and depth 2 mm) was prepared on 30 molars for the following restoration groups: group 1, conventional GIC restoration; group 2, chitosan (10%) modified GIC restoration; group 3, fluoride loaded chitosan nanoparticles (10%) modified GIC restoration. The restored teeth were subjected to 1,500 thermal cycles before undergoing a multi-species cariogenic biofilm challenge. The restored teeth were examined by micro-computed tomography (micro-CT), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). Data were analyzed by the one-way ANOVA, Tukey HDS, Kruskal Wallis, and Dunn's test.

RESULTS

Micro-CT determined outer lesion depths for groups 1-3 were: 614 ± 20 μm, 589 ± 17 μm, and 560 ± 19 μm respectively. Both modifications with chitosan and fluoride-loaded chitosan nanoparticles significantly affected outer lesion depth (p < 0.05). The modification with fluoride-loaded chitosan nanoparticles statistically significantly decreased the outer lesion depth compared to all other groups (p < 0.05). SEM/EDX showed an increase of calcium, phosphorus, and fluoride at the root dentine adjacent to the restoration in groups 2 and 3 (modified GIC). This increase was statistically significantly higher in the group modified with fluorine-loaded nano chitosan particles compared to the other groups (p < 0.05).

CONCLUSION

Incorporation of 10% chitosan and 10% fluoride-loaded chitosan nanoparticles into GIC restorative material can prevent secondary root caries development. 10% fluoride-loaded chitosan nanoparticles were more effective.

CLINICAL SIGNIFICANCE

Glass ionomer cement modified with fluoride-loaded chitosan nanoparticles may be a promising restorative material in pediatric and preventive dentistry due to their controlled release properties.

Evaluating antimicrobial, cytotoxic and immunomodulatory effects of glass ionomer cement modified by chitosan and hydroxyapatite

OBJECTIVES

This study aimed to assess antimicrobial efficacy, cytotoxicity, and cytokine release (IL-1b, IL-6, IL-10, TNF-α) from human dental pulp stem cells (hDPSCs) of chitosan (CH) and hydroxyapatite (HAp)-modified glass ionomer cements (GIC).

METHODS

GICs with varied CH and HAp concentrations (0 %, 0.16 %, 2 %, 5 %, 10 %) were tested against S. mutans for 24 h or 7 days. Antimicrobial activity was measured using an MTT test. Cytotoxicity evaluation followed for optimal concentrations, analyzing mitochondrial activity and apoptosis in hDPSCs. Cytokine release was assessed with MAGPIX. Antimicrobial analysis used Shapiro-Wilk, Kruskal-Wallis, and Dunnett tests. Two-way ANOVA, Tukey, and Dunnett tests were applied for hDP metabolism and cytokine release.

RESULTS

CH 2 % and HAp 5 % significantly enhanced GIC antimicrobial activity, especially after seven days. In immediate analysis, all materials showed reduced mitochondrial activity compared to the control. After 24 h, CH demonstrated mitochondrial metabolism similar to the control. All groups exhibited mild cytotoxicity (∼30 % cell death). Only IL-6 was influenced, with reduced release in experimental groups.

SIGNIFICANCE

CH 2 % and HAp 5 % were most effective for antibacterial effects. GIC-CH 2 % emerged as the most promising formula, displaying significant antibacterial effects with reduced hDPSC toxicity.

