Inhibition of human gingival gelatinases (MMP-2 and MMP-9) by metal salts

48-month clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A double-blind randomised clinical trial

OBJECTIVES

This study aimed to evaluate the effect of copper nanoparticles (CuNp) on the clinical performance of a universal adhesive system used as an etch-and-rinse or self-etch strategy.

METHODS

A total of 216 class V (non-carious lesions) restorations were randomly placed in 36 subjects according to the following groups: ERcu, adhesive in etch-and-rinse with 0.1% CuNp; ERct, adhesive in etch-and-rinse without CuNp; SEcu, adhesive in self-etch with 0.1% CuNp; and Sect, adhesive in self-etch without CuNp. Restorations were evaluated at baseline and at 6, 12, 18, 36, and 48 months, using the FDI and USPHS criteria. Appropriate statistical analyses were performed (α = 0.05).

RESULTS

After 48 months, 14 restorations were lost (two for ERcu, five for SEcu, and seven for SEct) and the retention rates (95% confidence interval [CI]) were 74.1% for ERcu (95% CI 61.1-83.8); 81.5% for ERct (95% CI 69.2-89.6); 64.8% (95% CI 51.5-76.2) for SEcu; and 64.8% (95% CI 51.5-76.2) for SEct, with statistical differences between SEct vs. ERct and SEcu vs. ERct (p < 0.05). No significant differences between the groups were observed when the secondary parameters were evaluated (p > 0.05). Nineteen restorations (two for ERcu, two for ERct, six for SEcu, and nine for SEct) showed minor marginal staining, and 44 restorations (7 for ERcu, 8 for ERct, 14 for SEcu, and 15 for SEct) presented minimal marginal adaptation defects.

SIGNIFICANCE

This is the first long-term clinical trial to show that the addition of CuNp to a universal adhesive system does not affect clinical performance.

Recent advances in the use of inorganic nanomaterials as anti caries agents

Caries is the most prevalent and widespread chronic oral disease. Traditional caries filling materials, due to their lack of anti-caries capabilities, can readily develop secondary caries. Nanomaterials proposed as an effective approach for caries treatment can inhibit biofilm formation. It also can not only reduce demineralization but also promote remineralization. In recent years, nanotechnology in anti-caries materials, particularly nano-adhesive and nano-composite resin, has advanced rapidly. Because inorganic nanoparticles (NPs) interfere with bacterial metabolism and inhibit biofilm development, inorganic NPs have emerged as a new trend in dental applications. Metal and metal oxide NPs by releasing metal ions, oxidative stress induction, and non-oxidative mechanisms showed significant antimicrobial activity. For applying metal and metal oxide NPs as anti caries agents, silver, zinc, titanium, copper, and calcium ions have been shown significant attention. Moreover, fluoride functionalized inorganic NPs were also employed to improve their efficacy of them. The fluoride-functionalized NPs can promote remineralization, and inhibit demineralization by enhancing apatite formation. In this review, we have provided an overview and recent advances in the use of inorganic NPs as anti caries agents. Furthermore, their antimicrobial, remineralizing, and mechanical impacts on dental materials were discussed.

Insight into the development of versatile dentin bonding agents to increase the durability of the bonding interface

Despite the huge improvements made in adhesive technology over the past 50 years, there are still some unresolved issues regarding the durability of the adhesive interface. A complete sealing of the interface between the resin and the dentin substrate remains difficult to achieve, and it is doubtful whether an optimal interdiffusion of the adhesive system within the demineralized collagen framework can be produced in a complete and homogeneous way. In fact, it is suggested that hydrolytic degradation, combined with the action of dentin matrix enzymes, destabilizes the tooth-adhesive bond and disrupts the unprotected collagen fibrils. While a sufficient resin–dentin adhesion is usually achieved immediately, bonding efficiency declines over time. Thus, here, a review will be carried out through a bibliographic survey of scientific articles published in the last few years to present strategies that have been proposed to improve and/or develop new adhesive systems that can help prevent degradation at the adhesive interface. It will specially focus on new clinical techniques or new materials with characteristics that contribute to increasing the durability of adhesive restorations and avoiding the recurrent replacement restorative cycle and the consequent increase in damage to the tooth.

Noninvasive Adaptation Appraisal of Antimicrobial Nano-Filled Composite

OBJECTIVE

The aim of this research was to assess the effect of incorporating zein-coated magnesium oxide (zMgO) nanofillers to resin-based composite on the internal adaptation of the restorations using cross-polarisation optical coherence tomography (CP-OCT).

METHODS

Thirty noncarious human molar teeth were used. Class V cavities (3 × 5 mm) were prepared on the buccal and lingual surfaces of each tooth. Clearfil SE Bond 2 was applied to all the cavities and then the teeth were divided into 3 groups (n = 10) as follows: group 1-restored with N-Flow composite; group 2 and group 3-restored with N-Flow composite mixed with different zMgO nanoparticle concentrations (0.3% and 0.5% by weight, respectively) and then light cured using an LED curing device. Specimens were examined for interfacial adaptation examination under CP-OCT. Characterisation of the dental composite incorporating zMgO was done by Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). Results were analysed with Kruskall-Wallis test followed by Mann-Whitney U test, at a significance level of P < .05.

RESULTS

XRD spectra exhibited the sharp peaks of zMgO in the composite enhanced with zMgO nanoparticles. FESEM analysis showed a uniform distribution of the zMgO nanoparticles in the composite and FTIR illustrated no change in the spectra. The gap percentage along the cavity floor was significantly lower in groups 2 and 3 in comparison to group 1 (P < .05). Also there was a significant difference in gap percentages between groups 2 and 3 (P < .05), with group 3 showing the lowest gap percentage.

CONCLUSIONS

The incorporation of 0.3% and 0.5% zMgO nanoparticles in flowable composite assists in improving the internal adaptation of the composite to the tooth surface.

Dental Adhesives-Surface Modifications of Dentin Structure for Stable Bonding

The latest advancements in dentin bonding have focused on strategies to impair degradation mechanisms in order to extend the longevity of bonded interfaces. Protease inhibitors can reduce collagen degradation within the hybrid layer (HL). Collagen cross-linkers allow better adhesive infiltration and also inhibit proteases activity. Particles added to adhesive can promote mineral precipitation within the HL, reducing nanoleakage and micropermeability, besides possible antimicrobial and enzymatic inhibition effects. Most of these approaches are still experimental, and aspects of the adhesive under the clinician's control are still determinant for the long-term stability of adhesive restorations.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Inhibitory activity of S-PRG filler on collagen-bound MMPs and dentin matrix degradation

OBJECTIVES

To evaluate the inhibitory activity of an ion-releasing filler (S-PRG) eluate on dentin collagen-bound metalloproteinases (MMPs) and dentin matrix degradation.

