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

Effect of nanomodified 3D printed photopolymerizable resin on flexural strength, color, and antimicrobial efficacy: An in vitro study

STATEMENT OF PROBLEM

Three-dimensional (3D) printing has become popular in dentistry, but studies on the influence of incorporating organic and inorganic nanofillers on 3D printed materials are lacking.

PURPOSE

The purpose of this in vitro study was to assess the flexural strength, color, and antimicrobial efficacy of 3D printed photopolymerizable resin upon adding titanium dioxide nanoparticles (TiO2 NPs) and silanized chitosan nanoparticles (sCS NPs).

MATERIAL AND METHODS

A stereolithographic material (VarseoSmile Crown plus; Bego) was used as a control group (VSC resin), and 3 nanocomposite resin groups were prepared by adding nanoparticles as follow: titanium dioxide group (VSC resin + 0.4% wt. TiO2 NPs), chitosan group (VSC resin + 0.4% wt. sCS NPs), and hybrid group (VSC resin + 0.2% wt. TiO2 NPs + 0.2% wt. sCS NPs). A total of 132 specimens were designed by using a free computer-aided design software program, printed, postpolymerized, and divided into 4 groups. The nanocomposite resins were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FTIR). Bar shaped specimens (n=44) were tested for 3-point flexural strength using a universal testing machine followed by the color measurement of disk-shaped specimens (n=44) with a spectrophotometer. Antimicrobial capacity was measured with Streptococcus mutans, and absorbance was measured using a microplate reader (n=44). Statistical assessments were made with 1-way ANOVA followed by the Tukey post hoc test with Bonferroni adjustment (α=.05).

RESULTS

The hybrid group recorded the highest mean value of flexural strength 135.51 MPa, showing a significant difference compared with that of the control group (P=.022). Regarding color, the mean ∆E00 for titanium was 1.18, for chitosan was 4.26, and for the hybrid group was 3.23 (P<.001). The optical density of the chitosan (2.42) was significantly higher than that of the titanium 1.36 (P=.007) and that of the control 1.63 (P=.042).

CONCLUSIONS

The incorporation of nanofillers resulted in an increase in flexural strength, but it adversely affected the color of nanocomposite resins. Antimicrobial efficacy was improved by incorporating titanium nanofillers.

Effect of Zeolite Incorporation on the Ion Release Properties of Silver-Reinforced Glass Ionomer Cement

BACKGROUND

Zeolite can release antimicrobial silver ions in a targeted and controlled manner for an extended time, selectively inhibiting the growth of pathogenic oral bacteria when added to dental materials. The objective of this study was to investigate the effect of the addition of zeolite to silver-reinforced glass ionomer cement on the release of silver ions over time.

METHODS

Five concentrations of silver-zeolite (0%, 0.5%, 1%, 2%, 4% wt) were incorporated into silver-reinforced GIC in the form of 10 mm × 2 mm circular disks (n = 5). The disks were incubated in deionized water at 37 °C and ion release from the samples was measured at 1, 2, 7, and 30 days after immersion by inductively coupled atomic emission spectroscopy.

RESULTS

Incorporating silver-zeolite increased silver ion release from silver-reinforced GIC disks compared to the control disks (p < 0.05), while incorporating zeolite alone had no effect. Higher concentrations of added silver-zeolite resulted in increased silver ion release. Sustained silver ion release was observed for up to 30 days.

CONCLUSION

Adding silver-zeolite to silver-reinforced GIC may enhance its extended antibacterial effect in the oral cavity.

Is Cention-N comparable to other direct dental restorative materials? A systematic review with network meta-analysis of in vitro studies

OBJECTIVES

To compare the performance of Cention-N® with direct restorative materials used at the daily practice (e.g., resin-based composites/RBC, glass ionomer cements/GIC, bioactive resins, silver amalgam) via a systematic review study.

METHODS

The review followed the PRISMA-NMA recommendations, and the protocol of the review was published at osf.io/ybde8. The search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Embase, Lilacs, and SciELO databases, as well as in the grey literature (Open Grey, Proquest, and Periódicos CAPES). Studies with an in vitro experimental design evaluating the characteristics and properties of Cention-N in comparison to other restorative materials were included. The risk of bias of included studies was assessed using the RoBDEMAT tool, and meta-analyses were conducted using Review Manager 5.4 and MetaInsight V3 tools.

