Silver nanoparticle incorporation effect on mechanical and thermal properties of denture base acrylic resins

Enhancing orthopedic outcomes: A comparative analysis of gentamicin sulphate and nanosilver in bone cement

Background

Orthopedic surgeries frequently utilize bone cement, which can increase the risk of postoperative infections. Addressing this challenge, this study aims to enhance the mechanical, physical, and handling properties of bone cement by integrating gentamicin sulfate (GS) and nanosilver (nAg). The objective is to evaluate and compare the effects of these additives on properties such as compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. By doing so, the study seeks to identify a safer and more effective alternative to traditional antibiotics in bone cement formulations, thereby improving clinical outcomes in orthopedic procedures.

Methods

This research involved a comparative analysis of modified cements against standard cements, focusing on compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. Various bone cement samples with GS and nAg additives were prepared and tested in accordance with international standards (ISO 5833:2002 and ASTM F451). Statistical analysis, including one-way and two-way ANOVA tests, was used to assess the significance of the results.

Results

nAg-loaded cements exhibit mechanical and physical properties on par with or supe-rior to those of GS-loaded and standard cements. Notably, nAg incorporation leads to significantly lower exothermic temperatures, reducing the risk of thermal bone tissue damage. This finding highlights that nAg-loaded cement is a safer alternative. Alongside unaltered or enhanced strength, nAgs demonstrate promise for orthopedic applications, particularly in primary arthroplasty. Additionally, nAgs reduce doughing time, enhancing the practicality of these methods in surgical settings.

Conclusions

In conclusion, this study underscores the potential advantages of incorporating GSs and nAgs into bone cement. nAg-loaded cement offers improved properties and reduced infection risk, making it a valuable choice for orthopedic procedures. It enhances both mechanical performance and safety, addressing crucial concerns in orthopedic surgery.

Effect of titanium dioxide and zirconium dioxide nanoparticle incorporation on the thermal conductivity of heat-activated polymethylmethacrylate denture base resins: An in vitro experimental study

AIM

The aim is to determine thermal conduction by heat-activated polymethylmethacrylate (PMMA) infiltrated with 1 weight% Titanium Dioxide (TiO2) and 1 weight% Zirconium Dioxide (ZrO2) nanoparticles and to compare with that of conventional PMMA.

STUDY SETTING AND DESIGN

In vitro experimental study.

MATERIALS AND METHODS

Eighteen disc shaped specimens with a thickness of 5 mm and diameter of 50 mm, were fabricated and grouped according to the material used: Group B1 (resin infiltrated with 1 weight% TiO2), Group B2 (resin infiltrated with 1 weight% ZrO2), and Control Group B3 (heat-activated conventional PMMA resin). Disc-shaped specimens were analyzed for thermal conductivity using "modified guarded hot plate apparatus" in the thermal lab of the Indian Space Research Organisation.

STATISTICAL ANALYSIS USED

One-way ANOVA followed by Tukey's post hoc test was used to compare the arithmetic means of all three groups.

RESULTS

A statistically significant difference was noted among all three groups. Group B2 had the maximum thermal conductivity, followed by Group B1. Thermal conductivity was the least for Group B3. A post hoc comparison revealed that the difference was significant between Group B2 and Group B3.

CONCLUSION

Nano ZrO2 addition in PMMA increased its thermal conductivity. There is evidence that it improves its mechanical properties as well. Hence, Nano ZrO2 addition in PMMA is highly recommended. Nano TiO2 addition in PMMA did not provide any significant advantage in terms of thermal conductivity, but its addition in PMMA is justified because of its mechanical and antimicrobial properties.

Comparative Evaluation of the Flexural Strength of Heat-Activated Polymethyl Methacrylate Denture Base Resin With and Without 0.2% by the Weight of Silver Nanoparticles Cured by Conventional and Autoclave Methods: An In Vitro Study

PURPOSE

Heat-activated polymethyl methacrylate (PMMA) is the most common and widely accepted denture base material. Two important drawbacks are the development of denture stomatitis and the high incidence of fracture of denture bases. The present study investigated the effect of adding 0.2% by weight of silver nanoparticles (AgNps) and using the autoclave method of terminal boiling on the flexural strength of heat-activated PMMA denture base resin.

METHODS

A total of 40 samples of heat-activated PMMA blocks were divided into four groups, with 10 samples (n = 10) in each group. Group 1 consisted of unmodified heat-activated PMMA resin (PMMA-1) polymerized by the conventional method of terminal boiling (conventional curing); Group 2 consisted of 0.2% by weight AgNPs added to heat-activated PMMA resin (PMMA-2) polymerized by conventional curing; Group 3 consisted of PMMA-1 polymerized by the autoclave method of terminal boiling (autoclave curing); and Group 4 consisted of PMMA-2 polymerized by autoclave curing. The flexural strength was tested using a universal testing machine. Descriptive statistics were expressed as mean ± SD and median flexural strength. Kruskal-Wallis ANOVA with Mann-Whitney U post hoc test was applied to test for statistical significance between the groups. The level of significance was set at p<0.05.

RESULTS

The results showed a statistically significant reduction in flexural strength in Group 2 compared to Group 1. The samples from Group 4 showed a statistically significant increase in flexural strength compared to Group 2. The Group 4 denture base had the highest flexural strength (115.72 ± 7.27 MPa) among the four groups, followed by Group 3 (104.16 ± 4.85 MPa). The Group 1 samples gave a flexural strength of 101.45 ± 3.13 MPa, and Group 2 gave the lowest flexural strength (85.98 ± 3.49 MPa) among the four groups tested.

