Titanium dioxide nanoparticles addition to a conventional glass-ionomer restorative: Influence on physical and antibacterial properties

Photoactivated rose bengal-doped TiO2 nanoparticles modified fifth-generation adhesive on the survival rate of Streptococcus mutants and mechanical properties of tooth-colored restorative material to carious dentin

Assessment of the antimicrobial, micro tensile bond strength (μTBS), and degree of conversion (DC) of fifth-generation adhesive modified using photoactivated 0.5% rose bengal (RB) and photoactivated RB-doped titanium dioxide nanoparticles (TiO2NPs) in different concentrations (2% and 5%) as compared with the unmodified adhesive bonded to the carious affected dentin (CAD). Forty mandibular molars with caries progression up to the middle third of the dentin, as per the International Caries Detection and Assessment System (ICDAS) score of 4 and 5 were included. Specimens were divided into four groups based on etch and rinse adhesive (ERA) modification group 1: unmodified ERA, group 2: photoactivated 0.5% RB photosensitizer (PS) modified ERA, group 3: photoactivated RB-doped 2 wt% TiO2NPs adhesive, group 4: photoactivated RB-doped 5 wt% TiO2NPs adhesive. Followed by adhesive and composite restoration on the CAD surface. All the specimens were thermocycled and an assessment of μTBS and failure pattern analysis was performed. The antibacterial potency of RB and RB-doped TiO2NPs (2% and 5%) followed by their activation using visible light against Streptococcus mutans (S.mutans) were tested. The survival rate of S.mutans was assessed using the Kruskal-Wallis test. The analysis of μTBS involved the use of ANOVA, followed by a post-hoc Tukey honestly significant difference (HSD) multiple comparisons test. Group 1 (Unmodified ERA) (0.52 ± 0.31 CFU/mL) treated samples unveiled the highest means of bacterial survival and lowest μTBS (11.32 ± 0.63 MPa). Nevertheless, group 4: photoactivated RB-doped 5 wt% TiO2NPs adhesive displayed the lowest outcomes of S.mutans survival (0.11 ± 0.02 CFU/mL) and highest bond strength (18.76 ± 1.45 MPa). The photoactivated RB-doped 2 wt% TiO2NPs in adhesive demonstrated promising enhancements in both μTBS and antibacterial efficacy against S.mutans. However, it is noteworthy that this modification led to a decrease in the DC of the adhesive. RESEARCH HIGHLIGHTS: Unmodified ERA-treated samples unveiled the highest bacterial survival and the lowest μTBS. Photoactivated RB-doped 5 wt% TiO2NPs adhesive displayed the lowest S.mutans survival rate and highest bond strength. DC decreased with an increase in concentration of TiO2.

Titanium dioxide nanotubes applied to conventional glass ionomer cement influence the expression of immunoinflammatory markers: An in vitro study

Objectives

To assess the impact of different concentrations TiO2-nt incorporated into a glass ionomer cement on the proliferation, mitochondrial metabolism, morphology, and pro- and anti-inflammatory cytokine production of cultured fibroblasts (NIH/3T3), whether or not stimulated by lipopolysaccharides (LPS-2 μg/mL, 24 h).

Methods

TiO2-nt was added to KM (Ketac Molar EasyMix™, 3 %, 5 %, 7 % in weight); unblended KM was used as the control. The analyses included: Cell proliferation assay (n = 6; 24/48/72h); Mitochondrial metabolism assay (n = 6; 24/48/72h); Confocal laser microscopy (n = 3; 24/48/72h); Determination of biomarkers (IL-1β/IL-6/IL-10/VEGF/TNF) by using both multiplex technology (n = 6; 12/18 h) and the quantitative real-time PCR assay (q-PCR) (n = 3, 24/72/120 h). The data underwent analysis using both the Shapiro-Wilk and Levene tests, and by generalized linear models (α = 0.05).

Results

It demonstrated that cell proliferation increased over time, regardless of the presence of TiO2-nt or LPS, and displayed a significant increase at 72 h; mitochondrial metabolism increased (p < 0.05), irrespective of exposure to LPS (p = 0.937); no cell morphology changes were observed; TiO2-nt reverted the impact of KM on the secreted levels of the evaluated proteins and the gene expressions in the presence of LPS (p < 0.0001).

Conclusions

TiO2-nt did not adversely affect the biological behavior of fibroblastic cells cultured on GIC discs.

Assessing the Influence of Thermocycling on Compressive Strength, Flexural Strength, and Microhardness in Green-Mediated Nanocomposite-Enhanced Glass Ionomer Cement Compared to Traditional Glass Ionomer Cement

Background and objective Glass ionomer cement (GIC), also known as polyalkenoate cement, has been extensively used in dentistry for both luting and restorative purposes. Despite being the first choice for aesthetic restorations due to their chemical bonding ability to teeth, GICs have faced challenges such as low mechanical properties, abrasion resistance, and sensitivity to moisture, leading to the search for improved materials.  This study aims to assess the effects of thermocycling on the compressive, flexural strength, and microhardness of green-mediated nanocomposite-modified GIC in comparison to traditional GIC. Methodology Green-mediated nanoparticles, consisting of chitosan, titanium, zirconia, and hydroxyapatite (Ch-Ti-Zr-HA), were synthesized using a one-pot synthesis technique to form nanocomposites. These nanocomposites were then incorporated into GIC specimens in varying concentrations (3%, 5%, and 10%), denoted as Group I, Group II, and Group III, respectively. Group IV served as the control, consisting of conventional GIC. To assess the performance of the novel restorative materials over an extended period, compressive strength, flexural strength, and microhardness were measured before and after thermocycling using a universal material testing machine. Furthermore, scanning electron microscopy (SEM) analysis was carried out following the thermocycling process. The collected data were subjected to statistical analysis through one-way analysis of variance (ANOVA) and paired t-tests. Results  The findings demonstrated that, in comparison to the control group, both the mean compressive strength and flexural strength, as well as hardness, were notably higher for the 10% and 5% nanocomposite-modified GIC specimens before and after thermocycling (P < 0.05). Notably, there was no notable difference observed between the 5% and 10% concentrations (P > 0.05). These results suggest that incorporating green-mediated nanocomposites (Ch-Ti-Zr-HA) modified GIC at either 5% or 10% concentration levels leads to improved mechanical properties, indicating their potential as promising alternatives in dental restorative materials. Conclusions Based on our findings, it can be inferred that the 10% and 5% concentrations of green-mediated (Ch-Ti-Zr-HA) modified GIC exhibit superior compressive and flexural strength compared to conventional GIC. Additionally, analysis of the scanning electron microscope (SEM) morphology revealed that green-mediated GIC displays smoother surface characteristics in contrast to conventional GIC. These results underscore the potential advantages of utilizing green-mediated nanocomposite-modified GIC in dental applications, suggesting enhanced mechanical properties and surface quality over conventional.

A Comparative In Vitro Analysis of Antimicrobial Effectiveness and Compressive Strength of Ginger and Clove-Modified Glass Ionomer Cement

Background Glass ionomer cement (GIC) is widely recognized for its self-adhesive characteristics and biocompatibility, making it commonly used as a restorative material. However, challenges related to limited antibacterial effectiveness and relatively low mechanical properties have hindered its widespread clinical use. Clove and ginger are recognized for their potent antimicrobial activity against numerous pathogenic microorganisms. The present study aims to enhance the clinical applicability of GIC by modifying it with clove and ginger extract. Aim The objective of the study is to assess the antimicrobial effectiveness and compressive strength of GIC modified with ginger and clove extract. Materials and methods Ginger and clove extracts were prepared and incorporated into conventional GIC at three concentrations for each, creating ginger-modified GIC groups (Group A, Group B, and Group C) and clove-modified GIC groups (Group D, Group E, and Group F), with Group G as the control (conventional GIC without modification). The antimicrobial assessment was conducted on disc-shaped GIC specimens (3.0 mm height x 6.0 mm diameter) prepared using molds. Bacterial strains were used to evaluate antimicrobial properties, with minimum inhibitory concentration (MIC) assays conducted at intervals of one to four hours for both modified and unmodified groups. Compressive strength specimens were prepared using cylindrical molds (6.0 mm height × 4.0 mm diameter), according to the ISO (International Organization for Standardization) guidelines. The evaluation was conducted using a Zwick universal testing machine (ElectroPuls® E3000, Instron, Bangalore, India), with the highest force at the point of specimen fracture recorded to determine compressive strength. Statistical analysis was conducted utilizing a one-way analysis of variance (ANOVA) alongside Tukey's post hoc test, with a significance threshold set at p < 0.01. Results The antimicrobial effectiveness of clove and ginger-modified GIC was assessed through a MIC assay, revealing a statistically significant improvement in antimicrobial potency against Streptococcus mutans and Lactobacillus within the modified groups compared to the control group (p < 0.01). Increased extract concentration correlated with enhanced antimicrobial activity. Clove-modified GIC exhibited superior antimicrobial efficacy compared to ginger extract. Compressive strength was higher in clove-modified GIC groups (p < 0.01), with Group F showing a maximum value of 175.88 MPa, while other modified groups demonstrated similar results to the control, with a value of 166.81 MPa (p > 0.01). Conclusion The study concludes that both clove-modified GIC and ginger-modified GIC exhibited antimicrobial activity against Streptococcus mutans and Lactobacillus species. The antimicrobial activity was notably higher in clove-modified GIC compared to ginger-modified GIC. Additionally, the compressive strength of clove-modified GIC surpassed all other groups. Thus, clove-modified GIC emerges as a promising restorative material for addressing recurrent caries. Future investigation is necessary to assess the long-term durability of the material.

