The Effect of Bioactive Glass-Enhanced Orthodontic Bonding Resins on Prevention of Demineralization: A Systematic Review

Gelatin-Modified Bioactive Glass for Treatment of Dentin Hypersensitivity

When dentin is directly exposed to the oral cavity for various reasons, such as a lack of enamel on the tooth surface, external stimuli to the dentin often cause transient discomfort known as dentin hypersensitivity. In order to block the incoming stimulus signal, an ideal treatment is to induce the production of minerals to block the dentinal tubules. In this work, a dentin-desensitizing plugging material was prepared by modifying mesoporous bioactive glass with gelatin, the mineralization and desensitization effects of which were compared with Gluma in in vitro experiments. These experiments confirmed that gelatin-modified bioactive glass (MBG@PDA@Gel) is more effective than traditional desensitizing agents at blocking dentin tubules. Following the successful synthesis of MBG@PDA@Gel, as confirmed by scanning electron microscopy, transmission electron microscopy, and other tests, the treatment of demineralized dentin with MBG@PDA@Gel demonstrated that the dentinal tubules were tightly blocked under scanning electron microscopy. MBG@PDA@Gel induces minerals in deeper layers of dentinal tubules, promoting remineralization and forming a unified structure with the tubule blockage. Animal studies showed that MBG@PDA@Gel can remineralize demineralized dentin, and it is stable in the oral cavity and does not fall out. MBG@PDA@Gel not only enhances the biocompatibility of the nanoparticle but also results in an overall uniform and rapid remineralization of the demineralized dentin.

Limitations, challenges and prospective solutions for bioactive glasses-based nanocomposites for dental applications: A critical review

Several nanomaterials have been recently used to overcome various challenges in the dental domain. Bioactive glasses, a class of bioceramics, with their outstanding properties including but not limited to their strong biocompatibility, antibacterial characteristics, and bioactivity inside the body's internal milieu have made them valuable biomaterials in a variety of dental domains. The utilization of nanomaterials has improved the performance of teeth, and the incorporation of bioactive glasses has the field of dentistry at an unsurpassed level in different categories such as esthetic and restorative dentistry, periodontics and dental implants, orthodontics, and endodontics. The current study discusses the most recent developments of the bioactive glasses' creation and implementation for dental applications, as well as the challenges and opportunities still facing the field. This work provides an overview of the current obstacles and potential future prospects for bioactive glasses-based nanocomposites to improve their dental uses. It also emphasizes the great potential synergistic effects of bioactive glasses used with other nanomaterials for dental applications.

Evaluation of Mechanical and Elemental Properties of Bioceramic-Coated Orthodontic Brackets and Enamel Surface

OBJECTIVE

 The aim is to coat orthodontic brackets with two different bioactive materials and to compare the mechanical and morphological properties of coated brackets and tooth surfaces.

MATERIALS AND METHODS

 A total of 120 stainless steel brackets were divided equally into three groups, that is, the uncoated brackets and nanohydroxyapatite (nHA)-coated, and nanobioactive glass (nBG)-coated brackets using a spin coater machine. The brackets were bonded on the enamel surface and underwent remineralization/demineralization cycles for days 1, 7, 14, and 30. At each time interval, the bond strength of the brackets was assessed using mechanical loading. An optical and scanning electron microscope (SEM) were used for surface evaluation, and the adhesive remanent index (ARI) values were obtained and quantified.

STATISTICAL ANALYSIS

 One-way analysis of variance using Tukey's test was used to compare the differences among the groups.

RESULTS

 A uniform distribution of nanoparticles occurred on the surfaces of brackets. The shear bond strength (SBS) showed no significant differences in any tested groups on days 1, 7, and 14. However, control and nBG showed a significant difference from nHA at day 30. On days 7, 14, and 30, the nHA group showed the highest SBS values among the groups. For ARI, most samples showed an adhesive nature of failure at the enamel-brackets interface. The images confirmed the presence of coated particles on brackets and remnants of adhesives after SBS.

CONCLUSION

 This study confirmed that the nHA- and nBG-coated brackets have a high potential for application in orthodontics regarding structural and mechanical properties.

