Epigallocatechin-3-gallate (EGCG) enhances the therapeutic activity of a dental adhesive

Organic antibacterial modifications of high-viscosity glass ionomer cement for atraumatic restorative treatment: A review

High viscosity glass ionomer cement (HVGIC) has been employed as a restorative material for Atraumatic Restorative Treatment (ART). As residual caries persist after caries removal in ART, the antibacterial activity of HVGIC gains importance. Organic and inorganic substances with antibacterial properties have been incorporated into HVGIC over the years, and their effects on the antibacterial and physical properties have been studied. The objective of this paper is to review the various alterations made to HVGIC using organic compounds, their effect on the antibacterial activity, and the physical properties of the cement. Various in vitro investigations have been conducted by adding antiseptics, antibiotics, and naturally occurring antibacterial substances. Most of these compounds render superior antibacterial properties to HVGIC, but higher concentrations affect physical properties in a dose-dependent manner. However, some naturally occurring antibacterial substances, such as chitosan, improve the physical properties of HVGIC, as they enhance cross-linking and polysalt bridging. There is potential for clinical benefits to be gained from the addition of organic antibacterial compounds to HVGIC. In-depth research is required to determine the optimum concentration at which the antibacterial effect is maximum without affecting the physical properties of the cement.

Biocompatible and nondegradable microcapsules using an ethylamine-bridged EGCG dimer for successful therapeutic cell transplantation

Conventional alginate microcapsules are widely used for encapsulating therapeutic cells to reduce the host immune response. However, the exchange of monovalent cations with divalent cations for crosslinking can lead to a sol-gel phase transition, resulting in gradual degradation and swelling of the microcapsules in the body. To address this limitation, we present a biocompatible and nondegradable epigallocatechin-3-gallate (EGCG)-based microencapsulation with ethylamine-bridged EGCG dimers (EGCG(d)), denoted as 'Epi-Capsules'. These Epi-Capsules showed increased physical properties and Ca2+ chelating resistance compared to conventional alginate microcapsules. Horseradish peroxidase (HRP) treatment is very effective in increasing the stability of Epi-Capsule((+)HRP) due to the crosslinking between EGCG(d) molecules. Interestingly, the Epi-Capsules(oxi) using a pre-oxidized EGCG(d) can support long-term survival (>90 days) of xenotransplanted insulin-secreting islets in diabetic mice in vivo, which is attributed to its structural stability and reactive oxygen species (ROS) scavenging for lower fibrotic activity. Collectively, this EGCG-based microencapsulation can create Ca2+ chelating-resistance and anti-oxidant activity, which could be a promising strategy for cell therapies for diabetes and other diseases.

Mixing ratio of nano hydroxyapatite and Epigallocatechin-3-gallate (EGCG) towards viscosity and antibacterial effect as a potential pulp capping Material: An experimental study

Background

Finding a new natural scaffold is challenging due to crucial impact on long-term treatment outcomes in pulp capping. In this context, nano hydroxyapatite (nano-HA) is a potential candidate having similar properties to bone tissue in the body. The compound is often synthesized with Epigallocatechin-3-gallate (EGCG) which offers anti-inflammatory and antibacterial properties. Therefore, this study aims to contribute novel insights into the development of effective pulp capping materials by determining the viscosity ratio of the combination of nano-HA and EGCG applied to the cavity according to standard pulp capping material, as well as proving the antibacterial effect against Lactobacillus acidophilus.

Methods

The combination of nano-HA - EGCG is divided into three treatment groups, (G1) 1:1 ratio, (G2) 1:1.5 ratio, (G3) 1:2 ratio, as well as control group G4 (Ca(OH)2 and aquadest) with a ratio of 1:1. Meanwhile, each group is tested for viscosity using a Brookfield viscometer. The well diffusion method is used to determine the antibacterial activity by measuring the diameter of the inhibition zone for each treatment, with C1 (Ca(OH)2 and aquadest) as control group at a ratio of 1:1, and three treatment groups (nano-HA - EGCG), (C2) 0.5:1 ratio, (C3) 1:1 ratio, and (C4) 2:1 ratio.

Results

The results show that there is a difference in the viscosity of each group with G3 having a viscosity of 12.0183 cP, which is closest to control. Furthermore, significant differences are also reported in antibacterial activity between control and treatment groups.

Conclusion

The ratio of 1:2 (G3) has a viscosity that closely matches the standard of pulp capping materials. The combinations of nano-HA and EGCG are proven to have antibacterial power against Lactobacillus acidophilus.

Matrix metalloproteinase inhibitors in restorative dentistry

Matrix metalloproteinases (MMPs) have been identified as agents that disintegrate the collagen structures of dental hybrid layers, resulting in reduced restorative bond strength. Multiple MMP inhibitors (MMPIs) are known to counteract this degenerative mechanism, thereby preserving bond strength and promoting the longevity of resin-based restorations. Additionally, literature suggests that certain MMPI materials possess antimicrobial/anticariogenic properties, potentially reducing the risk of secondary caries development. Therefore, this review article aims to narrate on the integration of matrix metalloproteinase inhibitors into adhesive systems and their impact on bond strength.

Exploring the role of flavonoids in caries-affected dentin adhesion: A comprehensive scoping review

OBJECTIVES

The aim of this scoping review was to evaluate the available scientific evidence regarding the use of flavonoids in the treatment of caries-affected dentin focusing on bonding to dentin.

METHODS

A comprehensive literature search was performed in five databases from March 2022 and updated in April 2023: PubMed, EMBASE, Scopus, Web of Science, and Scielo. Additionally, the references of included studies were manually searched. Gray literature was excluded from the review.

STUDY SELECTION

Inclusion criteria included in vitro, in situ, and in vivo studies (animal or human) published in English. Abstracts, reviews, case reports, book chapters, doctoral dissertations, guidelines, and studies using pure plant extracts were excluded. Data collected from the selected studies were summarized and subjected to narrative and descriptive analysis. Out of the 91 studies identified, only 16 studies met the inclusion criteria.

RESULTS

The review analyzed eight different flavonoids (hesperidin, galardin, proanthocyanidin, genipin, quercetin, naringin, epigallocatechin-3-gallate, and other catechins subtypes) used as pretreatment or loaded into adhesive systems, primers, and phosphoric acid. The use of flavonoids improved the mechanical properties of the materials and modified the biological properties of the dentin, reducing collagen loss by the inhibition of proteolytic activity of matrix metalloproteinases (MMPs).

CONCLUSIONS

Based on the findings of this scoping review, it can be concluded that the use of flavonoids as pretreatment or incorporation into dental materials preserves collagen in the hybrid layer, inhibiting the MMPs activities, modifying the collagen fibrils of the dentin matrix and improving the mechanical properties of the dental adhesive systems. Therefore, it represents a promising approach for promoting dentin biomodification. This can result in more stable bonding of adhesive restorations to caries-affected dentin.

Assessment of physical properties of bioactive glass-modified universal multimode adhesive and its bonding potential to artificially induced caries affected dentin

BACKGROUND

To evaluate the physical properties of bioactive glass-modified universal multimode adhesive and its micro-tensile bond strength (µTBS) to artificially induced caries-affected dentin.