A Comparative Evaluation of Surface Properties of Cention N and TiO2-Enriched Cention N After Brushing Simulation and Erosive Challenge: An In Vitro Study

Background This study aimed to evaluate and compare the abrasive and erosive wear resistance of Cention N and titanium dioxide (TiO2) nanoparticle-enriched Cention N after three years of brushing simulation. Methodology A total of 48 freshly extracted mandibular molars were mounted in acrylic blocks and divided into two groups of 24 molars based on the type of restorative material used to restore them. Cavities of a standardized size were prepared. Group A was restored with Cention N, and group B was restored with 5% TiO2-enriched Cention N. Each group was further divided into three subgroups of eight. Subgroup 1 was the control subgroup. Subgroup 2 was the abrasive subgroup, subjected to the abrasive challenge in a brushing stimulator with 30,000 cycles to 10,000 cycles in the linear X-axis and Y-axis each and another 10,000 cycles divided into 5,000 cycles clockwise and 5,000 cycles anticlockwise. The total number of brushing cycles was equal to three years of brushing with a duration of eight to nine hours. Subgroup 3 was the erosive and abrasive subgroup, subjected to an erosive pH cycle consisting of exposure to Coca‑Cola for five minutes thrice a day for seven days, and then subjected to brushing simulation as above. After the surface treatment, specimens were subjected to the Vickers microhardness test using a diamond indenter and the surface roughness test using an optical profilometer. The resulting values were subjected to statistical analysis. Results There was a significant decrease in mean surface roughness in group B, where TiO2 nanoparticles were added after erosive challenge and brushing simulation, than in group A. There was an increase in mean microhardness in group B which was not significant. Conclusions With the addition of 5% TiO2 to Cention N, there was a significant reduction in surface roughness. The surface microhardness of Cention N containing 5% TiO2 increased non-significantly compared to the control group.

The Impact of Nano- and Micro-Silica on the Setting Time and Microhardness of Conventional Glass-Ionomer Cements

The objective of this study was to investigate the effect of the incorporation of 2, 4 or 6 wt% of amorphous nano- or micro-silica (Aerosil® OX 50 or Aeroperl® 300 Pharma (Evonik Operations GmbH, Essen, Germany), respectively) on the net setting time and microhardness of Ketac™ Molar (3M ESPE, St. Paul, MN, USA) and Fuji IX GP® (GC Corporation, Tokyo, Japan) glass-ionomer cements (GICs) (viz. KM and FIX, respectively). Both silica particles were found to cause a non-linear, dose-dependent reduction in setting time that was within the clinically acceptable limits specified in the relevant international standard (ISO 9917-1:2007). The microhardness of KM was statistically unaffected by blending with 2 or 4 wt% nano-silica at all times, whereas 6 wt% addition decreased and increased the surface hardness at 1 and 21 days, respectively. The incorporation of 4 or 6 wt% nano-silica significantly improved the microhardness of FIX at 1, 14 and 21 days, with no change in this property noted for 2 wt% addition. Micro-silica also tended to enhance the microhardness of FIX, at all concentrations and times, to an extent that became statistically significant for all dosages at 21 days. Conversely, 4 and 6 wt% additions of micro-silica markedly decreased the initial 1-day microhardness of KM, and the 21-day sample blended at 4 wt% was the only specimen that demonstrated a significant increase in this property. Scanning electron microscopy indicated that the nano- and micro-silica particles were well distributed throughout the composite structures of both GICs with no evidence of aggregation or zoning. The specific mechanisms of the interaction of inorganic nanoparticles with the constituents of GICs require further understanding, and a lack of international standardization of the determination of microhardness is problematic in this respect.

Evaluation of the antibacterial effect of titanium dioxide nanoparticles combined with acrylic laminates for functional orthodontic appliances: a randomized controlled clinical trial

BACKGROUND

The objective of this study was to evaluate the antibacterial effect of titanium dioxide nanoparticles incorporated into the acrylic baseplates of the maxillary part of twin block appliances in orthodontic patients during the treatment period.

MATERIALS AND METHODS

Twenty-six patients were selected randomly and divided into two groups(n = 13). Test group patients used orthodontic functional appliances containing 1% titanium dioxide nanoparticles in acrylic baseplates. Control group patients used orthodontic functional appliances without titanium dioxide nanoparticles in acrylic baseplates. Swap samples were taken from the palatal gingiva facing the fitting surface of the acrylic component of the maxillary part of a twin block appliance for each patient at five-time intervals (baseline sample, after one, two, four, and six months) and then cultured in blood agar plates to calculate bacterial colony count. The Mann‒Whitney U test and the Friedman test were used to compare data. Bonferroni correction (p value ≤ 0.05) was applied to detect significant differences.

THE RESULTS

showed a decrease in the bacterial colony count in the test group compared to the control group. Pairwise comparisons revealed a statistically significant difference in samples after four- and six-month groups (p values = 0.002 and 0.011, respectively) vs. the one-month test group. A higher statistically significant difference was observed in the six-month group (p-value = 0.037) vs. the baseline group in the control group.

CONCLUSION

The addition of 1% titanium dioxide nanoparticles to acrylic baseplates of orthodontic functional appliances significantly reduced the bacterial colony count under the base plate after at least four months of application.

Comparative Evaluation of Mechanical Properties and Microleakage of Cention N and Titanium Dioxide Nanoparticles-Enriched Cention N: An In Vitro Study

Aim This study aimed to assess and compare the mechanical properties, including compressive strength, diametral tensile strength, flexural strength, fracture resistance, microhardness, and microleakage, between Cention N (Ivoclar Vivadent, Gurugram, India) and Cention N enriched with titanium dioxide (TiO2) nanoparticles. Methodology A total of 120 samples were involved in the study, which were split into two experimental groups. For evaluation of each mechanical property, 20 samples were included, of which 10 samples were used for evaluating the properties of Cention N and 10 samples were used for TiO2 nanoparticles-enriched Cention N. Samples, formed using Teflon molds, were filled with Cention N and TiO2-enriched Cention N powders mixed per the manufacturer's instructions. The universal testing machine (UTM) was used to assess compressive, flexural, diametral tensile strength, and fracture resistance. Microhardness was evaluated using a diamond indenter, while microleakage was examined utilizing a stereomicroscope. Results The nanotitania-enriched Cention N showed significantly increased mechanical properties and increased microhardness with the least microleakage. Conclusion The inclusion of TiO2 in Cention N has proved to yield promising results.

Exploration of Methodologies for Developing Antimicrobial Fused Filament Fabrication Parts

Composite 3D printing filaments integrating antimicrobial nanoparticles offer inherent microbial resistance, mitigating contamination and infections. Developing antimicrobial 3D-printed plastics is crucial for tailoring medical solutions, such as implants, and cutting costs when compared with metal options. Furthermore, hospital sustainability can be enhanced via on-demand 3D printing of medical tools. A PLA-based filament incorporating 5% TiO2 nanoparticles and 2% Joncryl as a chain extender was formulated to offer antimicrobial properties. Comparative analysis encompassed PLA 2% Joncryl filament and a TiO2 coating for 3D-printed specimens, evaluating mechanical and thermal properties, as well as wettability and antimicrobial characteristics. The antibacterial capability of the filaments was explored after 3D printing against Gram-positive Staphylococcus aureus (S. aureus, ATCC 25923), as well as Gram-negative Escherichia coli (E. coli, ATCC 25922), and the filaments with 5 wt.% embedded TiO2 were found to reduce the viability of both bacteria. This research aims to provide the optimal approach for antimicrobial and medical 3D printing outcomes.

3D-printed nanocomposite denture base resin: The effect of incorporating TiO2 nanoparticles on the growth of Candida albicans

PURPOSE

To develop a biocompatible denture base resin/TiO2 nanocomposite material with antifungal characteristics that is suitable for 3D-printing denture bases.

MATERIALS AND METHODS

TiO2 nanoparticles (NPs) with a 0.10, 0.25, 0.50, and 0.75 weight percent (wt.%) were incorporated into a commercially available 3D-printed resin material. The resulting nanocomposite material was analyzed using Lactate dehydrogenase (LDH) and AlamarBlue (AB) assays for biocompatibility testing with human gingival fibroblasts (HGF). The composite material was also tested for its antifungal efficacy against Candida albicans. Fourier transform infrared (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) mapping were conducted to assess the surface coating and the dispersion of the NPs.

RESULTS

LDH and AB assays confirmed the biocompatibility of the material showing cell proliferation at a rate of nearly 100% at day 10, with a cytotoxicity of less than 13% of the cells at day 10. The concentrations of 0.10, 0.25, and 0.50 wt.% caused a significant reduction (p < 0.05) in the number of candida cells attached to the surface of the specimens (p < 0.05), while 0.75 wt.% did not show any significant difference compared to the control (no TiO2 NPs) (p > 0.05). FTIR and EDX analysis confirmed the presence of TiO2 NPs within the nanocomposite material with a homogenous dispersion for 0.10 and 0.25 wt.% groups and an aggregation of the NPs within the material at higher concentrations.