METHODS

Dentin beams (5 × 2 × 0.5 mm) from human molars were completely demineralized to produce dentin matrix specimens. The dry mass was measured, and a colorimetric assay (Sensolyte) determined the initial total MMP activity to allocate the beams into four treatment groups (n = 10/group): 1) water for 1 min (negative control); 2) 2% chlorhexidine digluconate (CHX - inhibitor control) for 1 min; 3) S-PRG eluate for 1 min; 4) S-PRG eluate for 30 min. After the treatments, the total MMP activity was reassessed. The specimens were stored in simulated body fluid (SBF) at 37 °C for up to 21 days. The dry mass was reassessed weekly. On day 7, the dentin matrix degradation was analyzed for the presence of collagen fragments (CF; Sirius Red) and hydroxyproline (Hyp) in the SBF. Statistical analyses were performed with ANOVA/Tukey, paired t-tests, and RM-ANOVA/Sidak (α = 5%).

RESULTS

S-PRG eluate exposure for 1 and 30 min reduced (p < 0.0001) MMP activity. S-PRG exposure for 30 min presented MMP activity inhibition equivalent to CHX (p = 0.061). S-PRG and CHX decreased CF (p ≤ 0.007) and Hyp (p < 0.046) release. After 21 days of storage, S-PRG-treated beams, regardless of exposure time, presented a reduced (p ≤ 0.017) mass loss, intermediate between CHX and control.

CONCLUSION

Treating demineralized dentin with S-PRG eluate for 1 or 30 min reduced matrix-bound MMP activity and dentin matrix degradation for up to 21 days.

CLINICAL SIGNIFICANCE

S-PRG filler may hinder the progression of dentin carious/erosive lesions and enhance the stabilization of dentin bonding interfaces.

Multifunctional green synthesized Cu-Al layered double hydroxide (LDH) nanoparticles: anti-cancer and antibacterial activities

Doxorubicin (DOX) is a potent anti-cancer agent and there have been attempts in developing nanostructures for its delivery to tumor cells. The nanoparticles promote cytotoxicity of DOX against tumor cells and in turn, they reduce adverse impacts on normal cells. The safety profile of nanostructures is an important topic and recently, the green synthesis of nanoparticles has obtained much attention for the preparation of biocompatible carriers. In the present study, we prepared layered double hydroxide (LDH) nanostructures for doxorubicin (DOX) delivery. The Cu–Al LDH nanoparticles were synthesized by combining Cu(NO₃)₂·3H₂O and Al(NO₃)₃·9H₂O, and then, autoclave at 110. The green modification of LDH nanoparticles with Plantago ovata (PO) was performed and finally, DOX was loaded onto nanostructures. The FTIR, XRD, and FESEM were employed for the characterization of LDH nanoparticles, confirming their proper synthesis. The drug release study revealed the pH-sensitive release of DOX (highest release at pH 5.5) and prolonged DOX release due to PO modification. Furthermore, MTT assay revealed improved biocompatibility of Cu–Al LDH nanostructures upon PO modification and showed controlled and low cytotoxicity towards a wide range of cell lines. The CLSM demonstrated cellular uptake of nanoparticles, both in the HEK-293 and MCF-7 cell lines; however, the results were showed promising cellular internalizations to the HEK-293 rather than MCF-7 cells. The in vivo experiment highlighted the normal histopathological structure of kidneys and no side effects of nanoparticles, further confirming their safety profile and potential as promising nano-scale delivery systems. Finally, antibacterial test revealed toxicity of PO-modified Cu–Al LDH nanoparticles against Gram-positive and -negative bacteria.

Potential of Fluoride-Containing Zinc Oxide and Copper Oxide Nanocomposites on Dentin Bonding Ability

Despite recent advances in bonding restorations, which are the basis of restorative dentistry, secondary caries are still able to form. Previously, a novel fluoride-containing zinc and copper (ZCF) nanocomposite was introduced to prevent the formation of caries due to its antibacterial activity. In this study, we studied the impact of ZCF nanoparticles on the adhesive strength of bonding restorations through micro-tensile bond strength (µTBS) testing. The impact of antibacterial and matrix metalloproteinase (MMP) inhibitors on the nanoparticles was also examined. The nanocomposites were prepared using a simple one-step homogeneous co-precipitation method at a low temperature. A self-etch adhesive was applied to 10 extracted caries-free human molars with (test group) and without (control group) the ZCF nanoparticles. This was followed by composite resin build-up and µTBS testing, MMP activity assays, and evaluation of the antibacterial effects. The results showed no significant differences in the µTBS between the ZCF and the control groups. However, the ZCF exhibited a significant inhibitory effect against MMP-2, MMP-8, and MMP-9, in addition to an antibacterial effect on Streptococcus mutans. Therefore, the present study demonstrated that the addition of ZCF nanoparticles to adhesive systems can result in MMP inhibition and antibacterial action while maintaining the mechanical properties of the bonding restorations.

Zn-containing Adhesives Facilitate Collagen Protection and Remineralization at the Resin-Dentin Interface: A Narrative Review

This is a narrative review of the literature assessing the potential effectiveness of doping dentin polymeric adhesives with zinc compounds in order to improve bonding efficacy, remineralization and protection against degradation. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI and Web of Science. Through our search, we found literature demonstrating that Zn-doped dentin adhesives promote protection and remineralization of the resin-dentin interfaces. The increased bioactivity has also facilitated dentinal tubules' occlusion by crystals' precipitation contributing to improved sealing efficacy of restorations. Loading dentin adhesives with zinc gives rise to an increase of both crystallinity of mineral and crosslinking of collagen. The main role of zinc, in dentin adhesives, is to inhibit collagen proteolysis. We concluded that zinc exerts a protective effect through binding at the collagen-sensitive cleavage sites of matrix-metalloproteinases (MMPs), contributing to dentin matrix stabilization. Zinc may not only act as a MMPs inhibitor, but also influence signaling pathways and stimulate metabolic effects in dentin mineralization and remineralization processes. Zn-doped adhesives increase the longevity of dentin bonding through MMPs inhibition. Zn poses a remineralization strategy in demineralized dentin.