METHODS

All bond universal adhesive was used in the study. Specimens were divided into 2 main groups: control unmodified adhesive and 5 wt% BAG modified adhesive. The degree of conversion, pH, bioactivity, and viscosity of the adhesives were tested with n = 5 for each test. Micro-tensile bond strength evaluation was done in etch & rinse (ER) and selective-etch (SE) modes, where 24 human molar teeth were used (n = 3), 12 teeth for immediate bond strength, and the other 12 were tested after 6 months of storage in simulated body fluid (SBF).

RESULTS

No significant difference was found between the control and the 5wt% BAG groups regarding the degree of conversion (61.01 ± 0.43 and 60.44 ± 0.61 respectively) and the viscosity (109.77 ± 22.3 and 124.3 ± 9.92 respectively). The control group revealed significantly lower pH values than the 5wt% BAG group (3.16 ± 0.5 and 4.26 ± 0.09 respectively). Immediate bond strength results revealed that the 5wt% BAG in the ER mode had the highest bond strength followed by the control group in the ER mode (44.16 ± 7.53 and 44.00 ± 7.96 respectively). SE groups showed that the immediate strength of the 5wt% BAG group was higher than the control group (42.09 ± 6.02 and 39.29 ± 6.64 respectively). After 6 months of storage, bond strength results revealed a decrease in bond strength values for the control groups but not for the 5wt% BAG in both application modes.

CONCLUSIONS

The incorporation of BAG (5wt%) improved the universal adhesive micro-tensile bond strength and bond durability for both adhesive application modes without affecting its degree of conversion or viscosity.

Epigallocatechin gallate-immobilized antimicrobial resin with rechargeable fluorinated synergistic composite for enhanced caries control

OBJECTIVES

Given the global prevalence of dental caries, impacting 2.5 billion individuals, the development of sophisticated prevention filling materials is crucial. Streptococcus mutans, the principal caries-causing strain, produces acids that demineralize teeth and initiate dental caries. To address this issue, we aimed to develop a synergistic resin-based composite for enhancing caries control.

METHODS

The synergistic resin composite incorporates fluorinated kaolinite and silanized Al2O3 nanoparticle fillers into an epigallocatechin gallate (EGCG) immobilized urethane-modified epoxy acrylate (U-EA) resin matrix, referred to the as-prepared resin composite. The EGCG-modified TPGDA/U-EA network was synthesized by preparing methacrylate-functionalized isocyanate (HI), reacting it with EGCG to form HI-EGCG, and then incorporating HI-EGCG into the TPGDA/U-EA matrix. The lamellar space within the kaolinite layer was expanded through the intercalation of acrylamide into kaolinite, enhancing its capability to adsorb and release fluoride ions (F-). The layered structure of acrylamide/ kaolinite in the U-EA resin composite acts as a F- reservoir.

RESULTS

The physico-mechanical properties of the as-prepared resin composites are comparable to those of commercial products, exhibiting lower polymerization shrinkage, substantial F- release and recharge and favorable diametral tensile strength. The immobilized EGCG in the composite exhibits potent antimicrobial properties, effectively reducing the biofilm biomass. Furthermore, the synergistic effect of EGCG and fluorinated kaolinite efficiently counteracts acid-induced hydroxyapatite dissolution, thereby suppressing demineralization and promoting enamel remineralization.

SIGNIFICANCE

Our innovative EGCG and fluoride synergistic composite provides enhanced antimicrobial properties, durable anti-demineralization, and tooth remineralization effects, positioning it as a promising solution for effective caries control and long-term dental maintenance.

Enhancing dentin bonding through new adhesives formulations with natural polyphenols, tricalcium phosphate and chitosan

OBJECTIVES

The aim of the study was to develop new adhesive formulations that include natural polyphenols extracted from green tea (GTE), tricalcium phosphate (TCP) and chitosan to improve dentin bonding characteristics and cytotoxicity.

METHODS

Four experimental adhesives were formulated under laboratory conditions. The groups differed in the integration of either GTE and/or TCP + chitosan. The four experimental and one clinically proven reference adhesive underwent shear bond testing after 24 h and 6 months of aging (n = 200) with subsequent fractographic analysis. Bond morphology was analyzed under a scanning electron microscope. The presence of phenolic compounds was validated by high performance liquid chromatography. Cytotoxicity was assessed by the WST-1 colorimetric assay on eluates up to 6 months. Statistical analysis was performed by one- and three-way ANOVA, Games-Howell and Tukey's post-hoc test as well as multiple students t-tests (α = 0.05). Weibull analysis was further conducted.

RESULTS

The addition of GTE into the bonding agent did show immediate (p = 0.023, p = 0.013) and long-term (p < 0.001) effects on bond strength. After 24 h, GTE doped groups performed equal to the reference (p = 0.501, p = 0.270) and TCP and chitosan displayed improvements in reliability (m=4.0, m=4.3). Bond strength is retained after aging by adding GTE (p = 0.983). The additional presence of TCP and chitosan reduces it (p = 0.026). Excluding cohesive and mixed failures, the reference adhesive performed statistically equal to three of the four experimental groups. No long-term cytotoxic effects were shown.

SIGNIFICANCE

The integration of GTE can enhance bond strength and a calcium source helps to improve immediate bond reliability.

Biomodification of eroded and abraded dentin with epigallocatechin-3-gallate (EGCG)

This study aimed to evaluate in vitro the effects of epigallocatechin-3-gallate (EGCG) as a biomodifier of eroded and abraded dentin. Forty dentin specimens were obtained from the buccal surface of bovine teeth. The specimens were randomly distributed in 4 groups according to dentin substrate: sound or eroded/abraded and dentin biomodification: with 0.5% EGCG and no biomodification (control group). Specimens were subdivided according to aging time: 24 h and 3 months for the analysis of microtensile bond strength (n = 10), morphology of the adhesive interface by SEM (n = 3) and dentin micropermeability by fluorescence microscope (n = 8). Statistical analysis was performed using SPSS system version 20.0 with a significance level of 5%. The results revealed that the control group with eroded-abraded dentin exhibited the lowest bond strength values at 24 h and 3 months. However, the application of 0.5% EGCG as a biomodifier significantly increased bond strength on both sound and eroded-abraded substrates. After 3 months, all groups exhibited an adhesive interface with a more intense fluorescence in the adhesive layer, indicating an increase in porosity at the interface. In conclusion, the EGCG application as a biomodifier enhanced bond strength on both sound and eroded-abraded dentin substrates, however, adhesive interfaces are more regular when restorations are performed on sound dentin, regardless of the biomodification with EGCG.

Antibacterial efficacy of epigallocatechin-3-gallate cross-linked small intestinal submucosa guided bone regeneration membrane

The leading cause of guided bone regeneration (GBR) failure is infection. Herein, we developed a new GBR membrane with good mechanical and osteogenic properties by crosslinking the small intestinal submucosa (SIS) with epigallocatechin-3-gallate (EGCG). Meanwhile, EGCG is also a natural antibacterial agent. This study aimed to investigate the antibacterial efficacy of EGCG-crosslinked SIS (E-SIS) against Staphylococcus aureus and Escherichia coli through EGCG release, bacterial count, live/dead staining, scanning electron microscopy, growth curve, and biofilm formation tests. The results showed that E-SIS effectively inhibited bacteria's growth and adhesion, and its antibacterial activity against Staphylococcus aureus was stronger than that against Escherichia coli. 0.5% E-SIS had the most potent antibacterial activity. The antibacterial mechanism of E-SIS might be related to the release of EGCG and the surface properties of E-SIS. In conclusion, 0.5% E-SIS is a promising GBR membrane with good osteogenic and antibacterial properties.