CONCLUSION

The addition of TiO2 NPs into 3D-printed denture base resin proved to have an antifungal effect against Candida albicans. The resultant nanocomposite material was a biocompatible material with HGFs and was successfully used for 3D printing.

TiO2 nanotube-based nanotechnology applied to high-viscosity conventional glass-ionomer cement: ultrastructural analyses and physicochemical characterization

This study characterized TiO2 nanotube (TiO2-nt) ultrastructure and morphology, and the physicochemical impact on high-viscosity conventional glass-ionomer cement (GIC). TiO2-nt was synthesized by the alkaline method (n = 3), assessed by scanning (SEM) and transmission electron microscope (TEM), and was added (3%, 5%, 7%-in weight) to KM (Ketac Molar EasyMix™). Analyses included: SEM; Energy-dispersive spectroscopy (EDS); Raman spectroscopy (RAMAN); Setting time with Gillmore needles (ST); Color (Co); Radiopacity (XR); Water sorption (WS); and solubility (SO). Quantitative data were submitted to ANOVA and Tukey's tests (chr = 0.05). External and internal TiO2-nt diameters were 11 ± 2 nm and 6 ± 0 nm, respectively. Data analyses showed: (i) TiO2-nt present into KM matrix, with a concentration-dependent increase of Ti levels into KM, (ii) physical interaction between KM and TiO2-nt, (iii) longer initial ST for the 7% group compared to KM and 3% groups (p ≤ 0.01), (iv) decreased luminosity and yellowness for the 5% and 7% groups, (v) 36% greater radiopacity for the 5% group compared to enamel, dentin, and KM, and (vi) lower SO values for the 5% group, with no significant differences on WS across the groups. TiO2-nt displayed physical interaction with KM matrix, and also modified SO, XR and Co, without affecting ST. This study provides information on the potential impact of TiO2-nt on GIC performance. TiO2-nt may be proposed to boost confidence among dental surgeons in terms of GIC's handling characteristics, success rate and differential diagnostic.

Comparative Evaluation of Flexural Strength of Conventional and Modified with Chitosan, Titanium Dioxide Nanopowder and Nanohydroxyapatite: An In Vitro Study

Aim

To evaluate the effect of different add-ons on the flexural strength (FS) of glass ionomer cement (GIC).

Materials and methods

Around 72 samples were fabricated and divided among the following six different groups: group I-control (conventional GIC-nonmodified), group II-GIC powder modified with 3% titanium dioxide (TiO2) and liquid is unmodified, group III-powder modified with 10% nanohydroxyapatite (nHA) and liquid is unmodified, group IV-powder is unmodified and Liquid is modified with 10% chitosan (CH), group V-powder is modified with 3% TiO2 and liquid is modified with 10% CH, and group VI-powder is modified with 10% nHA and liquid is modified with 10% CH. The samples were then subjected to a three-point bending test on a universal testing machine for the evaluation of FS. The results obtained were analyzed statistically using the analysis of variance (ANOVA) test.

Result

The mean FS value of group V depicts significantly high FS among all groups (29.42 ± 3.35). A significant difference was present in FS amongst all the groups that is groups V>II>IV>VI>III>I.

Conclusion

Glass ionomer cement (GIC) powder can be modified with nHA, nanotitanium, and GIC liquid can be modified with CH to improve its FS.

Clinical significance

Glass ionomer cement (GIC) supplemented with additives like nanoparticles (NPs) and CH can be used as an enhanced filling material due to its potential antibacterial properties and in areas with a high masticatory load.

How to cite this article

Showkat I, Chaudhary S, Sinha AA, et al. Comparative Evaluation of Flexural Strength of Conventional Glass Ionomer Cement and Glass Ionomer Cement Modified with Chitosan, Titanium Dioxide Nanopowder and Nanohydroxyapatite: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S72-S76.

Mechanical and antibacterial properties of an experimental flowable composite containing Nb2O5 and NF_TiO2 nanoparticles

This study developed an experimental flowable composite incorporated with niobium pentoxide (Nb2O5) combined or not with titanium dioxide co-doped with fluorine and nitrogen (NF_TiO2) and evaluated the mechanical and antibacterial properties. The experimental flowable composite (TEGDMA + BisGMA 1:1 + 60%wt - inorganic filler - borosilicate 0.7 μm) was formulated according to the type and concentration of Nb2O5 and NF_TiO2 (0.5, 1, 1.5 and 2 wt%) or NF_TiO2 + Nb2O5 (0.25, 0.5, 0.75 and 1 wt% - 1:1). The control groups were formed by the experimental composite without the incorporation of Nb2O5 and/or NF_TiO2 (GC-E) and by a commercial flowable composite (GC). The characterization of the surface of the composite and its particles was carried out using scanning electron microscopy (SEM) and energy dispersive x-rays (EDX). Specimens were manufactured and subjected to mechanical tests of flexural strength (FS) (n = 12), flexural modulus (FM) (n = 12), roughness (Ra) (n = 10), microhardness (n = 10), and contact angle (n = 10); and, to evaluate the antibacterial activity, they were submitted to tests of biofilm formation against S. mutans (CFU/mL) (n = 5), biofilm biomass by dry weight (n = 5) and confocal laser microscopy (%LIVE/DEAD) (n = 5). Data were submitted to one-way ANOVA and Tukey's post-hoc and, those that were not homoscedastic, but with normality, were submitted to Welch's ANOVA and Games-Howell's post-hoc. Dunnet's test was used to compare the controls with the other experimental groups (α = 5). The Nb2O5 particles had an average size of 32.4 μm and the nanoparticles (NPs) of NF_TiO2, 10 nm. EDX analysis identified isolated peaks of N, F, Ti, and Nb confirming the presence of these particles in the resin matrix. The 1.5% NF_TiO2 group had a higher FS and FM than the controls (p < 0.05). GC showed higher microhardness between groups (p < 0.05). There was no difference between the experimental groups regarding contact angle and roughness (p > 0.05), except for GC, which had the highest Ra values and the lowest contact angle between groups (p < 0.05). Composites containing 0.5%, 1%, 1.5%, and 2% Nb2O5, 1%, 1.5%, and 2% NF_TiO2 and 2% Nb2O5 + NF_TiO2 showed lower biofilm formation (p < 0.05), lower total biofilm biomass (p < 0.05), and a higher percentage of dead cells (44%, 52%, 52%, 79%, 42% 43%, 62%, 65%, respectively) than GC and GC-E (5% and 1%, respectively). It is concluded that the incorporation of 1.5% NF_TiO2 promoted a greater FS and FM among the experimental composites and that the addition of Nb2O5 particles (0.5%, 1%, 1.5%, and 2%), NF_TiO2 (1%, 1.5% and 2%) and the combination Nb2O5 + NF_TiO2 (2%) showed significant antibacterial effects.

Mechanical Properties of Poly(Alkenoate) Cement Modified with Propolis as an Antiseptic

Background: We assessed the effect of propolis on the antibacterial, mechanical, and adhesive properties of a commercial poly(alkenoate) cement. Methods: The cement was modified with various concentrations of propolis, and antibacterial assays were performed against S. mutans by both MTT assays and agar diffusion tests. The compressive, flexural, and adhesive properties were also evaluated. Results: the modified cement showed activity against S. mutans in both assays, although reductions in compressive (from 211.21 to 59.3 MPa) and flexural strength (from 11.1 to 6.2 MPa) were noted with the addition of propolis, while adhesive strength (shear bond strength and a novel pull-out method) showed a statistical difference (p < 0.05). Conclusion: the antiseptic potential of modified material against S. mutans will allow this material to be used in cases in which low mechanical resistance is required (in addition to its anti-inflammatory properties) when using atraumatic restorative techniques, especially in deep cavities.

The In-Vitro Effect of Silver and Zinc Oxide Nanoparticles on Fluoride Release and Microhardness of a Resin-Modified Glass Ionomer Cement

Reinforcement of nanoparticles into existing restorative biomaterials in dentistry is an area of interest. The aim of the current investigation was to incorporate silver nanoparticles (SNP) and zinc oxide nanoparticles (ZnONP) into a commercially available resin-modified glass ionomer cement (RMGIC). Their effects on the fluoride (F-) release from RMGIC were also investigated over a period of 14-days. Nanoparticles were incorporated at a loading concentration of 5 wt%, either individually or in a combination of both. Scanning electron microscopy (SEM), Fourier Transform infrared spectroscopy (FTIR), Nanocomputerized tomography (NanoCT), and the Vickers microhardness tester were used to examine the specimens. The fluoride release was analyzed by high performance liquid chromatography (HPLC). Data were analysed using ANOVA and Tukey’s test. RMGIC containing 5% ZnONP and 5% SNP + 5% ZnONP showed significant alterations in the surface ultrastructure with pores being evident in the surface. Fluoride release in parts per million (ppm) was highest in the 5% SNP and 5% ZnO-NP incorporated RMGIC compared to the control group and 5% SNP-incorporated RMGIC. RMGIC, as well as change in color observed in the 5% SNP incorporated RMGIC.

