Antimicrobial effects and mechanical properties of poly(methyl methacrylate) as an orthodontic acrylic resin containing Curcumin-Nisin-poly(L-lactic acid) nanoparticle: an in vitro study

Nanoformulations for dismantling fungal biofilms: The latest arsenals of antifungal therapy

Globally, fungal infections have evolved as a strenuous challenge for clinicians, particularly in patients with compromised immunity in intensive care units. Fungal co-infection in Covid-19 patients has made the situation more formidable for healthcare practitioners. Surface adhered fungal population known as biofilm often develop at the diseased site to elicit antifungal tolerance and recalcitrant traits. Thus, an innovative strategy is required to impede/eradicate developed biofilm and avoid the formation of new colonies. The development of nanocomposite-based antibiofilm solutions is the most appropriate way to withstand and dismantle biofilm structures. Nanocomposites can be utilized as a drug delivery medium and for fabrication of anti-biofilm surfaces capable to resist fungal colonization. In this context, the present review comprehensively described different forms of nanocomposites and mode of their action against fungal biofilms. Amongst various nanocomposites, efficacy of metal/organic nanoparticles and nanofibers are particularly emphasized to highlight their role in the pursuit of antibiofilm strategies. Further, the inevitable concern of nanotoxicology has also been introduced and discussed with the exigent need of addressing it while developing nano-based therapies. Further, a list of FDA-approved nano-based antifungal formulations for therapeutic usage available to date has been described. Collectively, the review highlights the potential, scope, and future of nanocomposite-based antibiofilm therapeutics to address the fungal biofilm management issue.

The effect of antimicrobial peptide-added adhesive resins on shear bond strength and the adhesive remnant index of orthodontic brackets

OBJECTIVES

The aim of this study was to evaluate the effect of in-vivo produced Nisin which is an antimicrobial peptide (AMP) added to adhesive resin on shear bond strength (SBS) and the adhesive remnant index (ARI) of orthodontic brackets.

METHODS

Bacterial AMP was produced by fermentation and the ideal AMP/Bond concentration and antimicrobial efficacy of the mixture were tested. To evaluate the SBS and ARI scores of AMP-added adhesive resins, 80 maxillary premolar teeth extracted for orthodontic purposes were used and randomly assigned into 2 groups (n = 40). Group 1: Control Group (teeth bonded with standard adhesive resin); Group 2: Experimental Group (teeth bonded with AMP-added adhesive resin). Statistical analysis was performed using the SPSS package program and applying the Mann-Whitney U and Fisher's exact tests. P < 0.05 was considered as statistically significant.

RESULTS

Nisin synthesized in-vivo from Lactococcus lactis (L. lactis) (ATCC 7962) bacteria was provided to form a homogenous solution at an ideal concentration To find the minimum AMP/Bond mixture ratio that showed maximum antimicrobial activity, AMP and Bond mixtures were tested at various concentration levels between 1/160 and 1/2 (AMP/Bond). As a result, the optimum ratio was determined as 1/40. The antimicrobial efficacy of Nisin-added adhesive resin was tested against Streptococcus mutans (S. mutans) (ATCC 35,688) and Lactobacillus strains (cariogenic microorganisms). AMP formed a 2.7 cm diameter zone alone, while 1/40 AMP-bond mixture formed a 1.2 cm diameter zone. SBS values of the teeth bonded with Nisin added adhesive (17.49 ± 5.31) were significantly higher than the control group (14.54 ± 4.96) (P = 0.004). According to the four point scale, Nisin added adhesive provided a higher ARI score in favour of the adhesive and tooth compared to the control group (ARI = 3, n = 20).

CONCLUSIONS

Nisin produced from L. lactis (ATCC 7962) had greater antimicrobial effects after mixing with adhesive bond against cariogenic microorganisms S. mutans (ATCC 35,688) and Lactobacillus strains. Nisin added adhesive increased shear bond strength (SBS) of orthodontic brackets and ARI scores in favor of adhesive & teeth.