CONCLUSION

The reduction in flexural strength of the heat-activated PMMA denture base after adding 0.2% by weight of AgNP as an antifungal agent was a major concern among manufacturers of commercially available denture base materials. It was proved in the present study that employing the autoclave curing method of terminal boiling for the polymerization of 0.2% by weight of AgNp-added heat-activated PMMA denture base resulted in a significantly higher flexural strength compared to the conventional curing method of terminal boiling for polymerization. Unmodified heat-activated PMMA gave higher flexural strength values when polymerized by autoclave curing compared to the conventional curing method of terminal boiling.

Mapping the research landscape of nanoparticles and their use in denture base resins: a bibliometric analysis

BACKGROUND

Nanoparticles are increasingly used in dentistry for various applications, including enhancing the mechanical properties of denture base resins. This study aimed to comprehensively review and analyze the research landscape of nanoparticles and their effect on the flexural strength of denture base resins to identify key research areas and trends and to highlight the importance of collaboration between authors and institutions.

METHODS

A Bibliometric Analysis was conducted using the Keywords "Nanoparticle*" AND "Denture*" OR "CAD/CAM." The literature search from the WOS database was restricted to the publication years 2011 to 2022.

RESULTS

Key findings encompass an increase in research publications but a decline in citations. Saudi Arabia, China, and Iraq led this research, with specific institutions excelling. Notable journals with high impact factors were identified. Authorship patterns show variations in citation impact. Additionally, keyword analysis revealed that current research trends offer insights into influential authors and their networks.

CONCLUSIONS

The analysis of nanoparticles and denture base resins reveals a dynamic and evolving landscape that emphasizes the importance of collaboration, staying current with research trends, and conducting high-quality research in this ever-evolving domain.

Evaluating the antifungal effectiveness, leaching characteristics, flexural strength, and impact strength of polymethyl methacrylate added with small-scale silver nanoparticles - An in vitro study

AIM

(1) To assess the release of stable silver nanoparticles (AgNPs) of small scale dimension added to heat polymerized polymethyl methacrylate (PMMA) in 6 months. (2) Assessing the influence of incorporating minimal concentrations of stable AgNPs with nanoscale dimensions into heat polymerized PMMA over a 6 month period on its antifungal efficacy (AF), flexural strength (FS), and impact strength (IS).

SETTINGS AND DESIGN

Incorporating nanoparticles with a very small scale may have minimal impact on mechanical properties due to their diminutive size. However, the influence of these small scaled nanoparticles on antimicrobial efficacy and potential escalation in toxicity to host cells through leaching remains unexplored. AgNPs were prepared using an Ultrasonic Probe sonicator and the addition of ammonia to obtain stabilized AgNPs (< 0.01 nm) of small scale dimension. The characterization of these AgNPs involved ultraviolet visible spectroscopy, X ray diffraction, Zetasizer, and transmission electron microscopy with energy dispersive spectroscopy (TEM).

MATERIALS AND METHODS

The prepared AgNPs were then added in various percentages by weight (0%-0.5%) to fabricate 252 modified PMMA samples of sizes 10 mm × 3 mm (AF, n = 108), 65 mm × 10 mm × 3 mm (FS, n = 72), and 65 mm × 10 mm × 2.5 mm (IS, n = 72) as per ADA specification no. 12. These samples underwent testing for leaching out of AgNPs and efficacy against Candida albicans for 6 months. The effect on FS and IS was evaluated using the three point bending test and Charpy's Impact Tester, respectively.

STATISTICAL ANALYSIS USED

Intergroup comparison of CFU between various concentrations of AgNP was done using the Kruskal-Wallis ANOVA test succeeded by Mann-Whitney test for pair wise comparisons. Difference in CFU of various concentrations over 6 months was seen using one way ANOVA test. Intergroup comparison of FS and IS was performed using a one way ANOVA test, followed by a post hoc Tukey's test for pair wise comparisons.

RESULTS

Repeated tests showed no leaching out of AgNPs from the denture base resin into the storage medium. All concentrations of AgNPs incorporated in resin showed inhibition of Candida growth. Intergroup comparison of FS and IS revealed highly statistically significant differences (F = 15.076, P < 0.01 and F = 28.266, P < 0.01) between the groups showing a reduction in strength.

CONCLUSION

The AgNPs of small scale dimension incorporated into the denture base resin imparted a strong antifungal effectiveness against C. albicans, which did not decline during the study period and did not cause any release of nanoparticles. 0.5% showed the best antifungal efficacy. This may prove to be a viable and highly effective treatment for the prevention of Candida associated denture stomatitis. However, the inclusion of these particles resulted in a decrease in both FS and IS, and this reduction was directly proportional to the percentage of added AgNPs, with 0.5% demonstrating the least IS and FS.

Influence of inorganic nanoparticles on dental materials' mechanical properties. A narrative review

Inorganic nanoparticles have been widely incorporated in conventional dental materials to help in improving their properties. The literature has shown that incorporating nanoparticles in dental materials in different specialties could have a positive effect on reinforcing the mechanical properties of those materials; however, there was no consensus on the effectiveness of using nanoparticles in enhancing the mechanical properties of dental materials, due to the variety of the properties of nanoparticles itself and their effect on the mechanical properties. This article attempted to analytically review all the studies that assessed the effect of different types of inorganic nanoparticles on the most commonly used dental materials in dental specialties such as polymethyl methacrylate, glass ionomer cement, resin composite, resin adhesive, orthodontic adhesive, and endodontic sealer. The results had shown that those inorganic nanoparticles demonstrated positive potential in improving those mechanical properties in most of the dental materials studied. That potential was attributed to the ultra-small sizes and unique physical and chemical qualities that those inorganic nanoparticles possess, together with the significant surface area to volume ratio. It was concluded from this comprehensive analysis that while a definitive recommendation cannot be provided due to the variety of nanoparticle types, shapes, and incorporated dental material, the consensus suggests using nanoparticles in low concentrations less than 1% by weight along with a silane coupling agent to minimize agglomeration issues and benefit from their properties.

