Long-term antimicrobial assessment of orthodontic brackets coated with nitrogen-doped titanium dioxide against Streptococcus mutans

Antibacterial efficacy of nanoparticles on orthodontic materials-A systematic review and meta-analysis

AIM

This study aims to evaluate the efficacy of coated nanoparticles within orthodontic appliances as a novel strategy to enhance their antibacterial properties.

MATERIAL AND METHODS

A systematic search for relevant articles published between 2013 and March 2024 was conducted across electronic databases including PubMed, Scopus, Web of Science, and EBSCOhost. Studies meeting pre-defined eligibility criteria were included and assessed for methodological quality. Data on the antibacterial activity of coated nanoparticles on orthodontic appliances was extracted from included studies.

RESULTS

A range of antimicrobial agents, including metallic nanoparticles (silver, titanium dioxide, silver-platinum alloy, zinc oxide, copper oxide), and others like chitosan, quaternary ammonium-modified gold nanoclusters, titanium nitride doped with calcium phosphate, and graphene oxide, have been explored for incorporation into orthodontic materials. Studies have shown a significant boost in the antibacterial capacity of these materials compared to controls, suggesting promise for improved oral hygiene during orthodontic treatment.

CONCLUSION

It can be concluded that incorporating nanoparticles into orthodontic appliances holds promise for enhancing their antibacterial properties. However, the studies displayed significant heterogeneity therefore, further research with standardized protocols for factors like nanoparticle size, concentration, and incorporation techniques across various orthodontic materials is crucial to guide future clinical applications.

PROSPERO REGISTRATION

CRD42024521326.

Current trends and research advances on the application of TiO2 nanoparticles in dentistry: How far are we from clinical translation?

The great potential of nanotechnology-based knowledge during the past decade has shown great potential to elevate human living standards and enhance healthcare conditions through diagnosing, preventing, and treating different diseases. Among abundant nanoparticles (NPs), inorganic NPs feature distinctive biological and physicochemical properties compared to their conventional counterparts which do not endow. TiO2 NPs possess excellent properties including low-cast, antibacterial properties, biocompatibility, and physicochemical stability. The present review highlights and discusses the current trends in applying TiO2 NPs in dentistry ranging from TiO2-based nanocomposite in endodontics, orthodontics, and biofilm prevention. Moreover, the potential of TiO2 NPs in developing new photodynamic therapy and the next generation of oral care products is outlined. In the end, the clinical translation of TiO2-based dental materials is brought to the forefront which is impetus and of great importance to developing inorganic NP-based dental materials.

Spectrophotometrically, Spectroscopically, Microscopically and Thermogravimetrically Optimized TiO2 and ZnO Nanoparticles and their Bactericidal, Antioxidant and Cytotoxic Potential: A Novel Comparative Approach

Current study was aimed to determine the antibacterial, antioxidant and cytotoxic potential of Titanium dioxide nanoparticles (TiO2NPs) and Zinc oxide nanoparticles (ZnONPs). Nanoparticles were characterized by UV-Vis spectrophotometry, particle size analyzer (PSA), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The Minimum inhibitory concentration (MIC) was determined by standard agar dilution method. Antibacterial potential of nanoparticles was analyzed by standard disc diffusion method against bacterial strains including Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia. Different concentrations of NPs (0.2, 0.4, 0.6, 0.8, 1.0, 1.2 and 1.4 mg/mL) were incorporated to evaluate the antimicrobial activity. Antioxidant activity and cytotoxicity of these NPs was analyzed by DPPH method and brine shrimp cytotoxicity assay, respectively. The MIC of TiO2NPs against E. coli, P. aeruginosa and K. pneumoniae was 0.04, 0.08 and 0.07 mg/mL respectively while the MIC of ZnONPs against the above strains was 0.01, 0.015 and 0.01 mg/mL. The maximum zone of inhibition was observed for K. pneumoniae i.e., 20mm and 25mm against TiO2 and ZnO NPs respectively, at 1.4 mg/mL concentration of NPs. The susceptibility of NPs against bacterial strains was evaluated in the following order: K. pneumoniae > P. aeruginosa > E. coli. The antioxidant activity of nanoparticles increased by increasing the concentration of NPs while cytotoxic analysis exhibited non-toxic effect of ZnO NPs while TiO2 had toxic effects on 1.2 and 1.4 mg/mL concentrations. Results revealed that ZnO NPs have more antibacterial and negligible cytotoxic potential in contrast to TiO2 NPs.

Efficacy of peptide-based enamel coatings in the prevention of demineralization using fixed orthodontic brackets in a rat model

INTRODUCTION

White spot lesions (WSLs) represent a prominent pathology encountered during orthodontic treatment, originating from enamel demineralization induced by the accumulation of bacterial biofilms. The previously developed bioinspired enamel coating form of self-assembling antimicrobial peptide D-GL13K exhibited antimicrobial activity and enhanced acid impermeability, offering a potential solution to prevent demineralization. The primary aim of this investigation is to assess the in vivo anti-demineralization properties and biocompatibility of the D-GL13K coating.

METHODS

A rat model was developed to assess the antimicrobial enamel coating during fixed orthodontic treatment. The anti-demineralization efficacy attributed to the D-GL13K coating was evaluated by employing optical coherence tomography, Vickers microhardness testing, and scanning electron microscopy. The biocompatibility of the D-GL13K coating was investigated through histologic observations of vital organs and tissues using hematoxylin and eosin.

RESULTS

The D-GL13K coating demonstrated significant anti-demineralization effects, evidenced by reduced demineralization depth analyzed through optical coherence tomography and enhanced Vickers hardness than in the noncoated control group, showcasing the coating's potential to protect teeth from WSLs. Scanning electron microscopy analysis further elucidated the diminished enamel damage observed in the group treated with D-GL13K. Importantly, histologic examination of vital organs and tissues using hematoxylin and eosin staining revealed no overt disparities between the D-GL13K coated group and the noncoated control group.

CONCLUSIONS

The D-GL13K enamel coating demonstrated promising anti-demineralization and biocompatibility properties in a rat model, thereby suggesting its potential for averting WSLs after orthodontic interventions. Further research in human clinical settings is needed to evaluate the coating's long-term efficacy.