CLINICAL RELEVANCE

Clinicians should take into account that using Nisin-added adhesive resin in orthodontic treatments can provide prophylaxis against tooth decay, especially in patients with poor oral hygiene.

The flexural strength of orthodontic acrylic resin containing resveratrol nanoparticles as antimicrobial agent: An in vitro study

OBJECTIVE

This study aimed to evaluate how the addition of resveratrol nanoparticles (RNPs), which act as an antimicrobial agent, affects the strength of acrylic resin used in orthodontics.

METHODS

According to ISO 20795-1-2013, 76 cold cure acrylic resin samples (65×10×3.3mm) were prepared. The samples were divided into four groups (19 samples in each group) based on RN concentrations added to 1mL acrylic monomer (0 for control, 256, 512, and 1024μg/mL). Flexural strength was assessed in megapascal (MPa) using a universal testing machine. Data analysis involved nonparametric Kruskal-Wallis analysis of variance and pairwise post-hoc Dunn's test.

RESULTS

The flexural strength decreased as the concentration of RNPs increased, with the lowest value observed at 1024μg/mL (63.06±5.33MPa). The control group exhibited the highest mean of flexural strength (88.43±4.41MPa), followed by the groups with RNPs at the concentrations of 256μg/mL (82.69±4.41MPa) and 512μg/mL (76.02±4.59MPa).

CONCLUSION

In conclusion, the addition of RNs to orthodontic acrylic resin had a dose-dependent impact on its flexural strength. Based on the findings, we recommend incorporating RNs at a concentration of 256μg/mL as an antimicrobial agent in orthodontic acrylic resin. However, further research is necessary to assess the long-term effects and clinical applications of this approach.

From nature to nanomedicine: bioengineered metallic nanoparticles bridge the gap for medical applications

The escalating global challenge of antimicrobial resistance demands innovative approaches. This review delves into the current status and future prospects of bioengineered metallic nanoparticles derived from natural sources as potent antimicrobial agents. The unique attributes of metallic nanoparticles and the abundance of natural resources have sparked a burgeoning field of research in combating microbial infections. A systematic review of the literature was conducted, encompassing a wide range of studies investigating the synthesis, characterization, and antimicrobial mechanisms of bioengineered metallic nanoparticles. Databases such as PubMed, Scopus, Web of Science, ScienceDirect, Springer, Taylor & Francis online and OpenAthen were extensively searched to compile a comprehensive overview of the topic. The synthesis methods, including green and sustainable approaches, were examined, as were the diverse biological sources used in nanoparticle fabrication. The amalgamation of metallic nanoparticles and natural products has yielded promising antimicrobial agents. Their multifaceted mechanisms, including membrane disruption, oxidative stress induction, and enzyme inhibition, render them effective against various pathogens, including drug-resistant strains. Moreover, the potential for targeted drug delivery systems using these nanoparticles has opened new avenues for personalized medicine. Bioengineered metallic nanoparticles derived from natural sources represent a dynamic frontier in the battle against microbial infections. The current status of research underscores their remarkable antimicrobial efficacy and multifaceted mechanisms of action. Future prospects are bright, with opportunities for scalability and cost-effectiveness through sustainable synthesis methods. However, addressing toxicity, regulatory hurdles, and environmental considerations remains crucial. In conclusion, this review highlights the evolving landscape of bioengineered metallic nanoparticles, offering valuable insights into their current status and their potential to revolutionize antimicrobial therapy in the future.

