The inhibition effect of non-protein thiols on dentinal matrix metalloproteinase activity and HEMA cytotoxicity

Myricetin Modulates Matrix Metalloproteinases Expression Induced by TEGDMA in Human Odontoblast-Like Cells

The activity of matrix metalloproteinases (MMPs) plays a crucial role in the aging of the resin-dentin interface. The in situ action of MMP-2 and MMP-9 has been confirmed in the process of dentin-collagen degradation. However, the involvement of dental pulp cells in MMP secretion as a response to oxidative stress induced by contact with resin monomers has not been fully elucidated. Myricetin (MYR), like proanthocyanidin (PAC), has antioxidant properties and may help prevent extracellular matrix degradation. The objective was to evaluate the effect of MYR on the MMP expression and activity in response to reactive oxygen species (ROS) increase induced by triethylene glycol dimethacrylate (TEGDMA) in human odontoblast-like cells (hOLCs). hOLCs differentiated from dental pulp mesenchymal stem cells were exposed to TEGDMA released from dentin blocks using a barrier model with transwell inserts for 18, 24, and 36 h. Intracellular oxidation was evaluated using the 2',7'-dichlorofluorescein probe. The effect of 600 μM MYR on the MMP-2 and MMP-9 expression was determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The extracellular MMP levels were quantified using enzyme-linked immunosorbent assay, and their activation by means of a proteolytic fluorometric assay. The results were analyzed by one-way analysis of variance and Tukey's post hoc test, p ≤ 0.05. TEGDMA exposure increased intracellular ROS and upregulated MMP-2 and MMP-9 mRNA in hOLCs (p < 0.001). The levels of MMPs increased significantly 24 h after TEGDMA exposure (p = 0.013). These secreted proteases exhibited high activation ability. MYR reduced ROS production and downregulated MMP expression and activity at both mRNA and protein levels, similar to the effect found for PAC, which was used as a control. A relationship was observed between MMP-2 and MMP-9 expression, secretion, and early activation with ROS increase due to TEGDMA exposure. MYR showed potential as a therapeutic strategy to control MMP expression and modulate redox imbalance, offering a protective effect on cellular response.

Effect of glutathione on bond strength of composite resin to enamel following extracoronal bleaching

Background

Bleaching is a conservative treatment option to deliver esthetic smile makeover for discoloured tooth. Various concentration of bleaching agents can influence the bonding of the restoration to the tooth.

Aims and Objectives

The aim of the study was to determine the effect of glutathione on bond strength of composite resin to enamel following extra coronal bleaching at two different time intervals.

Materials and Methods

Forty molars were randomly assigned into four groups of ten each. Group A: Bleaching followed by immediate composite build up and no antioxidant application. Group B: bleaching followed by application of 20% Glutathione and immediate composite built-up was done. Group C: Bleaching followed by composite restoration after one week. Group D: Bleaching followed by application of 20% Glutathione before composite build up after one week. Shear bond strength was tested using a universal testing machine and fracture analysis was done using scanning electron microscope (SEM). Data were analyzed by one-way ANOVA and Post Hoc test with 95% level of significance (p<0.05).

Results

Group D, which was treated with glutathione and restored after one week, revealed the highest shear bond strength compared to group B which was immediately restored following treatment with glutathione.

Conclusion

Addition of 20% Glutathione as an antioxidant increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide.

In Vitro Investigation of the Effects of Various Reducing Agents on Dentin Treated with Hydrogen Peroxide

We assessed the effect of non-protein thiols (NPSH), reduced glutathione (GSH) and n-acetylcysteine (NAC), on resin shear bond strength (SBS) to hydrogen peroxide (H2O2)-treated dentin, and their effects on the characteristics of dentin in comparison to ascorbic acid (AA) and sodium thiosulfate (STS). H2O2-treated dentin was conditioned with 5% AA, GSH, NAC, or STS applied for 1 or 5 min. The positive control group received H2O2 without antioxidant application, and the first negative control group received distilled water (DW). The specimens received resin bonding immediately after treatment except for the second negative control group (delayed bonding). Microhardness, roughness, and topography were studied. The SBS values of all antioxidants were statistically greater than the positive control group (p < 0.05); however, NAC and AA applied for 1 min demonstrated the highest values, which were comparable to delayed bonding. All treatments removed the smear layer except DW, H2O2, and STS. The negative effect of H2O2 on resin-dentin bonding was mitigated by the application of the antioxidants; however, their efficiencies were dependent on the antioxidant type and time of application. NAC was more effective in optimizing resin bonding to bleached dentin compared to GSH at 1 min application and STS at both application times but was comparable to AA. Negligible negative effects on the substrate's roughness and microhardness were detected. The antioxidant properties of the agent and its capacity to remove the smear layer are the processes underpinning the ability of a certain antioxidant to reverse the effect of H2O2 on bonding.