Effect of matrix metalloproteinase inhibitors on bonding durability of universal adhesives

This study aimed to evaluate the effect of different matrix metalloproteinase inhibitors (MMPIs) on the microtensile bond strength (μTBS) and nanoleakage of universal adhesives. One hundred twenty non-carious human molars were prepared and randomly assigned to two groups: Scotchbond Bond Universal (SBU) and Gluma Bond Universal (GBU). The samples in each group were assigned to five subgroups (n=12) based on one control (water) and four MMPIs (Benzalkonium-chloride (BAC), Batimastat (BB94), Chlorhexidine (CHX), and Epigallocatechin-gallate (EGCG)). Each adhesive was applied in self-etch (SE) mode or etch-and-rinse (ER) mode. Dentin/composite sticks were fabricated and subjected to the μTBS test after 24 h or 6 months. At 6 months, MMPIs did not affect the μTBS of the adhesives, regardless of etching mode. Nanoleakage was more pronounced in ER mode than in SE mode for all subgroups. All MMPIs, with the exception of CHX, decreased the nanoleakage of GBU in ER mode.

Current antibacterial agents in dental bonding systems: a comprehensive overview

Dental caries is mainly caused by oral biofilm acid, and the most common dental restoration treatment is composite dental restorations. The main cause of failure is secondary caries adjacent to the restoration. Long-term survival of dental materials is improved by the presence of antibacterial agents, which selectively inhibit bacterial growth or survival. Chemical, natural and biomaterials have been studied for their antimicrobial activities and antibacterial bonding agents have been improved. Their usage has been increased to inhibit the growth of invading and residual bacteria in the oral cavity, as biofilm accumulation increases the risk of treatment failure. In this article, the success and applications of antibacterial agents are discussed in dental bonding systems.

Effect of Antibacterial Agents on Dentin Bond Strength of Bioactive Restorative Materials

Treating dentin surfaces with antibacterial agents prior to bonding bioactive restorations might affect their mechanical properties. In this study, we evaluated the effect of silver diamine fluoride (SDF) and chlorhexidine (CHX) on the shear bond strength (SBS) of bioactive restorative materials. Dentin discs were treated with SDF for 60 s or CHX for 20 s and bonded with four restorative materials, namely Activa Bioactive Restorative (AB), Beautifil II (BF), Fuji II LC (FJ), and Surefil One (SO). Control discs were bonded without treatment (n = 10). SBS was determined using a universal testing machine, and a scanning electron microscope (SEM) was used for the evaluation of the failure mode and the cross-sectional examination of adhesive interfaces. The SBS of each material between different treatments and of the different materials within each treatment were compared via a Kruskal-Wallis test. The SBS of AB and BF was significantly higher than that of FJ and SO in the control and CHX groups (p < 0.01). In the latter, SBS was higher in FJ than SO (p < 0.01). SO had a higher value with SDF compared to CHX (p = 0.01). The SBS of SDF-treated FJ was higher than that of the control (p < 0.01). SEM showed a more homogenous and improved interface of FJ and SO with SDF. Neither CHX nor SDF compromised the dentin bonding of bioactive restorative materials.

Release and MMP-9 Inhibition Assessment of Dental Adhesive Modified with EGCG-Encapsulated Halloysite Nanotubes

Degradation of the collagen fibrils at the dentin-resin interface by the enzymatic activity of matrix metalloproteinases (MMPs) has been known to permit some dental restoration complications, such as microleakage, secondary caries, and, ultimately, restoration failures. This study aimed to evaluate a modified adhesive by adding an MMP inhibitor from green tea extract with and without nanotube encapsulation to sustain the drug release. Epigallocatechin-3-gallate (EGCG) and Halloysite nanotubes (HNTs) were prepared to produce three variant combinations of modified adhesive (EGCG, EGCG-encapsulated HNT, and EGCG-free HNT). The drug loading efficiency and EGCG release over time were evaluated using UV-vis spectrometry. MMP-mediated β-casein (BCN) cleavage rate assays were used to determine the ability of the EGCG in eluates of the adhesive to inhibit MMP-9 activities. For up to 8 weeks, HNT encapsulation reduced release to a statistically significant level. MMP-mediated β-casein cleavage rate assays showed a significant decrease for the EGCG groups compared to the non-EGCG adhesive groups. Furthermore, the use of HNT for EGCG encapsulation to modify a dental adhesive helped slow down the rate of EGCG release without impacting its MMP inhibitory capabilities, which may help to maintain the dentin-resin interface's integrity over the long term after dental restoration placement.

Effect of collagen cross-linkers on dentin bond strength: A systematic review and network meta-analysis

Objective: This study aimed to evaluate the role of collagen cross-linkers in the bonding performance of the resin-dentin interface through a systematic review and a network meta-analysis. Sources: The literature search was conducted in several databases like PubMed, EMBASE, Cochrane, Scopus and Web of Science from their inception till 30 April 2022. Study selection: The inclusion criteria consisted of in vitro studies evaluating the micro-tensile and micro-shear bond strengths of different cross-linkers acting on dentin. Bayesian network meta-analysis was conducted using RStudio. Data: Out of the 294 studies evaluated in the full-text analysis, 40 were included in the systematic review and meta-analysis. Most studies have used cross-linkers as primer (65.1%), followed by incorporating them into in adhesives and acid etching agents. The application methods of the adhesive system were classified as "etch-and-rinse (ER) adhesives" (77%) and "self-etching (SE) adhesives". Moreover, there were six types of cross-linkers in this presented review, of which the most numerous were polyphenols. Conclusion: Different application methods of cross-linkers, the long-term results showed that were only effective when used for longer durations, the immediate results were not statistically different. According to immediate and long-term results, etch-and-rinse (ER) adhesives showed a greater bonding performance than the control groups (p ≤ 0.05), whereas self-etching (SE) adhesives showed similar bond strength values (p ≥ 0.05). The result of network meta-analysis (NMA) showed that Dope like compound showed higher long-term bonding performance than other cross-linkers. Clinical significance: Long-term clinical studies may be needed to determine the effect of the cross-linkers on the bonding properties.

Incorporation of MMP inhibitors into dental adhesive systems and bond strength of coronal composite restorations: A systematic review and meta-analysis of in vitro studies

Purpose

To systematically review in vitro studies that incorporated MMP inhibitors into adhesive systems in terms of the effect on immediate and aged bond strength of dental composite to dentine.

Materials and methods

Independently, two reviewers conducted an electronic search in three databases (MEDLINE, EMBASE, and Google Scholar) following the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA-P), up to 6 March 2022.

Results

The search resulted in 894 papers, 33 of which were eligible to be included in the review; of those, 13 fulfilled the meta-analysis eligibility criteria. Nineteen inhibitors were used among the studies, and those included in the meta-analysis were 2%, 0.2% chlorhexidine (CHX), 5 µM GM1489, and 0.5%, 1% benzalkonium chloride (BAC). In the meta-analysis, while above inhibitors showed no adverse effect on bond strength, 0.2% CHX and 5 µM GM1489 caused a significant increase in immediate and 12-months bond strength. All other inhibitors resulted in a significant increase in bond strength at six months of ageing.