Anti-erosive profile of an experimental 5% SnCl₂ varnish containing different concentrations of NaF

Abstract This in vitro study evaluated the anti-erosive effect of an experimental varnish containing 5% stannous chloride (SnCl₂) associated with different concentrations of NaF (NaF-free, 2.5% NaF, or 5.2% NaF) on bovine enamel and root dentin. One hundred samples were pre-eroded (0.3% citric acid, pH 2.6, 10 min) and randomized into five groups (n=10 for each substrate): Negative control - milli-Q water; NaF-free - Experimental varnish SnCl₂-free and NaF-free; 2.5 NaF - Experimental varnish 5% SnCl₂ associated with 2.5% NaF; 5.2 NaF: Experimental varnish 5% SnCl₂ associated with 5.2% NaF and positive control - Commercial varnish containing 5% NaF (Duraphat). After the varnishes were applied, the erosive and abrasive challenges were carried out for five days. Loss of tooth structure (TSL) was determined by optical profilometry, and the loss of calcium (ΔCa2+) using atomic absorption spectroscopy. Dentin analysis was also performed by SEM. A one-way ANOVA/Bonferroni test was performed to analyze the data (α=0.05). The experimental 2.5 NaF and 5.2 NaF groups showed greater effectiveness in preventing TSL when compared to the other groups (p <0.05), regardless of the substrate. In addition, these groups showed lower loss in Ca2+ content when compared to the other groups (p <0.05), for enamel and dentin. Dentin showed greater TSL and ΔCa2+ loss when compared to enamel in all treatments (p <0.05). The 5.2% and 2.5% NaF-containing experimental varnishes showed promising results in both, the prevention of TSL and the loss of Ca2+, regardless of the substrate studied.

Review of nano-technology applications in resin-based restorative materials

OBJECTIVE

Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin-based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin-based restorative materials with nanoparticles.

MATERIALS AND METHODS

A literature review was conducted using PubMed/Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin-based restorative materials containing nanoparticles were included.

RESULTS

A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti-bacterial properties were described. The clinical performance of resin-based restorative materials with nanoparticles was also reported.

CONCLUSIONS

The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future.

CLINICAL SIGNIFICANCE

In spite of the recent advancements of nanotechnology in resin-based restorative materials, some challenges need to be overcome before new nano-based restorative materials are considered permanent solutions to clinical problems.

Efficacy of MMP-inhibiting wound dressings in the treatment of chronic wounds: a systematic review

OBJECTIVE

Matrix metalloproteinases (MMPs) substantially contribute to the development of chronicity in wounds. Thus, MMP-inhibiting dressings may support healing. A systematic review was performed to determine the existing evidence base for the treatment of hard-to-heal wounds with these dressings.

METHODS

A systematic literature search in databases and clinical trial registers was conducted to identify randomised controlled trials (RCTs) investigating the efficacy of MMP-inhibiting dressings. Studies were analysed regarding their quality and clinical evidence.

RESULTS

Of 721 hits, 16 relevant studies were assessed. There were 13 studies performed with collagen and three with technology lipido-colloid nano oligosaccharide factor (TLC-NOSF) dressings. Indications included diabetic foot ulcers, venous leg ulcers, pressure ulcers or wounds of mixed origin. Patient-relevant endpoints comprised wound size reduction, complete wound closure, healing time and rate. Considerable differences in the quality and subsequent clinical evidence exist between the studies identified. Substantial evidence for significant improvement in healing was identified only for some dressings.

CONCLUSION

Evidence for the superiority of some MMP-inhibiting wound dressings exists regarding wound closure, wound size reduction, healing time and healing rate. More research is required to substantiate the existing evidence for different types of hard-to-heal wounds and to generate evidence for some of the different types of MMP-inhibiting wound dressings.

Effects of Zn-Doped Mesoporous Bioactive Glass Nanoparticles in Etch-and-Rinse Adhesive on the Microtensile Bond Strength

The purpose of this study was to assess the effects in the dentin bond strength of dental adhesives (DAs) and biological effects using zinc (Zn)-doped mesoporous bioactive glass nanoparticles (MBN-Zn). Synthesized MBN and MBN-Zn were characterized by scanning electron microscopy (SEM), X-ray diffraction and the Brunauer, Emmett and Teller (BET) method. The matrix metalloproteinases (MMP) inhibition effects of DA-MBN and DA-MBN-Zn were analyzed. The microtensile bond strength (MTBS) test was conducted before and after thermocycling to investigate the effects of MBN and MBN-Zn on the MTBS of DAs. The biological properties of DA-MBN and DA-MBN-Zn were analyzed with human dental pulp stem cells (hDPSCs). Compared with the DA, only the DA-1.0% MBN and DA-1.0% MBN-Zn exhibited a statistically significant decrease in MMP activity. The MTBS values after thermocycling were significantly increased in DA-1.0% MBN and DA-1.0% MBN-Zn compared with the DA (p < 0.05). It was confirmed via the MTT assay that there was no cytotoxicity for hDPSCs at 50% extract. In addition, significant increases in the alkaline phosphatase activity and Alizarin Red S staining were observed only in DA-1.0%MBN-Zn. These data suggest the 1.0% MBN and 1.0% MBN-Zn enhance the remineralization capability of DAs and stabilize the long-term MTBS of DAs by inhibiting MMPs.

Zinc-Calcium-Fluoride Bioglass-Based Innovative Multifunctional Dental Adhesive with Thick Adhesive Resin Film Thickness

Apart from producing high bond strength to tooth enamel and dentin, a dental adhesive with biotherapeutic potential is clinically desirable, aiming to further improve tooth restoration longevity. In this laboratory study, an experimental two-step universal adhesive, referred to as Exp_2UA, applicable in both the etch-and-rinse (E&R) and self-etch (SE) modes and combining a primer, containing 10-methacryloyloxydecyldihydrogen phosphate as a functional monomer with chemical binding potential to hydroxyapatite, with a bioglass-containing hydrophobic adhesive resin, was multifactorially investigated. In addition to primary property assessment, including measurement of bond strength, water sorption, solubility, and polymerization efficiency, the resultant adhesive-dentin interface was characterized by transmission electron microscopy (TEM), the filler composition was analyzed by energy-dispersive X-ray spectroscopy, and the bioactive potential of the adhesive was estimated by measuring the long-term ion release and assessing its antienzymatic and antibacterial potential. Four representative commercial adhesives were used as reference/controls. Application in both the E&R and SE modes resulted in a durable bonding performance to dentin, as evidenced by favorable 1 year aged bond strength data and a tight interfacial ultrastructure that, as examined by TEM, remained ultramorphologically unaltered upon 1 year of water storage aging. TEM revealed a 20 μm thick hydrophobic adhesive layer with a homogeneous bioglass filler distribution. Adequate polymerization conversion resulted in extremely low water sorption and solubility. In situ zymography revealed reduced endogenous proteolytic activity, while Streptococcus mutans biofilm formation was inhibited. In conclusion, the three-/two-step E&R/SE Exp_2UA combines the high bonding potential and bond degradation resistance with long-term ion release, rendering the adhesive antienzymatic and antibacterial potential.