Evaluation of Antimicrobial Efficiency, Shear Bond Strength, and Adhesive Remnant Index of TiO2 Infiltrated Orthodontic Adhesive - An In Vitro Study

Background

Enamel demineralization is an unavoidable adverse effect encountered with bonding brackets in orthodontic therapy. Introducing nanoparticles into the composite adhesive paste can prevent enamel demineralization. Titanium dioxide (TiO2) is known to exhibit direct antimicrobial efficiency. This study aimed to assess the antibacterial efficiency and shear bond strength (SBS) of an orthodontic bonding composite infiltrated with TiO2 nanoparticles.

Materials and Methods

This in vitro study evaluated the efficiency of TiO2 nanoparticle-incorporated light-curing orthodontic composite paste (ENLIGHT, ORMCO). Twenty extracted premolars were randomly and equally allocated to the two study groups, N = 10. While a conventional composite was utilized for the bonding brackets in Group I, a TiO2-incorporated composite was used in Group 2. The adhesive remnant index (ARI) scores given by Artun and Bergland et al. and SBS were determined. Furthermore, the antimicrobial efficiency was estimated using the minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) and agar well diffusion assay for six composite disc specimens. The results were statistically analyzed using the chi-square test and Student's t test, at P < 0.05.

Results

After 24 h of curing, no statistical mean difference was observed between the two groups in terms of ARI or SBS scores (P > 0.05). However, there was a significant increase in the antimicrobial efficiency of Group II when compared with Group I (P < 0.05).

Conclusion

TiO2 nanoparticle-incorporated orthodontic composites improve the antimicrobial efficiency with no significant change in the SBS. The ARI scores indicate the presence of 50% remnant orthodontic composite on the tooth enamel surface post debonding.

Evaluation of Antibacterial Effect of Hybrid Nano-coating of Stainless Steel Orthodontic Brackets on Streptococcus Mutans - An In vitro Study

Nano-coating of orthodontic brackets with a combination or hybrid of metals and metal oxides may reduce the streptococcus mutans count and incidence of enamel decalcification seen around brackets in patients undergoing fixed orthodontic treatment. In total, 255 orthodontic brackets (3M Unitek, Monrovia, California, USA) were divided into one control group (group I) of 60 and three experimental groups of 65 each (groups II, III, and IV). The experimental group brackets were coated with a combination of silver-zinc oxide, copper oxide -zinc oxide, and silver-copper oxide nanoparticles using physical vapour deposition method. The two nanoparticles used for each group were mixed in the ratio of 1:1 by weight for providing a uniform hybrid coating. Sixty brackets from each group were used for microbiological evaluation of antibacterial activity against Streptococcus mutans in blood agar medium, and the remaining five brackets from each experimental group were used for SEM analysis to check the uniformity of the coating. Nano-coated brackets demonstrated better antibacterial properties than uncoated brackets. Copper oxide-zinc oxide nanoparticles coated brackets demonstrated better antibacterial properties than the silver-zinc oxide and silver- copper oxide coated brackets.

New generation of orthodontic devices and materials with bioactive capacities to improve enamel demineralization

OBJECTIVE

The article reviewed novel orthodontic devices and materials with bioactive capacities in recent years and elaborated on their properties, aiming to provide guidance and reference for future scientific research and clinical applications.

DATA, SOURCES AND STUDY SELECTION

Researches on remineralization, protein repellent, antimicrobial activity and multifunctional novel bioactive orthodontic devices and materials were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus.

CONCLUSIONS

The new generation of orthodontic devices and materials with bioactive capacities has broad application prospects. However, most of the current studies are limited to in vitro studies and cannot explore the true effects of various bioactive devices and materials applied in oral environments. More research, especially in vivo researches, is needed to assist in clinical application.

CLINICAL SIGNIFICANCE

Enamel demineralization (ED) is a common complication in orthodontic treatments. Prolonged ED can lead to dental caries, impacting both the aesthetics and health of teeth. It is of great significance to develop antibacterial orthodontic devices and materials that can inhibit bacterial accumulation and prevent ED. However, materials with only preventive effect may fall short of addressing actual needs. Hence, the development of novel bioactive orthodontic materials with remineralizing abilities is imperative. The article reviewed the recent advancements in bioactive orthodontic devices and materials, offering guidance and serving as a reference for future scientific research and clinical applications.

Sustained antibacterial activity of orthodontic elastomeric ligature ties coated with a novel kombucha-derived bacterial nanocellulose: An in-vitro study

Incipient carious lesions, the most common complication in orthodontic patients with fixed appliances, call for the development of novel preventive dental materials that do not rely on patient adherence. The present study aimed to assess the ability of elastomeric ligatures coated with bacterial nanocellulose (BNC) to deliver sustained antibacterial activity, during the standard 28-day interval between orthodontic appointments, without compromising their mechanical properties. Kombucha membrane was used to produce cellulose as a secondary product from the fermentation of tea broth with symbiotic bacteria and yeast culture. Characterization of BNC-coated elastomeric ligatures was performed using Fourier Transform Infrared Spectroscopy and Energy Dispersive Spectroscopy analysis. The samples were pre-treated by immersion first in isopropyl alcohol, then in 8 mL nanocellulose solution for 7 days. Tensile strain and strength of the BNC-coated and conventional ligatures were evaluated using a tensile testing machine. Direct contact and agar diffusion tests were performed to assess the antibacterial activity of nanocellulose. In addition, the release profile of BNC was evaluated. Data analysis was performed by one-way analysis of variance (ANOVA) followed by post-hoc Tukey's test and Wilcoxon signed-rank test. P values less than 0.05 was regarded as significant. There was no statistically significant difference in tensile strain and strength between the BNC-coated and conventional ligatures. The coated ligatures provided sustained antibacterial activity during the required 28 days. The use of BNC-coated elastomeric ligatures in patients with fixed orthodontic appliances might be a promising solution to plaque formation and subsequent enamel decalcification.

Antibacterial Properties and Shear Bond Strength of Titanium Dioxide Nanoparticles Incorporated into an Orthodontic Adhesive: A Systematic Review

Objective

The present review was conducted to test whether the addition of titanium dioxide (TiO2) nanoparticles (NPs) within orthodontic bracket adhesives would alter their properties and assess their antimicrobial activity against cariogenic microorganisms in addition to noteworthy mechanical properties.