Effect of denture cleansers on color stability and surface properties of denture base material containing titanium dioxide nanoparticles

PURPOSE

To investigate the effect of different denture cleansers on color stability, surface roughness, and hardness of polymethylmethacrylate (PMMA) infused with titanium dioxide nanoparticles (TiO2 NPs) at concentrations of 1% and 2% by weight on each.

MATERIALS AND METHODS

In this in vitro study, 90 disc-shaped specimens (10×10×2 mm) were divided into 3 main groups: the non-containing nanoparticle group (0wt% concentration), 1wt% concentration, and 2wt% concentration TiO2 NPs groups. Each group was further assorted into 3 subgroups (n = 10): immersed in distilled water, oxygenating tablet (Corega), and 0.5% sodium hypochlorite. Color change, surface roughness, and hardness values were assessed after 90 and 180 days of storage. Color changes (∆E) were measured with a spectrophotometer (VITA, Easy Shade V, Germany) and assessed using the CIE L*a*b* colorimetric system and the American National Bureau of Standards (NBS = 0.92×∆E). The surface roughness and surface hardness values were measured using a profilometer device and Vickers hardness tester, respectively. First, ANOVA-repeated measurements were performed, followed by the Tukey test. The significance level in this study was considered 0.05.

RESULTS

At all concentrations, there were significant differences in the mean color changes of samples immersed in cleansers compared to distilled water (p < 0.01). Moreover, hypochlorite caused a significant increase compared to Corega at 0wt% concentration after 90 days and at 1wt% concentration after 90 and 180 days. Evaluations also showed that the mean NBS values in all cleanser groups were in the range of appreciable change, except the water group. In addition, only hypochlorite changed the color higher than the clinically acceptable range (∆E >3.7). The mean roughness of samples immersed in hypochlorite at 0wt% concentration was significantly higher than the samples containing TiO2 NPs (p = 0.006). No significant difference was observed in surface roughness of samples containing different concentrations of TiO2 NPs immersed in different cleansers; however, hypochlorite increased the surface roughness of samples without TiO2 NPs compared to samples containing TiO2 NPs after 180 days. The immersion time in cleansers had a significant influence on the surface roughness and hardness while having no effect on the color.

CONCLUSION

In general, the cleansers had a significant effect on color change in all groups compared to distilled water. The adverse effect of hypochlorite was more than Corega. The cleansers in the samples containing TiO2 NPs did not make a significant difference in surface roughness in comparison with the distilled water groups. Surface hardness of the samples was not affected in a steady pattern by the cleansers.

Geant4 Simulation of the Effect of Different Composites on Polyimide Photon and Neutron Shielding Properties

Polymers are widely used materials that have many medical and industrial applications. Some polymers have even been introduced as radiation-shielding materials; therefore, many studies are focusing on new polymers and their interactions with photons and neutrons. Research has recently focused on the theoretical estimation of the shielding effectiveness of Polyimide doped with different composites. It is well known that theoretical studies on the shielding properties of different materials through modeling and simulation have many benefits, as they help scientists to choose the right shielding material for a specific application, and they are also much more cost-effective and take much less time compared to experimental studies. In this study, Polyimide (C₃₅H₂₈N₂O₇) was investigated. It is a high-performance polymer, well known for its outstanding chemical and thermal stability, as well as for its high mechanical resistance. Because of its exceptional properties, it is used in high-end applications. The performance of Polyimide and Polyimide doped with different weight fractions of composites (5, 10, 15, 20 and 25 wt.%) as a shielding material against photons and neutrons were investigated using a Monte Carlo-based simulation toolkit Geant4 within a wide range of energies of both photons and neutrons from 10 to 2000 KeVs. Polyimide can be considered a good neutron shielding material, and its photon shielding abilities could be further enhanced when adding different high atomic number composites to it. The results showed that Au and Ag gave the best results in terms of the photon shielding properties, while ZnO and TiO₂ had the least negative effect on the neutron shielding properties. The results also indicate that Geant4 is a very reliable tool when it comes to evaluating the shielding properties against photons and neutrons of any material.

Comparison of titanium dioxide nanoparticles and silver nanoparticles for flexural strength once incorporated in heat-cure acrylic denture base resin: An in vitro Study

Aim

Polymethylmethacrylate (PMMA) resin is the most by and large used denture base material. Denture fractures are sequential to the flexure or impacting forces. Different nanoparticles such as titanium dioxide and silver nanoparticles have been used to improve its antimicrobial properties. There are limited data on their effect on flexural strength. The aim of the study was to assess the effect of silver nanoparticles and titanium dioxide nanoparticles addition on flexural strength of PMMA resins.

Settings and Design

One hundred and thirty specimens divided into four groups: Control Group A, TiO2-reinforced Group B, silver nanoparticles reinforced Group C, and mixture of TiO2 and silver nanoparticle reinforced Group D. Each reinforced group further divided based on concentrations -0.5%, 1%, 2%, and 3%.

Materials and Methods

Rectangular metal models of the American Dental Association (ADA)- specified dimensions: 65 mm × 10 mm × 3 mm were used to form a mold space for the fabrication of specimens. Three-point bend test was used to determine the flexural strength of the samples after immersion in distilled water for 2 weeks.

Statistical Analysis

The data collected were subjected to analysis of variance followed by post hoc Tukey's test.

Results

The comparison of the mean flexural strengths showed a statistically significant gradual decrease on increasing the concentrations of nanoparticles. Maximal flexural strength was seen in the control group and least with 3% Ag + TiO2 Nps. The modified specimen also showed color changes.