Evaluation of Mechanical Properties of Glass Ionomer Cements Reinforced with Synthesized Diopside Produced via Sol-Gel Method

This study aimed to fabricate a glass ionomer cement/diopside (GIC/DIO) nanocomposite to improve its mechanical properties for biomaterials applications. For this purpose, diopside was synthesized using a sol-gel method. Then, for preparing the nanocomposite, 2, 4, and 6 wt% diopside were added to a glass ionomer cement (GIC). Subsequently, X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and Fourier transform infrared spectrophotometry (FTIR) analyses were used to characterize the synthesized diopside. Furthermore, the compressive strength, microhardness, and fracture toughness of the fabricated nanocomposite were evaluated, and a fluoride-releasing test in artificial saliva was also applied. The highest concurrent enhancements of compressive strength (1155.7 MPa), microhardness (148 HV), and fracture toughness (5.189 MPa·m^1/2) were observed for the glass ionomer cement (GIC) with 4 wt% diopside nanocomposite. In addition, the results of the fluoride-releasing test showed that the amount of released fluoride from the prepared nanocomposite was slightly lower than the glass ionomer cement (GIC). Overall, the improvement in mechanical properties and optimal fluoride release of prepared nanocomposites can introduce suitable options for dental restorations under load and orthopedic implants.

New Technological Approaches for Dental Caries Treatment: From Liquid Crystalline Systems to Nanocarriers

Dental caries is the most common oral disease, with high prevalence rates in adolescents and low-income and lower-middle-income countries. This disease originates from acid production by bacteria, leading to demineralization of the dental enamel and the formation of cavities. The treatment of caries remains a global challenge and the development of effective drug delivery systems is a potential strategy. In this context, different drug delivery systems have been investigated to remove oral biofilms and remineralize dental enamel. For a successful application of these systems, it is necessary that they remain adhered to the surfaces of the teeth to allow enough time for the removal of biofilms and enamel remineralization, thus, the use of mucoadhesive systems is highly encouraged. Among the systems used for this purpose, liquid crystalline systems, polymer-based nanoparticles, lipid-based nanoparticles, and inorganic nanoparticles have demonstrated great potential for preventing and treating dental caries through their own antimicrobial and remineralization properties or through delivering drugs. Therefore, the present review addresses the main drug delivery systems investigated in the treatment and prevention of dental caries.

Evaluation and comparison of the effect of incorporating zinc oxide and titanium dioxide nanoparticles on the bond strength and microleakage of two orthodontic fixed retainer adhesives

BACKGROUND

An adhesive with both proper mechanical and antimicrobial properties seems to be beneficial. We aimed to investigate the effect of zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles (NPs) on bond strength and microleakage of two different fixed retainer adhesives.

METHODS

In this in vitro experimental study, 168 extracted human incisors were randomly divided into six groups of 28 (eight double-tooth specimens for the bond strength test and 12 specimens for the microleakage test). In three groups: Transbond XT (3M Unitek, Monrovia, CA) without NPs, with 1% ZnO NPs and with 1% TiO2 NPs were applied. The other three groups included Ortho Connect Flow (GC orthodontics, Tokyo, Japan) composite with the same order to bond a 0.175-inch multistrand wire to the lingual surfaces of the teeth. The bond strength was measured using the Universal Testing Machine, and the adhesive remnant index was reported using a stereomicroscope (Nikon, SMZ800, Tokyo, Japan). The dye-penetration method was used to determine the microleakage.

RESULTS

For bond strength, there was no significant difference among groups. For microleakage, there was no significant difference between GC and Transbond XT groups. However, in subgroups of Transbond XT, the addition of TiO₂ NPs increased the microleakage significantly in comparison with ZnO and control groups (P = 0.011). There was no significant statistical difference between the groups in terms of residual adhesives (P = 0.166).

CONCLUSIONS

Through the incorporation of 1% TiO₂ and ZnO NPs into the fixed retainer adhesive, the bond strength was maintained within the clinically acceptable range. The addition of TiO2 NPs to Transbond XT significantly increased the percentage of microleakage.

Effect of shape of titanium dioxide nanofillers on the properties of dental composites

The main objective of the present study was to evaluate the effect of the morphology of titanium dioxide nanofillers on the flexural strength and shear bond strength of the dental composite. Spherical and rhombic-shaped nano titanium dioxide fillers were synthesized via solvothermal method and were characterized. Subsequently, these fillers were incorporated into a flowable composite (Filtek^™ Z350 XT Flowable Restorative) at 0.5 wt.% and 1.5 wt.% and the prepared specimens were stored in water for 24 h. The specimens were then evaluated for flexural strength using a universal testing machine. Similarly, the shear bond strength of modified composites to the tooth was evaluated and bond failures were analyzed using stereomicroscope magnification. Incorporation of nanofillers significantly enhanced the flexural strength of flowable composite (p = 0.009) with a significant increase at 0.5wt.% of spherical (p = 0.015) and rhomboidal-shaped fillers (p = 0.010). However, no statistically significant difference in flexural strength was observed among the different shapes of nanofillers. The results of our study did not show a significant effect on the shear bond strength of the composites. Thus the reinforcing ability of titanium dioxide nanofillers on dental composite was confirmed in this study, although the effect of using nanofillers with different morphology was not significant.

Effect of titanium dioxide on Streptococcus mutans biofilm

BACKGROUND

Streptococcus mutans (S. mutans) participates in the dental caries process. Titanium dioxide (TiO₂) nanoparticles produce reactive oxygen species capable of disrupting bacterial DNA synthesis by creating pores in cell walls and membranes.

OBJECTIVE

The objective of this study was to determine the effect of TiO₂ on the disruption of S. mutans biofilm.

METHODS

This study was conducted in four phases involving a TiO₂-containing toothbrush and TiO₂ nanoparticles. Each phase was completed using 24 h established S. mutans biofilm growth. Phase one data was collected through a bacterial plating study, assessing biofilm viability. Biofilm mass was evaluated in phase two of the study by measuring S. mutans biofilm grown on microtiter plates following crystal violet staining. The third phase of the study involved a generalized oxygen radical assay to determine the relative amount of oxygen radicals released intracellularly. Phase four of the study included the measurement of insoluble glucan/extracellular polysaccharide (EPS) synthesis using a phenol-sulfuric acid assay.

RESULTS

Both exposure time and time intervals had a significant effect on bacterial viability counts (p = 0.0323 and p = 0.0014, respectively). Bacterial counts after 6 min of exposure were significantly lower than after 2 min (p = 0.034), compared to the no treatment control (p = 0.0056). As exposure time increased, the amount of remaining biofilm mass was statistically lower than the no treatment control. Exposure time had a significant effect on oxygen radical production. Both the 30 and 100 nm TiO₂ nanoparticles had a significant effect on bacterial mass. The silver nanoparticles and the 30 and 100 nm TiO₂ nanoparticles significantly inhibited EPS production.

CONCLUSION

The TiO₂-containing toothbrush kills, disrupts, and produces oxygen radicals that disrupt established S. mutans biofilm. TiO₂ and silver nanoparticles inhibit EPS production and reduce biofilm mass. The addition of TiO₂ to dental products may be effective in reducing cariogenic dental biofilm.

An ex vivo evaluation of physico-mechanical and anti-biofilm properties of resin-modified glass ionomer containing ultrasound waves-activated nanoparticles against Streptococcus mutans biofilm around orthodontic bands

BACKGROUND

The present study evaluated the physico-mechanical and antimicrobial properties of ultrasound waves-activated modified-resin glass ionomer containing nanosonosensitizers such as nano-curcumin (n-Cur), nano-emodin (n-Emo), and nano-quercetin (n-Qct) against Streptococcus mutans biofilm on the surface of modified-resin glass ionomer bonded orthodontic bands.

MATERIALS AND METHODS

A total of 50 human molar teeth were used in this study. The shear bond strength (SBS), adhesive remnant index (ARI), setting time, and fluoride release of modified orthodontics cement containing different concentrations of n-Cur, n-Emo, and n-Qct (0, 2, 5, and 10%) were measured. The antimicrobial effectiveness was assessed against S. mutans by the biofilm inhibition test, and the Log₁₀ colony-forming unit (CFU)/mL was evaluated.

RESULTS

SBS and setting time of modified glass ionomer decreased compared with the control group. 5% n-Emo, 2% n-Qct, and 5% n-Cur were the highest concentrations that had an insignificant difference in comparison with Transbond XT (P = 0.647, 0.819, and 0.292, respectively). The groups were not significantly different in terms of ARI score (P > 0.05). The highest and lowest setting time belonged to the control and 5% n-Emo groups, respectively; this difference in setting time was significant (P < 0.05). Ultrasound waves and 0.2% CHX significantly reduced S. mutans biofilms compared with the control group (P < 0.001), and minimum S. mutans colony count was shown in 0.2% CHX and 5% n-Emo groups. The addition of nanosonosensitizers to the glass ionomer did not compromise the fluoride release of the glass ionomer.

CONCLUSION

It could be concluded that resin-modified glass ionomer containing ultrasound waves-activated 5% n-Emo reduces S. mutans biofilm around orthodontic bands with no adverse effect on SBS, ARI, and its application in the clinic.