Cytotoxicity of Chelating Agents Used In Endodontics and Their Influence on MMPs of Cell Membranes

Abstract This study evaluated the cytotoxic effect and the ability to inhibit matrix metalloproteinases (MMP-2 and MMP-9) of 0.2% chitosan (CH) and 1% acetic acid (AA) compared with 17% ethylenediaminetetraacetic acid (EDTA). Cell viability assay was performed according to ISO 10993-5 with mouse fibroblasts (L929). The culture was exposed to 0.2% CH, 1% AA, and 17% EDTA. The chelating agents were evaluated immediately after contact with the cells and after 6 h, 12 h, and 24 h of incubation. Cell viability was analyzed using the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Inhibition of the gelatinolytic activity of MMP-2 and MMP-9 was evaluated by gelatin zymography. Different concentrations of CH were evaluated: 50 mM, 5 mM, 0.5 mM, and 0.05 mM. EDTA (0.5 mM) was used as a positive control. The results demonstrated that CH and AA had an initial cytotoxic effect, which decreased after 6 h, 12 h, and 24 h, being statistically similar to EDTA (P > 0.05). Additionally, CH at concentrations of 50 mM, 5 mM, and 0.5 mM had an inhibitory effect on MMP-2 and MMP-9, similar to that of the control with EDTA. The chelating agents had no cytotoxic effects after 24 h. MMP-2 and MMP-9 were inhibited by the experimental solutions.

Functionalized Graphene Oxide Shields Tooth Dentin from Decalcification

This in vitro study assessed the efficacy of functionalized graphene oxide (f-GO) nanocomposites on the decalcification of dentin, because dental caries of the root surface is becoming one of the new problems in aged society. Hydroxyapatite plates (HAP) and dentin slices were coated with f-GO nanocomposites by comparing them to silver diamine fluoride as a positive control, then treated with decalcification solutions such as ethylenediaminetetraacetic acid and citrate at 37°C for 24 h. Scanning electron microscopy (SEM) revealed significant protection of the surface morphology of HAP and dentin. On the other hand, a cariogenic Streptococcus mutans growth was inhibited by f-GO nanocomposites. In addition, cytotoxicity of them to epithelial cells was much less than that of povidone-iodine, which is commonly used for oral disinfectant. We synthesized 5 different f-GO nanocomposites such as GO–silver (Ag), GO-Ag–calcium fluoride (CaF2), GO-CaF2, GO-zinc, and GO–tricalcium phosphate (Ca3(PO4)2). They were standardized by evaluating under SEM, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TGA), and Raman spectra after being synthesized in an aseptic technique. The abilities of GO-Ag, GO-Ag-CaF2, and GO-CaF2 nanocomposites were most preventive for decalcification. In addition, GO-Ag and GO-Ag-CaF2 almost completely inhibited S. mutans growth. However, they did not exhibit cytotoxicity to epithelial cells except at the highest concentration (0.1 w/v%) of GO-Ag and GO-Ag-CaF2. Furthermore, these f-GO nanocomposites exhibited less or no discoloration of dentin, although commonly used silver diamine fluoride causes discoloration of dentin to black. Thus, these f-GO nanocomposites are useful to protect dental caries on the tooth root that becomes a social problem in aged society.

The effects of zinc treatment on matrix metalloproteinases: A systematic review

BACKGROUND

Zinc (Zn) acts as a cofactor of matrix metalloproteinases (MMPs) and is vital for their activity and controlling their expression. Alteration of Zn in the body could affect the expression, activity, and destructive impacts of MMPs.

OBJECTIVE

This systematic review aimed to summarize existing evidence on the effects of Zn treatment on the expression and activity of MMPs.

METHOD

International sources from Pub Med, Scopus and Google Scholar were searched for the original and English-language studies, published up to the end of May 2018.

RESULTS

During the initial search, 179 records were found, and 135 articles of them remained after the exclusion of duplicate articles. 47 studies met the inclusion criteria, after multiple stages of screening and critical reviews of articles.

CONCLUSION

Approximately 62% of the included studies (29 of 47) showed an inhibitory impact of Zn on MMPs production and activities. The inhibitory or stimulatory effect of Zn on MMPs seems to depend on physiological conditions of the cells or animals used, dose of Zn used, and duration of treatment.

18-month clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A double-blind, randomized controlled trial

OBJECTIVE

This study aimed to evaluate the addition of copper nanoparticles (CuNp) on the clinical performance of a universal adhesive system used as etch-and-rinse (ER) and self-etch (SE).

METHODS

216 restorations were randomly placed in 36 subjects according to the following groups: ERcu = etch-and-rinse with 0.1% CuNp; ERct = etch-and-rinse without CuNp; SEcu = self-etch with 0.1% CuNp; SEct = self-etch without CuNp. Resin composite was placed incrementally and light-cured. The restorations were evaluated at baseline and 6, 12 and 18 months using the FDI and USPHS criteria. Statistical analyses were performed using appropriate tests (α = 0.05).

RESULTS

The addition of CuNp did not increase the clinical performance (FDI / USPHS) of the universal adhesive tested after 18-month when applied in the ER mode (p > 0.05). The addition of CuNp in SE restorations increased the retention rate significantly and decreased the marginal discrepancies after 18 months (p < 0.05).

CONCLUSION

The clinical performance of universal adhesive was significantly increased when applied in the SE mode with the addition of copper nanoparticles.

CLINICAL RELEVANCE

This is the first study that demonstrates a slight improvement in the clinical performance of universal adhesive systems in non-carious cervical lesions when added CuNp in lower concentration.