Chemical profile and biological properties of the Piper corcovadense C.DC. essential oil

The essential oil from Piper corcovadense D.DC. (EOPc), an important plant belonging to the Piperaceae family, which is commonly found in the northern region of Brazil and poorly explored scientifically, was used in this study. Thus, the EOPc was characterized chemically by Gas Chromatography/Mass Spectrometry (GC/MS) and the antioxidant and antimicrobial activities and their potential effects on cutaneous melanoma (SK-MEL-28) and healthy peripheral blood mononuclear (PBMC) cells were determined. The major compounds identified in the EOPc were: trans-sesquisabinene hydrate, trans-caryophyllene, β-pinene, trans-β-farnesene, 14-hydroxycaryophyllene, limonene and p-cymene. The EOPc demonstrated antioxidant activity as evaluated by Folin-Ciocalteu reagent (FC) reducing capacity, DPPH, and ABTS methods. The values found were respectively 5.41 ± 0.17 mg GAE mL-1 (GAE: Gallic acid equivalent), 2.88 ± 0.17 µmol TE mL-1 (TE: Trolox equivalent) and 6.26 ± 0.02 µmol TE mL-1. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for different bacterial strains. The EOPc at a concentration of 2.61 µg mL-1 exhibited both bactericidal and bacteriostatic properties against Escherichia coli. The EOPc showed potential antitumor activity as it reduced the cell viability of human cutaneous melanoma cells SK-MEL-28. Besides, the EOPc did not exhibit cytotoxic activity against healthy PBMCs, indicating that it does not harm healthy cells at the tested concentrations. The EOPc increased the levels of ROS at concentrations of 250 µg mL-1. The EOPc also did not stimulate the mobilization of endogenous antioxidant defenses, as assessed by total thiol (PSH) and non-protein thiols (NPSH). Thus, the study suggests that the EOPc has antioxidant and antimicrobial properties due to the presence of specific compounds. It also exhibits antitumor potential against cutaneous melanoma cells while showing no cytotoxicity to healthy PBMCs. It directly influenced ROS levels at the highest tested concentration in the cells, suggesting an antitumor effect related to the intrinsic apoptosis pathway. Nevertheless, while the study has initial findings, the results are promising and indicate an attractive biological potential of P. corcovadense, mainly in human cutaneous melanoma cells.

Non-Protein Thiol Compounds and Antioxidant Responses Involved in Bryophyte Heavy-Metal Tolerance

Heavy-metal pollution represents a problem which has been widely discussed in recent years. The biological effects of heavy metals have been studied in both animals and plants, ranging from oxidative stress to genotoxicity. Plants, above all metal-tolerant species, have evolved a wide spectrum of strategies to counteract exposure to toxic metal concentrations. Among these strategies, the chelation and vacuolar sequestration of heavy metals are, after cell-wall immobilization, the first line of defence that prevent heavy metals from interacting with cell components. Furthermore, bryophytes activate a series of antioxidant non-enzymatic and enzymatic responses to counteract the effects of heavy metal in the cellular compartments. In this review, the role of non-protein thiol compounds and antioxidant molecules in bryophytes will be discussed.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin

OBJECTIVES

To study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6.

METHODS

Demineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet-visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined.

RESULTS

At 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol.

CONCLUSIONS

IP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD.

CLINICAL SIGNIFICANCE

These findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

The comparative evaluation of the effects of quercetin, α-tocopherol, and chlorhexidine dentin pretreatments on the durability of universal adhesives

OBJECTIVE

The aim of this study was to evaluate and compare the effects of chlorhexidine, quercetin, and α-tocopherol on the shear bond strength of universal adhesives in the short (24h) and long term (6 months).

MATERIAL AND METHODS

Ninety-six extracted sound molars were collected and divided randomly into four groups: control (no treatment), 2% chlorhexidine, 10% α-tocopherol, and 1% quercetin. The solutions were prepared and applied to the teeth for 60 s, followed by application of All-Bond universal adhesive and composite build-up. Half of the specimens in each group (n = 12) were tested for shear bond strength (SBS) after 24 h of storage and the other half were kept in distilled water for 6 months and then tested for shear bond strength. The shear bond strength test was performed and the failure modes were determined using a stereomicroscope. The data were analyzed using two-way analysis of variance and Tukey's post hoc tests with p ˂ .05 as the significance level.