An In Vitro Study Comparing the Antibacterial and Mechanical Properties of Zinc Oxide-Based Nanofillers in Orthodontic Adhesives for White Spot Lesion Prevention in Fixed Orthodontic Therapy

Introduction Preventing enamel demineralization (white spot lesions or WSLs) around the brackets during and after orthodontic therapy has been a challenging problem. Zinc oxide (ZnO) nanoparticles (NPs) show antibacterial effects against cariogenic bacteria Streptococcus (S.) mutans. Materials and methods In this study, researchers modified Transbond XT adhesive (Sigma Aldrich, St. Louis, Missouri, USA) by adding different concentrations of ZnO nanoparticles, i.e., 0.1% and 0.5wt%, in two experimental groups and a control group. We performed Fourier transform infrared spectroscopy and scanning electron microscopy for physio-structural characterization and investigated antibacterial ability by disc diffusion and colony-forming tests. We conducted shear bond strength and adhesive remnant index to determine the mechanical characteristics. Results The development and size of the inhibition zone were greatly dependent on the concentration of ZnO nanoparticles in the disc agar diffusion test. All ZnO NP-based experimental adhesives reduced the colony numbers for S. mutans. For S. mutans, the composite comprising 0.5wt% ZnO nanoparticles significantly reduced colony counts. The control group exhibited the maximum mean shear bond strength, whereas 0.5wt% nanoparticles composite had the lowest number. Conclusion Adding ZnO as nanofillers imparts antibacterial properties to the orthodontic adhesives. An increase in the concentration of ZnO nanoparticles in orthodontic adhesive increases its antibacterial properties. We found the shear bond strength of the novel composite with up to 0.5wt% ZnO nanoparticles to be in a clinically acceptable range.

Extensive Investigation on the Effect of Niobium Insertion on the Physical and Biological Properties of 45S5 Bioactive Glass for Dental Implant

Dental implants have emerged as one of the most consistent and predictable treatments in the oral surgery field. However, the placement of the implant is sometimes associated with bacterial infection leading to its loss. In this work, we intend to solve this problem through the development of a biomaterial for implant coatings based on 45S5 Bioglass® modified with different amounts of niobium pentoxide (Nb2O5). The structural feature of the glasses, assessed by XRD and FTIR, did not change in spite of Nb2O5 incorporation. The Raman spectra reveal the Nb2O5 incorporation related to the appearance of NbO4 and NbO6 structural units. Since the electrical characteristics of these biomaterials influence their osseointegration ability, AC and DC electrical conductivity were studied by impedance spectroscopy, in the frequency range of 102–106 Hz and temperature range of 200–400 K. The cytotoxicity of glasses was evaluated using the osteosarcoma Saos-2 cells line. The in vitro bioactivity studies and the antibacterial tests against Gram-positive and Gram-negative bacteria revealed that the samples loaded with 2 mol% Nb2O5 had the highest bioactivity and greatest antibacterial effect. Overall, the results showed that the modified 45S5 bioactive glasses can be used as an antibacterial coating material for implants, with high bioactivity, being also non-cytotoxic to mammalian cells.

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

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

Orthodontic resins loaded with niobium silicate particles: Impact of filler concentration on the physicochemical and biological properties

OBJECTIVES

White spot lesions (WSL) are prevalent in patients using orthodontic appliances. The presence of ion-releasing compounds in the tooth-appliance interface may limit enamel demineralization to control WSL incidence. Thus, this study aims to evaluate the mineral formation on SiNb-containing experimental orthodontic resins and the influence of these fillers on the physicochemical and biological properties of developed materials.

MATERIALS AND METHODS

The SiNb particles were synthesized via the sol-gel route and characterized by their molecular structure and morphology. Photopolymerizable orthodontic resins were produced with a 75 wt% Bis-GMA/25 wt% TEGDMA and 10 wt%, 20 wt%, or 30 wt% addition of SiNb. A control group was formulated without SiNb. These resins were tested for their degree of conversion, softening in solvent, cytotoxicity in fibroblasts, flexural strength, shear bond strength (SBS), and mineral deposition.

RESULTS

The addition of 10 wt% of SiNb did not impair the conversion of monomers, cytotoxicity, and flexural strength. All groups with SiNb addition presented similar softening in solvent. The presence of these particles did not affect the bond strength between metallic brackets and enamel, with SBS values ranging from 16.41 to 18.66 MPa. The mineral deposition was observed for all groups.

CONCLUSION

The use of niobium silicate as filler particles in resins may be a strategy for the adhesion of orthodontic appliances. The 10 wt% SiNb concentration resulted in a material with suitable physicochemical and biological properties while maintaining the bond strength to tooth enamel and promoting mineral deposition.

Anti-inflammatory properties of S53P4 bioactive glass implant material

OBJECTIVES

To assess whether the dissolution products of S53P4 bioactive glass (BG) affect cellular response of macrophages and clinically relevant peri‑implant cell populations to dental implant particles in vitro. Cells chosen were human gingival fibroblasts (HGFs), osteoblasts and bone marrow derived stromal cells (HBMSCs).