Physical and mechanical properties assessment of glass ionomer cements modified with TiO2 and Mg-doped hydroxyapatite nanoparticles

High viscosity glass ionomer cements (GICs) are widely used in various clinical applications, being particularly effective in atraumatic restorative treatment (ART) due to the synergistic interaction between the material and the technique. However, the inadequate mechanical properties of GICs raise concerns regarding the predictability and longevity of these restorations in areas exposed to occlusal stress. Various modifications of the powder components have been proposed to improve the mechanical strength of GICs to withstand occlusal loading during mastication. In this in vitro study, we investigated whether the nanoparticles (NPs) added to commercially available GICs could fulfill this requirement, which would likely broaden the spectrum of their potential clinical applications. Two commercially available GIC powders (Fuji IX and Ketac Molar), modified by the addition of 5 wt.% TiO2, MgHAp100 or MgHAp1000 NPs, were incorporated into the corresponding liquid in an appropriate ratio, and the mixed cements were evaluated in terms of fracture toughness, flexural strength, Vickers microhardness and rheological tests and compared with the original material. Fuji IX containing 5 wt.% MgHAp100 NPs had lower flexural strength, while Ketac Molar with 5 wt.% TiO2 NPs showed increased fracture toughness. Vickers microhardness increased in Fuji IX following the addition of 5 wt.% TiO2 and MgHAp100 but decreased in Ketac Molar comprising 5 wt.% MgHAp100 (p < 0.05). Achieving a predictable bond between NPs and cement matrix, as well as ensuring a uniform distribution of the NPs within the cement, are critical prerequisites for enhancing the mechanical performance of the original cement.

Improving the Antibacterial Properties of Dental Bonding Materials Loaded with Silver Compounds

Biofilm accumulation, the appearance of white spot lesions and the development of secondary caries are the main complications in orthodontic patients. A promising approach to fight this situation is the development of adhesive cements with improved antibacterial properties. The aim of the present study was to evaluate the possibility of improving the antibacterial properties of glass ionomer cements by incorporating different types of antimicrobial compounds without altering their physical and mechanical properties. Different concentrations of silver carbonate (SC) and an inorganic glass with encapsulated silver were added to the glass ionomer cement, as well as chitosan, to achieve synergistic antibacterial activity. Variations in the antibacterial capacity were evaluated using the agar diffusion test; the potential alteration of the physical and mechanical properties of the material was analyzed by the shear bond strength test. SEM characterization and colorimetric evaluation were also conducted. Samples of SC up to 1% and inorganic glass with encapsulated silver up to 5% showed significant improvement in their antibacterial ability without compromising shear strength. The highest antimicrobial activity was observed for Lactobacillus acidophilus, with inhibition zones of 3.8 and 3.1 mm for SC and inorganic glass, respectively. The characterization of the samples did not detect any major structural changes between the different samples. The only group that underwent a noticeable color change was the group with SC. The results show that the incorporation of silver carbonate and inorganic glass with encapsulated silver provided the glass ionomer cement with an antibacterial capacity without compromising the bond strength and without modifying the structure of the material.

Chitosan Resin-Modified Glass Ionomer Cement Containing Epidermal Growth Factor Promotes Pulp Cell Proliferation with a Minimum Effect on Fluoride and Aluminum Release

The development of biomaterials that are able to control the release of bioactive molecules is a challenging task for regenerative dentistry. This study aimed to enhance resin-modified glass ionomer cement (RMGIC) for the release of epidermal growth factor (EGF). This RMGIC was formulated from RMGIC powder supplemented with 15% (w/w) chitosan at a molecular weight of either 62 or 545 kDa with 5% bovine serum albumin mixed with the same liquid component as the Vitrebond. EGF was added while mixing. ELISA was used to determine EGF release from the specimen immersed in phosphate-buffered saline at 1 h, 3 h, 24 h, 3 d, 1 wk, 2 wks, and 3 wks. Fluoride and aluminum release at 1, 3, 5, and 7 d was measured by electrode and inductively coupled plasma optical emission spectrometry. Pulp cell viability was examined through MTT assays and the counting of cell numbers using a Coulter counter. The RMGIC with 65 kDa chitosan is able to prolong the release of EGF for significantly longer than RMGIC for at least 3 wks due to its retained bioactivity in promoting pulp cell proliferation. This modified RMGIC can prolong the release of fluoride, with a small amount of aluminum also released for a limited time. This biomaterial could be useful in regenerating pulp-dentin complexes.