Conclusions

In an in vitro environment, addition of TiO2 and silver decreases the flexural strength of the PMMA. It also causes visible color changes.

Long-term water sorption/solubility of two dental bonding agents containing a colloidal dispersion of titanium dioxide

The aim was to analyze the influence of the incorporation of 4% by mass of colloidal dispersion of titanium dioxide (TiO2) nanoparticles on the long-term water sorption and solubility of two commercial universal bonding agents. In vitro studies. A colloidal dispersion of TiO2 nanoparticles was formulated and blended into two commercial dental bonding agents, i.e., Ambar Universal (FGM, Brasil) and G-Premio Bond Universal (GC, America) at 4% by mass. Forty bonding agent discs were fabricated and segregated into four bonding agent groups of 10 discs each, i.e., GA: Ambar Universal (control), GB: Ambar Universal (4% TiO2 incorporated), GC: G-Premio Bond universal (control), and GD: G-Premio Bond (4% TiO2 incorporated). The bonding agent discs were developed by dispensing the bonding agents into a silicone cast of 5 mm diameter and 1 mm depth. After bonding agent discs were desiccated, the cured discs were weighed and kept in distilled water to be evaluated for water sorption and solubility over 1 year storage period. Statistical analysis was performed by independent variable t-test performed using the IBM SPSS software (Chicago, IL: SPSS Inc). The incorporated bonding agent groups (GA and GB) showed significantly lower (P < 0.05) water sorption and solubility following 1 year of water storage in comparison to the control bonding agents. Both GC and GD demonstrated remarkably lower water sorption and solubility than GA and GB. Incorporation of the colloidal dispersion of TiO2 nanoparticles at 4% by mass into the universal bonding agents has significantly reduced their water sorption and solubility contrast to their control groups.

Effects of silver nanoparticle-based antimicrobial formulations on the properties of denture polymer: A systematic review and meta-analysis of in vitro studies

STATEMENT OF PROBLEM

Denture stomatitis and other oral infections are prevalent in denture wearers and can be treated effectively with an antimicrobial agent such as a silver nanoparticle-based polymer. However, the physical properties of the denture should not be adversely affected by the addition.

PURPOSE

The purpose of this systematic review and meta-analysis of in vitro studies was to analyze the effects of a silver nanoparticle-based antimicrobial resin on the properties of polymethyl methacrylate(PMMA)-based denture resin.

MATERIAL AND METHODS

Full-length English language articles reporting silver nanoparticle-based PMMA resin were included in the review, with no limitation on the year till May 2020. Scopus, Web of Sciences, and PubMed databases were accessed for the literature survey. The review was formulated based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and used the Consolidated Standards of Reporting Trials (CONSORT) guidelines and risk of bias Cochrane tool for quality assessment. A meta-analysis of flexural strength was performed by using a random-effects model at a 95% confidence interval. The other properties were analyzed descriptively.

RESULTS

Silver nanoparticle reinforcement caused considerable differences in the inherent physical material properties of PMMA.

CONCLUSIONS

An antimicrobial polymer nanocomposite formulation can either negatively affect or bring no improvement to the physical properties of denture resin.

Polymethyl methacrylate resin containing ε-poly-L-lysine and 2-methacryloyloxyethyl phosphorylcholine with antimicrobial effects

STATEMENT OF PROBLEM

Polymethyl methacrylate (PMMA) is commonly used in dentistry, including as a denture base material. However, the colonization of a PMMA surface by microbial microorganisms could increase the risk of oral diseases such as denture stomatitis and gingivitis. The development of PMMA with antibacterial properties should improve its clinical application, but whether adding ε-poly-L-lysine (ε-PL) and 2-methacryloyloxyethyl phosphorylcholine (MPC) provides antimicrobial effects is unclear.

PURPOSE

This in vitro study aimed to develop a novel antibacterial PMMA resin containing the natural nontoxic antibacterial agent ε-PL and the protein repellent agent MPC. The mechanical properties, protein repellency, and antimicrobial activities of the resin were then evaluated.

MATERIAL AND METHODS

Different mass fractions of ε-PL and MPC were mixed into PMMA as the experimental groups, with unaltered PMMA as the control group. The flexural strength (n=10) and surface roughness (n=6) of the resulting mixtures were measured to determine their mechanical properties. The antiprotein properties were measured by using the micro bicinchoninic acid method (n=6). The antimicrobial effect of the resin was assessed using live/dead staining (n=6) and methyltransferase (MTT) assays (n=10). According to the variance homogeneity and normal distribution results, 1-way analysis of variance followed by the Tukey honestly significant difference test or the Welch test and the Games-Howell test were used (α=.05 for all tests).

RESULTS

No significant differences were found in the flexural strength values and surface roughness of the specimens containing 1.5% MPC and 1.5% ε-PL compared with those of the control (P>.05). The addition of ε-PL to the PMMA resin alone significantly increased its bactericidal properties (P<.05). Adding both ε-PL and MPC further increased the antibacterial activity of the PMMA resin without increasing protein adhesion more than in the control group.

CONCLUSIONS

The incorporation of both ε-PL and MPC into PMMA improved its antibacterial capacity without affecting its mechanical properties and did not increase protein adhesion. Therefore, the novel PMMA fabricated in this study shows promise for dental applications.