METHODS

Melt-derived S53P4 bioactive glass were prepared. HGFs, Saos-2 human osteoblastic cell line, HBMSCs and macrophages, derived from THP-1 human monocytic cell line, were cultured in the presence of particles from commercially pure titanium (Ti-CP4), grade 5 titanium alloy (Ti-6Al-4V), titanium-zirconium alloy (Ti-15Zr) or zirconia (Zr) (with respective diameters of 34.1 ± 3.8, 33.3 ± 4.4, 97.8 ± 8.2 and 71.3 ± 6.1 µm) with or without S53P4 dissolution products (conditioned media contained 327.30 ± 2.01 ppm Ca, 51.34 ± 0.41 ppm P and 61.48 ± 1.17 ppm Si, pH 8.01 ± 0.21). Inflammatory and macrophage polarisation markers including TNF-ɑ, IL-1, IL-6 and CD206 were quantified using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The presence of Ti-6Al-4V implant particles significantly induced the expression of pro-inflammatory markers in all tested cell types. S53P4 BG dissolution products regressed the particle induced up-regulation of pro-inflammatory markers and, appeared to suppress M1 macrophage polarisation.

CONCLUSIONS

Implant particles, Ti-6Al-4V in particular, resulted in significant inflammatory responses from cells. S53P4 BG may possess anti-inflammatory properties and potentially mediate macrophage polarisation behaviour.

CLINICAL SIGNIFICANCE

The findings highlight that the use and benefits of BG is a promising field of study. Authors believe more collective efforts are required to fully understand the reliability, efficiency and exact mechanisms of action of BG in the search for new generation of treatment modalities in dentistry.

Effects of Sr/F-Bioactive Glass Nanoparticles and Calcium Phosphate on Monomer Conversion, Biaxial Flexural Strength, Surface Microhardness, Mass/Volume Changes, and Color Stability of Dual-Cured Dental Composites for Core Build-Up Materials

This study prepared composites for core build-up containing Sr/F bioactive glass nanoparticles (Sr/F-BGNPs) and monocalcium phosphate monohydrate (MCPM) to prevent dental caries. The effect of the additives on the physical/mechanical properties of the materials was examined. Dual-cured resin composites were prepared using dimethacrylate monomers with added Sr/F-BGNPs (5 or 10 wt%) and MCPM (3 or 6 wt%). The additives reduced the light-activated monomer conversion by ~10%, but their effect on the conversion upon self-curing was negligible. The conversions of light-curing or self-curing polymerization of the experimental materials were greater than that of the commercial material. The additives reduced biaxial flexural strength (191 to 155 MPa), modulus (4.4 to 3.3), and surface microhardness (53 to 45 VHN). These values were comparable to that of the commercial material or within the acceptable range of the standard. The changes in the experimental composites' mass and volume (~1%) were similar to that of the commercial comparison. The color change of the commercial material (1.0) was lower than that of the experimental composites (1.5-5.8). The addition of Sr/F-BGNPs and MCPM negatively affected the physical/mechanical properties of the composites, but the results were satisfactory except for color stability.

Physical/mechanical and antibacterial properties of orthodontic adhesives containing Sr-bioactive glass nanoparticles, calcium phosphate, and andrographolide

White spot lesions around orthodontic brackets are the major complication during fixed orthodontic treatment. This study prepared orthodontic adhesives for promoting mineral precipitation and reducing bacterial growth. Adhesives with added calcium phosphate monohydrate/Sr-bioactive glass nanoparticles (Sr/CaP) and andrographolide were prepared. The physical/mechanical and antibacterial properties of the adhesives were tested. The additives reduced the monomer conversion of the materials (62 to 47%). The addition of Sr/CaP and andrographolide increased the water sorption (from 23 to 46 μg/mm³) and water solubility (from 0.2 to 5.9 μg/mm³) but reduced the biaxial flexural strength (from 193 to 119 MPa) of the adhesives. The enamel bond strengths of the experimental adhesives (19–34 MPa) were comparable to that of the commercial material (p > 0.05). The Sr/CaP fillers promoted Ca, Sr, and P ion release and the precipitation of calcium phosphate at the debonded interface. An increase in the Sr/CaP concentration enhanced the inhibition of S. mutans by 18%, while the effect of andrographolide was not detected. The abilities of the adhesives to promote ion release, calcium phosphate precipitation, and the growth inhibition of cariogenic bacteria were expected to reduce the occurrence of white spot lesions. The additives reduced the physical/mechanical properties of the materials, but the corresponding values were within the acceptable range.