Zinc oxide and copper nanoparticles addition in universal adhesive systems improve interface stability on caries-affected dentin

This study evaluated the MMP inhibition of the zinc oxide and copper nanoparticles (ZnO/CuNp), and the effects of their addition into adhesives on antimicrobial activity (AMA), ultimate tensile strength (UTS), in vitro degree of conversion (in vitro-DC), as well as, resin-dentin bond strength (μTBS), nanoleakage (NL) and in situ-DC on caries-affected dentin. Anti-MMP activity was evaluated for several MMPs. ZnO/CuNp (0% [control]; 5/0.1 and 5/0.2 wt%) were added into Prime&Bond Active (PBA) and Ambar Universal (AMB). The AMA was evaluated against Streptococcus mutans. UTS were tested after 24 h and 28d. After induced caries, adhesives and composite were applied to flat dentin surfaces, and specimens were sectioned to obtain resin-dentin sticks. μTBS, NL, in vitro-DC and in situ-DC were evaluated after 24 h. ANOVA and Tukey's test were applied (α = 0.05). ZnO/CuNp demonstrated anti-MMP activity (p < 0.05). The addition of ZnO/CuNp increased AMA and UTS (AMB; p < 0.05). UTS for PBA, in vitro-DC, in situ-DC and μTBS for both adhesives were maintained with ZnO/CuNp (p > 0.05). However, lower NL was observed for ZnO/CuNp groups (p < 0.05). The addition of ZnO/CuNp in adhesives may be an alternative to provide antimicrobial, anti-MMP activities and improves the integrity of the hybrid layer on caries-affected dentin.

Antibacterial and anti-inflammatory properties of Plantago ovata Forssk. leaves and seeds against periodontal pathogens: An in vitro study

Background:

Plantago commonly called as Isabgol (Plantago ovata Forssk.) is a perennial herb that belongs to the family Plantaginaceae. A range of biological activities has been found from plant extracts, including wound healing activity, anti-inflammatory, analgesic, antioxidant, weak antibiotic, immunomodulating and anti-ulcerogenic activity. Periodontal disease is a complex condition as a result of interaction between microorganisms and host inflammatory mediators. Hence, the extract of Isabgol is tested for its antibacterial and anti-inflammatory properties against periodontal disease.

Aim:

The aim of this in vitro study is to evaluate the antibacterial property of Isabgol leaves and seeds against periodontal pathogens, namely Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum and anti-inflammatory property against matrix metalloproteinase-2 (MMP-2) and MMP-9.

Materials and Methods:

In this in vitro study, aqueous extract of Isabgol is tested for its antibacterial property against the stock cultures of specified periodontal pathogens using the tube dilution method and anti-inflammatory property against MMP-2 and MMP-9 using zymogen gel electrography.

Results:

Minimum concentration at which the sensitivity of A. actinomycetemcomitans, P. gingivalis, P. intermedia, and F. nucleatum for the extract observed was 50 μl/ml, 0.8 μl/ml, 0.4 μl/ml and 12.5 μl/ml, respectively, concentrations below these showed no effect on the microorganisms. Zymogen electrographic test for anti-inflammatory activity showed percentage inhibition of 30% and 40% against MMP-2 and MMP-9, respectively.

Conclusion:

Isabgol is effective against the periodontal pathogens and inflammatory mediators which are responsible for periodontal disease.

The Copper(II)-Assisted Connection between NGF and BDNF by Means of Nerve Growth Factor-Mimicking Short Peptides

Nerve growth factor (NGF) is a protein necessary for development and maintenance of the sympathetic and sensory nervous systems. We have previously shown that the NGF N-terminus peptide NGF(1-14) is sufficient to activate TrkA signaling pathways essential for neuronal survival and to induce an increase in brain-derived neurotrophic factor (BDNF) expression. Cu2+ ions played a critical role in the modulation of the biological activity of NGF(1-14). Using computational, spectroscopic, and biochemical techniques, here we report on the ability of a newly synthesized peptide named d-NGF(1-15), which is the dimeric form of NGF(1-14), to interact with TrkA. We found that d-NGF(1-15) interacts with the TrkA-D5 domain and induces the activation of its signaling pathways. Copper binding to d-NGF(1-15) stabilizes the secondary structure of the peptides, suggesting a strengthening of the noncovalent interactions that allow for the molecular recognition of D5 domain of TrkA and the activation of the signaling pathways. Intriguingly, the signaling cascade induced by the NGF peptides ultimately involves cAMP response element-binding protein (CREB) activation and an increase in BDNF protein level, in keeping with our previous result showing an increase of BDNF mRNA. All these promising connections can pave the way for developing interesting novel drugs for neurodegenerative diseases.

Stannous chloride and stannous fluoride are inhibitors of matrix metalloproteinases

OBJECTIVES

Matrix metalloproteinases (MMPs) in dentin and saliva can degrade collagen. Divalent metals are known inhibitors of MMPs, but stannous - such as in the form of stannous chloride (SnCl₂) or stannous fluoride (SnF₂) - is yet to be tested for a possible inhibitory effect. In this study, we tested the inhibitory effect on the proteolytic activity of MMP-2 and MMP-9.

METHODS

Sodium chloride (NaCl), sodium fluoride (NaF), and chlorhexidine (CHX) were used as controls. Gelatin zymography was performed with recombinant human MMP-2 and MMP-9. SnCl₂, SnF₂, NaF, NaCl, and CHX were included either in the incubation buffer (M1) or added to the recombinant MMPs (M2) before the MMPs were analyzed using zymography. Furthermore, the effect of SnCl₂, SnF₂, and NaF on the enzymatic activity of MMP-2 and MMP-9 was measured in human dentin either before or after acid etching using 37%phosphoric acid. The effect of SnCl₂, NaF, and CHX on the viability and of SnCl₂ and NaF on the proliferation of human gingival fibroblasts and L929 mouse fibroblasts was also determined.

RESULTS

For M1, inhibitory concentrations (w/v%) of SnCl₂ 0.5% and 0.5%, SnF₂ 0.25% and 0.12%, NaF 0.12% and 0.5%, CHX 0.012% and 0.05%, were observed for MMP-2 and MMP-9, respectively. NaCl had no inhibitory effect. For M2, SnCl₂ 0.007% and 0.12%, and SnF₂ 0.03% and 0.5%, inhibited MMP-2 and MMP-9, respectively. NaF, NaCl and CHX had no effect. The enzymatic activity was slightly reduced when SnCl₂ and NaF were applied on dentin before the acid attack. Regarding cell viability and proliferation of the cells after stimulation with the respective substances, NaF showed almost no effect, SnCl₂ appeared to increase viability and proliferation of the cells, and CHX decreased the viability of cells.