RESULTS

A total of 85 studies were included in the review, from which 79 were meta-analyzed. Several characteristics of direct restorative materials were analyzed, including physical (color change, degree of conversion, hardness, microleakage, polymerization rate, roughness, water solubility, water sorption), mechanical (bond strength to dentin, compressive strength, diametral tensile strength, flexural modulus, flexural strength, load-to-fracture, wear), and biological (alkalinizing effect, antibacterial activity, calcium and fluoride release) properties.

SIGNIFICANCE

Cention-N presented similar physico-mechanical properties compared to RBCs, but a stronger behavior than GICs. Despite the Alkasite nature of Cention-N, GICs may still demonstrate the greatest fluoride releasing ability from all direct restorative materials. This review confirmed the adequate behavior of Cention-N when compared to several other more traditionally used materials, confirming its applicability for the permanent restoration of decayed or fractured teeth.

Microhardness, Surface Roughness, and Wear Resistance Enhancement of Reinforced Conventional Glass Ionomer Cement Using Fluorinated Graphene Oxide Nanosheets

OBJECTIVES

 Conventional glass ionomer cements (GICs) have been considered the most prevalent restorative material however; the reduced mechanical qualities and decreased wear resistance have been the main challenges facing their wide clinical application. This study was designed to assess the mechanical properties of fluorinated graphene (FG) oxide-modified conventional GIC.

MATERIALS AND METHODS

 Composites of FG/GIC samples were prepared using (Medifil from PROMEDICA, Germany, shade A3) at different concentrations (0wt%) control group and (1wt%, 2wt% and 3wt% FG) groups using cylindrical molds (3mm × 6mm). FG was prepared using hydrothermal technique and characterized using XPERT-PRO Powder Diffractometer system for X-ray diffraction analysis and JEOL JEM-2100 high resolution transmission electron microscope. Vickers' hardness and wear resistance of GI samples were measured. Mechanical abrasion was performed via three-body tooth brushing wear test using ROBOTA chewing simulator coupled with a thermocycling protocol (Model ACH-09075DC-T, AD-Tech Technology Co., Ltd., Leinfelden-Echterdingen, Germany).

STATISTICAL ANALYSIS

 Comparisons between groups with respect to normally distributed numeric variables were performed using one-way analysis of variance test followed by posthoc test. While paired t-test was utilized for comparing data within the same group.

RESULTS

The surface roughness values of GICs (1wt% FG) and (2wt% FG) composites were significantly lower than those of the control and 3wt%FG groups. Vickers' hardness numbers were significantly higher in FG/GICs composites than in the control group (p≤0.05).

CONCLUSION

 GIC/FG combinations have sufficient strength to resist the occlusion stresses with improved hardness as compared with conventional GIC. GIC/FG appeared to be a promising restorative material.

A Comprehensive Narrative Review of Nanomaterial Applications in Restorative Dentistry: Demineralization Inhibition and Remineralization Applications (Part I)

Nanotechnology is extensively employed in various aspects of dentistry, including restorative dentistry, because of its substantial improvement and promising potential in the clinical efficacy of restorative materials and procedures. The main purpose of this review is to explore the different uses of nanomaterials in restorative dentistry. The review is divided into two parts: the current review (Part 1) focuses on the prevention of demineralization and promotion of remineralization, while the upcoming review (Part 2) will discuss the reinforcement of restorative materials and their therapeutic applications. Nanofillers are added to dental materials to boost their antibacterial, anticaries, and demineralization inhibitory capabilities. Additionally, they improve remineralization and enhance both mechanical properties and therapeutic features. The nanoparticles (NPs) used to increase antibacterial and remineralization inhibitions can be classified into two main groups: inorganic and organic NPs. Examples of inorganic NPs include silver, zinc oxide, titanium oxide, and gold. Examples of organic NPs include silica, quaternary ammonium salt monomers, and chitosan NPs. Furthermore, the nanofillers utilized to enhance the process of remineralization include various types such as metals, nano-hydroxyapatite, nano-amorphous calcium phosphate (ACP), dicalcium phosphate NPs, casein phosphopeptide-ACP (CPP-ACP), and calcium fluoride NPs. These uses underscore the potential applications of NPs in restorative dentistry, although there are still some limitations to address.