Zirconia Crowns for Primary Teeth: A Systematic Review and Meta-Analyses

Objective: The aim of this systematic review was to summarize the literature regarding the clinical performance of zirconia crowns for primary teeth. Materials and Methods: Four electronic databases, Ovid, PubMed, Scopus, and Web of Science were searched. Clinical, observational, and laboratory studies were included. Studies that assessed the performance of zirconia crowns for primary teeth using outcomes such as gingival and periodontal health, parental satisfaction, color stability, crown retention, contour, fracture resistance, marginal integrity, surface roughness, and recurrent caries were included. Risk of bias was assessed using different assessment tools depending on the type of the assessed study. Results: Out of the 2400 retrieved records, 73 full-text records were assessed for eligibility. Thirty-six studies were included for qualitative analysis. The included studies reported that zirconia crowns for primary teeth were associated with better gingival and periodontal health, good retention, high fracture resistance, color stability, high parental acceptance, good marginal adaptation, smooth cosmetic surface, and no recurrent caries. Conclusion: Zirconia crowns are promising alternative to other restorative materials and crowns in the field of pediatric dentistry. They showed higher properties and performance in different clinical aspects and great parental satisfaction.

Remineralizing Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

The incorporation of remineralizing additives into sealants has been considered as a feasible way to prevent caries by potential remineralization through ions release. Thus, this systematic review aimed to identify the remineralizing additives in resin-based sealants (RBS) and assess their performance. Search strategies were built to search four databases (PubMed, MEDLINE, Web of Science and Scopus). The last search was conducted in June 2020. The screening, data extraction and quality assessment were completed by two independent reviewers. From the 8052 screened studies, 275 full-text articles were assessed for eligibility. A total of 39 laboratory studies matched the inclusion criteria. The methodologies used to assess the remineralizing effect included microhardness tests, micro-computed tomography, polarized-light microscopy, ions analysis and pH measurements. Calcium phosphate (CaP), fluoride (F), boron nitride nanotubes (BNN), calcium silicate (CS) and hydroxyapatite (HAP) were incorporated into resin-based sealants in order to improve their remineralizing abilities. Out of the 39 studies, 32 studies focused on F as a remineralizing agent. Most of the studies confirmed the effectiveness of F and CaP on enamel remineralization. On the other hand, BNN and CS showed a small or insignificant effect on remineralization. However, most of the included studies focused on the short-term effects of these additives, as the peak of the ions release and concentration of these additives was seen during the first 24 h. Due to the lack of a standardized in vitro study protocol, a meta-analysis was not conducted. In conclusion, studies have confirmed the effectiveness of the incorporation of remineralizing agents into RBSs. However, the careful interpretation of these results is recommended due to the variations in the studies’ settings and assessments.

Flexural Strength, Elastic Modulus and Remineralizing Abilities of Bioactive Resin-Based Dental Sealants

Objective: To assess the remineralizing abilities and compare the flexural strength and elastic modulus of different bioactive pit and fissure sealants. Materials and Methods: Human enamel samples were randomly and blindly sealed with one of the following bioactive materials: BioCoat (Bc), ACTIVA KIDS (Av) and BeautiSealant (Bu). Seal-it (Si) was used as a non-bioactive sealant beside a control blank (B) group with no sealant. The sealed samples were subjected to a pH-cycling model (7 days of demineralization–remineralization cycles). The enamel surface hardness change (SHC), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and polarized light microscopy were used to assess the remineralizing abilities of the studied sealants. Flexural strength and elastic modulus were also assessed following the ISO 4049 protocols. One-way analysis of variance (ANOVA) was used to analyze the results. Results: Bc sealant showed the highest FS and EM (p < 0.05). The contact with Bc and Bu sealants showed significantly lower %SHL (p < 0.05) in comparison to the other. These findings were supported by the results of SEM-EDX and polarized imaging by showing higher percentages of calcium and phosphate ions with the former sealants and thinner demineralized enamel bands. Conclusion: In this study, Bc showed the highest flexural strength. Bc and Bu sealants outperformed the other studied sealants in terms of their remineralization abilities.

Evaluation the properties of orthodontic adhesive incorporated with nano-hydroxyapatite particles

Objective

This research was designed to study the effects of calcium hydroxyapatite nanoparticle incorporation on polymerization as well as the shear bond strength for Heliosit adhesive.

Materials and methods

Calcium hydroxyapatite nanoparticles were prepared from natural products using the sol-gel method, and were inspected using a transmission electron microscope. The nanoparticles were added to the conventional orthodontic adhesive at 2% wt and 4% wt concentrations. The degree of conversion for each test group was measured using a Fourier transform infrared spectroscopy device. Each adhesive group was used for bonding metal brackets to the premolar buccal enamel surface. The shear bond strength of all samples was measured.