Materials and methods

Using predetermined inclusion criteria, an electronic search was conducted using Dissertations and Thesis Global, the Web of Science, Cochrane, Scopus, and Medline/PubMed. Specific terms were utilized while searching the database.

Results

Only seven of the 10 included studies assessed shear bond strength (SBS). The mean SBS among the control group varied from 9.43 ± 3.03 MPa to 34.4 ± 6.7 MPa in the included studies, while in the experimental group, it varied from 6.33 ± 1.51 MPa to 25.05 ± 0.5 MPa. Antibacterial activity was assessed in five of the 10 included studies using TiO2 NPs, which could easily diffuse through bacterial media to form the growth inhibition zone.

Conclusion

Antibacterial NPs added to orthodontic adhesives at a concentration of 1-5 wt% inhibit bacterial growth and have no effect on bond strength.

How to cite this article

D Tivanani MVD, Mulakala V, Keerthi VS. Antibacterial Properties and Shear Bond Strength of Titanium Dioxide Nanoparticles Incorporated into an Orthodontic Adhesive: A Systematic Review. Int J Clin Pediatr Dent 2024;17(1):102-108.

Corrosion of Fixed Orthodontic Appliances: Causes, Concerns, and Mitigation Strategies

The orthodontic supply market is a prosperous billion-dollar industry, driven by an increasing demand for orthodontic appliances. The supremacy of metallic first-generation biomaterials is evident for manufacturing brackets, archwires, bands, and other components due to their well-recognized chemical inertness, spontaneous passivation, biocompatibility, and favorable mechanical properties combination. However, the oral cavity is the ultimate corrosion-promoting environment for any metallic material. In this work, the general picture of the intraoral degradation of fixed orthodontic appliances is first addressed, from the causes to the harmful effects and their oral clinical implications. Current mitigation strategies are also pointed out, including the alloys’ bulk composition adjustment combined with new and advanced manufacturing processes and/or their surface treatment or coating deposition. The versatile use of thin films and coatings stands out with different deposition technologies: Many in vivo and in vitro efforts have been devoted to oral aging, from monolithic to composite architectures and micro- to nano-scale materials, to meet the best and safest oral practice demands. Unfortunately, literature data suggest that even the existing commercially available protective coatings have drawbacks and are fallible. Further multidisciplinary research is still required to effectively mitigate the corrosion behavior of fixed orthodontic appliances.

Effects of titanium oxide coating on the antimicrobial properties, surface characteristics, and cytotoxicity of orthodontic brackets - A systematic review and meta analysis of in-vitro studies

Objective

The objective of this review is to systematically analyze the available literature on the effects of titanium oxide (TiO₂) coating on the antimicrobial properties, surface characteristics, and cytotoxicity of orthodontic brackets.

Methods

In-vitro studies reporting on the effects of Titanium oxide (TiO₂) coatings on antimicrobial properties, surface roughness, cytotoxic activity and bacterial adhesion of orthodontic brackets were included in the review. Electronic databases such as PubMed, SCOPUS, Web of Science and Google Scholar, were searched till September 2022. Risk of Bias was analyzed by using RoBDEMAT tool. Meta-analysis using Random Effects Model was performed for assessing the antimicrobial activity against S. mutans, C. albicans and L. Acidophilus.

Results

A total of 11 studies were included the RoB analysis revealed sufficient reporting across all the domains and inconsistent reporting in only two of the domains. On qualitative analysis, a significant antimicrobial effect of TiO2 coating on orthodontic brackets against Streptococcus mutans, Candida albicans and Lactobacillus acidophilus was reported. The meta analysis revealed a significant overall antimicrobial effect with a high heterogeneity. (SMD: 3.5; p < 0.00001; i2 - 99.2%).

Conclusion

An overall significant antimicrobial effect of TiO₂ coated brackets against S. mutans, L. Acidophilus, C. Albicans was noted but with a high heterogeneity. The subgroup analysis revealed a significant antimicrobial effect on C albicans with a low heterogeneity but it was limited by a publication bias. The included studies reported reduced surface roughness, minimal bacterial adhesion and less cytotoxic activity with TiO₂ coated brackets than uncoated brackets.

Review of Antimicrobial Nanocoatings in Medicine and Dentistry: Mechanisms of Action, Biocompatibility Performance, Safety, and Benefits Compared to Antibiotics

This review discusses topics relevant to the development of antimicrobial nanocoatings and nanoscale surface modifications for medical and dental applications. Nanomaterials have unique properties compared to their micro- and macro-scale counterparts and can be used to reduce or inhibit bacterial growth, surface colonization and biofilm development. Generally, nanocoatings exert their antimicrobial effects through biochemical reactions, production of reactive oxygen species or ionic release, while modified nanotopographies create a physically hostile surface for bacteria, killing cells via biomechanical damage. Nanocoatings may consist of metal nanoparticles including silver, copper, gold, zinc, titanium, and aluminum, while nonmetallic compounds used in nanocoatings may be carbon-based in the form of graphene or carbon nanotubes, or composed of silica or chitosan. Surface nanotopography can be modified by the inclusion of nanoprotrusions or black silicon. Two or more nanomaterials can be combined to form nanocomposites with distinct chemical or physical characteristics, allowing combination of different properties such as antimicrobial activity, biocompatibility, strength, and durability. Despite their wide range of applications in medical engineering, questions have been raised regarding potential toxicity and hazards. Current legal frameworks do not effectively regulate antimicrobial nanocoatings in matters of safety, with open questions remaining about risk analysis and occupational exposure limits not considering coating-based approaches. Bacterial resistance to nanomaterials is also a concern, especially where it may affect wider antimicrobial resistance. Nanocoatings have excellent potential for future use, but safe development of antimicrobials requires careful consideration of the "One Health" agenda, appropriate legislation, and risk assessment.