Prospects on Tuning Bioactive and Antimicrobial Denture Base Resin Materials: A Narrative Review

Denture base resin (DBR) materials are used in dentistry in constructing removable dentures and implant-supported prostheses. A plethora of evidence has demonstrated that DBR materials are associated with a high risk of denture stomatitis, a clinical complication where the soft oral tissues underneath the resin-based material are inflamed. The prevalence of denture stomatitis among denture wearers is high worldwide. Plaque accumulation and the infiltration of oral microbes into DBRs are among the main risk factors for denture stomatitis. The attachment of fungal species, mainly Candida albicans, to DBRs can irritate the underneath soft tissues, leading to the onset of the disease. As a result, several attempts were achieved to functionalize antimicrobial compounds and particles into DBRs to prevent microbial attachment. This review article explored the advanced approaches in designing bioactive and antimicrobial DBR materials. It was reported that using monomer mixtures, quaternary ammonium compounds (QACs), and organic and inorganic particles can suppress the growth of denture stomatitis-related pathogens. This paper also highlighted the importance of characterizing bioactive DBRs to be mechanically and physically sustainable. Future directions may implement a clinical translational model to attempt these materials inside the oral cavity.

Preparation and characterization of acrylic resins with bioactive glasses

This study aimed to prepare a bioactive acrylic material by adding different types of glasses. Commercially available polymerized acrylic resin was mixed with 10% of four different types of glasses in the powder form and cured. Flexural strength, sorption, and solubility of the samples were tested according to ISO 20795-1:2013. The total number of samples used in the tests were 60. The materials were placed in artificial saliva of pH 4 and 7, and elution was performed for 0, 1, 28, and 42 days. The collected samples were analyzed using inductively coupled plasma atomic emission spectrometry to detect Ca, P, and Si ions and using ion chromatography to detect F ions. The materials obtained after modification with glasses showed lower compressive strength compared with pure polymethyl methacrylate but met the standard requirements. Two glass types showed higher solubility values compared with the value defined by the ISO standard. Biomin C and S53P4 released Ca, P, and Si ions, respectively, after 42 days in artificial saliva. Acrylic resins modified with 10% Biomin C and S53P4 glasses can be a valuable source of Ca and P ions under acid conditions for 28 and 42 days.

Effects of incorporation of nanoparticles into dental acrylic resins on antimicrobial and physico-mechanical properties: A meta-analysis of in vitro studies

Background

A meta-analysis study was conducted to determine whether the incorporation of nanoparticles into the dental acrylic resins influence the physico-mechanical properties and whether there are the appropriate nanoparticles exhibiting excellent antimicrobial activity against cariogenic bacteria along with acceptable physico-mechanical properties.

Methods

We systematically searched the various databases up to December 2021. The review was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Consolidated Standards of Reporting Trials (CONSORT) guidelines. A meta-analysis of physico-mechanical properties was performed by a random-effects model at a 95% confidence interval and the antimicrobial effects were analyzed descriptively.

Results

27 studies were included for the final analysis. There was no statistically significant difference in flexural strength (0.553, [95% confidence interval (CI) 0.501-0.604]), microhardness (0.509, [95% CI 0.278-0.736]), surface roughness (0.753, [95% CI 0.315-0.953]), impact strength (0.90, [95% CI 0.188-0.997]), and elastic modulus (0.848, [95% CI 0.514-0.967]), with nanoparticles addition compared with the control group. Forest plots were not generated for the thermal conductivity, tensile strength, and translucency because of the lack of comparison. Although the articles showed high heterogeneity without the high risk of bias, the finding showed the nanoparticles at low concentrations into dental acrylic resins could improve the antimicrobial activities without adverse effects on their physico-mechanical properties.

Conclusion

Adding the low concentration of nanoparticles such as 0.5% Ag, ≤0.25% TiO₂, and ≤0.25% SiO₂ as the most abundant antimicrobial nanoparticles do not influence their physico-mechanical properties and can be effective in the elimination of cariogenic pathogens.

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.

The Effects of Incorporating Ag-Zn Zeolite on the Surface Roughness and Hardness of Heat and Cold Cure Acrylic Resins

One of the most widely used materials for the fabrication of prosthetic dental parts is acrylic resin. Its reasonable mechanical and physical properties make it a popular material for a wide range of dental applications. Recently, many attempts have been made to improve the mechanical and biological properties of this material, such as by adding fibres, nanoparticles, and nanotubes. The current study aimed to evaluate the effects of adding an antimicrobial agent, Ag-Zn zeolite, on the surface roughness and hardness of the denture base resins. Ag-Zn zeolite particles were chemically prepared and added at different concentrations (0.50 wt.% and 0.75 wt.%) to the heat cure (HC) and cold cure (CC) acrylic resins. Zeolite particles were characterized and confirmed using X-ray diffraction (XRD) and Energy-Dispersive X-ray Spectroscopy (EDX) attached with a Scanning Electron Microscope (SEM). Sixty disk shape specimens (40 mm diameter and 2 mm thickness) were fabricated from the HC and CC resins with and without the zeolite. All the specimens were divided into two main groups based on the acrylic resins, then each was subdivided into three groups (n = 10) according to the concentration of the Ag-Zn zeolite. A surface roughness and a hardness tester were used to measure the surface finish and hardness of the specimens. The analysed data showed that the surface roughness values significantly decreased when 0.50 wt.% and 0.75 wt.% zeolite were incorporated in the HC resin specimens compared to the control group. However, this reduction was not significant in the case of CC resin, while the surface hardness was significantly improved after incorporating 0.50 wt.% and 0.75 wt.% zeolite for both the CC and HC resins. Incorporating Ag-Zn zeolite with acrylic resin materials could be beneficial for improving their surface finish and resistance to surface damage as defined by the higher hardness.

Nanomaterials for application in wound Healing: current state-of-the-art and future perspectives

Nanoparticles are the gateway to the new era in drug delivery of biocompatible agents. Several products have emerged from nanomaterials in quest of developing practical wound healing dressings that are nonantigenic, antishear stress, and gas-exchange permeable. Numerous studies have isolated and characterised various wound healing nanomaterials and nanoproducts. The electrospinning of natural and synthetic materials produces fine products that can be mixed with other wound healing medications and herbs. Various produced nanomaterials are highly influential in wound healing experimental models and can be used commercially as well. This article reviewed the current state-of-the-art and briefly specified the future concerns regarding the different systems of nanomaterials in wound healing (i.e., inorganic nanomaterials, organic and hybrid nanomaterials, and nanofibers). This review may be a comprehensive guidance to help health care professionals identify the proper wound healing materials to avoid the usual wound complications.