Biocompatible carboxymethyl chitosan-modified glass ionomer cement with enhanced mechanical and anti-bacterial properties

Due to the potential adverse effects of conventional dental cements, the demand for biocompatible cements have grown tremendously in the field of dentistry. In this respect, Glass ionomer cements (GICs) are being developed by different researchers. However, low mechanical strength of GIC make them unsuitable for application in high-stress areas. Thus, numerous initiatives to improve mechanical performance have been attempted till date including incorporation of reinforcing fillers. Novelty of the study lies in using carboxymethyl chitosan (CMC) to develop a biocompatible dental cement (DC/CMC-m-GP), which would have enhanced mechanical strength due to greater interaction of CMC with the particles of GIC and better cyto-compatibility due to its cell-proliferation activity. The mechanical strength, acid erosion and fluoride release of DC/CMC-m-GP were studied and compared with control dental cement (DC/Control). DC/CMC-m-GP shows compressive strength of 157.45 M Pa and flexural strength of 18.76 M Pa which was higher as compared to DC/Control. The morphology of the GICs were studied through FESEM. Anti-microbial activity of DC/CMC-m-GP was studied by Agar disc-diffusion method and biofilm assay against S. mutans, which shows that DC/CMC-m-GP inhibits bacterial adhesion on its surface. MTT assay infers that DC/CMC-m-GP was non-cytotoxic and did not affect the cell viability significantly.

Evaluation of Fluoride Release in Chitosan-Modified Glass Ionomer Cements

OBJECTIVE

This study assessed the influence of chitosan nanoparticles on the fluoride-releasing ability of 4 glass ionomer cement (GIC) through an in vitro analysis.

METHODS

Four types of GIC (type II light cure universal restorative, type II universal restorative, GC Fuji VII, and type IX) were modified with nanochitosan particles; 10% chitosan was added to the glass ionomer liquid. Six specimens for each of the 4 groups were created, using expendable Teflon moulds. Discs of each type of GIC (n = 6) were immersed in deionised water at various time intervals. Electrodes selective for fluoride ions were employed to analyse the amount of released fluoride at 1, 7, 14, 21, and 28 days.

RESULTS

Chitosan-modified GICs showed greater fluoride release than conventional GICs at all time points. All samples showed an initial high release of fluoride that tapered off with time. The total amount of fluoride released increased from the 1st day to the 28th day on adding chitosan to all the 4 types of GIC. Amongst those, type IX high-strength posterior extra with chitosan released a considerably higher quantity of fluoride at all time intervals.

CONCLUSIONS

In all the experimental groups, adding chitosan to the glass ionomer liquid had an accelerating effect on its fluoride-releasing property.

Evaluation of push-out bond strength of different concentrations of chitosan nanoparticles incorporated composite resin and eighth-generation bonding agent for class II restoration: An in vitro study

Aim

The aim of this study is to evaluate the push-out bonding strength of class II cavities of maxillary molars restored with different concentrations of chitosan nanoparticles (CSN) incorporated in universal composite resin and eighth-generation dentin bonding agent (DBA).

Materials and Methods

Seventy extracted human maxillary first molar teeth were cleaned and mounted in acrylic mold up to 2 mm below cementoenamel junction and mesio-occlusal Class II cavities with standard measurements were prepared. CSN 2% and 0.25% powder were added to the DBA and composite resin. The samples then arbitrarily divided into three groups for restoration: Group 1: composite restoration without CSN (control group) (n = 10), Group 2: 2% CSN (n = 30), and Group 3: 0.25% CSN (n = 30). Groups 2 and 3 were further subdivided into three subgroups (n = 10 each) subgroup A. CSN incorporated in composite resin. B. CSN incorporated in DBA and C. CSN incorporated in composite and DBA. After restoration, push-out bond strength was evaluated in each sample using a universal testing machine, and data collected were statistically analyzed by one-way analysis of variance and Post hoc Tukey tests (P ≤ 0.05).