Enhancement of fluoride release in glass ionomer cements modified with titanium dioxide nanoparticles

BACKGROUND

Several efforts have been made to improve the glass ionomer cements (GICs) properties with nanotechnology. Fluoride release in once of most beneficial properties of GICs. The purpose of this study was to evaluate the fluoride release, recharge, and cytotoxicity in GICs reinforced with titanium dioxide nanoparticles (TiO2N).

OBJECTIVE

Evaluate the fluoride release, recharge, and cytotoxicity in GICs reinforced with TiO2N.

METHODS

Four GICs, FUJI IX EXTRA (G1c), KETAC MOLAR (G2c), IONOFILL MOLAR (G3c), and FUJI IX (G4c) were combined with TiO2N (G1e, G2e, G3e, and G4e) and divided into blocks of 5-mm width and 1-mm thickness 10 each. A total of 80 samples were arranged as follows: GICs alone as negative control (n = 40) and GICs + TiO2N as experimental groups (n = 40). The fluoride release was determined for periods of 1, 2, 6, 10, 31, 90, 180, 240, and 300 days. On days 30 and 179, samples were recharged by submerging in 1 mL of 20,000 ppm sodium fluoride gel. Cytotoxic activity was carried out with gingival fibroblasts, using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide cell viability assay.

RESULTS

The experimental groups obtained the highest and more constant fluoride released when compared to control groups. After the first recharge, experimental groups (G1e, G3e, and G4e) showed statistically significant results (P = .001, 0.010, and 0.001 respectively) enhancing their recharge ability regarding control groups. The second recharge showed better results in G1e concerning the rest of the groups. No cytotoxic activity was observed in all experimental groups, although significant differences were observed in G3e and G4e regarding control group.

CONCLUSION

The incorporation of TiO2N enhance the fluoride release in glass ionomers with a noncytotoxic effect on human gingival fibroblasts.

Incorporation of Nanomaterials in Glass Ionomer Cements-Recent Developments and Future Perspectives: A Narrative Review

Glass ionomer cements (GICs), restorative materials with commercial availability spanning over five decades, are widely applied due to their advantages (including bio-compatibility, fluoride release, or excellent bonding properties). However, GICs have shortcomings. Among the disadvantages limiting the application of GICs, the poor mechanical properties are the most significant. In order to enhance the mechanical or antimicrobial properties of these materials, the addition of nanomaterials represents a viable approach. The present paper aims to review the literature on the application of different types of nanomaterials for the enhancement of GICs' mechanical and antimicrobial properties, which could lead to several clinical benefits, including better physical properties and the prevention of tooth decay. After applying the described methodology, representative articles published in the time period 2011-present were selected and included in the final review, covering the modification of GICs with metallic nanoparticles (Cu, Ag), metallic and metalloid oxide nanoparticles (TiO₂, ZnO, MgO, Al₂O₃, ZrO₂, SiO₂), apatitic nanomaterials, and other nanomaterials or multi-component nanocomposites.

Medical and Dental Applications of Titania Nanoparticles: An Overview

Currently, titanium oxide (TiO₂) nanoparticles are successfully employed in human food, drugs, cosmetics, advanced medicine, and dentistry because of their non-cytotoxic, non-allergic, and bio-compatible nature when used in direct close contact with the human body. These NPs are the most versatile oxides as a result of their acceptable chemical stability, lower cost, strong oxidation properties, high refractive index, and enhanced aesthetics. These NPs are fabricated by conventional (physical and chemical) methods and the latest biological methods (biological, green, and biological derivatives), with their advantages and disadvantages in this epoch. The significance of TiO₂ NPs as a medical material includes drug delivery release, cancer therapy, orthopedic implants, biosensors, instruments, and devices, whereas their significance as a dental biomaterial involves dentifrices, oral antibacterial disinfectants, whitening agents, and adhesives. In addition, TiO₂ NPs play an important role in orthodontics (wires and brackets), endodontics (sealers and obturating materials), maxillofacial surgeries (implants and bone plates), prosthodontics (veneers, crowns, bridges, and acrylic resin dentures), and restorative dentistry (GIC and composites).

Nanoparticle Impact on the Bacterial Adaptation: Focus on Nano-Titania

Titanium dioxide nanoparticles (nano-titania/TiO₂ NPs) are used in different fields and applications. However, the release of TiO₂ NPs into the environment has raised concerns about their biosafety and biosecurity. In light of the evidence that TiO₂ NPs could be used to counteract antibiotic resistance, they have been investigated for their antibacterial activity. Studies reported so far indicate a good performance of TiO₂ NPs against bacteria, alone or in combination with antibiotics. However, bacteria are able to invoke multiple response mechanisms in an attempt to adapt to TiO₂ NPs. Bacterial adaption arises from global changes in metabolic pathways via the modulation of regulatory networks and can be related to single-cell or multicellular communities. This review describes how the impact of TiO₂ NPs on bacteria leads to several changes in microorganisms, mainly during long-term exposure, that can evolve towards adaptation and/or increased virulence. Strategies employed by bacteria to cope with TiO₂ NPs suggest that their use as an antibacterial agent has still to be extensively investigated from the point of view of the risk of adaptation, to prevent the development of resistance. At the same time, possible effects on increased virulence following bacterial target modifications by TiO₂ NPs on cells or tissues have to be considered.

TiO2 nanoparticles added to dense bovine hydroxyapatite bioceramics increase human osteoblast mineralization activity

OBJECTIVES

This study evaluated the effect of TiO₂ nanoparticles + dense hydroxyapatite (HA) on human osteoblast cells (SAOS-2).

METHODS

Particulate bovine HA powder with or without the addition of either 5 or 8 % TiO₂ (HA, HA/TiO₂Np5 % or HA/TiO₂Np8 %) were pressed into disks (Ø = 12.5 mm; thickness = 1.3 mm) uniaxially (100 MPa) and isostatically (200 MPa/1 min) and sintered at 1300 °C. Y-TZP disks were used as control. The following tests were performed: Scanning Electron Microscopy and Dispersive Energy Spectroscopy (SEM/EDS), Atomic Force Microscopy (AFM), cell viability assay (Alamar Blue-AB) and mineralized matrix deposition (Alizarin Red-AR). AB and AR data were submitted to 2-way ANOVA/Tukey tests and ANOVA/Tukey tests, respectively.

RESULTS

SEM revealed that the surface of HA/TiO₂Np5% resembles DPBHA surface, but also contains smaller granules. HA/TiO₂Np8% characteristics resembles HA/TiO₂Np5% surface, but with irregular topography. Y-TZP showed a typical oxide ceramic surface pattern. EDS revealed Ca, O, and P in all samples. C, O, and Zr appeared in Y-TZP samples. AFM data corroborates SEM analysis. AB test revealed excellent cellular viability for HA/TiO₂Np5% group. AR test showed that all groups containing TiO₂np had more mineralized matrix deposition than all other groups, with statistically differences between HA/TiO₂Np8% and HA cultivated in non-osteogenic medium. Culture in osteogenic medium exhibited much more mineralized matrix deposition by TiO₂np groups.

SIGNIFICANCE

In conclusion, the addition of TiO₂np showed chemical, superficial, and biological changes in the reinforced materials. HA/TiO₂Np5% showed the best results for cell viability and HA/TiO₂Np8% for mineralized matrix deposition.

Applications of Titanium Dioxide Nanostructure in Stomatology

Breakthroughs in the field of nanotechnology, especially in nanochemistry and nanofabrication technologies, have been attracting much attention, and various nanomaterials have recently been developed for biomedical applications. Among these nanomaterials, nanoscale titanium dioxide (nano-TiO₂) has been widely valued in stomatology due to the fact of its excellent biocompatibility, antibacterial activity, and photocatalytic activity as well as its potential use for applications such as dental implant surface modification, tissue engineering and regenerative medicine, drug delivery carrier, dental material additives, and oral tumor diagnosis and treatment. However, the biosafety of nano-TiO₂ is controversial and has become a key constraint in the development of nano-TiO₂ applications in stomatology. Therefore, in this review, we summarize recent research regarding the applications of nano-TiO₂ in stomatology, with an emphasis on its performance characteristics in different fields, and evaluations of the biological security of nano-TiO₂ applications. In addition, we discuss the challenges, prospects, and future research directions regarding applications of nano-TiO₂ in stomatology that are significant and worthy of further exploration.

Effect of Different Concentrations of Silver Nanoparticles on the Quality of the Chemical Bond of Glass Ionomer Cement Dentine in Primary Teeth

Background: The nanotechnologies have been applied for dental restorative materials manufacturing such as glass ionomer cement, composites, tooth regeneration, and endodontic sealers. The study aimed to investigate the chemical bond of conventional glass ionomer cement and to evaluate the addition of different concentrations of silver nanoparticles (AgNPs) on the quality of the chemical bond of glass ionomer cement to primary dentin.

Methods: Silver nanoparticle (AgNP) powder was added in concentrations of 0.2, 0.4, and 0.6% to the conventional powder of GIC Fuji II. Then, the powder was added to the liquid and mixed with the recommended powder/liquid ratio of 3.6:1 g. The Fourier-transform infrared spectra (FTIR) of teeth with 0.2%, 0.4%, and 0.6% w/w of silver nanoparticles in GIC fills and the control tooth were obtained. The conventional glass ionomer was used as a control group. The control and the plain silver tooth were subjected to FTIR analysis using an ATR–FTIR spectrophotometer (ThermoFisher Scientific, Waltham, MA, United States) with zinc selenide (ZnSe) ATR crystal (attenuated total reflection) and OPUS v7.5 software. All spectra were recorded in the range of 500–3,500 cm⁻¹ in the transmission mode with an ATR module.