Nanoparticles in Prosthetic Materials: A Literature Review

The commonly used prosthodontic materials are resins, ceramics, metals and silicones. A comprehensive review of literature was completed about the incorporation of nanomaterials in prosthetic dentistry using PubMed and Google Scholar databases. This was supplemented with a manual search of selected journals. English language articles in peer- reviewed journals were selected. Current literature reveals that incorporation of nanomaterials has significantly improved the properties of the prosthetic materials within the clinically acceptable ranges. There appears to be a need for a standardization for these in vitro studies carried out to evaluate their physical, mechanical and antimicrobial properties

Nanoparticles in Dentistry: A Comprehensive Review

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

Association of Graphene Silver Polymethyl Methacrylate (PMMA) with Photodynamic Therapy for Inactivation of Halitosis Responsible Bacteria in Denture Wearers

(1) Background: Poor hygiene and denture presence in the oral cavity are factors that favor bacterial accumulation, the cause of halitosis and of various oral and general diseases. Aim: This study aimed to evaluate the possibility of inactivating bacteria associated with halitosis in acrylic denture wearers using polymethyl methacrylate resin enhanced with graphene silver nanoparticles and the effect of the resin association with extra oral photodynamic therapy. (2) Methods: Graphene silver nanoparticles in 1 and 2 wt% were added to a commercial acrylic resin powder. Three study groups containing samples from the three different materials were established. The first group was not exposed to the light treatment, and the other two were exposed to red light (laser and light emitting diode) after photosensitizer placement on the disk’s surface. Samples were incubated with Porphyromonas gingivalis and Enterococcus faecalis. (3) Results: For both bacterial strains, inhibition zones were obtained, showing significant differences for the light-treated samples. (4) Conclusions: Denture resins with antibacterial properties associated with extra oral photodynamic therapy exhibited enhanced antibacterial effects. The procedure could be used as a safer and more efficient alternative technique against halitosis and oral infections in denture wearers.

Mechanical properties and surface roughness of chitosan reinforced heat polymerized denture base resin

PURPOSE

The antifungal property of chitosan (Ch) in denture base resin (DBR) was well established. Ch influence on the mechanical properties of DBR is less studied in the literature and is vital for clinical success of denture. This study estimates the effect of different concentrations of Ch on the flexural strength (FS), fracture toughness (FT), impact strength (IS) and surface roughness (Ra) in heat polymerized DBR.

METHODS

A total of 160 samples were divided into 4 groups (n =10) by weight percentage - Ch 0, Ch 5, Ch 10, Ch 15. FS and FT were estimated by three-point bending test. IS was determined by Charpy test. Ra was evaluated by non-contact laser surface profilometer. The tested samples were characterized by scanning electron microscope and Fourier transformation infra-red spectroscopy. Data were statistical analyzed with one-way ANOVA and Post hoc Bonferroni test.

RESULTS

FS, FT and IS improved with Ch addition when compared to control group. Ch5 showed higher "FS, FT, IS. (p<0.001)". Increased Ra was observed in Ch5 and Ch10 with significant statistical differences among the g roups. (p <0.001) Ch15 displayed decrease in Ra compared to control group.

CONCLUSIONS

The addition of Ch to DBR improved the "FS, FT, IS at 5%wt and Ra at 15%wt" of Ch.

Application of Selected Nanomaterials and Ozone in Modern Clinical Dentistry

This review is an attempt to summarize current research on ozone, titanium dioxide (TiO₂), silver (Ag), copper oxide CuO and platinum (Pt) nanoparticles (NPs). These agents can be used in various fields of dentistry such as conservative dentistry, endodontic, prosthetic or dental surgery. Nanotechnology and ozone can facilitate the dentist’s work by providing antimicrobial properties to dental materials or ensuring a decontaminated work area. However, the high potential of these agents for use in medicine should be confirmed in further research due to possible side effects, especially in long duration of observation so that the best way to apply them can be obtained.

The effects of adding fluorescent carbon nanoparticles on various mechanical properties of denture liners

The aim of this in vitro study was to evaluate the effects of incorporating fluorescent carbon nanoparticles (FCNs) on the hardness, tear, and tensile bond strength of an acrylic-based tissue conditioner and a silicone-based soft denture liner. FCNs added to an acrylic-based tissue conditioner (Viscogel, Dentsply; Group V) and a silicone-based soft denture liner (Ufigel P, Voco; Group U) were divided into subgroups according to the concentrations (Group 0: no water, Group 1: with only water, Group 2: 0.5% FCNs, Group 3: 1% FCNs and Group 4: 10% FCNs) (n=10/per group). Shore A hardness, tear, and tensile bond strength tests were performed. Significant decreases occurred in Groups U2, U3, and U4 compared to the control groups (Groups U0 and U1) in the tear and tensile bond strength test parameters (p<0.025). However, in both types of the tested materials, there were no statistically significant differences among the shore A hardness test results (p>0.025).

Double-layered acrylic resin denture base with nanoparticle additions: An in vitro study

STATEMENT OF PROBLEM

Whether the addition of different antifungal nanoparticles to denture base materials may affect physical or esthetic properties of the resulting nanocomposite is unclear.

PURPOSE

The purpose of this in vitro study was to determine how a new method of adding antifungal nanofiller affects the properties of the processed nanocomposite denture base material.