Results

Subgroup 3A (0.25% CSN + composite) has shown an increase in bond strength among all experimental groups with no significant difference between group 1 (control group).

Conclusion

CSN 0.25% incorporated in composite or DBA exhibits no harmful effect on the bond strength of class II restorations. Hence, it can be used to improve the antibacterial action and longevity of composite resin.

Long-Term Effect of Modified Glass Ionomer Cement with Mimicked Biological Property of Recombinant Translationally Controlled Protein

This study modified glass ionomer cement (GIC) by adding mimicked biological molecules to reduce cell death. GIC was modified to BIOGIC by adding chitosan and bovine serum albumin for enhancing protein release. The BIOGIC was supplemented with tricalcium phosphate (TCP) and recombinant translationally controlled tumor protein (TCTP) to improve its biological properties. Four groups of materials, GIC, BIOGIC, BIOGIC+TCP, and BIOGIC + TCP + TCTP, were examined by XRD and SEM-EDX. TCTP released from the specimens was determined by an ELISA method. Human dental pulp stem cells (hDPSCs) were harvested and analyzed by MTT assay, apoptosis, gene expression, and cell differentiation. All groups had the same crystallization characteristic peaks of La2O3. The elemental compositions composed of La, Si, and Al are the main inorganic components. The results show that BIOGIC + TCP + TCTP presented significantly higher percentages of cell viability than other groups on day 1 to day 23 (p < 0.05), but were not different after day 24 to day 41 and had reduced cell apoptosis including BAX, TPT1, BCL-2, and Caspase-3. The BIOGIC + TCP + TCTP demonstrated higher odontoblast mineralization and differentiation markers including ALP activity, DSPP, DMP-1, ALP, BMP-2, and OPN. It enhanced cell proliferation and differentiation as well as mineralization with down-regulation of genes related to apoptosis compared with other groups.

Analysis of clinical trials on biomaterial and therapeutic applications of chitosan: A review

Chitosan is a modified natural carbohydrate polymer derived from chitin that occurs in many natural sources. It has a diverse range of applications in medical and pharmaceutical sciences. Its primary and permitted use is biomaterial in medical devices. Chitosan and its derivatives also find utility in pharmaceuticals as an excipient, drug carrier, or therapeutic agent. The USFDA has approved chitosan usage as a biomaterial but not for pharmaceutical use, primarily because of the concerns over its source, purity, and immunogenicity. A large number of clinical studies are underway on chitosan-based materials/ products because of their diverse applications. Herein, we analyze clinical studies to understand their clinical usage portfolio. Our analysis shows that >100 clinical studies are underway to investigate the safety/efficacy of chitosan or its biomaterials/ nanoparticles, comprising ~95% interventional and ~ 5% observational studies. The regulatory considerations that limit the use of chitosan in pharmaceuticals are also deliberated. TEASER: Clinical Trials of Chitosan.

Evaluation of Adhesive Bond Strength, and the Sustained Release of Fluoride by Chitosan-infused Resin-modified Glass Ionomer Cement: An In Vitro Study

Aim and objective

To evaluate the adhesive bond strength, and sustained release of fluoride in chitosan (CH)-infused RMGIC.

Materials and methods

Twenty caries-free human permanent premolar teeth, extracted for orthodontic purposes, were cleaned and stored in thymol solution. The crown of each tooth was cut into two halves and RMGIC (n = 10) and CH-infused RMGIC (n = 10) was placed between the two halves of the crown. The tooth was then stored in 10 mL of artificial saliva for a period of 30 days. The fluoride levels of the saliva were checked on the 15th- and the 30th-day using ion chromatography. The adhesive bond strength was checked on the 30th day using a universal testing machine.