CONCLUSIONS

Stannous ions caused a direct inhibition of the matrix metalloproteinases, whereas F^- only had an inhibitory effect when added to the zymography buffer.

CLINICAL SIGNIFICANCE

Inhibition of MMPs using SnCl₂ and SnF₂ could play an important role in the prevention of dental erosion and caries. However, the clinical relevance of these findings needs to be proven.

Multi-functional nano-adhesive releasing therapeutic ions for MMP-deactivation and remineralization

Restoration of hard tissue in conjunction with adhesive is a globally challenging issue in medicine and dentistry. Common clinical therapies involving application of adhesive and substitute material for functional or anatomical recovery are still suboptimal. Biomaterials with bioactivity and inhibitory effects of enzyme-mediated adhesive degradation can render a solution to this. Here, we designed a novel copper-doped bioactive glass nanoparticles (CuBGn) to offer multifunction: metalloproteinases (MMP) deactivation and remineralization and incorporated the CuBGn in resin-dentin adhesive systems, which showed most common failure of MMP mediated adhesive degradation among hard tissue adhesives, to evaluate proposed therapeutic effects. A sol-gel derived bioactive glass nanoparticles doping 10 wt% of Cu (Cu-BGn) for releasing Cu ions, which were well-known MMP deactivator, were successfully created and included in light-curing dental adhesive (DA), a filler-free co-monomer resin blend, at different concentrations (up to 2 wt%). These therapeutic adhesives (CuBGn-DA) showed enhanced (a)cellular bioactivity, cytocompatibility, microtensile bond strength and MMP deactivation-ability. In conclusion, the incorporation of Cu ions releasing nano-bioactive glass demonstrated multifunctional properties at the resin-dentin interface; MMP deactivation and remineralization, representing a suitable strategy to extend the longevity of adhesive-hard tissue (i.e. resin-dentin) interfaces.

The evaluation of zinc and copper content in tooth enamel without any pathological changes - an in vitro study

Objectives

The objectives of the study were to evaluate the content of copper and zinc in individual layers of tooth enamel and to analyze the relationships between the study minerals in individual layers of tooth enamel.

Patients and methods

Fifteen human permanent teeth were cut off every 150 μm alongside the labial surface. Acid biopsy of each layer was performed. The zinc content was determined using the air-acetylene flame method. The copper content was determined using the electrothermal technique with argon.

Results

The mean zinc concentrations increased significantly starting from the outer enamel surface, with the maximum concentration in the 150-300 μm layer. The mean copper concentrations increased substantially from the outer enamel surface to a depth of 150 μm, and then a slight downward trend of this mineral levels was seen, down to a depth of 450 μm. Strong positive correlation was found between the zinc and copper concentrations at depths of 150-300, 450-600 and 600-750 μm.

Conclusion

The levels of zinc and copper in the outer enamel layers may have an effect on the increased content of unipolar minerals at deeper enamel layers. The content of the study elements determined may reflect the process of mineralization and maturation of enamel in the pre-eruption period.

Effect of zinc on the collagen degradation in acid-etched dentin

Background/purpose

Matrix metalloproteinases (MMPs) play a crucial role in the pathogenesis of dental caries, collapse of adhesive interface, and chemical erosion of teeth. The objective of this study was to investigate the inhibitory effect of zinc on collagen degradation.

Materials and methods

Human dentin was ground and demineralized by citric acid (pH 2.0). The demineralized ground dentin was incubated in six different media: artificial saliva (AS); 5 mg/ml doxycycline in AS; 3.33, 6.82, 13.63, and 27.26 mg/ml of zinc chloride (Zn) in AS. Each group was divided into two subgroups, and active MMP-2 was incorporated into one subgroup. Specimens were incubated for 24 h, 1 week, and 2 weeks. Collagen degradation product was assessed using ELISA. The results were analyzed using repeated measured ANOVA and Duncan's post hoc analysis (α = 0.05).

Results

The amount of collagen degradation was the lowest in Doxy group. Zn groups showed a significant inhibitory effect in collagen degradation for all concentrations (P < 0.05). In subgroups without exogenous MMP-2, zinc-mediated inhibition increased in a concentration-dependent manner with increasing zinc concentration. The amount of collagen degradation product slightly increased with increased incubation time from 24 h to 2 weeks. However, in subgroups with exogenous MMP, the inhibitory effect of zinc on collagen degradation did not depend on zinc concentration.

Conclusion

All Zn groups for the four concentrations tested exhibited statistically significant inhibitory effect on collagen degradation.

The role of protease inhibitors on the remineralization of demineralized dentin using the PILP method

Mineralized and sound dentin matrices contain inactive preforms of proteolytic enzymes that may be activated during the demineralization cycle. In this study, we tested the hypothesis that protease inhibitors (PI) preserve demineralized collagen fibrils and other constituents of the dentin matrix and thereby affect the potential for remineralization. Artificial carious lesions with lesion depths of 140 μm were created with acetate buffer (pH = 5.0, 66 hours), and remineralized using a polymer-induced-liquid-precursor (PILP) process (pH = 7.4, 14 days) containing poly(aspartic acid) (pAsp) as the process-directing agent. De- and remineralizing procedures were performed in the presence or absence of PI. Ultrastructure and mechanical recovery of demineralized dentin following PILP remineralization were examined and measured in water with atomic force microscopy (AFM) and nanoindentation. Nanomechanical properties of hydrated artificial lesions had a low elastic modulus (E_R <0.4 GPa) extending about 100 μm into the lesion, followed by a sloped region of about 140 μm depth where values reached those of normal dentin (18.0–20.0 GPa). Mapping of mineral content by both micro-FTIR and micro x-ray computed tomography correlated well with modulus profiles obtained by nanoindentation. Tissue demineralized in the presence of PI exhibited higher elastic moduli (average 2.8 GPa) across the lesion and comprised a narrow zone in the outer lesion with strongly increased modulus (up to 8 GPa; p < 0.05), which might be related to the preservation of non-collagenous proteins that appear to induce calcium phosphate mineral formation even under demineralizing physical-chemical conditions. However, mechanical aspects of remineralization through the elastic modulus change, and the micromorphological aspects with SEM and TEM observation were almost identical with PILP treatments being conducted in the presence or absence of PI. Thus, the application of the protease inhibitors (PI) seemed to be less effective in promoting the remineralization of demineralized dentin.