Functional Surface Coatings on Orthodontic Appliances: Reviews of Friction Reduction, Antibacterial Properties, and Corrosion Resistance

Surface coating technology is an important way to improve the properties of orthodontic appliances, allowing for reduced friction, antibacterial properties, and enhanced corrosion resistance. It improves treatment efficiency, reduces side effects, and increases the safety and durability of orthodontic appliances. Existing functional coatings are prepared with suitable additional layers on the surface of the substrate to achieve the abovementioned modifications, and commonly used materials mainly include metal and metallic compound materials, carbon-based materials, polymers, and bioactive materials. In addition to single-use materials, metal-metal or metal-nonmetal materials can be combined. Methods of coating preparation include, but are not limited to, physical vapor deposition (PVD), chemical deposition, sol-gel dip coating, etc., with a variety of different conditions for preparing the coatings. In the reviewed studies, a wide variety of surface coatings were found to be effective. However, the present coating materials have not yet achieved a perfect combination of these three functions, and their safety and durability need further verification. This paper reviews and summarizes the effectiveness, advantages and disadvantages, and clinical perspectives of different coating materials for orthodontic appliances in terms of friction reduction, antibacterial properties, and enhanced corrosion resistance, and discusses more possibilities for follow-up studies as well as for clinical applications in detail.

Recent advances in antibacterial coatings for orthodontic appliances

In the process of orthodontic treatment, the presence of orthodontic appliances makes it difficult to clean tooth surfaces. This can lead to an increased level of bacterial colonization, resulting in enamel demineralization and periodontal diseases. Considering the large surface area that orthodontic appliances usually have and that they can be in direct contact with bacteria throughout the treatment, modifications in the form of coatings on the surface of orthodontic appliances can be an effective and practical approach to reducing bacterial proliferation and preventing relevant adverse effects. In this mini-review, we discuss various antibacterial coatings which have been applied onto orthodontic appliances in recent 5 years, as well as their antibacterial mechanisms and methods for the preparation of these coatings. From this mini-review, both orthodontists and researchers can get the latest findings in the field of antibacterial coatings onto orthodontic appliances, which is helpful for the decision-making in clinical practice and research activities.

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.

Shear Bond Strength and Color Stability of Novel Antibacterial Nanofilled Dental Adhesive Resins

Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained by dispersing nitrogen and fluorine co-doped titanium dioxide nanoparticles (NF_TiO2, 10%, 20% or 30%, v/v%) into OptiBond Solo Plus (OPTB). Dentin surfaces were wet-polished (600-Grit). Specimens (n = 5/group) of Tetric EvoCeram were fabricated and bonded using either OPTB or experimental (OPTB + NF_TiO2) adhesives. Specimens were stored in water (37 °C) for twenty-four hours (T1), three months (T2), and six months (T3). At T1, T2, or T3, specimens were removed from water storage and were tested for SBS. Disc-shaped specimens (n = 10/group; d = 6.0 mm, t = 0.5 mm) of adhesives investigated were fabricated and subjected to thermocycling (10,000 cycles, 5−55 °C, 15 s dwell time). Specimens’ colors were determined with a VITA Easyshade® V spectrophotometer (after every 1000 cycles). SBS data was analyzed using two-way ANOVA and post-hoc Tukey tests, while CS data was analyzed using one-way ANOVA and post-hoc Tukey tests (α = 0.05). Mean values of SBS ranged from 16.39 ± 4.20 MPa (OPTB + 30%NF_TiO2) to 19.11 ± 1.11 MPa (OPTB), from 12.99 ± 2.53 MPa (OPTB + 30% NF_TiO2) to 14.87 ± 2.02 (OPTB) and from 11.37 ± 1.89 (OPTB + 20% NF_TiO2) to 14.19 ± 2.24 (OPTB) after twenty-four hours, three months, and six months of water storage, respectively. Experimental materials had SBS values that were comparable (p > 0.05) to those from OPTB independently of nanoparticle concentration or time-point considered. Experimental materials with higher NF_TiO2 concentrations had less intense color variations and were more color stable than OPTB even after 10,000 thermocycles. In combination, the results reported have demonstrated that experimental adhesives can establish strong and durable bonds to human dentin while displaying colors that are more stable, thereby suggesting that the antibacterial nanotechnology investigated can withstand the harsh conditions within the oral cavity without compromising the esthetic component of dental restorations.

Bioinspired Anti-demineralization Enamel Coating for Orthodontics

White spot lesions and enamel cracks are the 2 most prominent diseases that occur after orthodontic treatment and are caused by enamel demineralization from accumulated bacterial biofilms and/or enamel damage caused by the removal of residual adhesive after bracket debonding. Inspired by the self-assembled amelogenin nanoribbons in enamel, we developed an enamel coating with a self-assembling antimicrobial peptide, D-GL13K, to simultaneously reduce demineralization and residual adhesive. The self-assembled amphiphilic nanoribbons significantly increased the hydrophobicity of the etched enamel, which reduced the permeability of the coated enamel surfaces as desired. The antimicrobial activity of this coating was evaluated against Streptococcus mutans by colony-forming unit counting and live/dead assays. The anti-demineralization effect was demonstrated by the reduced demineralization depth analyzed by optical coherence tomography and the increased Vickers hardness. The coatings did not reduce the shear bond strength but significantly reduced the adhesive remnant index score. This bioinspired enamel coating may provide a new strategy for preventing white spot lesions and enamel cracks after orthodontic treatment.

Titanium dioxide nanoparticles: Recent progress in antimicrobial applications

For decades, the antimicrobial applications of nanoparticles (NPs) have attracted the attention of scientists as a strategy for controlling the ever-increasing threat of multidrug-resistant microorganisms. The photo-induced antimicrobial properties of titanium dioxide (TiO₂ ) NPs by ultraviolet (UV) light are well known. This review elaborates on the modern methods and antimicrobial mechanisms of TiO₂ NPs and their modifications to better understand and utilize their potential in various biomedical applications. Additional compounds can be grafted onto TiO₂ nanomaterial, leading to hybrid metallic or non-metallic materials. To improve the antimicrobial properties, many approaches involving TiO₂ have been tested. The results of selected studies from the past few years covering the most recent trends in this field are discussed in this review. There is extensive evidence to show that TiO₂ NPs can exhibit certain antimicrobial features with disputable roles of UV light. Hence, they are effective in treating bacterial infections, although the majority of these conclusions came from in vitro studies and in the presence of some additional nanomaterials. The methods of evaluation varied depending on the nature of the research while researchers incorporated different techniques, including determining the minimum inhibitory concentration, cell count, and using disk and well diffusion methods, with a noticeable indication that cell count was the most and dominant criterion used to evaluate the antimicrobial activity. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Effect of 8% arginine toothpaste on Streptococcus mutans in patients undergoing fixed orthodontic treatment: randomized controlled trial

Objective:

To assess the effect of toothpaste containing 8% arginine on Streptococcus mutans (S. mutans) in dental plaque around orthodontic brackets, and to draw a comparison with a regular fluoride toothpaste.