Results

A significant difference was found among all the study groups (p ≤ 0.05) in terms of the degree of conversion and shear bond strength. The 2% wt nanoparticle group showed the highest values for both variables. The lowest value was recorded within the 4% wt nanoparticle group in comparison to the control group.

Conclusions

Calcium hydroxyapatite nanoparticle incorporation with a conventional Heliosit adhesive resin to a limited concentration has improved the mechanical properties of orthodontic adhesive.

Comparative evaluation of nano-filled and conventional adhesives for bonding of molar tubes

It is of interest to compare the bonding characteristics of the two nano filled adhesives, Grandio (Voco, Cuxhaven, Germany) and Transbond Supreme LV (TSLV, 3M Unitek, Monrovia, California) with conventional bonding adhesive Transbond XT (TBXT, 3M Unitek) for bonding of molar tubes. 45 extracted human permanent molar teeth, divided into three groups of 15 each, were bonded with stainless steel molar tubes (3M Unitek, USA) using TBXT in Group 1, Grandio in Group 2, TSLV in Group 3. Remnant Index and shear bond strength was evaluated after 24 hrs. of storage with the aid of Instron Universal testing machine and Stereomicroscope respectively. Data were analysed using Analysis of Variance (ANOVA) test, Post-hoc Bonferroni test and Kruskal Wallis test. The mean SBS of Group 1(TBXT) was 13.86±3.27 MPa, Group 2 (Grandio) was 9.48±2.36 MPa and Group 3 (TSLV) was 11.64±2.71 MPa. Both nano-filled adhesives had SBS well above the clinically acceptable range. Assessment of ARI scores and type of bond failure revealed that adhesive failure for TBXT and TSLV and cohesive failure for Grandio. Nano-filled adhesives can be an appropriate substitute for the conventional adhesive for bonding of molar tubes.

The Antibacterial Effects of Resin-Based Dental Sealants: A Systematic Review of In Vitro Studies

This review aimed to assess the antimicrobial effects of different antibacterial agents/compounds incorporated in resin-based dental sealants. Four databases (PubMed, MEDLINE, Web of Science and Scopus) were searched. From the 8052 records retrieved, 275 records were considered eligible for full-text screening. Nineteen studies met the inclusion criteria. Data extraction and quality assessment was performed by two independent reviewers. Six of the nineteen included studies were judged to have low risk of bias, and the rest had medium risk of bias. Compounds and particles such as zinc, tin, Selenium, chitosan, chlorhexidine, fluoride and methyl methacrylate were found to be effective in reducing the colony-forming unit counts, producing inhibition zones, reducing the optical density, reducing the metabolic activities, reducing the lactic acid and polysaccharide production and neutralizing the pH when they are added to the resin-based dental sealants. In addition, some studies showed that the antibacterial effect was not significantly different after 2 weeks, 2 months and 6 months aging in distilled water or phosphate-buffered saline. In conclusion, studies have confirmed the effectiveness of adding antibacterial agents/compounds to dental sealants. However, we should consider that these results are based on laboratory studies with a high degree of heterogeneity.

Resin-Based Sealant with Bioactive Glass and Zwitterionic Material for Remineralisation and Multi-Species Biofilm Inhibition

Since pits and fissures are the areas most commonly affected by caries due to their structural irregularity, bioactive resin-based sealant (RBS) may contribute to the prevention of secondary caries. This study aims to investigate the mechanical, physical, ion-release, enamel remineralisation, and antibacterial capabilities of the novel RBS with bioactive glass (BAG) and 2-methacryloyloxyethyl phosphorylcholine (MPC). For the synthesis, 12.5 wt% BAG and 3 wt% MPC were incorporated into RBS. The contact angle, flexural strength, water sorption, solubility, and viscosity were investigated. The release of multiple ions relating to enamel remineralisation was investigated. Further, the attachments of bovine serum albumin, brain heart infusion broth, and Streptococcus mutans on RBS were studied. Finally, the thickness and biomass of a human saliva-derived microsm biofilm model were analysed before aging, with static immersion aging and with thermocycling aging. In comparison to commercial RBS, BAG+MPC increased the wettability, water sorption, solubility, viscosity, and release of multiple ions, while the flexural strength did not significantly differ. Furthermore, RBS with MPC and BAG+MPC significantly reduced protein and bacteria adhesion and suppressed multi-species biofilm attachment regardless of the existence of aging and its type. The novel RBS has great potential to facilitate enamel remineralisation and suppress biofilm adhesion, which could prevent secondary dental caries.