Results: The AgNPs added at 0.2, 0.4, and 0.6% concentration to GIC provided some information in the context of bond interaction with the dentin. Various bond peaks were seen for calcium, carbonate, phosphate, and amide. In our study, only the amide and phosphate were generated. The amide peaks were almost similar to the control, 0.2%, 0.4%, and 0.6%, with the peaks in the range of 1250–1650 cm⁻¹. There was a clear shift in the phosphate peak from the control, 0.2, and 0.4%, which was about 1050 cm⁻¹, whereas for 0.6%, there was a clear shift from 1050 cm⁻¹ to 880 cm⁻¹.

Conclusion: GIC supplemented with AgNPs showed that a concentration above 0.4% of AgNPs altered the bond quality in dentin interaction. In conclusion, adding AgNPs at a minimal level improves the mechanical properties and maintains the same bond quality as GIC.

Synthesis and Characterization of Titanium Oxide Nanoparticles with a Novel Biogenic Process for Dental Application

The prevalence of dental caries has been largely consonant over time despite the enhancement in dental technologies. This study aims to produce novel GIC restorative material by incorporating TiO₂ nanoparticles synthesized by Bacillus subtilis for the treatment of dental caries. The TiO₂ nanoparticles were prepared by inoculating a fresh culture of Bacillus subtilis into a nutrient broth for 24 h, which was then characterized by XRD, DRS, FTIR, AFM, SEM, TEM and EDX. These TiO₂ nanoparticles were incorporated in GIC restorative material at different concentrations (0–10% TiO₂ -GIC) and were tested for their mechanical properties in a universal testing machine. The XRD analysis revealed synthesis of anatase and rutile-phased TiO₂ nanoparticles with a particle size of 70.17 nm that was further confirmed by SEM and TEM analysis. The EDX spectrum indicated prominent peaks of titanium and oxygen with no impurities in the prepared material. Treatment with 5% TiO₂ -GIC proved to be most effective for the treatment of dental caries with no observable cytotoxic effect. An increase in the compressive strength of TiO₂ nanoparticle-reinforced GIC was observed as the concentration of the TiO₂ nanoparticles was increased up to 5%; subsequently, the compressive strength was lowered. An increase in the flexural strength was observed in GIC containing 0%, 3% and 5% TiO₂ nanoparticles sequentially. Based on the results, it can be concluded that Bacillus subtilis-derived TiO₂ nanoparticles have excellent potential for developing next generation of restorative materials for dental issues.

Evaluation of Mechanical Properties and Antibacterial Activity of Nano Titania-Enriched Alkasite Restorative Material: An In Vitro Study

Background:

A biocompatible additive with the ability to establish antibacterial action for restorative materials without sacrificing their physical properties is always in demand. Nano titania (TiO2 nanoparticles) was shown to have antimicrobial action against a wide range of microorganisms. Alkasite is a modern esthetic restorative material that has outstanding properties; however, it is deficient in antibacterial activity.

Objective:

TiO2 nanoparticles (NPs) were included in alkasite, and both mechanical properties and antibacterial activity of the new formulations were assessed.

Materials and Methods:

Nano titania powder was coupled to alkasite powder in proportions of 3 and 5% (w/w). There were 105 specimens made in total. Evaluation parameters were compressive strength, surface microhardness, surface roughness, water sorption and solubility, and antibacterial activity. One and two-way ANOVA were used for the statistical analysis, followed by Tukey′s test (p<0.05).

Results:

Both ratios of nano titania, 3 and 5% (w/w), significantly increased compressive strength, antibacterial activity against different pathogens, and decreased water solubility of alkasite (p<0.05). Only 5% (w/w) nano titania-modified alkasite exhibited significant decrease in water sorption (p<0.05). Conversely, an insignificant increase in microhardness and surface roughness was observed with both ratios, 3 and 5% (w/w) of nano titania (p˃0.05).

Conclusion:

Nano titania seems to be a very promising complementary additive to the alkasite restorative material, capable of generating considerable antibacterial effectiveness while also enhancing certain mechanical properties.

Evaluation of antibacterial properties and shear bond strength of orthodontic composites containing silver nanoparticles, titanium dioxide nanoparticles and fluoride: An in vitro study

ABSTRACT Objective: The study aimed at determining the antibacterial properties of composites containing silver nanoparticles (Ag NPs) or titanium dioxide nanoparticles (TiO2 NPs), and a fluoride-releasing composite against Streptococcus mutans and Lactobacillus acidophilus, and to evaluate the effect on shear bond strength (SBS) of nanoparticles-modified composites. Materials and Methods: An orthodontic composite was modified by adding 1% w/w Ag NPs or 1% w/w TiO2 NPs. Composite discs were prepared to evaluate the antibacterial properties of these modified composites against Streptococcus mutans and Lactobacillus acidophilus, using three different antibacterial tests, namely: Disk agar diffusion test, Biofilm inhibition test and eluted component test. For evaluating the shear bond strength, 80 extracted premolars were collected and divided into four groups (n=20 each), which were bonded with stainless steel preadjusted Edgewise brackets, by using these modified composites. Their SBS was then compared with that of the control group, using a universal testing machine. Results: Composite discs containing nanoparticles and fluoride were capable of producing growth inhibition zones for all bacterial types. Results of the biofilm inhibition test showed that all the study groups inhibited the bacterial count, in comparison to the control group. A significant difference of SBS was observed between all groups. Conclusion: The antibacterial activity of orthodontic composites modified with Ag and TiO2 nanoparticles was significant, compared with conventional and fluoride-containing composites. The control group showed the highest SBS, followed by fluoride, titanium, and silver groups, with statistically significant difference in mean SBS values among all groups.

Push-out bond strength of mineral trioxide aggregate with addition of titanium dioxide, silver, and silicon dioxide nanoparticles: An in vitro comparative study

Background

The ultimate goal of endodontic therapy is to eliminate all microorganisms present inside root canal and thereby sealing all the possible communicating pathways between pulpal and periradicular tissues, which prevents all the factors that cause recontamination and reinfection of the root canal system. If endodontic treatment fails, next approach is surgical endodontics. Bioceramics are recently introduced materials specifically designed for their potential use in medical field and dentistry.

Aim

To evaluate and compare the push-out bond strength of mineral trioxide aggregate (MTA) by adding titanium dioxide (TiO2), silver, and silicon dioxide nanoparticles.

Materials and Methods

Totally, 60 single-rooted human teeth were used. Middle third of the root was sectioned to obtain 2-mm thick root section. Acrylic was adapted to the section to obtain disks of 5 mm diameter and 2 mm thickness. Canal was prepared by GG Drill. Samples were divided into four groups of 15 each (n = 15): • Group I (control): MTA • Group II: MTA + TiO₂ nanoparticles. • Group III: MTA + silver nanoparticles. • Group IV: MTA + silicon dioxide nanoparticles. The cement mixture was compacted into the canal. Samples were subjected to push-out bond strength using universal testing machine.

Statistical Analysis Used

The data were analyzed statistically by analysis of variance and post hoc comparison by Tukey's t-test.

Results

The highest push-out bond strength was shown by Group II (MTA with TiO2 nanoparticles), followed by Group III (MTA with silver nanoparticles) and Group I (MTA control group). The lowest push-out bond strength was shown by Group III (MTA with silicon dioxide nanoparticles).

Conclusions

TiO₂ and silver nanoparticles when added into MTA lead to an increase in push-out bond strength of MTA.

Mechanical response assessment of antibacterial PA12/TiO2 3D printed parts: parameters optimization through artificial neural networks modeling

This study investigates the mechanical response of antibacterial PA12/TiO₂ nanocomposite 3D printed specimens by varying the TiO₂ loading in the filament, raster deposition angle, and nozzle temperature. The prediction of the antibacterial and mechanical performance of such nanocomposites is a challenging field, especially nowadays with the covid-19 pandemic dilemma. The experimental work in this study utilizes a fully factorial design approach to analyze the effect of three parameters on the mechanical response of 3D printed components. Therefore, all combinations of these three parameters were tested, resulting in twenty-seven independent experiments, in which each combination was repeated three times (a total of eighty-one experiments). The antibacterial performance of the fabricated PA12/TiO₂ nanocomposite materials was confirmed, and regression and arithmetic artificial neural network (ANN) models were developed and validated for mechanical response prediction. The analysis of the results showed that an increase in the TiO₂% loading decreased the mechanical responses but increased the antibacterial performance of the nanocomposites. In addition, higher nozzle temperatures and zero deposition angles optimize the mechanical performance of all TiO₂% nanocomposites. Independent experiments evaluated the proposed models with mean absolute percentage errors (MAPE) similar to the ANN models. These findings and the interaction charts show a strong interaction between the studied parameters. Therefore, the authors propose the improvement of predictions by utilizing artificial neural network models and genetic algorithms as future work and the spreading of the experimental area with extra variable parameters and levels.