Conclusions

Incorporation of MMP inhibitors into the adhesive system has no unfavourable effect on immediate bond strength but a favourable effect on longer-term bond strength. Additionally, inhibitors other than CHX could have similar or better effects on bond strength.

Effect of Collagen Crosslinkers on Dentin Bond Strength of Adhesive Systems: A Systematic Review and Meta-Analysis

This study aimed to identify the role of crosslinking agents in the resin–dentin bond strength (BS) when used as modifiers in adhesives or pretreatments to the dentin surface through a systematic review and meta-analysis. This paper was conducted according to the directions of the PRISMA 2020 statement. The research question of this review was: “Would the use of crosslinkers agents improve the BS of resin-based materials to dentin?” The literature search was conducted in the following databases: Embase, PubMed, Scielo, Scopus, and Web of Science. Manuscripts that reported the effect on the BS after the use of crosslinking agents were included. The meta-analyses were performed using Review Manager v5.4.1. The comparisons were performed by comparing the standardized mean difference between the BS values obtained using the crosslinker agent or the control group. The subgroup comparisons were performed based on the adhesive strategy used (total-etch or self-etch). The immediate and long-term data were analyzed separately. A total of 50 articles were included in the qualitative analysis, while 45 articles were considered for the quantitative analysis. The meta-analysis suggested that pretreatment with epigallocatechin-3-gallate (EGCG), carbodiimide, ethylenediaminetetraacetic acid (EDTA), glutaraldehyde, and riboflavin crosslinking agents improved the long-term BS of resin composites to dentin (p ≤ 0.02). On the other hand, the use of proanthocyanidins as a pretreatment improved both the immediate and long-term BS values (p ≤ 0.02). When incorporated within the adhesive formulation, only glutaraldehyde, riboflavin, and EGCG improved the long-term BS to dentin. It could be concluded that the application of different crosslinking agents such as carbodiimide, EDTA, glutaraldehyde, riboflavin, and EGCG improved the long-term BS of adhesive systems to dentin. This effect was observed when these crosslinkers were used as a separate step and when incorporated within the formulation of the adhesive system.

Is dentin biomodification with collagen cross-linking agents effective for improving dentin adhesion? A systematic review and meta-analysis

Objectives

The aim of this investigation was to evaluate the effectiveness of collagen cross-linking agents (CCLAs) used in combination with the adhesive technique in restorative procedures.

Materials and Methods

In this systematic review, the authors followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. An electronic search was performed using PubMed, Scopus, Web of Science, Cochrane Library, LILACS, and DOSS, up to October 2020. The gray literature was also researched. Only randomized clinical trials were selected.

Results

The selection process yielded 3 studies from the 838 retrieved. The addition of CCLAs in the retention of restorations increased the number of events. The postoperative sensitivity scores and marginal adaptation scores showed no significant difference between the CCLA and control groups, and the marginal pigmentation scores showed a significant increase in the CCLA group. There were no caries events in any group throughout the evaluation period.

Conclusions

This systematic review showed that there is no clinical efficacy to justify the use of CCLAs in the protocols performed.

Minocycline incorporated cobalt oxide nanoparticles in dental sealants: An in vitro study

The purpose of this study was to introduce antibacterial property to pits and fissure sealant (PFS) in order to mitigate the major clinical problems associated with PFS, such as microleakage and secondary caries. We prepared a pH reliant cobalt oxide nanoparticle incorporated with minocycline (MNC@CO) and characterized to investigate its antibacterial potential against Streptococcus sobrinus. The physiochemical, morphological, and drug release kinetics at different pH (7.4, 5.0, and 3.5) from nanoparticles were investigated. The MNC@CO were added at 2.5% and 5.0% into experimental PFS and characterized for their antibiofilm capacity, biocompatibility, and mechanical properties including compressive and flexural strength. The groups 2.5% and 5.0% has shown statistically significant antimicrobial capacity against S. sobrinus compared to control (p < .05). The highest percentage of MNC release at different pH (especially at pH 5.0 and 3.5) was observed from 5.0% MNC@CO doped PFS. The PFS doped with 2.5% MNC@CO showed a highest compressive strength (110 MPa) over a period of 70 days as compared to 5.0% MNC@CO (75 MPa) and control (80 MPa). The flexural strength of both experimental groups was lower for both time points (24 h and 30 days) than control. In conclusion, the present study found that 2.5% MNC@CO doped PFS showed considerable anti-biofilm potential without compromising mechanical properties.

Effects of Plant Extracts on Dentin Bonding Strength: A Systematic Review and Meta-Analysis

Objective: To systematically review in vitro studies that evaluated the effects of plant extracts on dentin bonding strength.

Materials and Methods: Six electronic databases (PubMed, Embase, VIP, CNKI, Wanfang and The Cochrane Library) were searched from inception to September 2021 in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA). In vitro studies that compared the performance of dental adhesives with and without the plant extracts participation were included. The reference lists of the included studies were manually searched. Two researchers carried out study screening, data extraction and risk of bias assessment, independently and in duplicate. Meta-analysis was conducted using Review Manager 5.3.

Results: A total of 62 studies were selected for full-text analysis. 25 articles used the plant extracts as primers, while five added the plant extracts into adhesives. The meta-analysis included 14 articles of in vitro studies investigating the effects of different plant extract primers on dentin bonding strength of etch-and-rinse and self-etch adhesives, respectively. The global analysis showed statistically significant difference between dental adhesives with and without plant extract primers. It showed that the immediate bond strength of dental adhesives was improved with the application of plant extract primers.

Conclusion: The application of proanthocyanidin (PA) primers have positive effect on the in vitro immediate bonding strength of dental adhesives irrespective of etch-and-rinse or self-etch modes.

Dual role of tannic acid and pyrogallol incorporated in plaster of Paris: Morphology modification and release for antimicrobial properties

The design of bioactive plasters is of major interest for the amelioration of dental and bone cements. In this article, a one pot and environmentally friendly strategy based on the addition of a cheap polyphenol-tannic acid (TA) or the main phenolic constituent of TA, namely pyrogallol (PY)- able to interact with calcium sulfate is proposed. Tannic acid and pyrogallol not only modify the morphology of the obtained plaster+TA/PY composites but a part of it is released and provides strong-up to twenty fold- antibacterial effect against Staphylococcus aureus. It is shown that the higher antibacterial efficiency of PY is related to a greater release compared to TA even if in solution the antibacterial effect of PY is lower than that of TA when reported on the basis of the molar concentration in PY units.

Antibacterial and Bonding Properties of Universal Adhesive Dental Polymers Doped with Pyrogallol

This study investigated the antibacterial activity, bond strength to dentin (SBS), and ultra-morphology of the polymer-dentin interface of experimental adhesive systems doped with pyrogallol (PY), which is a ubiquitous phenolic moiety that is present in flavonoids and polyphenols. A universal adhesive containing 4-META and 10-MDP was used in this study. PY behaves as an antioxidant and anti-cancerogenic agent and it was incorporated into the adhesive at different concentrations (0.5 and 1 wt.%). The antibacterial activity and SBS were analyzed and the results were statistically analyzed. The ultra-morphology of the polymer-dentin interface was assessed using scanning electron microscopy (SEM). At 24 h, a lower antibacterial activity was observed for the control adhesive compared to those with 0.5% and 1% PY. No difference was seen in SBS between the three groups at 24 h. After 6 months, the SBS of the 0.5% PY adhesive was significantly lower than the other tested adhesives. The specimens created with 1% PY adhesive presented a higher bond strength at six months compared with that found at 24 h. No morphological differences were found at the polymer-dentin interfaces of the tested adhesives. Pyrogallol may be incorporated into modern universal adhesive systems to preserve the polymer-dentin bonding interface and confer a certain degree of antibacterial activity.