Trial design:

A single-center, parallel-arm, triple-blind, randomized controlled trial was conducted.

Methods:

The clinical trial was conducted at the Orthodontic Clinic, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Seventy-two patients (age range: 15-30 years) who required fixed orthodontic treatment were recruited and randomly assigned to arginine and fluoride groups. Randomization was performed using RANDOM.ORG online software, and the participants were divided into two parallel groups, with a 1:1 allocation ratio. Patients were requested to brush their teeth twice daily for 30 days with an experimental toothpaste. Plaque sampling was performed at two intervals, namely at the beginning of the study (T₀) and 30 days later (T₁). Real-time PCR was used to assess plaque samples in terms of the number of S. mutans surrounding stainless steel brackets in orthodontic patients. A triple-blind design was employed.

Results:

The baseline characteristics (age, sex, and the relative number of S. mutans) between the groups were similar (p>0.05). Only the arginine group showed a significant decrease in the relative number of bacteria between T₀ and T₁ (p=0.02).

Conclusion:

Arginine is an important prebiotic agent in maintaining healthy oral biofilms, and prevent dental caries during fixed orthodontic treatments.

Trial registration:

The trial was registered at the Iranian Registry of Clinical Trials (IRCT20181121041713N2), https://en.irct.ir/user/trial/42409/view.

Application of antibacterial nanoparticles in orthodontic materials

During the orthodontic process, increased microbial colonization and dental plaque formation on the orthodontic appliances and auxiliaries are major complications, causing oral infectious diseases, such as dental caries and periodontal diseases. To reduce plaque accumulation, antimicrobial materials are increasingly being investigated and applied to orthodontic appliances and auxiliaries by various methods. Through the development of nanotechnology, nanoparticles (NPs) have been reported to exhibit excellent antibacterial properties and have been applied in orthodontic materials to decrease dental plaque accumulation. In this review, we present the current development, antibacterial mechanisms, biocompatibility, and application of antibacterial NPs in orthodontic materials.

The antibacterial effect of silver, zinc-oxide and combination of silver/ zinc oxide nanoparticles coating of orthodontic brackets (an in vitro study)

Background

Preventive measures are essential during the length of orthodontic treatment to reduce the risk of decalcification and white spot lesions formation. With the evolution of procedures that enable coating of the orthodontic brackets using nanoparticles known for their good antibacterial activity, coating the brackets with nanoparticles of silver, zinc oxide and combination of silver and zinc oxide to evaluate their antibacterial effect in comparison to a control group without coating was carried out in this study.

Methods

Four groups of 12 brackets each were included in the study. The coating procedure was carried out using physical vapor deposition. The antibacterial activity was tested on Streptococcus mutans and Lactobacillus Acidophilus using colony forming count. The antibacterial activity was evaluated immediately after coating and later after 3 months.

Results

Brackets coated with combination of silver and zinc oxide nanoparticles had the highest ability on reduction of both Streptococcus mutans and Lactobacillus Acidophilus count followed by silver nanoparticles and then zinc oxide nanoparticles. No significant difference was found between the first and second antibacterial tests.

Conclusion

The silver/zinc oxide nanoparticles coated brackets had the highest antibacterial effect in comparison to silver nanoparticles and zinc oxide nanoparticles individually coated brackets on Streptococcus mutans and Lactobacillus acidophilus, and all types of coatings showed enhanced antibacterial effect in comparison to the uncoated bracket. Coating of orthodontic brackets could be further assessed in clinical application to prevent decalcification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02263-6.

Study on the role of nano antibacterial materials in orthodontics (a review)

Nanoparticles (NPs) are insoluble particles with a diameter of fewer than 100 nanometers. Two main methods have been utilized in orthodontic therapy to avoid microbial adherence or enamel demineralization. Certain NPs are included in orthodontic adhesives or acrylic resins (fluorohydroxyapatite, fluorapatite, hydroxyapatite, SiO2, TiO2, silver, nanofillers), and NPs (i.e., a thin layer of nitrogen-doped TiO2 on the bracket surfaces) are coated on the surfaces of orthodontic equipment. Although using NPs in orthodontics may open up modern facilities, prior research looked at antibacterial or physical characteristics for a limited period of time, ranging from one day to several weeks, and the limits of in vitro studies must be understood. The long-term effectiveness of nanotechnology-based orthodontic materials has not yet been conclusively confirmed and needs further study, as well as potential safety concerns (toxic effects) associated with NP size.

The effect of nitrogen-doped titanium dioxide–modified stainless steel brackets on Streptococcus mutans:

Objectives

To evaluate the effect of nitrogen (N)-doped titanium dioxide (TiO2) coated stainless steel brackets activated with natural visible light and dental operating lights on Streptococcus mutans concentration in the plaque of orthodontic patients at 30 and 60 days.

Materials and Methods

A total of 30 patients were recruited for this split-mouth study; 60 upper lateral incisor brackets constituted the study sample. A total of 30 brackets (15 right and 15 left) were coated with N-doped TiO2 using the (radio frequency) magnetron sputtering method. Plaque samples were collected at 30 days and 60 days after appliance placement. S mutans concentration was evaluated using real-time polymerase chain reaction.

Results

At both time intervals, the concentration of S mutans in the control group was greater than that in the study group (P = .005). In both the study and the control groups, the S mutans concentrations significantly increased from 30 to 60 days (P = .005).

Conclusions

N-doped TiO2, on exposure to natural visible light and dental operating light, was effective in reducing the plaque concentration of S mutans in orthodontic patients. The efficacy was better at 30 days than at 60 days after placing the orthodontic appliances.