RESULTS

The results of the two-way analysis of variance test showed that there was no significant difference in immediate SBS, and after 6 months, α-tocopherol had the lowest SBS in comparison to the control and CHX subgroups (p < .05). The t-test showed that the shear bond strength in the α-tocopherol and quercetin groups was significantly decreased after 6 months.

CONCLUSION

It can be concluded that the solutions used in this study had no adverse effect on immediate SBS. After 6 months, the CHX could preserve SBS in comparison to other groups.

In Vitro and In Vivo Efficacy of New Composite for Direct Pulp Capping

Objectives

To investigate physicochemical properties, dentin bonding, cytotoxicity, and in vivo pulp response of experimental self-adhesive composites tailored to direct pulp capping.

Materials and Methods

Experimental composites were prepared with beta-tricalcium phosphate and hydroxyapatite nanoparticles adsorbed with simvastatin and glutathione added at 0% (control resin), 1 wt% (Res 1%), and 10 wt% (Res 10%). A commercial light-curable calcium hydroxide (Ca(OH)₂) (Ultra-Blend Plus) was used as control material. The physicochemical properties investigated were flexural strength and modulus, calcium release, and degree of conversion. Dentin bonding was assessed by the push-out test. Proliferation and cell counting assays were performed to evaluate in vitro cytotoxicity using fluorescence microscopy. In vivo pulp capping was performed on molars of Wistar rats, which were euthanized after 14 days and evaluated by histological analysis.

Results

No statistical difference was observed in flexural strength and cell viability (p > 0.05). Res 10% presented higher modulus than control resin and Ca(OH)₂. Also, Res 10% attained statistically higher degree of conversion when compared to other experimental composites. Ca(OH)₂ showed higher calcium release after 28 and 45 days of storage, with no statistical difference at 45 days to Res 10%. All experimental composites achieved significantly higher bond strength when compared to Ca(OH)₂. While no significant difference was observed in the cell proliferation rates, resins at lower concentrations showed higher cell viability. In vivo evaluation of pulp response demonstrated no pulp damage with experimental composites.

Conclusions

The experimental composite investigated in this study achieved adequate physicochemical properties with minor in vivo pulpal inflammation and proved to be a valuable alternative for direct pulp capping.

The effect of phytic acid on enzymatic degradation of dentin

We evaluated the effect of phytic acid on matrix metalloproteinase (MMP)- or cysteine cathepsin (CC)-mediated dentin degradation. Demineralized dentin beams were divided into five groups (n = 12) and treated with 1%, 2%, or 3% phytic acid or with 37% phosphoric acid. Untreated demineralized beams served as controls. After incubation for 1 or 3 wk, dry mass loss was determined and aliquots of incubation media were analysed for cross-linked telopeptide of type I collagen (ICTP) fragments for MMP-mediated and c-terminal telopeptide of type I collagen (CTX) for cathepsin-k-mediated degradation. The direct effect of phytic acid was evaluated using MMP activity assay. Data were analysed using repeated-measures anova. ICTP releases with 1% and 2% phytic acid treatment were statistically significantly lower than those following phosphoric acid treatment at 3 wk. The CTX release for phytic acid-treated beams at 3 wk was not significantly different from that of untreated control beams, but it was significantly lower than that of phosphoric acid-treated beams. Their MMP activities at 3 wk were not significantly different from those of the controls but they were significantly lower than those seen for phosphoric acid-treated beams. Compared to phosphoric acid, phytic acid treatment resulted in a reduced dentinal host-derived endogenous enzymatic activity and collagen degradation.

Analysis of the mylohyoid nerve in elderly Japanese cadavers for dental implant surgery

OBJECTIVES

Injury to the mandibular nerve (MN) branches may cause pain and irregular occlusal movement during mastication after mandibular dental treatments. Growing evidence indicates that the calcitonin gene-related peptide (CGRP) plays a key role in the development of peripheral sensitization and the associated enhanced pain, suggesting it may be a sign to ensure a safe and reliable dental implant treatment. Our focus was on the distribution of the MN branches and their communication with the lingual nerve (LN), the localized expression of CGRP, and the identification of a pain area related to the mylohyoid muscle (MM) fascia in the mandibular floor.

MATERIAL AND METHODS

In this study, MM samples from 440 sides of 303 human cadavers aged 61-103 years were examined microscopically and immunohistochemically. These data were further evaluated by the use of principal component analysis.