Anti-Bacterial effect, fluoride release, and compressive strength of a glass ionomer containing silver and titanium nanoparticles

Background

Many attempts have been made to enhance the anti-cariogenic properties of the conventional glass ionomer through incorporation of variable materials. However, most importantly, the incorporation of such materials should not jeopardise the physical or mechanical properties of the final restoration.

Aims

To investigate the effect of adding silver nanoparticles (Ag-NPs) and titanium dioxide nanoparticles (TiO₂-NPs) to conventional glass ionomer cement (GIC) on its anti-bacterial effect against Streptococcus mutans (S. mutans), fluoride ion release, and compressive strength (CS).

Settings and Design

This study was an in vitro investigation where 30-disc specimens were prepared in each of the three studied groups.

Materials and Methods

The specimens were categorized into the control group (Group C), in which conventional GIC was used, and Group Ag and Group Ti, in which 5 wt% of Ag-NP and TiO₂-NP were added, respectively, to GIC powder. In each group, the anti-bacterial effect against S. mutans, fluoride ion release at 24 hours and 14 and 28 days, and CS were assessed. Data were analysed using one-way analysis of variance, followed by Tukey honest significant difference post-hoc test.

Results

Both Ag and Ti groups showed a significantly higher anti-bacterial effect than the control group. Ag-NP increased fluoride ion release, whereas TiO₂-NP decreased fluoride release; however, cumulative ion release of both experimental groups did not differ significantly compared to the control group. Adding Ag-NP and TiO₂-NP increased CS, yet only the Ti group showed the highest CS mean value that was statistically significant compared to other groups.

Conclusions

Adding 5 wt% TiO₂-NP or Ag-NP to conventional GIC significantly increased its anti-bacterial effect and its CS without affecting fluoride release.

Evaluation of the Surface Hardness and Roughness of a Resin-Modified Glass Ionomer Cement Containing Bacterial Cellulose Nanocrystals

The purpose of this study was to evaluate the performance of a resin-modified glass ionomer cement (RMGIC) to which bacterial cellulose nanocrystals (BCNs) were added. BCNs were incorporated into the RMGIC powder in ratios of 0.3%, 0.5%, and 1% (w/w). One control and three experimental groups were enrolled in the study: unmodified RMGIC (control), 0.3% (w/w) BCN-modified RMGIC, 0.5% (w/w) BCN-modified RMGIC, and 1% (w/w) BCN-modified RMGIC. The surface hardness and surface roughness were the parameters assessed. The materials were characterized by scanning electron microscopy (SEM). The data were analyzed using the one-way ANOVA and Kruskal–Wallis tests for surface hardness and roughness, respectively. The addition of BCN resulted in the improvement of surface roughness in all the specimens compared with the control material. The RMGIC modified by 1% (w/w) BCN showed the lowest surface roughness (decreased by 52%) among all tested groups. However, BCN had a negative effect on the surface hardness of RMGIC. The group with 0.3% (w/w) BCN had the least decrease in microhardness (13%). According to the results, the RMGIC group modified by 1% (w/w) BCN had a smoother surface than the other groups. The surface microhardness of the RMGIC decreased after BCNs were added to it.

Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles' nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.

Effect of Nanostructures on the Properties of Glass Ionomer Dental Restoratives/Cements: A Comprehensive Narrative Review

Overall perspective of nanotechnology and reinforcement of dental biomaterials by nanoparticles has been reported in the literature. However, the literature regarding the reinforcement of dental biomaterials after incorporating various nanostructures is sparse. The present review addresses current developments of glass ionomer cements (GICs) after incorporating various metallic, polymeric, inorganic and carbon-based nanostructures. In addition, types, applications, and implications of various nanostructures incorporated in GICs are discussed. Most of the attempts by researchers are based on the laboratory-based studies; hence, it warrants long-term clinical trials to aid the development of suitable materials for the load bearing posterior dentition. Nevertheless, a few meaningful conclusions are drawn from this substantial piece of work; they are as follows: (1) most of the nanostructures are likely to enhance the mechanical strength of GICs; (2) certain nanostructures improve the antibacterial activity of GICs against the cariogenic bacteria; (3) clinical translation of these promising outcomes are completely missing, and (4) the nanostructured modified GICs could perform better than their conventional counterparts in the load bearing posterior dentition.

Ion Capture and Release Ability of Glass Ionomer Cement Containing Nanoporous Silica Particles with Different Pore and Particle Size

This study prepared glass ionomer cement (GIC) containing nanoporous silica (NPS) (GIC-NPS) at 5 wt% concentrations using 3 types of NPS with different pore and particle sizes and evaluated the differences in their cationic ion capture/release abilities and mechanical properties. The cationic water-soluble dye was used as cationic ion. The test GIC-NPS complexes captured dyes by immersion in 1 wt% dye solutions. All the GIC-NPS complexes released dyes for 28 d, and the amount of dye released from the complexes increased with decreasing pore size; however, the particle size of NPS did not affect the amount of dye released. Additionally, GIC-NPS was able to recharge the dye, and the amount of released the dye by the complexes after recharge was almost identical to the amount released on the first charge. Although not significantly different, the compressive strength of GIC-NPS was slightly greater than that of GIC without NPS regardless of the type of NPS. These results suggest that the degree of capture and release of cationic molecules, such as drugs, can be controlled by optimizing the pore size of NPS without sacrificing its mechanical strength when its content is 5 wt%.

Comparison between the effect of adding microhydroxyapatite and chitosan on surface roughness and Microhardness of resin modified and conventional glass ionomer cements

Background

This study aimed to compare the effect of chitosan (CH) and hydroxyapatite (HP) on the surface roughness and microhardness of a conventional glass ionomer cement (CGIC) and a resin modified glass ionomer cement (RMGIC).

Material and Methods

60 disk-shaped specimens (2mm x 6mm) were prepared in 6 groups; group I: CGIC, group II: RMGIC, group III: CGIC + 15% volume CH solution in liquid, group IV: CGIC +10% weight micro-HP in powder, group V: RMGIC + 15% volume CH, group VI: RMGIC + 10% weight micro-HP. After storage in deionized water at room temperature for 24 hours, the surface roughness and microhardness of the specimens were measured using a surface profilometer and Vickers microhardness (VHN) tester, respectively. Data were analyzed using two-way ANOVA, Tukey HSD test and paired t-test (P<0.05).

Results

The microhardness values of RMGIC and CGIC decreased significantly with the addition of micro-HP (P<0.001). None of the CH-containing GICs showed significant changes in microhardness (P = 0.552). The VHN values of CGIC were higher than RMGIC, regardless of the added substance (P<0.001). The surface roughness (Ra) values (μm) of both RMGIC and CGIC decreased significantly with the addition of CH (P = 0.004). The incorporation of micro-HP into GICs did not have a significant effect on surface roughness values (P = 0.700). The RMGIC showed less Ra values compared to the CGIC regardless of the added substance (P<0.001). The lowest and highest Ra values were observed in RMGIC + CH and CGIC + micro-HP groups, respectively.

Conclusions

The addition of CH to GIC and RMGIC reduced the surface roughness and did not have an adverse effect on the microhardness. Mixing GIC and RMGIC with micro-HP resulted in microhardness reduction and did not affect the surface roughness.

Key words:Glass ionomer, hydroxyapatite, chitosan, hardness, surface roughness

Compressive Strength of Conventional Glass Ionomer Cement Modified with TiO2 Nano-Powder and Marine-Derived HAp Micro-Powder

The aim of this research was to investigate the compressive strength (CS), breaking strength (BS), and compressive modulus (CM) of conventional glass ionomer cement (GIC) modified with TiO₂ nano particles, marine-derived hydroxyapatite (md-HAp) microparticles (<45 µm), and a combination of TiO₂ NP and md-HAp particles. The materials used in the study were conventional GIC Fuji IX GP Extra (GC Corporation, Tokyo, Japan), TiO₂ powder P25 (Degussa, Essen, Germany), and HAp synthesized from cuttlefish bone and ground in a mortar to obtain md-HAp powder. md-HAp was characterized using FTIR and SEM analysis. There were four groups of GIC samples: (i) Fuji IX control group, (ii) powder modified with 3 wt% TiO2, (iii) powder modified with 3 wt% HAp, and (iv) powder modified with 1.5 wt% TiO2 + 1.5 wt% HAp. Measurements were performed in a universal testing machine, and CS, BS, and CM were calculated. Statistical analysis was performed using ANOVA and Tukey’s tests. CS, BS, and CM differed significantly between the Fuji IX control group and all experimental groups while differences between the experimental groups were not statistically significant. The addition of TiO₂ NP, md-HAp micro-sized particles, and a combination of TiO₂ and md-HAp reduced the CS, BS, and CM of conventional GICs when mixed at the powder/liquid (p/l) ratio recommended by the manufacturer.