Quercetin as an Auxiliary Endodontic Irrigant for Root Canal Treatment: Anti-Biofilm and Dentin Collagen-Stabilizing Effects In Vitro

Bacterial reinfection and root fracture are the main culprits related to root canal treatment failure. This study aimed to assess the utility of quercetin solution as an adjunctive endodontic irrigant that does not weaken root canal dentin with commitment anti-biofilm activity and bio-safety. Based on a noninvasive dentin infection model, dentin tubules infected with Enterococcus faecalis (E. faecalis) were irrigated with sterile water (control group), and 0, 1, 2, 4 wt% quercetin-containing ethanol solutions. Live and dead bacteria percentages in E. faecalis biofilms were analyzed by confocal laser scanning microscopy (CLSM). Elastic modulus, hydroxyproline release and X-ray photoelectron spectroscopy (XPS) characterization were tested to evaluate the irrigants’ collagen-stabilizing effect. The cytotoxicity was tested by CCK-8 assay. Quercetin increased the proportion of dead bacteria volumes within E. faecalis and improved the flexural strength of dentin compared to control group (p < 0.05). Quercetin-treated dentin matrix had less elasticity loss and hydroxyproline release after collagenase degradation (p < 0.05). Moreover, quercetin solutions revealed an increase in the C-O peak area under both C1s and O1s narrow-scan spectra of XPS characterization, and no cytotoxicity (p > 0.05). Quercetin exhibited anti-biofilm activity, a collagen-stabilizing effect with cytocompatibility, supporting quercetin as a potential candidate for endodontic irrigant.

Effect of natural primer associated to bioactive glass-ceramic on adhesive/dentin interface

OBJECTIVES

This study evaluated the effect of propolis associated with Biosilicate on the bond strength (BS) and gelatinolytic activity at the adhesive/dentin interface.

METHODS

Occlusal cavities were prepared in 320 human molars. Half of them were submitted to cariogenic challenge. All the teeth were separated into eight groups (n = 20): Control - Adhesive System (Single Bond Universal, 3 MESPE); CHX - 0.12 % Chlorhexidine; Bio - 10 % Biosilicate; P16 - Propolis with low levels of polyphenols; P45 - Propolis with high levels of polyphenols; CHX Bio - CHX + Bio; P16 Bio - P16+Bio; P45 Bio - P45+Bio. The adhesive was applied (self-etch mode) after treatments. Restorations (Filtek Z350, 3 MESPE) were performed and samples sectioned into sticks, separated and stored in distilled water at 37 °C for 24 h, 6 months and 1 year. Microtensile BS (0.5 mm/min) was tested and analyzed (2-way ANOVA, Bonferroni's Test, p < .05 and Weibull analysis). Fracture patterns (VH-M100, Keyence) and adhesive interfaces (SEM, EVO-MA10, ZEISS and TEM, JEM-1010, JEOL) were observed; and biodegradation and in situ zymography performed.

RESULTS

P16 presented the highest BS values on sound dentin after 6 months. In caries-affected dentin (CAD), the association of treatments promoted the highest BS after 24 h. Sound dentin obtained significantly higher Weibull modulus than CAD. SEM displayed resin tags in P16, P45 and association of treatments. TEM showed good interaction between adhesive and dentin. According to the in situ zymography and biodegradation assay all natural primers reduced the gelatinolytic activity. P45 presented the lowest biodegradation and enzymatic activity.

CONCLUSIONS

Propolis and the association of treatments promoted the highest bond strength results and preserved the dentin. All the experimental groups exhibited low gelatinolytic activity.

CLINICAL SIGNIFICANCE

Propolis and the association of treatments with Biosilicate could preserve the dentin substrate and improve the longevity of composite restorations.

Bibliometric Analysis of Literature Published on Antibacterial Dental Adhesive from 1996-2020

This study aimed to investigate the current state of research on antibacterial dental adhesives. The interest in this field can be drawn from an increasing number of scholarly works in this area. However, there is still a lack of quantitative measurement of this topic. The main aim of this study was to consolidate the research published on the antibacterial adhesive from 1996 to 2020 in Web of Science indexed journals. The bibliometric method, a quantitative study of investigating publishing trends and patterns, was used for this study. The result has shown that a gradual increase in research was found, whereby a substantial increase was observed from 2013. A total of 248 documents were published in 84 journals with total citations of 5107. The highly cited articles were published mainly in Q1 category journals. Most of the published articles were from the USA, China, and other developed countries; however, some developing countries contributed as well. The authorship pattern showed an interdisciplinary and collaborative approach among researchers. The thematic evaluation of keywords along with a three-factor analysis showed that 'antibacterial adhesives' and 'quaternary ammonium' have been used commonly. This bibliometric analysis can provide direction not only to researchers but also to funding organizations and policymakers.

Catechin-based Dentin Pretreatment and the Clinical Performance of a Universal Adhesive: A Two-year Randomized Clinical Trial

CLINICAL RELEVANCE

At 24 months, the dentin pretreatment with epigallocatechin-3-gallate did not impair the clinical performance of the adhesive Single Bond Universal regardless of the bonding strategy used.

SUMMARY

Purpose: To evaluate the two-year effect of dentin pretreatment with epigallocatechin-3-gallate (EGCG) on the clinical performance of restorations of noncarious cervical lesions (NCCLs) with Single Bond Universal, applied in two different modes (self-etch and etch-and-rinse).Methods and Materials: In this randomized clinical trial, 33 volunteers were selected, and 156 NCCLs were assigned to four groups: ER, etch-and-rinse; ER-EGCG, 0.1% EGCG dentin pretreatment + etch-and-rinse; SE, self-etch; and SE-EGCG, 0.1% EGCG dentin pretreatment + self-etch. The NCCLs were restored with a nanofilled resin composite and evaluated at baseline and at six, 12, 18, and 24 months using FDI criteria for retention, marginal staining, marginal adaptation, caries, and postoperative sensitivity. Two evaluators were blinded to the treatments performed, and impressions were taken for resin replicas to allow indirect observations. Statistical analyses were performed with Kruskal-Wallis and McNemar tests with a significance level of 5%.Results: Six restorations (one from ER, two from SE, one from ER-EGCG, and two from SEEGCG) were lost at 24 months with no significant differences (p>0.05). The retention rates were 97.0% (ER and ER-EGCG), 94.1% (SE), and 94.2% (SE-EGCG). For marginal adaptation, a significant difference was detected between the baseline and 24 months for the SE group (p=0.0313). There were no statistical differences among all other evaluated criteria at 24 months, neither for each group at baseline nor for 24-month comparisons (p>0.05).Conclusions: The pretreatment with EGCG provided no benefit in the clinical performance of the adhesive regardless of the bonding strategy used. In addition, it adds an additional required step to the restorative procedure.