Noninvasive assessment of novel nanohybrid resin cement adaptation using cross-polarization optical coherence tomography

OBJECTIVES

Zein-coated magnesium oxide nanoparticles (zMgO NPs) can potentially improve cement adaptation to the tooth-restoration interface, which would aid in minimizing marginal leakage and secondary caries. The aim of this study was to assess the effect of incorporating zMgO NPs on the adaptation of self-adhesive resin cement using cross-polarization optical coherence tomography (CP-OCT) and scanning electron microscopy (SEM).

METHODS

Resin inlays were fabricated to be cemented in Class-I cavities of extracted human molars. All specimens were randomly divided into five groups (n = 10), and the resin inlays were cemented using self-adhesive resin cement with various concentrations of zMgO NPs (0% [control], 0.3%, 0.5%, 1%, 2%). Characterization was done by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and SEM. The specimens were examined for interfacial adaptation under CP-OCT. Floor and wall adaptation measurements were analyzed by software on 20 B-scans, and samples were sectioned for interfacial measurement by SEM.

RESULTS

Results for CP-OCT and SEM showed a statistically significant increase of adaptation in the floor and wall of resin cement filled with zMgO NPs compared to the control. The samples enhanced with 0.3% and 0.5% showed a statistically significantly better adaptation in floor and wall in CP-OCT and SEM. However, there was no significant difference between the 1%, 2%, and control groups for CP-OCT and SEM analysis.

SIGNIFICANCE

The incorporation of zMgO NPs in self-adhesive resin cement can enhance the cement's properties by significantly improving its wall and floor adaptation.

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

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

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

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

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

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

Evaluation of the Effect of Nanographene Oxide on Microleakage of Conventional and Resin-Modified Glass Ionomer

Objectives

One of the important features of the restorative materials is the ability to seal and prevent the microleakage. Glass ionomer cement (GIC) still exhibits some microleakage despite establishing a chemical bond to the tooth. The aim of this study was to evaluate the effect of nanographene oxide (nGO) on the microleakage of conventional (CGIC) and resin-modified glass ionomer cement (RMGIC).

Methods

Thirty intact extracted molars were used. Class V cavities were prepared on their buccal and lingual surfaces. The samples randomly divided into two main groups of CGIC and RMGIC; each of them was randomly subdivided into three subgroups, including the group without nGO (control), the group with 1% nGO, and the group with 2% nGO. After restoring the cavities, they were subjected to thermocycling (1,000 cycles at 5/55°C). Two percent basic fuchsin solution was used to perform the microleakage test, and then the sectioned samples were examined by a stereomicroscope 40x. Kruskal-Wallis test, Dunn's test, and Mann-Whitney U test were used to analyze the data (P < 0.05).

Results

Group CGIC + 1% nGO at the gingival margin and group RMGIC + 1% nGO at both gingival and occlusal margins had significantly less microleakage than their control groups (P=0.008, P=0.002, P=0.023, respectively). Also, in these two groups, there were no significant differences between the microleakage of the occlusal and gingival margins (P=0.132, P=0.511, respectively), while in all other groups, the gingival microleakage was significantly higher than that of occlusal microleakage.

Conclusions

The addition of 1% nGO significantly reduced the gingival microleakage of CGIC and the occlusal and the gingival microleakage of RMGIC, while the addition of 2% nGO did not cause a significant reduction in microleakage.

Color behavior of composite resin enhanced with different shapes of new antimicrobial polymer coated nanoparticles

BACKGROUND

Zein-coated magnesium oxide nanoparticles (zMgO NPs) demonstrate a potent antimicrobial effect, endorsing it as a compelling additive to dental materials formulations for oral health care advances. However, currently there is no data on the imprint of zMgO NPs on the color permanence of dental composites. The objective of this study is to evaluate the color stability of different types of composite enhanced with antimicrobial zein-coated magnesium oxide nanoparticles (zMgO NPs) of different shapes before and after thermocycling.