MATERIAL AND METHODS

Heat-polymerized acrylic resin specimens were prepared according to each test specification. Zirconium dioxide nanoparticles (ZrO₂NPs) and silver nanoparticles (AgNPs) were added in 0.5, 1.0, and 1.5% of acrylic resin powder. The specimens were divided into 2 groups according to the acrylic resin packing method: 1 layer packed conventionally in one step and 2 layers packed in 2 steps, first with unmodified acrylic resin and then by a thin layer of modified acrylic resin before the final closure. The control group was made of unaltered acrylic resin in 1 step. Flexural strength (FS), translucency, and surface roughness (R_a) were measured. A microbial assay was performed by using the direct culture and slide count methods. Three-way ANOVA and Tukey post hoc tests were used to identify statistical differences among groups (α=.05).

RESULTS

The addition of ZrO₂NPs and AgNPs in the 1- or 2-layer specimens reduced Candida albicans adhesion (P<.001). In the 1- and 2-layer specimens, FS significantly increased with ZrO₂NPs. AgNPs decreased FS only in the 1-layer specimen (P<.001). Surface roughness was not changed for the 1- and 2-layer specimens with ZrO₂NPs or the 1-layer specimen with 0.5% AgNPs (P>.05), while other AgNP groups exhibited increased surface roughness (P<.001). AgNPs significantly lowered translucency in the 1- and 2-layer specimens (P<.001), while ZrO₂NPs decreased translucency only in the 1-layer specimen (P<.001).

CONCLUSIONS

The addition of ZrO₂NPs in the double-layer technique decreased Candida adhesion and improved FS without affecting surface roughness, while AgNPs decreased Candida adhesion and FS and increased surface roughness. Both nanofillers decreased the translucency except 0.5% ZrO₂NPs, which did not change translucency when applied in 2 layers.

Mechanical properties of new denture base material modified with gold nanoparticles

PURPOSE

Poly(methyl methacrylate) (PMMA) is the most commonly used material in the production of dental prostheses, and its application is often accompanied by the formation of biofilm. The aim of this work was the preparation of a PMMA/gold nanoparticles (AuNps) composite to improve the antimicrobial properties of heat-polymerised PMMA. The AuNPs were synthesised from gold (III) acetate by Ultrasonic Spray Pyrolysis (USP).In the present study, flexural strength and elastic modulus were investigated, as well as thermal conductivity, density and hardness of the PMMA/AuNps` nanocomposite, with different concentrations of AuNps. Flexural strength and elastic modulus were measured using a three-point bending test, and surface hardness was evaluated using the Vickers hardness test. The thermal conductivity of the samples was measured using the Transient Plane Source (TPS) technique. Density was determined by the pycnometry procedure. Statistical analysis was conducted on the data obtained from the experiments.

RESULTS

The flexural strength and elastic modulus of AuNps/PMMA nanocomposites decreased for all groups containing AuNps. Thermal conductivity and density increased in all groups containing AuNps compared to the control group, but it was not significant in all groups. Vickers hardness values increased significantly with an increase in AuNps` content, with the highest value 21.45 HV obtained at 0.74 wt% of AuNps. Statistical analysis was performed by means of the SPSS 19 software package.

CONCLUSIONS

Incorporation of AuNps into heat-polymerised PMMA resin led to decrease of the flexural strength and elastic modulus. At the same time, the density, thermal conductivity and hardness increased.

Synthesis and characterization of a silver nanoparticle-containing polymer composite with antimicrobial abilities for application in prosthetic and orthotic devices

Background

The presence of skin problems in patients using external lower limb prosthesis is recurrent. This has generated the need to develop interfaces for prosthesis with the ability to control microbial growth. Silver nanoparticles (AgNPs) have been implemented in the development of biomaterials because of their high antimicrobial activity. This article discusses the development of an AgNP-containing polymer composite with antimicrobial activity for developing prosthetic liners.

Methods

AgNPs were synthesized using a photochemical method and certain physicochemical properties were characterized. Furthermore, the antimicrobial activity of AgNPs against Staphylococcus aureus ATCC 25923 and methicillin-resistant Staphylococcus aureus (MRSA), was assessed on the basis of their minimum inhibitory concentrations (MICs). AgNPs were incorporated into a silicon elastomer to assess certain physicomechanical properties, antimicrobial activity and cytotoxic effect of the material.

Results

The maximum antimicrobial activity of the material against Staphylococcus aureus ATCC 25923 and MRSA was 41.58% ±2.97% at AgNP concentration of 32.98 μg/mL and 14.85% ±5.94% at AgNP concentration of 16.49 μg/mL, respectively. Additionally, the material exhibited tensile yield strength, rupture tensile strength, and tensile modulus of elasticity of 0.70 - 1.10 MPa, 0.71–1.06 MPa, and 0.20 - 0.30 MPa, respectively. The mechanical characteristics of the material were within the acceptable range for use in external lower limb prosthetic and orthotic interfaces.

Conclusions

It was possible to incorporate the AgNPs in a silicone elastomer, finding that the composite developed presented antimicrobial activity against Staphylococcus aureus ATCC 25923 and MRSA when compared to non-AgNP material samples.