Antifungal activity of nisin against clinical isolates of azole-resistant Candida tropicalis

The rapid emergence of invasive infections caused by azole-resistant Candida tropicalis has become a public health concern, and there is an urgent need for alternative treatment strategies. Studies have demonstrated the antibacterial effects of nisin, a well-known peptide naturally produced by Lactococcus lactis subsp. lactis. However, there is scant information about the antifungal effect of nisin against C. tropicalis. The present study aims to investigate the in vitro antifungal activity of nisin against clinical isolates of azole-resistant C. tropicalis strains, as well as its inhibitory effect on biofilm formation. A total of 35 C. tropicalis strains isolated from patients with invasive fungal infections were divided into the azole-resistant group and the azole-sensitive group, containing 21 and 14 strains, respectively. The relative expression levels of the ERG11 and UPC2 genes in the azole-resistant group were higher than those in the azole-sensitive group (p < 0.0001), while no significant differences were observed in the expression levels of the MDR1 and CDR1 genes. The minimum inhibitory concentration of nisin against C. tropicalis ranged from 2 to 8 μg/mL. Nisin treatment inhibited the growth of azole-resistant C. tropicalis, with over a four-fold reduction in OD600 nm values observed at the 8-h time point, while it promoted the transition of C. tropicalis from the spore phase to the hyphal phase, as observed on cryo-scanning electron microscopy. The results of biofilm quantification using crystal violet staining indicated a significant decrease in OD570 nm values in the nisin-treated group compared to the controls (p < 0.0001). Among the 21 azole-resistant C. tropicalis strains, the biofilm formation was inhibited in 17 strains (17/21, 81%), and more than 85% inhibition of biofilm formation was observed in the representative strains. With regard to the molecular mechanisms, the expression of the BCR1 and UPC2 genes in the azole-resistant strains was down-regulated on nisin treatment (p < 0.05). In conclusion, we demonstrated, for the first time, that nisin has antifungal activity and significant anti-biofilm activity against clinical isolates of azole-resistant C. tropicalis strains. Based on the findings, nisin could be a promising alternative antifungal agent for combating azole-resistant C. tropicalis infections.

Curcumin effects on age-related changes in oral immunity: an in vivo study

The current study aimed to investigate the effects of ageing on oral immunity using β-defensin (DEFB) 1/2 as a marker and evaluate the effects of curcumin (CUR) on these processes. The study sample included thirty male C57BL/6J mice divided into three groups based on the treatment method used. The young control (YC) and old control (OC) groups received 0·5 % methylcellulose-400 (CUR vehicle) orally for 5 days, whereas the CUR group of older mice received a CUR solution suspended in 0·5 % methylcellulose-400 (dose: 3·0 mg/kg body). DEFB1/2 and immune indicator levels were measured in the saliva and salivary glands post-treatment. The saliva volume and protein content were significantly reduced in the OC group compared with the YC group. CUR administration restored these parameters, decreased DEFB1 expression in the salivary gland and increased DEFB1/2 secretion and DEFB2 expression. These findings were supported by epigenetic gene regulation and partial cytokine activation from changes in WD40 repeat protein 5, TNF alpha and IL-1beta. CUR can partially restore age-related changes in oral immune responses and promote oral health, thereby preventing frailty in the older population through a nutritional therapeutic pathway.

The effects of antimicrobial photocatalytic nanoparticles on the flexural strength of orthodontic acrylic resins: A systematic review and meta-analysis

BACKGROUND/PURPOSE

Orthodontic acrylic resins containing antimicrobial photocatalytic nanoparticles aims to reduce oral lesions including denture stomatitis and white spot lesions but they should not imperil its mechanical properties. This systematic review was done to evaluate the effect of various photocatalytic nanoparticles on the flexural strength (FS) of acrylic resins.

MATERIALS AND METHODS

We systematically searched the PubMed/Medline, Cochrane Library, and Scopus databases from January 2018 to October 2023. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the quality of the studies was evaluated using the QUIN tool, which is specifically designed to assess the risk of bias in vitro studies.