METHODS

Two hundred composite samples were divided into four groups: Gp1: Tetric N-Flow with zMgO nanowires, Gp2: Tetric N-Flow with zMgO nanospheres, Gp3: Tetric N-Ceram with zMgO nanowires; Gp4: Tetric N-Ceram with zMgO nanospheres. Each group was subdivided into 5 subgroups (n = 10) with concentrations of zMgO NPs 0%, 0.3%, 0.5%, 1% and 2%. The characterization of the modified composite containing the zMgO was done via X-ray Diffraction, Field Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infrared Spectroscopy (FTIR). Colorimetric evaluation was performed through spectrophotometry with a white background. Samples underwent color assessment using a spectrophotometer, followed by thermocycling, and then another color assessment.

RESULTS

FESEM analysis showed a uniform distribution of the zMgO nanoparticles in the composite and FTIR illustrated no change in the spectra. However, the XRD spectra exhibited an amorphous pattern in the composite enhanced with zMgO NPs. There was no compelling discrepancy in color variation ΔE among the different groups before and after thermocycling (p > 0.05). A statistically notable variation in ΔL was found amid the control and N-Flow and N-Ceram with 2% zMgO nanospheres before and after thermocycling respectively (p < 0.05). While after thermocycling, there was a statistically significant difference in Δa in N-Flow and N-Ceram wires amid the control and the different groups (p < 0.05). Additionally, after thermocycling there was a statistically significant difference in Δb in N-Flow and N-Ceram wires between the control and the different groups (p < 0.05). The Tukey test exhibited no variation among the groups with different zMgO concentrations (p > 0.05).

CONCLUSION

Enhancing N-Flow and N-Ceram composite with antimicrobial zMgO nanowires and nanospheres did not alter the total color stability of the materials before and after thermocycling.

Evaluation of the effect of nano-graphene oxide on shear bond strength of conventional and resin-modified glass ionomer cement

OBJECTIVES

Recently, nano-graphene oxide (nGO), a material with unique mechanical properties, has been introduced to improve the properties of glass ionomer cement (GIC). The purpose of this study was to investigate the effect of adding nGO on the shear bond strength (SBS) of conventional (CGIC) and resin-modified GIC (RMGIC).

METHODS

Sixty intact molars were mounted and their occlusal surface was cut at a depth of 1 mm below the dentinoenamel junction. 1 wt.% and 2 wt.% of nGO (US Research Nanomaterials, Inc.) were added to CGIC and RMGIC (GC Corporation). The samples were randomly divided into six groups (n = 10), including 1: CGIC,  2: CGIC + 1% GO, 3: CGIC + 2% GO, 4: RMGIC, 5: RMGIC + 1% GO, and 6: RMGIC + 2% GO. Plastic molds were placed on the surface of the dentin pretreated with 10% polyacrylic acid (GC Corporation) and filled with prepared cement according to the manufacturer's instruction. After 24 h of storage in an incubator, the SBS test was done by the universal testing machine. Data were analyzed using two-way analysis of variance and post hoc Tukey tests (p < .05).

RESULTS

In the group of CGIC, mean SBS was significantly lower than all other study groups (p < .001), and groups 5 (RMGIC + 1% GO) and 6 (RMGIC + 2% GO) showed significantly higher values compared to all other study groups (p < .001). However, the difference between groups 2 and 3, as well as the difference between groups 5 and 6, was not significant (p = .999 andp = .994, respectively). RMGI groups had significantly higher SBS than their corresponding CGIC groups.

CONCLUSIONS

The addition of 1% and 2% nGO significantly increased the SBS of CGIC and RMGIC to the dentin, which can be considered as a promising point for wider clinical application of this material.

