Streptococcus Mutans Biofilm Influences on the Antimicrobial Properties of Glass Ionomer Cements

Antibacterial, cytotoxic and mechanical properties of a orthodontic cement with phosphate nano-sized and phosphorylated chitosan: An in vitro study

OBJECTIVES

Evaluate, in vitro, the effect of incorporating nano-sized sodium trimetaphosphate (TMPnano) and phosphorylated chitosan (Chi-Ph) into resin-modified glass ionomer cement (RMGIC) used for orthodontic bracket cementation, on mechanical, fluoride release, antimicrobial and cytotoxic properties.

METHODS

RMGIC was combined with Chi-Ph (0.25%/0.5%) and/or TMPnano (14%). The diametral compressive/tensile strength (DCS/TS), surface hardness (SH) and degree of conversion (%DC) were determined. For fluoride (F) release, samples were immersed in des/remineralizing solutions. Antimicrobial/antibiofilm activity was evaluated by the agar diffusion test and biofilm metabolism (XTT). Cytotoxicity in fibroblasts was assessed with the resazurin method.

RESULTS

After 24 h, the RMGIC-14%TMPnano group showed a lower TS value (p < 0.001); after 7 days the RMGIC-14%TMPnano-0.25%Chi-Ph group showed the highest value (p < 0.001). For DCS, the RMGIC group (24 h) showed the highest value (p < 0.001); after 7 days, the highest value was observed for the RMGIC-14%TMPnano-0.25%Chi-Ph (p < 0.001). RMGIC-14%TMPnano, RMGIC-14%TMPnano-0.25%Chi-Ph, RMGIC-14%TMPnano-0.5%Chi-Ph showed higher and similar release of F (p > 0.001). In the SH, the RMGIC-0.25%Chi-Ph; RMGIC-0.5%Chi-Ph; RMGIC-14%TMPnano-0.5%Chi-Ph groups showed similar results after 7 days (p > 0.001). The RMGIC-14%TMPnano-0.25%Chi-Ph group showed a better effect on microbial/antibiofilm growth, and the highest efficacy on cell viability (p < 0.001). After 72 h, only the RMGIC-14%TMPnano-0.25%Chi-Ph group showed cell viability (p < 0.001).

CONCLUSION

The RMGIC-14%TMPnano-0.25%Chi-Ph did not alter the physical-mechanical properties, was not toxic to fibroblasts and reduced the viability and metabolism of S. mutans.

CLINICAL RELEVANCE

The addition of phosphorylated chitosan and organic phosphate to RMGIC could provide an antibiofilm and remineralizing effect on the tooth enamel of orthodontic patients, who are prone to a high cariogenic challenge due to fluctuations in oral pH and progression of carious lesions.

Mechanical properties and sustainable bacterial resistance effect of strontium-modified phosphate-based glass microfiller in dental composite resins

Dental composite resins are widely used in dental restorations. However, their clinical application is limited by the occurrence of secondary caries. Strontium-modified phosphate-based glass (Sr-PBG) is a material known to have a sustainable bacterial resistance effect. The mechanical properties (in particular, flexural strength, modulus of elasticity, and hardness) of dental materials determine their function. Therefore, this study aimed to investigate the mechanical and ion-releasing properties as well as the sustainable bacterial resistance effect of bioactive resin composites containing Sr-PBG. The data were analyzed by ANOVA and Tuckey's tests (p < 0.05). We incorporated a Sr-PBG microfiller at 3, 6, and 9 wt.% concentrations into a commercially available composite resin and investigated the mechanical properties (flexural strength, elastic modulus, and micro hardness), ion release characteristics, and color of the resultant resins. In addition, we examined the antibacterial effects of the composite resins against Streptococcus mutans (S. mutans). The mechanical properties of the Sr-PBG groups differed only slightly from those of the control group (p > 0.05). However, the optical density at 600 nm of S. mutans incubated on the experimental group was significantly lower compared to that observed with the control (p < 0.05) both before and after thermocycling between 5 and 55 ℃ for 850 cycles (dwell time: 45 s). Therefore, strontium-modified resin materials exhibited a sustainable bacterial resistance effect in vitro while maintaining some of the mechanical properties of ordinary acrylic resins.

Comparative evaluation of compressive and flexural strength, fluoride release and bacterial adhesion of GIC modified with CPP-ACP, bioactive glass, chitosan and MDPB

Background. This study evaluated the incorporation of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), calcium sodium phosphosilicate bioactive glass (BAG), chitosan (CH), and methacryloyloxydodecylpyridinium bromide (MDPB) on the compressive and flexural strength, fluoride (F^‒ ) release, and bacterial adhesion of conventional glass-ionomer cement (C-GIC).