Results

This study has shown that the bond strength of RMGIC was not affected by the inclusion of CH in it. Whereas, the sustained fluoride release of CH-modified RMGIC indicated that the fluoride release of CH-RMGIC was 8.47% >RMGIC at the end of 15 days, and, 39.68% >RMGIC at the end of 30 days.

Conclusion

The inclusion of CH in RMGIC does not alter its bond strength, while it does cause a greater release of fluoride.

Clinical significance

In progression with these results, the inclusion of CH in RMGIC could provide desirable properties like mechanical reinforcement effects and catalytic effects on the fluoride release and growth factors.

How to cite this article

Patel A, Dhupar JKMS, Jajoo SS, et al. Evaluation of Adhesive Bond Strength, and the Sustained Release of Fluoride by Chitosan-infused Resin-modified Glass Ionomer Cement: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(2):254–257.

Nanoparticles in Dentistry: A Comprehensive Review

In recent years, nanoparticles (NPs) have been receiving more attention in dentistry. Their advantageous physicochemical and biological properties can improve the diagnosis, prevention, and treatment of numerous oral diseases, including dental caries, periodontal diseases, pulp and periapical lesions, oral candidiasis, denture stomatitis, hyposalivation, and head, neck, and oral cancer. NPs can also enhance the mechanical and microbiological properties of dental prostheses and implants and can be used to improve drug delivery through the oral mucosa. This paper reviewed studies from 2015 to 2020 and summarized the potential applications of different types of NPs in the many fields of dentistry.

The effects of chitosan addition to glass ionomer cement on microhardness and surface roughness

OBJECTIVE

The aim of this study was to investigate the surface microhardness and roughness properties of a modified glass ionomer cement formed by adding different ratios of Chitosan, when exposed to saliva and acid erosive gastric acid cycle environments.

METHODS

Chitosan was added to conventional glass ionomer liquid at volumes of 5% and 10%. The chitosan-modified glass ionomer was used for the experimental group, and traditional glass ionomer formed the control group. All the groups were separated into two subgroups. One of these subgroups was subjected to a gastric acid erosive cycle. The other subgroup was immersed in artificial saliva. Microhardness, surface roughness with optical profilometer and AFM measurements of all the samples were taken. Qualitative surface topographic evaluations were made using a SEM. The data were analyzed by Kruskal-Wallis and Mann Whitney U-test for pairwise comparisons of the groups at the 0.05 level of significance.

RESULTS

The addition of chitosan to GIC had a positive effect on the microhardness values. The gastric acid erosive cycle application negatively affected the microhardness and surface roughness properties of the sample groups.

CONCLUSION

The chitosan-modified glass ionomer cement samples showed clinically acceptable surface roughness values. Although the results of the addition of the biopolymer, chitosan, to GIC are promising, there is a need for further in-vivo studies.

Antibacterial Bio-Based Polymers for Cranio-Maxillofacial Regeneration Applications

Cranio-maxillofacial structure is a region of particular interest in the field of regenerative medicine due to both its anatomical complexity and the numerous abnormalities affecting this area. However, this anatomical complexity is what makes possible the coexistence of different microbial ecosystems in the oral cavity and the maxillofacial region, contributing to the increased risk of bacterial infections. In this regard, different materials have been used for their application in this field. These materials can be obtained from natural and renewable feedstocks, or by synthetic routes with desired mechanical properties, biocompatibility and antimicrobial activity. Hence, in this review, we have focused on bio-based polymers which, by their own nature, by chemical modifications of their structure, or by their combination with other elements, provide a useful antibacterial activity as well as the suitable conditions for cranio-maxillofacial tissue regeneration. This approach has not been reviewed previously, and we have specifically arranged the content of this article according to the resulting material and its corresponding application; we review guided bone regeneration membranes, bone cements and devices and scaffolds for both soft and hard maxillofacial tissue regeneration, including hybrid scaffolds, dental implants, hydrogels and composites.