Silver Nanoparticles in Dental Applications: A Descriptive Review

Silver nanoparticles have been a recent focus of many researchers in dentistry, and their potential uses and benefits have drawn attention in dentistry and medicine. The fabrication and utilization of nanoscale substances and structures are at the core of the rapidly developing areas of nanotechnology. They are often used in the dental industry because they prevent bacteria from making nanoparticles, oxides, and biofilms. They also stop the metabolism of bacteria. Silver nanoparticles (AgNPs) are a type of zero-dimensional material with different shapes. Dentistry has to keep up with changing patient needs and new technology. Silver nanoparticles (AgNPs) can be used in dentistry for disinfection and preventing infections in the oral cavity. One of the most interesting metallic nanoparticles used in biomedical applications is silver nanoparticles (AgNPs). The dental field has found promising uses for silver nanoparticles (AgNPs) in the elimination of plaque and tartar, as well as the elimination of bacterial and fungal infections in the mouth. The incorporation of AgNPs into dental materials has been shown to significantly enhance patients' oral health, leading to their widespread use. This review focuses on AgNP synthesis, chemical properties, biocompatibility, uses in various dental fields, and biomaterials used in dentistry. With an emphasis on aspects related to the inclusion of silver nanoparticles, this descriptive review paper also intends to address the recent developments of AgNPs in dentistry.

Medical and Dental Applications of Titania Nanoparticles: An Overview

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

Effect of Currently Available Nanoparticle Synthesis Routes on Their Biocompatibility with Fibroblast Cell Lines

Nanotechnology has acquired significance in dental applications, but its safety regarding human health is still questionable due to the chemicals utilized during various synthesis procedures. Titanium nanoparticles were produced by three novel routes, including Bacillus subtilis, Cassia fistula and hydrothermal heating, and then characterized for shape, phase state, size, surface roughness, elemental composition, texture and morphology by SEM, TEM, XRD, AFM, DRS, DLS and FTIR. These novel titanium nanoparticles were tested for cytotoxicity through the MTT assay. L929 mouse fibroblast cells were used to test the cytotoxicity of the prepared titanium nanoparticles. Cell suspension of 10% DMEM with 1 × 104 cells was seeded in a 96-well plate and incubated. Titanium nanoparticles were used in a 1 mg/mL concentration. Control (water) and titanium nanoparticles stock solutions were prepared with 28 microliters of MTT dye and poured into each well, incubated at 37 °C for 2 h. Readings were recorded on day 1, day 15, day 31, day 41 and day 51. The results concluded that titanium nanoparticles produced by Bacillus subtilis remained non-cytotoxic because cell viability was >90%. Titanium nanoparticles produced by Cassia fistula revealed mild cytotoxicity on day 1, day 15 and day 31 because cell viability was 60−90%, while moderate cytotoxicity was found at day 41 and day 51, as cell viability was 30−60%. Titanium nanoparticles produced by hydrothermal heating depicted mild cytotoxicity on day 1 and day 15; moderate cytotoxicity on day 31; and severe cytotoxicity on day 41 and day 51 because cell viability was less than 30% (p < 0.001). The current study concluded that novel titanium nanoparticles prepared by Bacillus subtilis were the safest, more sustainable and most biocompatible for future restorative nano-dentistry purposes.

Effect of the Addition of Varying Concentrations of Silver Nanoparticles on the Fluoride Uptake and Recharge of Glass Ionomer Cement

This study aimed to compare the amount of fluoride uptake and the recharge and release characteristics of conventional glass ionomer cement (GIC) without any additives in comparison to conventional glass ionomer cement supplemented with silver nanoparticles (AgNPs) at two concentrations: 0.1% and 0.2% (w/w). A total of 60 specimens were used in this in vitro study. The sample was divided into six groups—including three groups without fluoride charge: Group 1 (conventional GIC), Group 2 (GIC with 0.1% silver nanoparticles), and Group 3 (GIC with 0.2% silver nanoparticles; and three groups with fluoride charge: Group 4 (conventional GIC with fluoride); Group 5 (GIC with 0.1% silver nanoparticles with fluoride); Group 6 (GIC with 0.2% silver nanoparticles with fluoride), where Group 1 is considered the control group and the other five groups are used as the test groups. The amount of fluoride released was measured on days 1, 2, 7, 15, and 30. The comparisons were made between the groups with and without fluoride and among all the groups. A significant difference in the amount of fluoride released was observed between the groups, with the highest amount occurring in Group 1, followed by Group 2; the lowest amount of fluoride released was observed in Group 3 (p < 0.05). The groups with fluoride recharge (Groups 4, 5, and 6) exhibited a higher amount of fluoride release than the groups with no recharge (Groups 1, 2, and 3); however, Group 1 has more fluoride release compared to all other groups on days 1, 2, 7, 15, and 30 (p < 0.05). The amount of released fluoride decreased from day 1 to day 30 in all of the groups in the study. Despite the antimicrobial and anticariogenic benefits of adding silver nanoparticles to GIC, it seems that fluoride release characteristics are significantly affected by the addition of this material. This may force the clinician to a compromise between the antimicrobial benefit of silver nanoparticles and the remineralizing advantage of fluoride.