Methods. Modifications were implemented by adding CPP-ACP, BAG, and CH to the glass powder, while MDPB-GIC was prepared by incorporating MDPB to the liquid of C-GIC. Custom-made molds were used for specimen preparation. Compressive and flexural strengths were evaluated using a universal testing machine. F^‒ release was calculated with Erichrome cyanide reagent, using UV-spectrophotometry, at two time intervals of 24 hours and seven days. For bacterial adhesion, the test specimens were exposed to the bacterial suspension of Streptococcus mutans and Lactobacillus acidophilus for 4 hours, and the adherent bacteria were quantified using colorimetry as the optical density (OD).

Results. The incorporation of MDPB increased the flexural strength of C-GIC, with no effect on its compressive strength. CH significantly improved the compressive and flexural strength; modifications with CPP-ACP, BAG, and MDPB significantly improved the flexural strength of C-GIC. While MDPB-GIC released significantly higher F^‒ at 24 hours, CPP-ACP- and BAG-modified GICs were comparable to C-GIC on day 7. C-GIC exhibited the highest bacterial adhesion, and MDPB-GIC showed the least. The data were analyzed with one-way (ANOVA), and pairwise comparisons were made with Tukey HSD tests.

Conclusion. Hence, it can be concluded that the incorporation of CPP-ACP, BAG, and CH improved the mechanical properties of C-GIC, whereas MDPB improved the resistance of C-GIC to bacterial adhesion.

The influence of light-curing time on fluoride release, surface topography, and bacterial adhesion in resin-modified glass ionomer cements: AFM and SEM in vitro study

Reinforced glass ionomer cements have been widely used in pediatric dentistry to prevent dental caries. However, the influence of biomaterial light-curing and its anti-cariogenic effects remain unclear. This study evaluates the influence of the light-curing time on fluoride release, surface topography, and bacterial adhesion in two types of resin-modified glass ionomer cements (RMGICs). One hundred disks were made, and samples were divided into two groups (n = 50 per group), according to each dental material (Vitremer™ and Ketac™ N100), and also divided into different light-cured times (10, 20, 30, 40, and 60 s). They were placed in phosphate-buffered saline solution (PBS) to measure the fluoride release. Subsequently, an independent sample of RMGICs per group was examined using atomic force microscopy (AFM). Four disks per group were incubated in a brain heart infusion (BHI) medium that was inoculated with Streptococcus mutans GS5 to evaluate the bacterial adhesion by 3-4, [5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide cell viability assay (MTT assay). The fluoride release was related to the light-curing time and gradually decreased as the light-curing time increased in both materials. Surface topography in Vitremer™ presents more irregular surfaces than Ketac™ N100. For S. mutans adhesion, the smallest number of cells per milliliter (cell/ml) was found at 40 s for Vitremer™ and at 30 s for Ketac™ N100. Thus, the shorter light-curing times allowed for major fluoride release in both materials. However, the RMGICs showed different patterns of bacterial adhesion according to the brand and light-curing time.

Comparative evaluation of long-term fluoride release and antibacterial activity of an alkasite, nanoionomer, and glass ionomer restorative material – An in vitro study

Background:

The antibacterial activity of restorative material and the amount of fluoride released are interlinked. Hence, these are the two foremost properties to be studied.

Aim:

This study aimed to evaluate and compare the amount and pattern of fluoride release from Type IX GIC (GC HS posterior), nanoionomer (Ketac N100), and alkasite (Cention N), and the antibacterial activity against Streptococcus mutans at 24 and 48 h.

Settings and Design:

This in vitro study was carried out in laboratory settings with six samples of each group for fluoride release using an ion-chromatography (IC) machine and five samples of each group for antibacterial activity using agar plates.

Materials and Methodology:

Samples of each group, Group I – Type IX GIC, Group II – nanoionomer, and Group III –alkasite, were prepared, immersed in 2 ml of artificial saliva, and fluoride release recorded using IC after 1, 7, 14, and 28 days intervals. The antibacterial activity against S. mutans was evaluated by placing samples of each group in the agar plates and measuring the diameter of zones of inhibition after 24 and 48 h.

Statistical Analysis:

One-way ANOVA test to check to mean differences between the groups and Tukey's honestly significant difference post hoc test for multiple intergroup comparisons (P = 0.05).