RESULTS

A complex but weak attachment site was identified for the fascia of the MM. CGRP expression was mainly located in small vessels and was scattered throughout the whole fascia of the MM. Communication between the MN and LN was found in 62.5% (275/440) of the samples. The results from the principal component analysis showed that the positive contributions were from the descending branch in the premolar region (correlation coefficient value R = 0.665), the ascending branch in the molar region (R = 0.709) and the intermediate branch of the digastric branch (R = 0.720) in component 1. In the fascia off the MM, strongly labeled CGRP-positive cells were also found around the blood vessels and the nerve.

CONCLUSIONS

The findings reported in this study indicate that there is a risk of damage when pulling the fascia off the MM at the border of the molar and premolar regions during dental implant surgery.

Comparative Evaluation of Effect of Potassium Iodide and Glutathione on Tooth Discoloration after Application of 38% Silver Diamine Fluoride in Primary Molars: An In Vitro Study

Aim

To evaluate and compare the effect of potassium iodide (KI) and glutathione (GSH) on tooth discoloration after application of 38% silver diamine fluoride (SDF) in primary molars.Method: Total of 30 primary molars were randomly divided into three groups of 10 each. Teeth were prepared and divided into: Group A—SDF only, Group B—SDF followed immediately by application of KI, and Group C—SDF was mixed with 25 mg of GSH. Final restoration was done using glass ionomer cement. Visual examination and color assessments using spectrophotometer were recorded at three time interval points, that is, day 1, 1 week, and 4 weeks.

Results

Statistical analysis was done using a repeated measures analysis of variances (ANOVA) test. The spectrophotometer results showed that Group A (SDF) exhibited the greatest amount of discoloration at all time intervals, while Group C (SDF + GSH) group was effective in decreasing the discoloration. Whereas, Group B (SDF + KI) significantly reduced the discoloration over the period of time. (p = 0.008).

Conclusion

KI can effectively reduce discoloration after application of 38% SDF. GSH can also be used as an alternative.

Clinical Significance

This two-step treatment for arresting caries can be a practical and low-cost option in areas with limited access to comprehensive dental care.

How to cite this article

Kamble AN, Chimata VK, Katge F A, et al. Comparative Evaluation of Effect of Potassium Iodide and Glutathione on Tooth Discoloration after Application of 38% Silver Diamine Fluoride in Primary Molars: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(6):752–756.

Effect of Dentin Pretreatment with Arginine on Microshear Bond Strength of Etch-and-Rinse or Self-Etch Adhesive Systems

Objective The main purpose of this study was to evaluate the effect of dentin pretreatment with 8% arginine on the immediate and 6-month bond strength (BS) of adhesive systems and surface morphology of dentin.

Materials and Methods Dentin bovine specimens (5 × 5 mm) were allocated into following pretreatments: without pretreatment (conventional technique, C) or exposure to arginine solution (A) for 5 minutes prior to tooth restoration. The adhesive procedure was performed using ( n = 12): 3-step etch-and-rinse adhesive (Scotchbond Multipurpose—SBMP [C+SBMP and A+SBMP]); 2-step etch-and-rinse adhesive (Single Bond 2 - SB [C+SB and A+SB]); or 2-step self-etch adhesive (Clearfil SE Bond - CSEB [C+CSEB and A+CSEB]). After 24 hours, the composite resin restorations were evaluated immediately and after 6 months of water storage using a microshear test and fracture pattern. The dentin surface exposed to A was assessed by scanning electron microscopy (SEM). The immediate BS data were submitted to a two-way analysis of variance and Tukey's test, and the long-term BS results were analyzed using Kruskal–Wallis and Dunn tests (α = 0.05).

Results There was a significant decrease in immediate and 6-month BS for the A+SB and A+CSEB groups, which differed statistically from the C group. The fracture pattern was predominantly adhesive for SB and CSEB adhesive for C and A. The SEM images presented a different conditioning pattern of the dentin exposed to A.

Conclusion The dentin pretreatment with arginine interfered negatively in the immediate and long-term BS of the simplified adhesive system. However, the SBMP adhesive was not affected by arginine pretreatment presenting the most satisfactory results.