Assessment of frictional resistance and surface roughness in orthodontic wires coated with two different nanoparticles

Several mechanical and biological factors may change the orthodontic wire frictional resistance (FR). Titanium dioxide (TiO₂ ) and silica dioxide (SiO₂ ) nanoparticle (NP) coatings may be used to improve the characteristics of materials, reducing FR between archwire and bracket. This in vitro study aimed to evaluate the FR of orthodontic wires with and without coating in both dry and wet environments and measure the surface roughness (SR). One hundred and eighty segments of rectangular Cr-Ni orthodontic wires (Morelli Co, Brazil) were divided into three groups according to the NP coating applied: TiO₂ group; SiO₂ group; and control group. The SR parameters were measured in an optical profilometer, the surface morphology was analyzed with scanning electron microscopy (SEM), and FR was performed in a universal testing machine in dry and wet environments (n = 30). The statistical analysis was performed using the Generalized Estimated Equations model with a Bonferroni post-test (α = 0.05). It was observed that SiO₂ NP coating decreased FR significantly when compared to the TiO₂ and control groups, in both environments (p < .001). The SiO₂ and TiO₂ groups presented statistically lower SR than the control group and were similar to each other (p < .001). The SiO₂ group presented the lower depth of Valley parameter than the TiO₂ group (p < .001). The SEM showed that the TiO₂ coating had the most heterogeneous surface morphology than the SiO₂ and control groups. The orthodontic wires with NP coating modified the FR and morphology. The SiO₂ coating reduced FR in both dry and wet environments and decreased SR.

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.

Nitrogen doped titanium dioxide as an aesthetic antimicrobial filler in dental polymers

OBJECTIVE

To develop an aesthetic resin composite using a nitrogen-doped titanium dioxide (NTiO₂) filler that possesses antimicrobial properties against cariogenic bacteria.

METHODS

N-TiO₂ powder was manufactured by calcining commercial TiO₂ with urea. Free radical release from the N-TiO₂ powder under visible light irradiation was analysed using UV-Vis spectrophotometry. The N-TiO₂ powder was incorporated into a dental resin and the photocatalytic activity assessed using a dye under both visible light and dark conditions. Using XTT assay to measure the cellular metabolic activity, the antibacterial properties of the N-TiO₂ /resin composite discs were tested using Streptococcus mutans.

RESULTS

Doping nitrogen of TiO₂ resulted in a band gap shift towards the visible light spectrum, which enabled the powder to release reactive oxygen species when exposed to visible light. When incorporated into a dental resin, the N-TiO₂/resin composite still demonstrated sustained release of reactive oxygen species, maintaining its photocatalytic activity and showing an antibacterial effect towards Streptococcus mutans under visible light conditions.

SIGNIFICANCE

N-TiO₂ filled resin composite shows great promise as a potential aesthetic resin based adhesive for orthodontic bonding.

In-vitro Comparative Assessment of Antibacterial and Anti-adherent Effect of Two Types of Surface Modificants on Stainless Steel Orthodontic Brackets Against Streptococcus mutans

Objective:

Comparative evaluation of antibacterial and anti-adherent properties of surface-modified stainless steel (SS) orthodontic brackets against Streptococcus mutans ( S. mutans).

Materials and Methods:

The study was conducted on 120 SS orthodontic McLaughlin, Bennett, Trevisi (MBT) 0.022″ slot by Leone, Italy. Orthodontic brackets that constituted the sample size were divided into 6 groups, consisting of 20 samples each in two control (non-surface coated) and four experimental groups. The experimental group’s surface coatings were photocatalytic zinc oxide (ZnO) and photocatalytic titanium oxide (TiO2), which were carried out by radiofrequency (RF) magnetron sputtering method for surface modification. Brackets were subjected to microbiological tests against S. mutans. For anti-adherence, weight change, pre- and postexposure, was evaluated to gauge the adherence of bacteria and colony-forming units/milliliter (CFU/mL) count measuring the survival rate of bacterial cells for antibacterial activity.

Results:

The TiO2-coated group showed statistically significant anti-adherence ( P-value < .05) against S. mutans than control and ZnO groups. The CFU count of TiO2 group was lower than control as well as ZnO group.

Conclusion:

TiO2 is superior to ZnO and should be continued to be considered for surface modification of orthodontic brackets against White Spot Lesions (WSLs) and gingivitis.

Effect of the addition of Chitosan and TiO2nanoparticles on antibacterial properties of an orthodontic composite in fixed orthodontic treatment: a randomized clinical trial study

Due to the existing demands for methods independent of patient co-operation in preventing and overcoming the incidence of white spot lesions (WSLs) and caries in fixed orthodontic treatments, several studies have considered the modification of orthodontic composites using antimicrobial nanomaterials. In this regard, the aim of this study is to investigate the effect of the addition of chitosan nanoparticles (NPs) and TiO₂NPs onStreptococcus mutans(S. mutans) counts and the enamel mineral content in fixed orthodontic patients. A double-blind randomized clinical trial study was carried out in 24 patients (i.e., 48 upper second premolars and 48 maxillary lateral incisors) who were candidates for fixed orthodontic treatment. In the case of the control group, the bracket was bonded to the tooth with an orthodontic adhesive (Transbond XT, 3M Unitek, USA) while, in the experimental group, the bracket was bonded to the tooth with Transbond XT containing 1% chitosan NPs and 1% TiO₂NPs. For the maxillary lateral incisor and upper second premolar teeth, theS. mutanscounts around the brackets were measured, through the usage of real-time PCR, at the time points of 1 day, 2 months, and 6 months after bonding the brackets to the tooth. Furthermore, the enamel mineral content measurement was also performed around the brackets at 1 day, 2 months, and 6 months after bonding the brackets to the tooth. TheS. mutanscounts were analyzed using Friedman and Mann-Whitney U tests. The Repeated measures ANOVA test and Independent samples T-test were also applied, in order to evaluate the mineral content. According to the results, there was a significant reduction in theS. mutanscounts of experimental group at the time points of 1 day, 2 months, and 6 months in both maxillary lateral incisor and upper second premolar teeth. However, we did not observe any significant differences in the control group between the reports at 1 day, 2 months, and 6 months in both maxillary lateral incisor and upper second premolar teeth. The outcomes of this study indicate that, with regard to maxillary lateral incisor teeth, there were no significant differences between the results of the experimental group and control group at the time points of 1 day, 2 months, and 6 months. Furthermore, with respect to the upper second premolar teeth, no significant differences were observed between the two groups at 1 day and 2 months; however,S. mutanscounts were significantly lower in the experimental group than in the control group at the time point of 6 months. Moreover, our gathered data confirmed the absence of any significant differences between the experimental group and control group, in terms of enamel mineral content, at the time intervals of 1 day, 2 months, and 6 months. In conclusion, the incorporation of chitosan NPs and TiO₂NPs in orthodontic composites induces an antibacterial property in the resultant adhesive to be used for fixed orthodontic treatment.