Copper/Carbon Core/Shell Nanoparticles: A Potential Material to Control the Fish Pathogen Saprolegnia parasitica

Copper-based fungicides have a long history of usage in agriculture and aquaculture. With the rapid development of metal-based nanoparticles, copper-based nanoparticles have attracted attention as a potential material for prevention and control of Saprolegnia parasitica. The present study investigated the effectiveness of copper/carbon core/shell nanoparticles (CCCSNs) and a commercial CCCSNs filter product (COPPERWARE®) against S. parasitica in a recirculating system. Results showed that the growth of agar plugs with mycelium was significantly suppressed after exposure to both CCCSNs powder and COPPERWARE® filters. Even the lowest concentration of CCCSNs used in our study (i.e., 100 mg/mL) exhibited significant inhibitory effects on S. parasitica. The smallest quantity of the filter product COPPERWARE® (3.75 × 3.7 × 1.2 cm, 2.58 g) used in our aquarium study also demonstrated significant inhibition compared with the control group. However, we observed leaching of copper into the water especially when larger quantities of COPPERWARE® were used. Water turbidity issues were also observed in tanks with the filter material. Besides these issues, which should be further investigated if the product is to be used on aquatic species sensitive to copper, CCCSNs has promising potential for water disinfection.

Aluminum-free glass ionomer cements containing 45S5 Bioglass® and its bioglass-ceramic

Although the incorporation of bioactive glasses into glass ionomer cements (GICs) has led to promising results, using a bioactive glass as the only solid component of GICs has never been investigated. In this study, we developed an Al-free GIC with standard compressive strength using various combinations of 45S5 Bioglass® and its glass-ceramic as the solid component. The glass-ceramic particles with 74% crystallinity were used for this purpose as they can best act as both remineralizing and reinforcing agents. Strengthening mechanisms including crack deflection and crack-tip shielding were activated for the GICs containing 50-50 wt% bioglass and bioglass-ceramic as the optimum ratio. The progression of the GIC setting reaction at its early stages was also monitored and verified. We also discussed that our bimodal particle size distribution containing both micron- and nanosized particles may enhance the packing density and integrity of the structure of the cements after setting. In such GICs produced in this study, the toxic effects of Al are avoided while chemical bonds are expected to form between the cement and the surrounding hard tissue(s) through interfacial biomineralization and adhesion.

Titanium dioxide nanotubes added to glass ionomer cements affect S. mutans viability and mechanisms of virulence

This in vitro study evaluated the impact of TiO2 nanotubes (n-TiO2) incorporated into glass ionomer cement (GIC) on Streptococcus mutans (S. mutans) characteristics at cellular and molecular levels. n-TiO2, synthesized by the alkaline method (20 nm in size), was added to Ketac Molar EasyMix® at 0%, 3%, 5%, and 7% by weight. S. mutans strains were cultured on GIC disks with addition or not of n-TiO2 for 1, 3, and 7 days and the following parameters were assessed: inhibition halo (mm) (n=3/group); cell viability (live/dead) (n=5/group); cell morphology (SEM) (n=3/group); and gene expression by real-time PCR (vicR, covR, gtfB, gtfC, and gtfD) (n=6/group). The data were analyzed by the Kruskal-Wallis test, repeated-measures ANOVA or two-way ANOVA, and Tukey's and Dunn's post-hoc tests (α=0.05). The agar diffusion test showed a higher antibacterial property for 5% n-TiO2 compared with 3% and 7% (p<0.05) with no effect of time (1, 3, and 7 days). The cell number was significantly affected by all n-TiO2 groups, while viability was mostly affected by 3% and 5% n-TiO2, which also affected cell morphology and organization. Real-time PCR demonstrated that n-TiO2 reduced the expression of covR when compared with GIC with no n-TiO2 (p<0.05), with no effect of time, except for 3% n-TiO2 on vicR expression. Within-group and between-group analyses revealed n-TiO2 did not affect mRNA levels of gtfB, gtfC, and gtfD (p>0.05). Incorporation of n-TiO2 at 3% and 5% potentially affected S. mutans viability and the expression of key genes for bacterial survival and growth, improving the anticariogenic properties of GIC.

Effect of the Incorporation of Chitosan and TiO2 Nanoparticles on the Shear Bond Strength of an Orthodontic Adhesive: An In Vitro Study

Aim:

This in vitro study was aimed to evaluate the effect of adding different concentrations of chitosan nanoparticles (NPs) and TiO2 NPs on the shear bond strength (SBS) of an orthodontic adhesive.

Materials and Methods:

In this in vitro study, 72 extracted human premolars were embedded in an acrylic resin and randomly allocated into four groups of 18 specimens. In group 1 (control), brackets were bonded to the tooth with the Transbond XT orthodontic adhesive. In groups 2, 3, and 4, 0.5% chitosan NPs and 0.5% TiO2 NPs, 1% chitosan NPs and 1% TiO2 NPs, and 1.5% chitosan NPs and 1.5% TiO2 NPs were added to Transbond XT, respectively. Then, the brackets were bonded by the modified adhesive. The SBS and adhesive remnant index (ARI) of each group were assessed with a universal testing machine. The SBS test results were analyzed using one-way analysis of variance followed by the posthoc Tukey’s honestly significant difference (HSD) test. The Kruskal–Wallis test was also applied to evaluate the ARI scores.

Results:

The results showed no statistically significant difference between groups 1, 2, and 3, but SBS decreased significantly in group 4. With increasing the concentration of NPs up to 1% chitosan NPs and 1% TiO2 NPs, SBS did not change significantly. However, in 1.5% chitosan NPs and 1.5% TiO2 NPs, SBS decreased compared to the other three groups. No significant differences were found between the groups in terms of ARI scores.

Conclusion:

It is concluded that the orthodontic composite containing 1% chitosan NPs and 1% TiO2 NPs has adequate SBS for use in the clinical setting.

Microshear Bond Strength of Nanoparticle-Incorporated Conventional and Resin-Modified Glass Ionomer to Caries-Affected Dentin

The purpose of this study was to assess the influence of three different types of nanoparticles (silver (SNPs), titanium dioxide (TNPs), and zinc oxide (ZNPs)) on the microshear bond strength of conventional glass ionomer cement (CGIC) and resin-modified glass ionomer cement based on whether CGIC or RMGIC is used with four subgroups (based on the incorporation of SNPs, ZNPs, and TNPs in addition to a control subgroup) (n = 12) as follows: CGIC, CGIC + TNP, CGIC + ZNP, CGIC + SNP, RMGIC, RMGIC + TNP, RMGIC + ZNP, and RMGIC + SNP. After 24 hours, the μSBS of specimens was tested and the obtained data were analyzed using two-way ANOVA and Tukey's HSD test. The obtained results showed that the incorporation of TNPs in two glass ionomers was not statistically significant compared with the control subgroups (p > 0.05). In the first group, the highest and lowest mean μSBS were, respectively, observed in the CGIC + SNP subgroup and CGIC + ZNP subgroup. In the second group, RMGIC + ZNP and RMGIC + SNP, respectively, showed the highest and lowest mean μSBS compared to the other subgroups. According to the results, it can be concluded that TNPs can be incorporated into both CGIC and RMGIC without compromising the bond strength of glass ionomers. SNPs and ZNPs can be, respectively, added to CGICs and RMGICs to improve the bond strength of the restoration.

Mechanical properties and water-aging resistance of glass ionomer cements reinforced with 3-aminopropyltriethoxysilane treated basalt fibers

In order to improve interfacial adhesion between basalt fibers (BF) and glass ionomer cement (GIC) matrix, a silane named 3-aminopropyltriethoxysilane (APS) was used to modify the surface of BF. APS treated BF (APS-BF) was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The influence of APS concentration on mechanical properties of APS-BF reinforced GIC (APS-BF-GIC) was investigated, and water aging resistance of optimum APS-BF-GIC was also studied. The results showed that 5 wt% of APS was the optimum concentration for BF modification, for 5%APS-BF-GIC had the best comprehensive mechanical properties in all of APS-BF-GICs. Though 5%APS-BF-GIC had higher water sorption than BF-GIC and GIC, it still had higher flexural strength and exhibited better water-aging resistance.

Advances of Anti-Caries Nanomaterials

Caries is the most common and extensive oral chronic disease. Due to the lack of anti-caries properties, traditional caries filling materials can easily cause secondary caries and lead to treatment failure. Nanomaterials can interfere with the bacteria metabolism, inhibit the formation of biofilm, reduce demineralization, and promote remineralization, which is expected to be an effective strategy for caries management. The nanotechnology in anti-caries materials, especially nano-adhesive and nano-composite resin, has developed fast in recent years. In this review, the antibacterial nanomaterials, remineralization nanomaterials, and nano-drug delivery systems are reviewed. We are aimed to provide a theoretical basis for the future development of anti-caries nanomaterials.

Nanometals in Dentistry: Applications and Toxicological Implications-a Systematic Review

Nanotechnology is a vital part of health care system, including the dentistry. This branch of technology has been incorporated into various fields of dentistry ranging from diagnosis to prevention and treatment. The latter involves application of numerous biomaterials that help in restoration of esthetic and functional dentition. Over the past decade, these materials were modified through the incorporation of metal nanoparticles (NP) like silver (Ag), gold (Au), titanium (Ti), zinc (Zn), copper (Cu), and zirconia (Zr). They enhanced antimicrobial, mechanical, and regenerative properties of these materials. However, lately, the toxicological implications of these nanometal particles have been realized. They were associated with cytotoxicity, genotoxicity altered inflammatory processes, and reticuloendothelial system toxicity. As dental biomaterials containing metal NPs remain functional in oral cavity over prolonged periods, it is important to know their toxicological effects in humans. With this background, the present systematic review is aimed to gain an insight into the plausible applications and toxic implications of nano-metal particles as related to dentistry.