RESULTS

Following screening of 1016 initial records, 23 studies were deemed eligible for inclusion. The addition of photocatalytic nanoparticles, such as emodin (Emo), curcumin (Cur), Cur nisin (CurNis), zeolite/zinc oxide (Zeo/ZnO), and Ulva lactuca (U. lactuca), to acrylic resins resulted in a reduction in FS, with the extent of reduction dependent on the nanoparticle concentration. Specifically, the addition of Emo (≥0.5 %), Cur (≥0.5 %), CurNis (≥5 %), Zeo/ZnO (≥2), and U. lactuca (≥1 %) to acrylic resins significantly decreased FS. Conversely, the inclusion of ZnO and titanium dioxide (TiO2) in acrylic resins improved FS, but higher concentrations (≥5 % for TiO2) had a limited positive effect.

CONCLUSION

Our study supports the use of low concentrations of photocatalytic nanoparticles, such as ZnO (≤2 %), TiO2 (≤3 %), Emo (≤0.5 %), Cur (≤0.5 %), CurNis (≤5 %), and U. lactuca (≤1 %), in orthodontic acrylic resins without compromising FS.

Physico-mechanical and antimicrobial properties of an elastomeric ligature coated with reduced nanographene oxide-nano curcumin subjected to dual-modal photodynamic and photothermal inactivation against Streptococcus mutans biofilms

BACKGROUND

White spot lesions (WSLs) are a common side effect of fixed orthodontic treatment. Streptococcus mutans is the primary causative agent of WSLs and dental caries on the teeth during treatment. According to the unique features of reduced graphene oxide-nano curcumin (rGO-nCur), this study aimed to investigate the mechanical properties and antimicrobial potency of rGO-nCur coated orthodontic elastomeric ligatures as a novel coating composite following dual-modal photodynamic inactivation (PDI) and photothermal inactivation (PTI) against S. mutans biofilms.

METHODS

After confirmation of rGO-nCur synthesis and coating elastomeric ligatures with different concentration levels of 1.25, 2.5, 5, 7.5, and 10 % of rGO-nCur, tensile strength, force decay, extension to tensile strength, and contact angle of the coated elastomeric ligatures were measured using universal testing machine and sessile drop method, respectively. To investigate the mechanism through which irradiated rGO-nCur can inhibit the formation of S. mutans biofilms, intracellular reactive oxygen species (ROS) generation, and increase in temperature of rGO-nCur solutions under the 450 and 980 nm laser irradiation, respectively, were measured. The anti-biofilm activity and inhibition of water-insoluble extracellular polysaccharide (EPS) production ability of irradiated rGO-nCur coated elastomeric ligatures using a 450 nm diode laser (195 J/cm2), a 980 nm diode laser (195 J/cm2), and a combination of both (78 J/cm2 of irradiation from each one) (i.e., PDI, PTI, and dual-modal PDI/PTI, respectively) were determined. Also, the expression of virulence genes involved in biofilm formation (comDE, gtfD, and smuT) was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) following the mentioned treatment. One-way ANOVA test and Tukey post-hoc test at a p-value equal to/or less than 0.05 were used to analyze the obtained data.