Results:

The Type IX GIC showed the highest fluoride release after day1. However, nanoionomer showed the maximum fluoride release for the remaining days. The least amount of fluoride released was from the alkasite throughout the study. The antibacterial activity of nanoionomer was the highest, followed by Type IX GIC and alkasite at both 24 and 48 h.

Conclusions:

Nanoionomer showed the highest fluoride release and antibacterial activity.

Antimicrobial properties, compressive strength and fluoride release capacity of essential oil-modified glass ionomer cements-an in vitro study

OBJECTIVES

This study was designed to investigate the antimicrobial properties, compressive strength and fluoride release capacities of high-viscous glass ionomer cements (GICs) after incorporation of cinnamon and thyme essential oils.

MATERIALS AND METHODS

Experimental-modified GICs were prepared by incorporation of thyme and cinnamon essential oils into the liquid phase of the cement at 5 and 10% v/v. Antimicrobial activity against selected microorganisms (Streptococcus mutans and Candida albicans) was done using direct contact test. Compressive strength of the four new formulations and control group was tested using a universal testing machine while fluoride ion release was measured by ion-selective electrode at 1, 7, 14 and 28 days. Data analysis and comparisons between groups were performed using factorial and one-way ANOVA and Tukey's tests.

RESULTS

All newly formulated GICs exhibited significantly higher inhibitory effects against both Streptococcus mutans and Candida albicans growth when compared to conventional GIC (p < 0.05). Compressive strength of 5% cinnamon-modified GIC (MPa = 160.32 ± 6.66) showed no significant difference when compared with conventional GIC (MPa = 165.7 ± 5.769) (p value > 0.05). Cumulative fluoride-releasing pattern at days 7, 14, and 28 were 10% cinnamon-GIC > 5% thyme-GIC > 5% cinnamon-GIC > 10% thyme GIC > conventional GIC.

CONCLUSIONS

Incorporation of 5% cinnamon oil into glass ionomer resulted in better antimicrobial effects against S. mutans and C. albicans and increased fluoride-release capacity without jeopardizing its compressive strength.

CLINICAL RELEVANCE

The 5% cinnamon-modified GIC appears to be a promising alternative restorative material in ART technique.

Antibacterial activity of a glass ionomer cement doped with copper nanoparticles

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

Acidity-induced release of zinc ion from BioUnionTM filler and its inhibitory effects against Streptococcus mutans

BioUnion filler incorporated into restorative/coating materials is a new bio-functional glass powder. The most unique function of BioUnion filler is its ability to release Zn²⁺ in acidic environments. In this study, the ion release profile of BioUnion filler under acidic conditions and its antibacterial effects against Streptococcus mutans were evaluated. The concentrations of Zn²⁺ released from BioUnion fillers into acetic acids were greater than those released into water. S. mutans inhibition by BioUnion fillers was greater with sucrose than without sucrose, reflecting a decrease in suspension pH in response to the addition of sucrose. Exposure to acids increased Zn²⁺ release from BioUnion fillers, and the fillers after repeated exposure to acids demonstrated inhibitory effects against S. mutans. These findings suggest that BioUnion filler accelerated the release of Zn²⁺ under acidic conditions, which induced bactericidal/inhibitory effects against S. mutans.

Antibiofilm activities of fluoride releasing restorative materials

Backround/Aim: The purpose of this in vitro study is to evaluate the antibiofilm and antimicrobial activities of 5 different restorative materials that release fluoride. Material and Methods: Five different fluoride releasing restorative materials [Riva Self Cure (SDI, Australia), Riva Light Cure (SDI, Australia), Riva Silver (SDI, Australia), Dyract® XP (DENTSPLY, Germany) and Beautifil II (SHOFU, Japan)] and one composite resin material (Grandio, VOCO, Germany) were selected for this study. A total of 48 specimens (8 of each) were prepared using Teflon molds (4.0 mm-diameter and 2.0 mm-thickness). The antibacterial and antibiofilm activities of the mentioned restorative materials on Streptococcus mutans were evaluated. The data obtained were evaluated by One-Way analysis and Tukey's Test (p<0.05). Results: As a result, no correlation was found in terms of antibacterial and antibiofilm activities of the restorative materials evaluated in the study. While the dental plaque (matrix) accumulation was detected at least on the Grandio resin, the materials with the least cell adhesion were Light Cure and Riva Self Cure since it showed antiadhesive properties for S. mutans. Conclusions: Although the highest antibacterial activity against S. mutans was detected in resin-modified glass ionomers, biofilm matrix (dental plaque) accumulation was mostly detected on these material surface in our study.