The role of copper nanoparticles in an etch-and-rinse adhesive on antimicrobial activity, mechanical properties and the durability of resin-dentine interfaces

OBJECTIVES

To evaluate the effect of addition of copper nanoparticles at different concentrations into an etch-and-rinse adhesive (ER) on antimicrobial activity, Knoop microhardness (KHN), in vitro and in situ degree of conversion (DC), as well as the immediate (IM) and 2-year (2Y) resin-dentine bond strength (μTBS) and nanoleakage (NL).

METHODS

Seven experimental ER adhesives were formulated according to the amount of copper nanoparticles incorporated into the adhesives (0 [control], 0.0075 to 1wt.%). We tested the antimicrobial activity of adhesives against Streptococcus mutans using agar diffusion assay after IM and 2Y. The Knoop microhardness and in vitro DC were tested after IM and 2Y. The adhesives were applied to flat occlusal dentine surfaces after acid etching. After resin build-ups, specimens were longitudinally sectioned to obtain beam-like resin-dentine specimens (0.8mm²), which were used for evaluation of μTBS and nanoleakage at the IM and 2Y periods. In situ DC was evaluated at the IM period in these beam-like specimens. Data were submitted to appropriate statistical analyses (α=0.05).

RESULTS

The addition of copper nanoparticles provided antimicrobial activity to the adhesives only in the IM evaluation and slightly reduced the KHN, the in vitro and in situ DC (copper concentrations of 1wt.%). However, KHN increase for all concentrations after 2Y. After 2Y, no significant reductions of μTBS (0.06 to 1% wt.%) and increases of nanoleakage were observed for copper containing adhesives compared to the control group.

CONCLUSION

Copper nanoparticles addition up to 0.5wt.% may provide antimicrobial properties to ER adhesives and prevent the degradation of the adhesive interface, without reducing the mechanical properties of the formulations.

[Progress on matrix metalloproteinase inhibitors]

Continuing advances in dentin bonding technology and adhesives revolutionized bonding of resin-based composite restorations. However, hybrid layers created by contemporary dentin adhesives present imperfect durability, and degradation of collagen matrix by endogenous enzymes is a significant factor causing destruction of hybrid layers. Bond durability can be improved by using enzyme inhibitors to prevent collagen degradation and to preserve integrity of collagen matrix. This review summarizes progress on matrix metalloproteinase inhibitors (including chlorhexidine, ethylenediaminetetraacetic acid, quaternary ammonium salt, tetracycline and its derivatives, hydroxamic acid inhibitors, bisphosphonate derivative, and cross-linking agents) and suggests prospects for these compounds.

Radiographic, antibacterial and bond-strength effects of radiopaque caries tagging

Selectively excavated carious lesions remain radiographically detectable. Radiopaque tagging could resolve the resulting diagnostic uncertainty. We aimed to evaluate if tagging depends on lesions depths, is antibacterial, or affects dentin bond-strengths. Artificial lesions (depth-range: 152-682 μm, n = 34/group) were induced in human dentin samples, evaluated using wavelength-independent microradiography, treated with one of two tagging materials (70% SnCl2, 30% SnF2) and re-evaluated. To evaluate antimicrobial effects, 40 dentin samples were submitted to a Lactobacillus rhamnosus invasion-model. Infected samples were treated with placebo, 0.2% chlorhexidine, SnCl2, SnF2 (n = 10/group). Dentin was sampled and colony-forming units/mg determined. Micro-tensile bond-strengths of adhesive restorations (OptiBond FL, Filtek Z250) to tagged or untagged, sound and carious dentin were assessed (n = 12/group). Tagged surfaces were evaluated microscopically and via energy-dispersive X-ray-spectroscopy (EDS). Tagging effects of both materials decreased with increasing lesion depths (p < 0.001). Un-/chlorhexidine-treated dentin contained significantly more viable bacteria (median 7.3/3.7 × 10(5) CFU/mg) than tagged dentin (no CFU detectable, p < 0.001). Tagging decreased bond strengths (p < 0.001) on sound (-22%/-33% for SnCl2/SnF2) and carious dentin (-50%/-54%). This might be due to widespread tin chloride or fluoride precipitation, as detected via microscopy and EDS. While radiopaque tagging seems beneficial, an optimized application protocol needs to be developed prior clinical use.

Role of Host-Derived Proteinases in Dentine Caries and Erosion

Demineralization in dentinal caries and erosion exposes dentine organic matrix. This exposed matrix, containing type I collagen and non-collagenous proteins, is then degraded by host collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins. The knowledge of the identities and function of these enzymes in dentine has accumulated only within the last 15 years, but has already formed a field of research called ‘dentine degradomics'. This research has demonstrated the role of endogenous collagenolytic enzymes in caries and erosion development. In demineralized dentine, the enzymes degrade triple-helical collagen molecules, leading to the gradual loss of collagen matrix. Even before that, they can cleave off the terminal non-helical ends of collagen molecules called telopeptides, leading to the structural changes at the intramolecular gap areas, which may affect or even prevent intrafibrillar remineralization, which is considered essential in restoring the dentine's mechanical properties. They may also cause the loss of non-collagenous proteins that could serve as nucleation sites for remineralization. Here we review the findings demonstrating that inhibition of salivary or dentine endogenous MMPs and cysteine cathepsins may provide preventive means against the progression of caries or erosion. Furthermore, we also suggest the future directions for the new experimental preventive research to gain more knowledge of the enzymes and their function during and after dentine demineralization, and the pathways to find the clinically acceptable means to prevent the functional activity of these enzymes.