Biomimetic Mineralizing Agents Recover the Micro Tensile Bond Strength of Demineralized Dentin

Biomimetic remineralization is an approach that mimics natural biomineralization, and improves adhesive procedures. The aim of this paper was to investigate the influence of Dentin Caries-like Lesions (DCLL)-Producing Model on microtensile bond strength (μTBS) of etch and rinse adhesive systems and investigate the effect of remineralizing agents such as Sodium Fluoride (NaF), MI Paste™ (MP) and Curodont™ Repair (CR) on caries-affected dentin (n = 6). Nine groups were established: (1) Sound dentin; (2) Demineralized dentin/Chemical DCLL: (3) Demineralized dentin/Biological DCLL; (4) Chemical/DCLL + NaF; (5) Chemical/DCLL + MP; (6) Chemical/DCLL + CR; (7) Biological/DCLL + NaF; (8) Biological/DCLL + MP; (9) Biological/DCLL + CR. Then all dentin blocks were subjected to a bonding procedure with Adper™ Single Bond 2 adhesive system/Filtek Z350XT 4 mm high block, following this they were immersed in deionized water/24 h and then sectioned with ≅1 mm² beams. The μTBS test was conducted at 1 mm/min/500 N loading. Failure sites were evaluated by SEM (scanning electron microscopy (150×). μTBS data were submitted to factorial ANOVA and Tukey’s test (p < 0.05). The highest values were found when demineralized dentin was treated with MP and CR, regardless caries lesion depth (p < 0.05). There was a predominance of adhesive/mixed in the present study. It was concluded that the use of the artificial dentin caries production models produces differences in the μTBS. Additionally MP and CR remineralizing agents could enhance adhesive procedures even at different models of caries lesion.

Effect of Glutathione Bio-Molecule on Tooth Discoloration Associated with Silver Diammine Fluoride

This study evaluated the effect of Glutathione (GSH) bio-molecule on the reduction of enamel and dentin discoloration after application of 38% silver diammine fluoride solution (SDF). One hundred and twenty bovine teeth specimens were used. The enamel and dentin specimens were divided into three groups: (1) SDF only (control); (2) SDF followed by application of a potassium iodide solution (KI); and (3) SDF mixed with 20% GSH. Half the specimens were exposed to light and the remainder kept in dark conditions (n = 10) Color changes were measured using a spectrophotometer at the following time intervals: before solution application (baseline) and immediately after application, then 3, 6, 24, 48, 72 h, and 7, 10 and 14 days. SEM/EDS analysis was performed on treated enamel and dentin. Statistical analysis was done using a repeated measures ANOVA test. The spectrophotometer results showed that the SDF group exhibited the greatest color changes under both light exposed and dark conditions, while SDF + GSH group was effective in decreasing the color changes in both light and dark conditions. The SDF + KI group showed an insignificant color changes over time. SEM/EDS analysis showed different patterns for the silver crystal formation in each group (SDF, SDF + GSH, and SDF + KI group). It was concluded GSH can effectively minimize color changes after application of SDF, especially on enamel and to a lesser extent on dentin.

Influence of Etching Mode on Enamel Bond Durability of Universal Adhesive Systems

The purpose of this study was to determine the enamel bond durability of three universal adhesives in different etching modes through fatigue testing. The three universal adhesives used were Scotchbond Universal, Prime&Bond Elect universal dental adhesive, and All-Bond Universal light-cured dental adhesive. A single-step self-etch adhesive, Clearfil S³ Bond Plus was used as a control. The shear bond strength (SBS) and shear fatigue strength (SFS) to human enamel were evaluated in total-etch mode and self-etch mode. A stainless steel metal ring with an internal diameter of 2.4 mm was used to bond the resin composite to the flat-ground (4000-grit) tooth surfaces for determination of both SBS and SFS. For each enamel surface treatment, 15 specimens were prepared for SBS and 30 specimens for SFS. The staircase method for fatigue testing was then used to determine the SFS of the resin composite bonded to the enamel using 10-Hz frequencies for 50,000 cycles or until failure occurred. Scanning electron microscopy was used to observe representative debonded specimen surfaces and the resin-enamel interfaces. A two-way analysis of variance and the Tukey post hoc test were used for analysis of the SBS data, whereas a modified t-test with Bonferroni correction was used for the SFS data. All adhesives in total-etch mode showed significantly higher SBS and SFS values than those in self-etch mode. Although All-Bond Universal in self-etch mode showed a significantly lower SBS value than the other adhesives, there was no significant difference in SFS values among the adhesives in this mode. All adhesives showed higher SFS:SBS ratios in total-etch mode than in self-etch mode. With regard to the adhesive systems used in this study, universal adhesives showed higher enamel bond strengths in total-etch mode. Although the influence of different etching modes on the enamel-bonding performance of universal adhesives was found to be dependent on the adhesive material, total-etch mode effectively increased the enamel bond strength and durability, as measured by fatigue testing.