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.

Nanomaterials Application in Orthodontics

Nanotechnology has gained importance in recent years due to its ability to enhance material properties, including antimicrobial characteristics. Nanotechnology is applicable in various aspects of orthodontics. This scientific work focuses on the concept of nanotechnology and its applications in the field of orthodontics, including, among others, enhancement of antimicrobial characteristics of orthodontic resins, leading to reduction of enamel demineralization or control of friction force during orthodontic movement. The latter one enables effective orthodontic treatment while using less force. Emphasis is put on antimicrobial and mechanical characteristics of nanomaterials during orthodontic treatment. The manuscript sums up the current knowledge about nanomaterials' influence on orthodontic appliances.

Effect of high concentration nano-hydroxyapatite serum on shear bond strength of metal brackets following three different enamel surface preparation methods: An in vitro study

OBJECTIVE

White spot lesion (WSL) is one of the most important complications of fixed orthodontic treatment. Many methods have been studied to prevent this problem. This study is aimed to investigate the effect of high concentration nano-hydroxyapatite (nHAP) on shear bond strength (SBS) of metal brackets and Adhesive Remnant Index (ARI) score in different preparation methods.

MATERIAL AND METHODS

Sixty human premolars, which were extracted for orthodontic reasons were included in this in vitro study. The teeth were randomly divided into 4 groups of 15 each: one control group and three nHAP groups. After applying nHAP for 2 to 3 minutes daily for 10 days, the groups 2 to 4 underwent sandblasting using 50μm aluminium oxide and 30 seconds etching, 60 and 30 seconds etching, respectively, and the brackets were then bonded to the teeth. After debonding, SBS and ARI scores were recorded. Data were analysed using the ANOVA test and posthoc test for pairwise comparisons.

RESULTS

No significant difference was observed in SBS between the control group and the nHAP groups. The sandblasted teeth showed significantly higher SBS than the 30 seconds etching after nHAP application (P=0.02). The teeth etched for 60 seconds showed a significantly higher ARI score than the 30 seconds etched teeth with (P=0.003) or without (P<0.001) nHAP application.

CONCLUSIONS

The use of nHAP before bracket bonding can be considered as a caries preventive method since it did not compromise the SBS. Sixty seconds etching is recommended for less likely damage to the enamel after debonding.

Low-Cost Deposition of Antibacterial Ion-Substituted Hydroxyapatite Coatings onto 316L Stainless Steel for Biomedical and Dental Applications

Substitutions of ions into an apatitic lattice may result in antibacterial properties. In this study, magnesium (Mg)-, zinc (Zn)-, and silicon (Si)-substituted hydroxyapatite (HA) were synthesized using a microwave irradiation technique. Polyvinyl alcohol (PVA) was added during the synthesis of the substituted HA as a binding agent. The synthesized Mg-, Zn-, and Si-substituted HAs were then coated onto a 316L-grade stainless-steel substrate using low-cost electrophoretic deposition (EPD), thereby avoiding exposure to high temperatures. The deposited layer thickness was measured and the structural, phase and morphological analysis were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The bacterial adhesion of Staphylococcus aureus was characterized at 30 min, 2 h and 6 h. The results showed homogeneous, uniform thickness (50–70 µm) of the substrate. FTIR and XRD showed the characteristic spectral peaks of HA, where the presence of Mg, Zn and Si changed the spectral peak intensities. The Mg–HA coating showed the least bacterial adhesion at 30 min and 2 h. In contrast, the Si–HA coating showed the least adhesion at 6 h. EPD showed an effective way to get a uniform coating on bio-grade metal implants, where ionic-substituted HA appeared as alternative coating material compared to conventional HA and showed the least bacterial adhesion.

Silver nanoparticles in orthodontics, a new alternative in bacterial inhibition: in vitro study

BACKGROUND

The purpose of the study is to assess the antiadherent and antibacterial properties of surface-modified different orthodontic brackets with silver nanoparticles against Streptococcus mutans and Streptococcus sobrinus, using radiomarker.

METHODS

In this study evaluated quantitatively the adherence of Streptococci to orthodontic brackets, 300 samples of orthodontic brackets were selected and classified in to 10 groups as follow: GIn (InVu-Roth), GIIn (System-AlexanderLTS), GIIIn (Gemini-Roth), GIVn (NuEdge-Roth), GVn (Radiance plus-Roth), GVI (InVu-Roth), GVII (System-AlexanderLTS), GVIII (Gemini-Roth), GIX (NuEdge-Roth), GX (Radiance plus-Roth). All the samples were sonicated and Streptococci were cultivated by gender. A radioactive marker (3H) was used to codify the bacteria and measure them. After that, the brackets were submerged in a radiolabelled solution, and the radiation was measured. The statistical analysis was calculated with ANOVA test (Sheffè post hoc).

RESULTS

The results showed significant differences were found among the groups. GIIIn shown the lowest scores for both bacteria; in contrast, GIX for Streptococcus mutans and GVI for Streptococcus sobrinus were the highest values.

CONCLUSIONS

Surface modification of orthodontic brackets with silver nanoparticles can be used to prevent the accumulation of dental plaque and the development of dental caries during orthodontic treatment.

Evaluation of titanium dioxide coating on surface roughness of nickel-titanium archwires and its influence on Streptococcus mutans adhesion and enamel mineralization: A prospective clinical study

INTRODUCTION

This research aimed to evaluate the effect of titanium dioxide (TiO₂) coating on surface roughness (R_a) of nickel-titanium (NiTi) archwires and its influence on Streptococcus mutans (S mutans) adhesion and enamel mineralization at the end of 1 month in orthodontic patients and to evaluate the integrity of the TiO₂ coating.