Polyphenols in Dental Applications

(1) Background: polyphenols are a broad class of molecules extracted from plants and have a large repertoire of biological activities. Biomimetic inspiration from the effects of tea or red wine on the surface of cups or glass lead to the emergence of versatile surface chemistry with polyphenols. Owing to their hydrogen bonding abilities, coordination chemistry with metallic cations and redox properties, polyphenols are able to interact, covalently or not, with a large repertoire of chemical moieties, and can hence be used to modify the surface chemistry of almost all classes of materials. (2) Methods: the use of polyphenols to modify the surface properties of dental materials, mostly enamel and dentin, to afford them with better adhesion to resins and improved biological properties, such as antimicrobial activity, started more than 20 years ago, but no general overview has been written to our knowledge. (3) Results: the present review is aimed to show that molecules from all the major classes of polyphenolics allow for low coast improvements of dental materials and engineering of dental tissues.

Osteopontin in Bone Metabolism and Bone Diseases

Osteopontin (OPN), a secreted phosphoprotein, is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family of cell matrix proteins and participates in many biological activities. Studies have shown that OPN plays a role in bone metabolism and homeostasis. OPN not only is an important factor in neuron-mediated and endocrine-regulated bone mass, but also is involved in biological activities such as proliferation, migration, and adhesion of several bone-related cells, including bone marrow mesenchymal stem cells, hematopoietic stem cells, osteoclasts, and osteoblasts. OPN has been demonstrated to be closely related to the occurrence and development of many bone-related diseases, such as osteoporosis, rheumatoid arthritis, and osteosarcoma. As expected, the functions of OPN in the bone have become a research hotspot. In this article, we try to decipher the mechanism of OPN-regulated bone metabolism and bone diseases.

Dimeric Proanthocyanidins on the Stability of Dentin and Adhesive Biointerfaces

A dentin biomodification strategy with selective proanthocyanidin (PAC)-enriched extracts reinforces dentin and dentin-resin interfaces. Enrichment of the extracts according to the degree of polymerization allows exploration of bioactive principles of PACs and structure-activity relationships. This study investigated the sustained dentin matrix biomodification and dentin-resin bioadhesion of 2 fractions consisting exclusively of B-type PAC dimers with or without a single galloyl motif (specifically, DIMER_G and DIMER_NG) and their precursor material, enriched grape seed extract (e-GSE; Vitis vinifera). The biomodification potential was determined by long-term evaluation of the apparent modulus of elasticity and collagen solubility (hydroxyproline release). Chemical characterization of the dentin matrix was performed by attenuated total reflectance-Fourier-transform infrared spectroscopy. The bioadhesive properties were assessed by a microtensile bond strength test at different time points, and macro-hybrid layers were produced to verify the degree of conversion of the adhesive resin. Fractions consisting of DIMER_G, DIMER_NG, and their precursor, e-GSE, increased the modulus of elasticity at all time points and reduced collagen degradation. Specimens treated with DIMER_NG remained stable throughout 12 mo of storage, whereas a significant drop in the modulus of elasticity was observed for the DIMER_G and e-GSE groups at 6 mo. The fractions and precursor did not affect the degree of resin conversion at the hybrid layer. Changes in infrared resonances corresponding to collagen cross-links in the dentin matrix occurred for all treatments. Higher bond strength was observed for dentin treated with e-GSE as compared with DIMER_G and DIMER_NG; all biointerfaces remained stable after 12 mo. Nongalloylated PACs mediate stable dentin biomodification, which includes protective activity against collagen degradation and reinforcement of the anchoring dentin matrix. Collectively, PACs with a higher degree of oligomerization offer a robust bioadhesion between the hydrophilic dentin matrix and the hydrophobic adhesive.

Development of muco-adhesive orally disintegrating tablets containing tamarind gum-coated tea powders for oral care

The aim of this study was to design and evaluate muco-adhesive orally disintegrating tablets manufactured by microwave irradiation and containing polysaccharide. We prepared orally disintegrating tea tablets (ODTTs) containing a 1 w/w% mass fraction of one of five polysaccharides (gum arabic, carrageenan, guar gum, tamarind gum, or pectin) and evaluated the swelling degree, tablet hardness, friability, disintegration time, and adhesive properties. All tablets had a swelling degree of about 1 mm, a hardness of over 13 N, and a friability degree of <1%. Tablets containing gum arabic and tamarind gum had disintegration times of 30 s or less and satisfied requirements as orally disintegrating tablets. This could be attributed to their high void contents, which allowed for water penetration. The adhesive properties and particle retention ratios were highest in ODTTs containing tamarind gum, which was thought to be caused by the rapid disintegration and high viscosity of the tamarind gum itself. When we investigated changing the mass fraction of tamarind gum, we found 1 w/w% was most suitable for rapid disintegration and high adhesiveness. The ODTTs containing 1 w/w% tamarind gum showed significant growth inhibition towards Streptococcus mutans. Therefore, microwave irradiation technology and addition of tamarind gum could be used to manufacture muco-adhesive orally disintegrating tablets for oral care.

Effect of gallic acid addition on some mechanical properties of self-adhesive resin cements

Self-adhesive resin cements (RCs) activate matrix metalloproteinase (MMP) and cathepsin-related collagen degradation, and gallic acid (GA) inhibits the activity of both MMPs and cysteine cathepsins. The purpose of this study was to evaluate the setting time, biaxial flexural strength, and Vickers hardness of self-adhesive RCs after the addition of two different concentrations of GA. RelyX U200 (3M ESPE) and Panavia SA (Kuraray) were modified with 0.5 and 1 wt% GA. The setting time of five samples in each RC group was assessed using a thermocouple apparatus as described in the ISO 4049 test. Biaxial flexure strength was measured using a universal testing machine until failure. Vickers hardness was measured with three randomized indentations on the surface of each resin disc. RCs without GA were used as control. Data were analyzed using a one-way analysis of variance and Tukey's HSD test (α = 0.05). The setting times ranged from 2.4 to 4.6 min for RelyX and from 4.9 to 6.0 min for Panavia. The biaxial flexure strength ranged from 76.5 to 109.7 MPa for RelyX and from 73.3 to 108.2 MPa for Panavia. Vickers hardness values ranged from 41.6 to 58.6 for RelyX and 27.2 to 33.6 for Panavia. The addition of 0.5 and 1 wt% GA to improve durability of resin-dentin bonds had no adverse effects on setting time, whereas the biaxial flexure strength and Vickers hardness values for the tested materials were significantly reduced.

Targeting Bacterial Biofilms by the Green Tea Polyphenol EGCG

Bacterial biofilms are multicellular aggregates in which cells are embedded in an extracellular matrix of self-produced biopolymers. Being refractory to antibiotic treatment and host immune systems, biofilms are involved in most chronic infections, and anti-biofilm agents are being searched for urgently. Epigallocatechin-3-gallate (EGCG) was recently shown to act against biofilms by strongly interfering with the assembly of amyloid fibres and the production of phosphoethanolamin-modified cellulose fibrils. Mechanistically, this includes a direct inhibition of the fibre assembly, but also triggers a cell envelope stress response that down-regulates the synthesis of these widely occurring biofilm matrix polymers. Based on its anti-amyloidogenic properties, EGCG seems useful against biofilms involved in cariogenesis or chronic wound infection. However, EGCG seems inefficient against or may even sometimes promote biofilms which rely on other types of matrix polymers, suggesting that searching for 'magic bullet' anti-biofilm agents is an unrealistic goal. Combining molecular and ecophysiological aspects in this review also illustrates why plants control the formation of biofilms on their surfaces by producing anti-amyloidogenic compounds such as EGCG. These agents are not only helpful in combating certain biofilms in chronic infections but even seem effective against the toxic amyloids associated with neuropathological diseases.