Streptococcus mutans Growth and Resultant Material Surface Roughness on Modified Glass Ionomers

The present study investigate the optical density of Streptococcus mutans (S. mutans) at 450 nm (OD450 nm) as well as the change in surface roughness of three commercially available chitosan- and nanodiamond-modified glass ionomers. The results indicated that the optical density of S. mutans OD450 nm decreased significantly (p < 0.0001) from 0 h through 2–4 h for each of the control materials. The lowest S. mutans OD450 nm was noted for Fuji IX followed by Ketac Universal. Riva Self Cure had the largest increase in the S. mutans OD450 nm. The control materials and their chitosan/nanodiamond modifications showed significant growth at 6 h compare to the preceding time periods of 2 and 4 h. The materials Fuji IX, Fuji IX modified with 5% Nanodiamonds, Fuji IX modified with 10% Chitosan and Ketac Universal modified with 10% Chitosan performed the best with regard to the bacterial reduction. Only the chitosan modifications showed an increase in the surface roughness after 24 h of exposure to the S. mutans. The chitosan and the nanodiamond modifications provided the best disruption of the S. mutans biofilm formation.

Preparation and application of chitosan biomaterials in dentistry

Chitosan is a biodegradable and biocompatible natural polysaccharide that has a wide range of applications in the field of dentistry due to its functional versatility and ease of access. Recent studies find that chitosan and its derivatives can be embedded in materials for dental adhesives, barrier membranes, bone replacement, tissue regeneration, and antimicrobial agent to better manage oral diseases. In this paper, we provide a comprehensive overview on the preparation, applications, and major breakthroughs of chitosan biomaterials. Furthermore, incorporation of chitosan additives for the modification and improvement of dental materials has been discussed in depth to promote more advanced chitosan-related research in the future.

The antimicrobial and cytotoxic effects of a copper-loaded zinc oxide phosphate cement

Objectives

Evidence about modifications of dental luting materials to minimize biological failure at the “marginal gap” between teeth and fixed prosthodontics is scarce. We compared a copper-modified (Co-ZOP) and a conventional zinc oxide phosphate cement (ZOP) in terms of antimicrobial and cytotoxic potentials in vitro and in vivo.

Materials and methods

Specimens of ZOP and Co-ZOP were characterized by the mean arithmetic roughness (Ra) and surface free energy (SFE). Powder components were examined using scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDX) showed elemental material compositions. In vitro microbial adhesion was shown using SEM, luminescence, and fluorescence assays. CCK-8 assays of mouse fibroblasts (L929) and human gingival fibroblasts (GF-1) were performed after 6, 24, and 48 h of specimen incubation. In vivo, ZOP and Co-ZOP specimens were applied intraorally for 12 h; biofilm accumulation was shown using SEM.

Results

Ra of ZOP and Co-ZOP showed no significant differences; SFE was significantly higher for Co-ZOP. EDX exhibited minor copper radiation for Co-ZOP, none for ZOP. In vitro fungal adhesion to Co-ZOP was significantly higher than to ZOP; in vitro streptococcal adhesion, cytotoxicity, and in vivo biofilm formation were not significantly different.

Conclusions

Co-ZOP showed low surface allocations of copper with no improved antimicrobial properties compared with conventional ZOP in vitro or in vivo.

Clinical relevance

Antimicrobial effects and low cytotoxicity of biomaterials are important for the clinical outcome. Based on our in vitro and in vivo results, no clinical recommendation can be given for the tested Co-ZOP.

Fluoride varnish containing chitosan demonstrated sustained fluoride release

Fluoride varnish is a professionally applied product that prevents dental caries. However, fluoride varnishes do not provide sustained fluoride release. The objective of this study was to prepare fluoride varnish formulations containing various amounts of chitosan that would generate sustained fluoride release. We evaluated their chemical structure, viscosity, and in vitro fluoride release. Furthermore, the 3-(4, 5-dimethylthiazolyl-2)-2,5diphenyltetrazolium bromide (MTT) assay and direct contact test were used to determine varnish cytotoxicity. We found that all fluoride varnish formulations had the same chemical structure. Their viscosity demonstrated a chitosan concentration-dependent increase. In vitro fluoride release showed a sustained fluoride release. The chitosan fluoride varnishes were cytotoxic to human gingival fibroblasts. We propose the new fluoride varnish formulation as a potential material to be used as a sustained release fluoride varnish.