RESULTS

The synthesis of GO nano-sheets in a layered structure with a thickness of 0.76 nm was confirmed by AFM analysis. FESEM showed that the exfoliated sheet of synthesized GO had several micrometers in lateral size. DLS revealed that the mean particle size and density index of synthesized nCur were 57.47 ± 2.14 nm and 10 % respectively. In DLS analysis, rGO-nCur showed more positive surface charge (24 mV) than the nano-sheets of GO. FESEM confirmed the coating of rGO-nCur on elastomeric ligatures. ANOVA revealed that tensile strength of 1.25, 2.5, and 5 % rGO-nCur coated elastomeric ligatures were not decreased statistically significantly (P > 0.05). Mean tensile strength and recorded force of 7.5 and 10 % rGO-nCur coated elastomeric ligatures decreased significantly after 14 days' immersion in the artificial saliva (P < 0.05). On the 28th day of the study, the mean of the tensile strength of elastomeric ligatures coated with 10 % rGO-nCur (13.03 ± 0.10 N) was recorded as 55.90 % of the initial tensile strength (23.31 ± 0.41 N in uncoated elastomeric ligatures), while the mean tensile strength of elastomeric ligatures coated with 7.5 % rGO-nCur (16.01 ± 0.10 N) was measured as 68.94 % of the initial tensile strength (23.22 ± 0.09 N in uncoated elastomeric ligatures). When comparing the coated elastomeric ligatures at 7.5 % and 10 % to the original uncoated elastomeric ligatures at similar time intervals, statistically significant decreases in extension to tensile strength (0.42 to 0.71 mm or 3.02 to 5.05 %; all P < 0.05) were observed. The largest contact angle was measured in elastomeric ligatures coated by 10 % rGO-nCur followed by 7.5 and 5 % rGO-nCur (128 ± 2.19°, 117 ± 2.23°, and 99 ± 1.83°; respectively). The results revealed a rise of 6.4-fold in intracellular ROS and an 11.2 °C increase in the temperature of rGO-nCur solutions following the 450 nm and 980 nm laser irradiation, respectively. The 5 % rGO-nCur coated elastomeric ligature mediated dual-modal PDI/PTI showed the most inhibition of the biofilm formation of S. mutans by 83.62 % (P = 0.00). Significant reductions in water-insoluble EPS were detected in biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 nm and 980 nm diode lasers (i.e., dual-modal PDI/PTI; 96.17 %; P = 0.00). The expression levels of comDE, gtfD, and smuT virulence genes were significantly downregulated (7.52-, 13.92-, and 8.23-fold, respectively) in the biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following dual-modal PDI/PTI in comparison with biofilm cultures on non-coated elastomeric ligatures.

CONCLUSION

5 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 and 980 nm diode lasers (dual-modal PDI/PTI), without adverse effects on the physico-mechanical properties of elastomeric ligatures, can be used to inhibit the formation of S. mutans biofilms on the coated elastomeric ligatures around orthodontic brackets.

The effect of zinc oxide (ZnO) nanoparticle concentration on the adhesion of mucin and Streptococcus mutans to heat-cured acrylic resin

Incorporating zinc oxide (ZnO) nanoparticles as antibacterial fillers in heat-cured acrylic resin could decrease mucin and Streptococcus mutans (S. mutans) adhesion, reducing the incidence of dental caries in the baseplates of orthodontic patients. Here, ZnO nanoparticles were modified using 3-(trimethoxysilyl)propyl methacrylate with various concentrations, added to acrylic resin powder, homogenized, mixed with acrylic resin liquid, and processed. The composite systems interfered well with mucin and S. mutans adhesion. The lowest mean of the amount of mucin adhered was on heat-cured acrylic resin with 7.5% ZnO nanoparticles, with a standard deviation of 18.07±0.80 mg/mL. The ZnO nanoparticles with a concentration of 7.5% showed an 87.09±0.88% S. mutans adhesion in control groups with no additives. These composite systems were proven to have better physicochemical characteristics and antibacterial abilities. Combining ZnO nanoparticles with heat-cured acrylic resin has great potential for self-cleaning baseplates of orthodontic patients in the future.

Multiple potential strategies for the application of nisin and derivatives

Nisin is a naturally occurring bioactive small peptide produced by Lactococcus lactis subsp. lactis and belongs to the Type A (I) lantibiotics. Due to its potent antimicrobial activity, it has been broadly employed to preserve various food materials as well as to combat a variety of microbial pathogens. The present review discusses the antimicrobial properties of nisin and different types of their derivatives employed to treat microbial pathogens with a detailed underlying mechanism of action. Several alternative strategies such as combination, conjugation, and nanoformulations have been discussed in order to address several issues such as rapid degradation, instability, and reduced activity due to the various environmental factors that arise in the applications of nisin. Furthermore, the evolutionary relationship of many nisin genes from different nisin-producing bacterial species has been investigated. A detailed description of the natural and bioengineered nisin variants, as well as the underlying action mechanisms, has also been provided. The chemistry used to apply nisin in conjugation with natural or synthetic compounds as a synergetic mode of antimicrobial action has also been thoroughly discussed. The current review will be useful in learning about recent and past research that has been performed on nisin and its derivatives as antimicrobial agents.