Developing biocompatible silver nanoparticles using epigallocatechin gallate for dental use

OBJECTIVE

To develop silver nanoparticles (AgNPs) using epigallocatechin gallate (EGCG) and evaluate its biocompatibility and inhibition effect on Streptococcus mutans biofilm growth.

DESIGN

AgNPs were synthesized using EGCG as a reducing agent. Cytotoxicity was assessed using half-maximal inhibitory concentration (IC₅₀) against human gingival fibroblast (HGF-1) and stem cells from human exfoliated deciduous teeth (SHED). Antibacterial properties were evaluated with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against S. mutans. Dentine blocks were treated with AgNPs, silver nitrate (AgNO₃), or water before being incubated with S. mutans. The kinetics, morphology and viability of the biofilm at different time points were assessed by colony-forming units (CFUs), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM), respectively. Lactic acid and polysaccharide production of the biofilm were also investigated.

RESULTS

Spherical AgNPs with diameter 17 ± 7 nm were developed. The IC₅₀ of AgNPs and AgNO₃ against HGF-1 were 44.88 ± 11.39 μg/mL and 11.53 ± 6.96 μg/mL, respectively (p < 0.001), whereas those against SHED were 68.02 ± 24.48 μg/mL and 9.54 ± 6.63 μg/mL, respectively (p = 0.02). The MIC of AgNPs and AgNO₃ were 32.22 ± 7.34 μg/mL and 48.89 ± 15.11 μg/mL, respectively (p = 0.01), whereas their MBC was 63.33 ± 11.73 μg/mL and 85.00 ± 20.77 μg/mL, respectively (p = 0.02). Log CFUs of the AgNPs group were the lowest among the groups (p < 0.001). SEM and CLSM found a confluent biofilm in AgNO₃ and water groups but not in AgNPs group. Biofilms in AgNPs group was revealed with lowest level of acidic acid and polysaccharides production (p < 0.001).

CONCLUSION

This study developed biocompatible AgNPs which inhibited the growth of a cariogenic biofilm.

Effect of Polymeric Microparticles Loaded With Catechin on the Physicochemical Properties of an Adhesive System

The objective of this study was to synthesize and characterize epigallocatechin-3-gallate (EGCG)-loaded/poly(D-L lactide-co-glycolide) acid (PLGA) microparticles, evaluate their effects on degree of conversion and release assay of adhesives, and subsequently to examine the resin-dentin bond strength of two EGCG formulations (free EGCG or loaded into PLGA microparticles) applied as a pretreatment or incorporated into an adhesive system. The formulations were prepared according to a PLGA:EGCG ratio of 16:1 using the spray-drying technique. The size and polydispersity index were determined by light scattering in aqueous dispersion. The degree of conversion (%DC) and release assay were assessed by Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer, respectively. Subsequently, 45 third molars were divided into five groups (n=9) according to the different EGCG application modes and prepared for bond strength testing in a universal testing machine. Results demonstrated no statistically significant difference among the DC means after the PLGA microparticles were loaded with EGCG. For the release assay, the 1.0% PLGA/EGCG group presented better results after being elected for use in the bond strength test. The resin-dentin bond strengths of the experimental groups after 12 months of water storage were significantly higher than in the control group. EGCG could improve the durability of the resin-dentin bond over time and promote a new era for adhesive dentistry with the concept of controlled release.

Effect of epigallocatechin-3- gallate solutions on bond durability at the adhesive interface in caries-affected dentin

Hydrolytic and enzymatic degradation by matrix metalloproteinases (MMPs) reduces the durability of composite resin restorations on caries-affected dentin (CAD). The use of MMP inhibitors such as epigallocatechin-3-gallate (EGCG) could increase the longevity of the bond to dentin. This study aimed to evaluate the use of EGCG at different aqueous concentrations on the resin-dentin microtensile bond strength (μTBS), fracture pattern and nanoleakage (NL) in immediate (IM) time interval and after 12-months of water storage (1Y) when using a two-step etch-and-rinse adhesive system on CAD. Dentin surfaces of 40 human molars were submitted to a microbiological caries induction protocol and randomized into 5 groups (n = 8) (0.02% EGCG; 0.2% EGCG; 0.5% EGCG; 2% Chlorhexidine [CHX] and no treatment as Control Group - [NT]). After acid etching, the solutions were applied for 60 s followed by application of dental adhesive (Adper Single Bond 2, 3 M ESPE) to CAD surfaces. Subsequently, a resin composite (4 mm) block was built on the dentin. After 24 h, the teeth were sectioned into beam-shaped specimens (cross-sectional area of 1 mm² and 8-mm high). Half of the specimens were tested in IM and the other half after 1Y. Two samples per tooth were submitted to SEM for NL evaluation. Data were statistically analyzed by two-way ANOVA and Tukey tests (α = 0.05). The results showed that use of EGCG and CHX did not affect μTBS in IM (p > 0.05). After 1Y, there was a reduction in μTBS for all experimental groups (p < 0.05). Adhesive fractures predominated in IM in all groups, except for 0.05% EGCG and NT. After 1Y, there was an increase in these adhesive fractures in all groups. For NL, all agents applied reduced NL in comparison with CT (p < 0.001). CHX showed lower NL (p < 0.001), followed by 0.02% and 0.5% EGCG. NT showed highest NL for both time intervals (p < 0.001). Thus, although the use of EGCG at different concentrations and CHX reduced the NL, they were unable to reduce degradation of μTBS to CAD over time.

Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins

Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations.

Two-year Effects of Chlorhexidine-containing Adhesives on the In Vitro Durability of Resin-dentin Interfaces and Modeling of Drug Release

OBJECTIVES

To evaluate the effects of addition of diacetate chlorhexidine (CHX) at different concentrations into two etch-and-rinse adhesive systems on CHX release, as well as the immediate (IM) and two-year (2-Y) resin-dentin microtensile bond strength (μTBS) and nanoleakage (NL).

METHODS

CHX was added to XP Bond (XP) and Ambar (AM) at concentrations of 0.0 wt% (control); 0.01 wt%; 0.05 wt%; and 0.1 to 0.2 wt%. To assess the cumulative CHX release, adhesive disks were made in a metallic matrix and after light-curing were stored in water. Ultraviolet spectrophotometric measurements of the storage solution were performed to examine the release kinetics of CHX. For μTBS and NL, the occlusal enamel of molars was removed and the adhesives were applied to the dentin surface after acid etching. After composite resin build-up, specimens were sectioned to obtain μTBS sticks. The specimens were subjected to μTBS and NL at IM and after 2-Y. In addition, specimens underwent examination for CHX using micro-Raman spectroscopy. All data were submitted to statistical analysis (α=0.05).

RESULTS

With regard to CHX release, AM showed a slower and gradual release of CHX while XP released CHX more quickly ( p<0.05), and CHX was still present in the hybrid layers after 2-Y. Both adhesives showed CHX release at 2-Y water storage. Both CHX-containing adhesives showed higher μTBS values than did the control group ( p<0.05).