The effect of gastric acid on chitosan modified glass ionomer cement: SEM-EDS

This study aimed to use scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) to examine the elements that passed into the gastric acid solution after the application of a gastric acid erosive cycle to chitosan modified glass ionomer cement (GIC). Chitosan modified GIC samples were obtained by adding chitosan (vol/vol) of 5 and 10% to GIC for the experimental groups. These two experimental groups and a control group were subjected to gastric acid erosive treatment for 60 s six times a day for 10 days. The sample surfaces were coated with approximately 1 nm of gold to increase conductivity with the Q 150R ES device (Quorum Technologies, East Sussex, England). Surface topography images were obtained with a SEM. Besides, EDS analysis was also determined the number of elements graphically in the region where the fast electron beam hit. In the samples examined, the amount of element was determined. After gastric acid application, cracks and voids were observed on the surfaces of the samples. In the EDS analysis of the 5 and 10% chitosan modified GIC and control groups, Si, Al, Na, and F was found. It is necessary to investigate the antibacterial properties and physical properties of chitosan modified glass ionomer-free elements and fluorine ions using advanced techniques.

Effect of a novel glass ionomer cement containing fluoro-zinc-silicate fillers on biofilm formation and dentin ion incorporation

OBJECTIVES

This study is aimed at evaluating the effect of a new glass ionomer cement (GIC) containing fluoro-zinc-silicate fillers on biofilm formation and ion incorporation.

MATERIALS AND METHODS

Streptococcus mutans biofilms were developed on two GIC materials: Caredyne Restore (CD) and Fuji VII (FJ); and hydroxyapatite (HA) for 24 h at 37 °C using a flow cell system. The morphological structure and bacterial viability were analyzed using a confocal laser scanning microscopy. Bacterial adhesion during the initial 2 h was also assessed by viable cell counting. To study the ion incorporation, restored cavities prepared on the root surfaces of human incisors were subjected to the elemental mapping of the zinc and fluoride ions in the GIC-dentin interface using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer.

RESULTS

Morphological observations revealed that biofilm formation in the CD group was remarkably inhibited compared with the HA and FJ groups, exhibiting sparse, thinner biofilm clusters. The microorganisms adhering to the CD group were significantly inhibited, revealing 2.9 ± 0.4 for CD, 4.9 ± 0.2 for FJ, and 5.4 ± 0.4 log colony-forming units (CFU) for HA. The CD zinc ion incorporation depth was 72.2 ± 8.0 μm. The fluoride penetration of CD was three times deeper than that of FJ; this difference was statistically significant (p < 0.05).

CONCLUSIONS

Enhanced by the incorporation of zinc and fluoride ions, the new GIC inhibited biofilm formation by interfering with bacterial adhesion.

CLINICAL RELEVANCE

A novel GIC comprised of fluoro-zinc-silicate fillers may improve clinical outcomes, such as root caries and minimally invasive dentistry.