Nanocurcumin Release from Self-Cured Acrylic Resins; Effects on Antimicrobial Action and Flexural Strength

The placement of orthodontic appliances into the oral area can lead to infection, inflammatory and gingival collapse. Using an antimicrobial and anti-inflammatory material in the matrix of orthodontic appliance may help to reduce these issues. This study aimed to assess the release pattern, the antimicrobial action and the flexural strength of self-cured acrylic resins after adding different weight percentages of curcumin nanoparticles (nanocurcumin). In this in-vitro study, 60 acrylic resin samples were divided into five groups (n = 12) based on the weight percentage of curcumin nanoparticles added to the acrylic powder (0 for control, 0.5, 1, 2.5, and 5%). Then, the dissolution apparatus was used for the release assessment of nanocurcumin form the resins. For antimicrobial action assessment, the disk diffusion method was used and a three-point bending test was performed with a speed of 5 mm/min to determine the flexural strength. Data were analyzed using one-way analysis of variance (ANOVA) and Post-Hoc Tukey tests (with p < 0.05 as significant level). The microscopic images showed the homogeny distribution of nanocuricumin in self-cured acrylic resins in varied concentrations. The release pattern showed a two-step release pattern for all concentrations of nanocurcumin. The one-way ANOVA outcomes indicated that adding curcumin nanoparticles to self-cured resin increased the diameter of the inhibition zones for the groups against Streptococcus mutans (S. mutans) significantly (p < 0.0001). Additionally, as the weight percentage of curcumin nanoparticles increased, the flexural strength decreased (p < 0.0001). However, all strength values were higher than the standard value (50 MPa). No significant difference was detected between the control group and the group with 0.5 percent (p = 0.57). Considering the proper release pattern and the potent antimicrobial activity of curcumin nanoparticles, then the preparing self-cured resins containing curcumin nanoparticles can be beneficial for antimicrobial aims without damaging the flexural strength to use in orthodontic removable applications.

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.

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.

Clinical Applications of Poly-Methyl-Methacrylate in Neurosurgery: The In Vivo Cranial Bone Reconstruction

Background: Biomaterials and biotechnology are becoming increasingly important fields in modern medicine. For cranial bone defects of various aetiologies, artificial materials, such as poly-methyl-methacrylate, are often used. We report our clinical experience with poly-methyl-methacrylate for a novel in vivo bone defect closure and artificial bone flap development in various neurosurgical operations. Methods: The experimental study included 12 patients at a single centre in 2018. They presented with cranial bone defects after various neurosurgical procedures, including tumour, traumatic brain injury and vascular pathologies. The patients underwent an in vivo bone reconstruction from poly-methyl-methacrylate, which was performed immediately after the tumour removal in the tumour group, whereas the trauma and vascular patients required a second surgery for cranial bone reconstruction due to the bone decompression. The artificial bone flap was modelled in vivo just before the skin closure. Clinical and surgical data were reviewed. Results: All patients had significant bony destruction or unusable bone flap. The tumour group included five patients with meningiomas destruction and the trauma group comprised four patients, all with severe traumatic brain injury. In the vascular group, there were three patients. The average modelling time for the artificial flap modelling was approximately 10 min. The convenient location of the bone defect enabled a relatively straightforward and fast reconstruction procedure. No deformations of flaps or other complications were encountered, except in one patient, who suffered a postoperative infection. Conclusions: Poly-methyl-methacrylate can be used as a suitable material to deliver good cranioplasty cosmesis. It offers an optimal dural covering and brain protection and allows fast intraoperative reconstruction with excellent cosmetic effect during the one-stage procedure. The observations of our study support the use of poly-methyl-methacrylate for the ad hoc reconstruction of cranial bone defects.

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.