Chlorhexidine-encapsulated mesoporous silica-modified dentin adhesive

OBJECTIVES

This work aims to explore the feasibility of chlorhexidine-encapsulated mesoporous silica (CHX@pMSN) as a modifier of a commercial dental adhesive via the evaluation of physicochemical properties and antibacterial capabilities of adhesive-dentin interface.

METHODS

Therapeutic adhesives were developed in the present study by incorporating CHX@pMSN into a commercial adhesive at four mass fractions (0, 1, 5 and 10 wt.%). The antibacterial capability on Streptococcus mutans (S. mutans) biofilm, conversion degree, adhesive morphology, microtensile bond strength (MTBS) and nanoleakage expression were evaluated comprehensively.

RESULTS

MTT and CLSM evaluation showed that CHX@pMSN-doped adhesive inhibits S. mutans biofilm growth, while CHX is released from the modified adhesive continuously. The incorporation of CHX@pMSN did not affect immediate bond strength at the concentration of 1% and 5% (P >  0.05). Moreover, these bonds were mainly preserved in 5% CHX@pMSN group after one month of collagenase ageing. Meanwhile, CHX@pMSN-doped adhesive groups exhibited similar nanoleakage distribution compared with the control.

CONCLUSION

This study showed that the 5% CHX@pMSN-modified adhesive achieved balance amongst unaffected immediate bonding strength, well-preserved bonds against collagenase ageing and effective inhibition of S. mutans biofilm growth.

CLINICAL SIGNIFICANCE

CHX@pMSN-modified dentin adhesive can potentially extend the service life of adhesive restoration in clinic.

High-performance therapeutic quercetin-doped adhesive for adhesive-dentin interfaces

Almost half of dental restorations have failed in less than 10 years, and approximately 60% of practice time has been consumed to replace these dental restorations. As such, contemporary dentin adhesives should be modified to treat secondary caries and prevent the degradation of adhesive–dentin interfaces. To achieve this goal, we developed a versatile therapeutic adhesive in the present study by incorporating quercetin, which is a naturally derived plant extract, into a commercial adhesive at three concentrations (100, 500 and 1000 µg/mL). An unmodified adhesive served as a control. The antibacterial ability on Streptococcus mutans biofilm, conversion degree, microtensile bond strength, failure modes, in situ zymography, nanoleakage expression and cytotoxicity of quercetin-doped adhesive were comprehensively evaluated. Results showed that the quercetin-doped adhesive (500 µg/mL) preserved its bonding properties against collagenase ageing and inhibited the growth of S. mutans biofilm. Efficient bonding interface sealing ability, matrix metalloproteinase inhibition and acceptable biocompatibility were also achieved. Thus, a simple, safe and workable strategy was successfully developed to produce therapeutic adhesives for the extension of the service life of adhesive restorations.

Development of Epigallocatechin-3-gallate-Encapsulated Nanohydroxyapatite/Mesoporous Silica for Therapeutic Management of Dentin Surface

In dental clinic, unsatisfactory management of the dentin surface after dentin exposure often leads to the occurrence of dentin hypersensitivity and caries. Current approaches can occlude the tubules on the dentin surface to relieve dentin hypersensitivity; however, the blocked tubules are generally weak in combating daily tooth erosion and abrasion. Moreover, cariogenic bacteria, such as Streptococcus mutans, produce biofilm on the dentin surface, causing caries and compromising the tubules' sealing efficacy. To overcome this problem, the present study focused on establishing a versatile biomaterial, epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica nanoparticle (EGCG@nHAp@MSN), for therapeutic management of the dentin surface. The effectiveness of the biomaterial on dentinal tubule occlusion, including resistances against acid and abrasion, was evaluated by field-emission scanning electron microscopy (FESEM) and dentin permeability measurement. The inhibitory capability of the biomaterial on S. mutans biofilm formation was investigated by confocal laser scanning microscopy (CLSM), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, colony forming units (CFU) counts, and FESEM. Results demonstrated for the first time that the use of EGCG@nHAp@MSN on the dentin surface was capable of effectively occluding dentinal tubules, reducing dentin permeability, and achieving favorable acid- and abrasion-resistant stability. Furthermore, EGCG@nHAp@MSN held the capability to continuously release EGCG, Ca, and P, and significantly inhibit the formation and growth of S. mutans biofilm on the dentin surface. Thus, the development of EGCG@nHAp@MSN bridges the gap between multifunctional concept and dental clinical practice and is promising in providing dentists a therapeutic strategy for the management of the dentin surface to counter dentin hypersensitivity and caries.

Effects of Epigallocatechin-3-gallate (EGCG) on the bond strength of fiber posts to Sodium hypochlorite (NaOCl) treated intraradicular dentin

This study was to evaluate the effect of Epigallocatechin-3-gallate (EGCG) on the bond strength of two adhesive systems to the Sodium hypochlorite (NaOCl) treated intraradicular dentin. The roots were accepted regular root canal treatments and post space preparations, and further divided into eight groups according to the four post space pretreatments and two dentin adhesives [Single Bond 2 (SB2) and Clearfil SE Bond (CSB)] used. The push-out strength before and after thermocycling in different root region (coronal and apical), DC of the adhesive and morphologic patterns of treated post space were evaluated. NaOCl + EGCG groups showed the highest push-out strength regardless of the adhesive type, root region and time (P < 0.05). NaOCl pretreatment significantly decreased the push-out strengths and DC of CSB (P < 0.05). EGCG could improve the bonding properties of both SB2 and CSB to NaOCl treated intraradicular dentin. The effect of NaOCl on bonding of a fiber post depended on the type of the adhesive.

Epigallocatechin-3-gallate and Epigallocatechin-3-O-(3-O-methyl)-gallate Enhance the Bonding Stability of an Etch-and-Rinse Adhesive to Dentin

This study evaluated epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their antibacterial effect and bonding stability to dentin. EGCG-3Me was isolated and purified with column chromatography and preparative high performance liquid chromatography. EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, 400, and 600 µg/mL. The effect of cured adhesives on the growth of Streptococcus mutans (S. mutans) was determined with scanning electron microscopy and confocal laser scanning microscopy; the biofilm of bacteria was further quantified via optical density 600 values. The inhibition of EGCG and EGCG-3Me on dentin-originated collagen proteases activities was evaluated with a proteases fluorometric assay kit. The degree of conversion (DC) of the adhesives was tested with micro-Raman spectrum. The immediate and post-thermocycling (5000 cycles) bond strength was assessed through Microtensile Bond Strength (MTBS) test. Cured EGCG/EGCG-3Me modified adhesives inhibit the growth of S. mutans in a concentration-dependent manner. The immediate MTBS of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher MTBS than SB 2 after thermocycling, showing no correlation with concentration. The DC of the adhesive system was affected depending on the concentration of EGCG/EGCG-3Me and the depth of the hybrid layer. EGCG/EGCG-3Me modified adhesives could inhibit S. mutans adhesion to dentin–resin interface, and maintain the bonding stability. The adhesive modified with 400 µg/mL EGCG-3Me showed antibacterial effect and enhanced bonding stability without affect the DC of adhesive.

Quercetin as a simple but versatile primer in dentin bonding

A quercetin/ethanol solution may serve as a simple but versatile primer to obtain desirable bonding stability and prevent secondary caries.