Characteristics of chitosan-modified glass ionomer cement and their effects on the adhesion and proliferation of human gingival fibroblasts: an in vitro study

This study explores the possibility of adhering gingival tissue to a root surface that was restored with chitosan (CS)-modified glass ionomer cement (GIC) in the case of gingival recessions associated with root caries, which provides a theoretical basis for clinical application at the cellular level. The specimens were mixed after integrating 1, 2, and 4 wt% CS into the GIC fluid. The characteristics and cytocompatibility were then examined. As more CS was incorporated into the GIC fluid, the mechanical properties and cytocompatibility of chitosan-modified glass ionomer cement (CS-GIC) first improved but then reduced. Under scanning electron microscopy, microcracks were observed on the surface of all materials, but the fewest microcracks were observed on the surface of 2 wt% CS-GIC. The compressive strength of 2 wt% CS-GIC was significantly higher than that of the other groups at 5 days (P < 0.05) and the addition of chitosan didn't change the basic fracture mode of materials. Additionally, the integration 2 wt% CS into GIC can obviously reduce acidity of the original GIC (P < 0.01) when using extracts with concentrations of 100 and 50%. The Cell Counting Kit-8 assay and adhesion and proliferation of human gingival fibroblasts (HGFs) on the surface of the materials indicated that 2 wt% CS-GIC presented better cytocompatibility and was more suitable for the growth of HGFs. In summary, 2 wt% CS-GIC could be considered as a potential root filling material to allow the adhesion and growth of gingival tissue.

Modification of glass ionomer cements on their physical-mechanical and antimicrobial properties

OBJECTIVE

The aim of this review was to provide an insight about the factors affecting the properties of glass ionomer cements and provides a review regarding studies that are related to modification of glass ionomer cements to improve their properties, particularly on physical-mechanical and antimicrobial activity.

METHODS

PubMed and Science Direct were searched for papers published between the years 1974 and 2018. The search was restricted to articles written in English related to modification of glass ionomer cements. Only articles published in peer-reviewed journals were included. The search included literature reviews, in vitro, and in vivo studies. Articles written in other languages, without available abstracts and those related to other field were excluded. About 198 peer-review articles in the English language were reviewed.

CONCLUSION

Based on the finding, most of the modification has improved physical-mechanical properties of glass ionomer cements. Recently, researchers have attempted to improve their antimicrobial properties. However, the attempts were reported to compromise the physical-mechanical properties of modified glass ionomer cements.

CLINICAL SIGNIFICANCE

As the modification of glass ionomer cement with different material improved the physical-mechanical and antimicrobial properties, it could be used as restorative material for wider application in dentistry.

Comparative Evaluation of Antibacterial and Adhesive Properties of Chitosan Modified Glass Ionomer Cement and Conventional Glass Ionomer Cement: an In vitro Study

INTRODUCTION

Recent studies have reported the incorporation of modifiers with conventional Glass Ionomer Cement (GIC) to enhance its antibacterial effect. One such modification being the addition of Chitosan (CH). However, these modifiers might affect the physical properties of the restorations.

AIM

The aim of the present study was to investigate the effect of modifying the liquid phase of conventional GIC with 10% v/v CH on the antibacterial properties and adhesion to enamel in comparison to conventional GIC.

MATERIALS AND METHODS

The liquid of commercially available restorative GIC (Fuji IX, GC Industrial Corporation, Japan) was modified with 10% v/v CH solution (Everest Biotech, Bengaluru). GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid ratio. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the setting reaction between the conventional and CH modified GIC liquid with GIC powder. For evaluation of the antibacterial properties, biofilms of Streptococcus mutans (S. mutans) were formed on the GIC discs and characterized by Scanning Electron Microscope (SEM). For the characterization of the adhesive properties, the unmodified and CH-modified GICs were bonded to the enamel surface and the microshear bond strength (μSBs) was evaluated. Student's paired t-test was used to compare the micro-shear bond strength between CH modified GIC and unmodified GIC.

RESULTS

Modification with 10% v/v CH solution improved the antibacterial properties of GIC against S. mutans in terms of resistance to biofilm formation which was assessed using SEM. Microshear bond strength of CH modified GIC was 85.40 MPa compared to 46.94 MPa of conventional GIC. This difference was found to be statistically significant.

CONCLUSION

Modifying the liquid phase of a conventional GIC with 10% v/v CH significantly improves the antibacterial property of GIC as well as its adhesion to enamel.