The effect of the addition of propolis to resin-modified glass ionomer cement bracket adhesive materials on the growth inhibition zone of Streptococcus mutans

Background: Orthodontic treatments progress alongside the development of adhesive materials. The present study aimed to determine the antibacterial properties of propolis, a natural product, in a mixture of resin-modified glass ionomer cement by observing the growth inhibition zone of  Streptococcus mutans.Methods: This was an in vitro study conducted on 45 samples of adhesive material, which were divided into control group (resin-modified glass ionomer cement bracket adhesive material), two groups of propolis concentrations (15%, and 25%) and duration (0, 15, and 30 days). The antibacterial effect of each sample was evaluated against S. mutans using an agar plate diffusion test. Measurement of the diameter of the growth inhibition zone of S. mutans was carried out. The data obtained were analyzed statisticallyThe significance value of the Kruskal Wallis and Mann-Whitney test was set at p <0.05, while the significance value of the normality and homogeneity test was set at p> 0.05). Datas in this study that were not normally distributed (p = 0.012) but homogeneous (p = 0.110) were analyzed by the Kruskal-Wallis test (p = 0.003) and then the Mann-Whitney test was performed to determine differences in significance between groups. Results: There was a relationship between concentration and duration of propolis to the growth inhibition zone of S. mutans (p=0.003). The addition of 25% propolis concentration inhibited the growth of S. mutans more than the addition of 15% and without propolis (control group). The addition of propolis to resin-modified glass ionomer cement for 15 days was more effective in inhibiting the growth of S. mutans.Conclusion: The addition of propolis to adhesive materials provides an inhibitory effect on the growth of S. mutans, which may be effective in the world of preventive dentistry.

The effect of the addition of propolis to resin modified glass ionomer cement bracket adhesive materials on the growth inhibition zone of Streptococcus mutans

Background: Orthodontic treatments progress alongside the development of adhesive materials. The aim of the present study was to determine the antibacterial properties of propolis, a natural product, in a mixture of resin modified glass ionomer cement by observing the growth inhibition zone of Streptococcus mutans. Methods: This was an in vitro study conducted on 45 samples of adhesive material, which were divided into three groups of propolis concentrations (0%, 15%, and 25%) and duration (0, 15, and 30 days). The antibacterial effect of each sample was evaluated against S. mutans using an agar plate diffusion test. Measurement of the diameter of the growth inhibition zone of S. mutans were carried out. The data obtained were analyzed statistically by Kruskal Wallis test. Results: There was a relationship between concentration and duration of propolis to the growth inhibition zone of S. mutans (p<0.05). The addition of 25% propolis concentration inhibited the growth of S. mutans more than the addition of 15% and 0% propolis concentration. The addition of 0%, 15%, and 25% propolis concentration to resin modified glass ionomer cement for 15 days was more effective in inhibiting the growth of S. mutans.Conclusion: The addition of propolis to adhesive materials provides an inhibitory effect on the growth of S. mutans, which may be effective in the world of preventive dentistry.

Experimental composites containing quaternary ammonium methacrylates reduce demineralization at enamel-restoration margins after cariogenic challenge

OBJECTIVE

This study evaluated the influence of experimental composites containing quaternary ammonium monomers (QAM) at different concentrations and alkyl chains on demineralization at enamel-composite margins after cariogenic challenge.

METHODS

Standardized 4×4mm cavities were cut into 35 bovine enamel blocks, which were randomly divided into seven groups (n=5) and restored with the following experimental composites and commercial materials: (G12.5) - 5% dimethylaminododecyl methacrylate (DMADDM) with a 12-carbon alkyl chain (G12.10) - 10% DMADDM, (G16.5) - 5% dimethylaminohexadecyl methacrylate (DMAHDM) with a 16-carbon alkyl chain (G16.10) - 10% DMAHDM, (CG) - control group (without QAM), (GZ250) - commercial composite (Filtek Z250^®), and (GIC) - glass ionomer cement (Maxxion R^®). After restorative procedures, initial microhardness was measured and experimental composites were subjected to Streptococcus mutans biofilm formation for 48h. After cariogenic challenge, the samples were washed and microhardness was reassessed. A 3D non-contact profilometer was used to determine surface roughness and enamel demineralization was assessed by micro-CT. Microhardness results were analyzed by the Kruskal-Wallis and Mann-Whitney tests and micro-CT results were analyzed by Tukey's HSD test (95% confidence interval).