Cadmium exposure inhibits MMP2 and MMP9 activities in the prostate and testis

Matrix metalloproteinases (MMPs) are zinc (Zn(2+)) and calcium (Ca(2+)) dependant endopeptidases, capable of degradation of numerous components of the extracellular matrix. Cadmium (Cd(2+)) is a well known environmental contaminant which could impair the activity of MMPs. In this sense, this study was conducted to evaluate if Cd(2+) intake inhibits these endopeptidases activities at the rat prostate and testicles and if it directly inhibits the activity of MMP2 and MMP9 at gelatinolytic assays when present in the incubation buffer. To investigate this hypothesis, Wistar rats (5 weeks old), were given tap water (untreated, n = 9), or 15 ppm CdCl2 diluted in drinking water, during 10 weeks (n = 9) and 20 weeks (n = 9). The animals were euthanized and their ventral prostate, dorsal prostate, and testicles were removed. These tissue samples were processed for protein extraction and subjected to gelatin zymography evaluation. Additionally, we performed an experiment of gelatin zymography in which 5 μM or 2 mM cadmium chloride (CdCl2) was directly dissolved at the incubation buffer, using the prostatic tissue samples from untreated animals that exhibited the highest MMP2 and MMP9 activities in the previous experiment. We have found that CdCl2 intake in the drinking water led to the inhibition of 35% and 30% of MMP2 and MMP9 (p < 0.05) at the ventral prostate and testis, respectively, in Cd(2+) treated animals when compared to controls. Moreover, the activities of the referred enzymes were 80% and 100% inhibited by 5 μM and 2 mM of CdCl2, respectively, even in the presence of 10 mM of CaCl2 within the incubation buffer solution. These important findings demonstrate that environmental cadmium contamination may deregulate the natural balance in the extracellular matrix turnover, through MMPs downregulation, which could contribute to the toxic effects observed in prostatic and testicular tissue after its exposure.

Antibacterial properties of metal and metalloid ions in chronic periodontitis and peri-implantitis therapy

Periodontal diseases like periodontitis and peri-implantitis have been linked with Gram-negative anaerobes. The incorporation of various chemotherapeutic agents, including metal ions, into several materials and devices has been extensively studied against periodontal bacteria, and materials doped with metal ions have been proposed for the treatment of periodontal and peri-implant diseases. The aim of this review is to discuss the effectiveness of materials doped with metal and metalloid ions already used in the treatment of periodontal diseases, as well as the potential use of alternative materials that are currently available for other applications but have been proved to be cytotoxic to the specific periodontal pathogens. The sources of this review included English articles using Google Scholar™, ScienceDirect, Scopus and PubMed. Search terms included the combinations of the descriptors "disease", "ionic species" and "bacterium". Articles that discuss the biocidal properties of materials doped with metal and metalloid ions against the specific periodontal bacteria were included. The articles were independently extracted by two authors using predefined data fields. The evaluation of resources was based on the quality of the content and the relevance to the topic, which was evaluated by the ionic species and the bacteria used in the study, while the final application was not considered as relevant. The present review summarizes the extensive previous and current research efforts concerning the use of metal ions in periodontal diseases therapy, while it points out the challenges and opportunities lying ahead.

Radiopaque Tagging Masks Caries Lesions following Incomplete Excavation in vitro

One-step incomplete excavation seals caries-affected dentin under a restoration and appears to be advantageous in the treatment of deep lesions. However, it is impossible to discriminate radiographically between intentionally left, arrested lesions and overlooked or active lesions. This diagnostic uncertainty decreases the acceptance of minimally invasive excavation and might lead to unnecessary re-treatment of incompletely excavated teeth. Radiopaque tagging of sealed lesions might mask arrested lesions and assist in discrimination from progressing lesions. Therefore, we microradiographically screened 4 substances (SnCl2, AgNO3, CsF, CsCH3COO) for their effect on artificial lesions. Since water-dissolved tin chloride (SnCl2×Aq) was found to stably mask artificial lesions, we then investigated its radiographic effects on progressing lesions. Natural lesions were incompletely excavated and radiopaque tagging performed. Grey-value differences (△GV) between sound and carious dentin were determined and radiographs assessed by 20 dentists. While radiographic effects of SnCl2×Aq were stable for non-progressing lesions, they significantly decreased during a second demineralization ( p < .001, t test). For natural lesions, tagging with SnCl2×Aq significantly reduced △GV ( p < .001, Wilcoxon). Tagged lesions were detected significantly less often than untagged lesions ( p < .001). SnCl2×Aq was suitable to mask caries-affected dentin and discriminate between arrested and progressing lesions in vitro. Radiopaque tagging could resolve diagnostic uncertainties associated with incomplete excavation.

Zn(II)-Chlorido complexes of phytohormone kinetin and its derivatives modulate expression of inflammatory mediators in THP-1 cells

Kinetin (N6-furfuryladenine) belongs to a group of plant growth hormones involved in cell division, differentiation and other physiological processes. One of the possible ways to obtain biologically active compounds is to complex biologically relevant natural compounds to suitable metal atoms. In this work, two structural groups of Zn(II) complexes [Zn(Lⁿ)₂Cl₂]·Solv (1–5) and [Zn(HLⁿ)Cl₃]·xLⁿ (6–7); n = 1–5, Solv = CH₃OH for 1 and 2H₂O for 2; x = 1 for 6 and 2 for 7; involving a phytohormone kinetin and its derivatives (Lⁿ) were evaluated for their ability to modulate secretion of tumour necrosis factor (TNF)-α, interleukin (IL)-1β and matrix metalloproteinase (MMP)-2 in a lipopolysaccharide (LPS)-activated macrophage-like THP-1 cell model. The penetration of the complexes to cells was also detected. The mechanism of interactions of the zinc(II) complexes with a fluorescent sensor N-(6-methoxy-8-quinolyl)-p-toluene sulphonamide (TSQ) and sulfur-containing biomolecules (l-cysteine and reduced glutathione) was studied by electrospray-ionization mass spectrometry and flow-injection analysis with fluorescence detection. The present study showed that the tested complexes exhibited a low cytotoxic effect on the THP-1 cell line (IC₅₀>40 µM), apart from complex 4, with an IC₅₀ = 10.9±1.1 µM. Regarding the inflammation-related processes, the Zn(II) complexes significantly decreased IL-1β production by a factor of 1.47–2.22 compared with the control (DMSO), but did not affect TNF-α and MMP-2 secretions. However, application of the Zn(II) complexes noticeably changed the pro-MMP-2/MMP-2 ratio towards a higher amount of maturated MMP-2, when they induced a 4-times higher production of maturated MMP-2 in comparison with the vehicle-treated cells under LPS stimulation. These results indicated that the complexes are able to modulate an inflammatory response by influencing secretion and activity of several inflammation-related cytokines and enzymes.

Iron supplementation reduces the erosive potential of a cola drink on enamel and dentin in situ

Iron has been suggested to reduce the erosive potential of cola drinks in vitro.