METHODS

Twelve patients undergoing orthodontic treatment with preadjusted edgewise appliance formed the sample for this prospective clinical study. Uncoated NiTi archwires and TiO₂ nanoparticle coated NiTi archwires in as-received condition and after 1 month of intraoral use were subjected to R_a analysis using surface profilometry, and surface topography using scanning electron microscopy. S mutans adhesion was evaluated on the retrieved archwires using real-time polymerase chain reaction (PCR). Enamel mineral content in the arches related to the uncoated and coated archwires was evaluated using DIAGNOdent.

RESULTS

After 1 month of intraoral use, both coated and uncoated archwires exhibited a rougher surface with coated archwires demonstrating greater quantum of increase (control, P = 0.002; experimental, P = 0.002). S mutans adhesion was more in uncoated archwires (P = 0.0005). The TiO₂ nanoparticle coating on the NiTi archwires showed delamination, deterioration and was lost by 60% at the end of 1 month. Laser fluorescence values did not show any significant difference (control, P = 0.182; experimental, P = 0.105).

CONCLUSIONS

TiO₂ nanoparticle coating on NiTi archwires causes an initial reduction in roughness; however, at the end of 1 month, the benefit was lost. S mutans adhesion was lesser on the coated wires, which could be attributed to reduced initial R_a and antibacterial property of TiO₂. Orthodontic archwire appears to have a limited role in enamel demineralization.

Antibacterial activity and debonding force of different lingual retainers bonded with conventional composite and nanoparticle containing composite: An in vitro study

BACKGROUND

To evaluate the antibacterial activity and debonding force of retainers bonded with conventional and nanoparticle (TiO₂) containing composite.

METHODOLOGY

Antibacterial activity was tested against Streptococcus mutans and Lactobacillus acidophilus using disk agar diffusion, biofilm inhibition, and eluted components tests. For the eluted components test, colony counts of bacteria were tested on 0, 3, and 30 days. Three different retainers were bonded to the lingual surface of extracted lower incisors using conventional and 1% TiO₂ composite. Samples were divided as follows: Group 1: 1a, stainless steel retainer (Bond-a-Braid) with conventional composite, and 1b, stainless steel retainer with nanoparticle composite; Group 2: 2a, titanium retainer with conventional composite, and 2b, titanium retainer with nanoparticle composite; Group 3: 3a, fiber-reinforced retainer (Interlig) with conventional composite, and 3b, fiber-reinforced retainer with nanoparticle composite. The Instron stereomicroscope was used to test debonding force and failure sites respectively.

RESULTS

In the disk agar diffusion test, TiO₂ composite has shown more inhibition zones. Biofilm inhibition test showed a significant decrease in colony counts of both organisms in the TiO₂ group. The eluted component test showed a significant decrease in colony counts from day 0 to day 30 in the TiO₂ group compared with the control group. The highest debonding force was observed in stainless steel retainers with conventional composite, and lowest in fiber-reinforced composite retainers with TiO2 composite, with no significant difference in Adhesive Remnant Index scores.

CONCLUSION

The TiO₂ composite group showed greater antibacterial activity without compromising the bond strength, which was statistically significant. Compared with other groups, stainless steel wires bonded with conventional composite showed the highest debonding force.

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.

Appraisal of Comparative Therapeutic Potential of Undoped and Nitrogen-Doped Titanium Dioxide Nanoparticles

Nitrogen-doped and undoped titanium dioxide nanoparticles were successfully fabricated by simple chemical method and characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and transmission electron microscopy (TEM) techniques. The reduction in crystalline size of TiO2 nanoparticles (from 20-25 nm to 10-15 nm) was observed by TEM after doping with N. Antibacterial, antifungal, antioxidant, antidiabetic, protein kinase inhibition and cytotoxic properties were assessed in vitro to compare the therapeutic potential of both kinds of TiO2 nanoparticles. All biological activities depicted significant enhancement as a result of addition of N as doping agent to TiO2 nanoparticles. Klebsiella pneumoniae has been illuminated to be the most susceptible bacterial strain out of various Gram-positive and Gram-negative isolates of bacteria used in this study. Good fungicidal activity has been revealed against Aspergillus flavus. 38.2% of antidiabetic activity and 80% of cytotoxicity has been elucidated by N-doped TiO2 nanoparticles towards alpha-amylase enzyme and Artemia salina (brine shrimps), respectively. Moreover, notable protein kinase inhibition against Streptomyces and antioxidant effect including reducing power and % inhibition of DPPH has been demonstrated. This investigation unveils the more effective nature of N-doped TiO2 nanoparticles in comparison to undoped TiO2 nanoparticles indicated by various biological tests. Hence, N-doped TiO2 nanoparticles have more potential to be employed in biomedicine for the cure of numerous infections.

Recent advances and challenges on applications of nanotechnology in food packaging. A literature review

Nanotechnology applied to food and beverage packaging has created enormous interest in recent years, but in the same time there are many controversial issues surrounding nanotechnology and food. The benefits of engineered nanoparticles (ENPs) in food-contact applications are accompanied by safety concerns due to gaps in understanding of their possible toxicology. In case of incorporation in food contact polymers, the first step to consumer exposure is the transfer of ENPs from the polymer to the food. Hence, to improve understanding of risk and benefit, the key questions are whether nanoparticles can be released from food contact polymers and under which conditions. This review has two main goals. Firstly, it will presents the current advancements in the application of ENPs in food and beverage packaging sector to grant active and intelligent properties. A particular focus will be placed on current demands in terms of risk assessment strategies associated with the use ENPs in food contact materials (FCMs), i.e. up-to-date migration/cytotoxicity studies of ENPs which are partly contradictory. Food matrix effects are often ignored, and may have a pronounced impact on the behaviour of ENPs in the gastrointestinal tract (GIT). A standardized food model (SFM) for evaluating the toxicity and fate of ingested ENPs was recently proposed and herein discussed with the aims to offer an overview to the reader. It is therefore clear that further systematic research is needed, which must account for interactions and transformations of ENMs in foods (food matrix effect) and in the gastrointestinal tract (GIT) that are likely to determine nano-biointeractions. Secondly, the review provides an extensive analysis of present market dynamics on ENPs in food/beverage packaging moving beyond concept to current industrial applications.