RESULTS

None of the materials could prevent mineral loss at the enamel-restoration margins. The addition of 10% DMAHDM yielded the lowest, albeit statistically significant, mineral loss (p<0.05). 3D non-contact profilometry showed enamel surface roughness modification after biofilm exposure. The CG had the highest roughness values. Micro-CT analysis revealed mineral loss, except for GIC.

SIGNIFICANCE

The addition of 10% QAM with a 16-carbon chain in experimental composites reduced mineral loss at the enamel-restoration margins after cariogenic challenge.

Fluoride Release from Glass Ionomer with Nano Filled Coat and Varnish

OBJECTIVE

This in vitro study compares the fluoride release from microlaminated glass ionomer based on glass hybrid technology coated with two different surface coating agents.

MATERIALS AND METHODS

A total of 18 samples were divided into three groups of six samples each: (1) glass ionomer Equia Forte Fil coated with Equia Forte Coat (Equia+EC), (2) glass ionomer Equia Forte Fil coated with GC Fuji Varnish (Equia+VC) and (3) uncoated glass ionomer Equia Forte (EQUIA cont). Fluoride release was measured using an ion-selective electrode (ORION EA 940) after 24 hours, 4 days, 30 days and 64 days. Repeated measures ANOVA, multiple comparisons, Tukey's test and paired t-test were used to test the differences between the groups.

RESULTS

The differences between the groups and four time points were statistically significant (ANOVA, p<0.0001). Cumulative fluoride ion release after 64 days was 66.01 mg/l, 123.54mg/l and 203.22 mg/l for EQUIA+EC, EQUIA+VC and EQUIA cont, respectively. All the differences were statistically significant except the difference between EQUIA+VC and EQUIA cont after 24 hours.

CONCLUSIONS

The amount of released fluoride was significantly lower in the samples coated with nanofilled surface coating agent compared to the samples coated with varnish and uncoated samples.

Influence of Dental Prosthesis and Restorative Materials Interface on Oral Biofilms

Oral biofilms attach onto both teeth surfaces and dental material surfaces in oral cavities. In the meantime, oral biofilms are not only the pathogenesis of dental caries and periodontitis, but also secondary caries and peri-implantitis, which would lead to the failure of clinical treatments. The material surfaces exposed to oral conditions can influence pellicle coating, initial bacterial adhesion, and biofilm formation, due to their specific physical and chemical characteristics. To define the effect of physical and chemical characteristics of dental prosthesis and restorative material on oral biofilms, we discuss resin-based composites, glass ionomer cements, amalgams, dental alloys, ceramic, and dental implant material surface properties. In conclusion, each particular chemical composition (organic matrix, inorganic filler, fluoride, and various metallic ions) can enhance or inhibit biofilm formation. Irregular topography and rough surfaces provide favorable interface for bacterial colonization, protecting bacteria against shear forces during their initial reversible binding and biofilm formation. Moreover, the surface free energy, hydrophobicity, and surface-coating techniques, also have a significant influence on oral biofilms. However, controversies still exist in the current research for the different methods and models applied. In addition, more in situ studies are needed to clarify the role and mechanism of each surface parameter on oral biofilm development.

Esthetic restorative materials and glass ionomer cements: Influence of acidic drink exposure on bacterial adhesion

OBJECTIVE

The purpose of this research was to evaluate and compare bacterial adhesion on five esthetic restorative materials, three glass ionomer cements (GIC), and two GIC with coat. All the materials were considered after acidic drink exposure.

MATERIALS AND METHODS

Thirty cylindrical sample of each of the 10 materials were prepared and then divided into three groups: group 1 (baseline), Group 2 (1 day in acidic soft drink), and Group 3 (7 days in acidic soft drink). Bacterial suspension of Streptococcus mutans was cultured and deposited onto each material, and the adhesion was evaluated through the colony-forming units determination. One-way ANOVA and Bonferroni's post hoc tests were applied to estimate significant differences between the esthetic materials.

RESULTS

The highest amount of S. mutans was recorded in Group 3 and the lowest in Group 1 (baseline). In general, the GIC showed bacterial adhesion values higher than the ones related to composites both in Group 2 than in Group 3. Acidic soft drinks lead a time-dependent degradation of restorative materials causing an increase of the surface rugosity. In fact, a general increase in S. mutans cells adhesion to treated samples was observed.

CONCLUSIONS

The use of acidic soft drink resulted in a degradation of the surface layer of the restorative material with consequent increase of bacterial adhesion. The GIC can be considered a more friendly environment for bacterial adhesion. This is true in particular if acid substances have already deteriorated the surface.