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

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

Application of Selected Biomaterials and Stem Cells in the Regeneration of Hard Dental Tissue in Paediatric Dentistry-Based on the Current Literature

Currently, the development of the use of biomaterials and their application in medicine is causing rapid changes in the fields of regenerative dentistry. Each year, new research studies allow for the discovery of additional possibilities of dental tissue restoration. The structure and functions of teeth are complex. They consist of several diverse tissues that need to act together to ensure the tooth’s function and durability. The integrity of a tooth’s enamel, dentin, cementum, and pulp tissue allows for successful mastication. Biomaterials that are needed in dentistry must withstand excessive loading forces, be biocompatible with the hosts’ tissues, and stable in the oral cavity environment. Moreover, each tooth’s tissue, as well as aesthetic qualities in most cases, should closely resemble the natural dental tissues. This is why tissue regeneration in dentistry is such a challenge. This scientific research focuses on paediatric dentistry, its classification of caries, and the use of biomaterials in rebuilding hard dental tissues. There are several methods described in the study, including classical conservative methods such as caries infiltration or stainless-steel crowns. Several clinical cases are present, allowing a reader to better understand the described methods. Although the biomaterials mentioned in this work are artificial, there is currently ongoing research regarding clinical stem cell applications, which have a high potential for becoming one of the most common techniques of lost dental-tissue regeneration in the near future. The current state of stem cell development is mentioned, as well as the various methods of its possible application in dentistry.

Rehardening and the Protective Effect of Gamma-Polyglutamic Acid/Nano-Hydroxyapatite Paste on Surface-Etched Enamel

Many revolutionary approaches are on the way pertaining to the high occurrence of tooth decay, which is an enduring challenge in the field of preventive dentistry. However, an ideal dental care material has yet to be fully developed. With this aim, this research reports a dramatic enhancement in the rehardening potential of surface-etched enamels through a plausible synergistic effect of the novel combination of γ-polyglutamic acid (γ-PGA) and nano-hydroxyapatite (nano-HAp) paste, within the limitations of the study. The percentage of recovery of the surface microhardness (SMHR%) and the surface parameters for 9 wt% γ-PGA/nano-HAp paste on acid-etched enamel were investigated with a Vickers microhardness tester and an atomic force microscope, respectively. This in vitro study demonstrates that γ-PGA/nano-HAp treatment could increase the SMHR% of etched enamel to 39.59 ± 6.69% in 30 min. To test the hypothesis of the rehardening mechanism and the preventive effect of the γ-PGA/nano-HAp paste, the surface parameters of mean peak spacing (Rsm) and mean arithmetic surface roughness (Ra) were both measured and compared to the specimens subjected to demineralization and/or remineralization. After the treatment of γ-PGA/nano-HAp on the etched surface, the reduction in Rsm from 999 ± 120 nm to 700 ± 80 nm suggests the possible mechanism of void-filling within a short treatment time of 10 min. Furthermore, ΔRa-I, the roughness change due to etching before remineralization, was 23.15 ± 3.23 nm, while ΔRa-II, the roughness change after remineralization, was 11.99 ± 3.90 nm. This statistically significant reduction in roughness change (p < 0.05) implies a protective effect against the demineralization process. The as-developed novel γ-PGA/nano-HAp paste possesses a high efficacy towards tooth microhardness rehardening, and a protective effect against acid etching.