Surface and Structural Properties of Medical Acrylonitrile Butadiene Styrene Modified with Silver Nanoparticles

Acrylonitrile butadiene styrene/silver nanoparticles (ABS/AgNPs) composites were manufactured through the plastic processing method. Three different matrices were used to obtain polymer and composite samples containing 0.5 wt % and 1.0 wt % of silver nanoparticles, respectively. The aim of this study was to examine physicochemical properties and stability of the materials in the in vitro conditions for two years. The results showed that composites made from amorphous matrices had comparable mechanical properties after incorporation of AgNPs. The values of Young modulus and tensile strength increased after the first and second year of investigation. Silver nanoparticles did not alter the surface parameters-e.g., roughness and contact angle also retained stable values after the in vitro incubation in water solution. The scanning electron observation revealed homogeneous distribution of silver modifier in all the matrices. The 24-month incubation of materials proved the stability of the composites microstructure. The DSC analysis revealed that addition of AgNPs may decrease glass transition temperature of the composite materials which was also reduced after 12 and 24 months of incubation. The attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic studies did not indicate significant changes in the ABS matrices either upon their modification with AgNPs or after the long-term testing. The conducted studies proved that all the composites are stable and may be used for a long-term working period.

Polymeric and inorganic nanoscopical antimicrobial fillers in dentistry

Failure of dental treatments is mainly due to the biofilm accumulated on the dental materials. Many investigations have been conducted on the advancements of antimicrobial dental materials. Polymeric and inorganic nanoscopical agents are capable of inhibiting microorganism proliferation. Applying them as fillers in dental materials can achieve enhanced microbicidal ability. The present review provides a broad overview on the state-of-the-art research in the field of antimicrobial fillers which have been adopted for incorporation into dental materials over the last 5 years. The antibacterial agents and applications are described, with the aim of providing information for future investigations. STATEMENT OF SIGNIFICANCE: Microbial infection is the primary cause of dental treatment failure. The present review provides an overview on the state-of-art in the field of antimicrobial nanoscopical or polymeric fillers that have been applied in dental materials. Trends in the biotechnological development of these antimicrobial fillers over the last 5 years are reviewed to provide a backdrop for further advancement in this field of research.

The Influence of Graphene in Improvement of Physico-Mechanical Properties in PMMA Denture Base Resins

The clinical performances of dental materials depend on their mechanical profiles, determining their long-term deformation and wear resistance. This paper describes a study on the mechanical properties, water absorption and morphological properties of a polymethyl methacrylate (PMMA) resin enriched with graphene-silver nanoparticles (Gr-Ag). Two different concentrations—1 and 2 wt.%—of Gr-Ag were loaded into the PMMA material. For the mechanical characterization, the compression behavior, flexural strength and tensile strength were evaluated. Optical microscopy in polarized light and scanning electron microscopy were used for filler analysis. The filler addition led to an improvement in all mechanical properties, with slight changes being derived from the filler content variation. Gr-Ag use led to an increase in the applied maximum loads. Moreover, 1 wt.% Gr-Ag determined an increase of 174% in the modulus of rupture, which indicates high flexibility.

Silver nanoparticles coated with dodecanethiol used as fillers in non-cytotoxic and antifungal PBAT surface based on nanocomposites

In the present study, we report the preparation of antifungal and non-cytotoxic polymer nanocomposites with potential application in biomedical materials. Dodecanethiol-protected silver nanoparticles (AgNPs-DDT) were synthesized by a reduction/precipitation method and dispersed in chloroform to obtain stable colloidal dispersions. PBAT-based nanocomposites containing 0.25, 0.5 and 2 wt% AgNPs-DDT were prepared by casting method. The incorporation of AgNPs-DDT in PBAT matrix resulted in nanocomposites which combine improved mechanical performance and antifungal properties with a non-cytotoxic characteristic.

Biocompatible Nanocomposite Implant with Silver Nanoparticles for Otology-In Vivo Evaluation

The aim of this work was to investigate of biocompatibility of polymeric implants modified with silver nanoparticles (AgNPs). Middle ear prostheses (otoimplants) made of the (poly)acrylonitrile butadiene styrene (ABS) and ABS modified with silver nanoparticles were prepared through extrusion and injection moulding process. The obtained prostheses were characterized by SEM-EDX, micro-CT and mechanical tests, confirming their proper shape, good AgNPs homogenization and mechanical parameters stability. The biocompatibility of the implants was evaluated in vivo on rats, after 4, 12, 24 and 48 weeks of implantation. The tissue-healing process and cytotoxicity of the implants were evaluated on the basis of microscopic observations of the materials morphology after histochemical staining with cytochrome c oxidase (OCC) and acid phosphatase (AP), as well as via micro-tomography (ex vivo). The in vivo studies confirmed biocompatibility of the implants in the surrounding tissue environment. Both the pure ABS and nanosilver-modified ABS implants exhibited a distinct decrease in the area of granulation tissue which was replaced with the regenerating muscle tissue. Moreover, a slightly smaller area of granulation tissue was observed in the surroundings of the silver-doped prosthesis than in the case of pure ABS prosthesis. The kinetics of silver ions releasing from implants was investigated by ICP-MS spectrometry. The measurement confirmed that concentration of the silver ions increased within the implant’s immersion period. Our results showed that middle ear implant with the nanoscale modification is biocompatible and might be used in ossicular reconstruction.

An overview of application of silver nanoparticles for biomaterials in dentistry

Oral cavity is a gateway to the entire body and protection of this gateway is a major goal in dentistry. Plaque biofilm is a major cause of majority of dental diseases and although various biomaterials have been applied for their cure, limitations pertaining to the material properties prevent achievement of desired outcomes. Nanoparticle applications have become useful tools for various dental applications in endodontics, periodontics, restorative dentistry, orthodontics and oral cancers. Off these, silver nanoparticles (AgNPs) have been used in medicine and dentistry due to its antimicrobial properties. AgNPs have been incorporated into biomaterials in order to prevent or reduce biofilm formation. Due to greater surface to volume ratio and small particle size, they possess excellent antimicrobial action without affecting the mechanical properties of the material. This unique property of AgNPs makes these materials as fillers of choice in different biomaterials whereby they play a vital role in improving the properties. This review aims to discuss the influence of addition of AgNPs to various biomaterials used in different dental applications.