Effect of carbodiimide on the structural stability of resin/dentin interface

Analysis of the adhesive interface of dentine treated with carbodiimide and chitosan before cementation of fiberglass posts with different resin cements

The objective of this study is to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and chitosan (CHI) on the adhesive interface of resin cements to root dentine. Forty-five upper canines were sectioned, endodontically treated, prepared and divided into three groups according to dentine treatment (distilled water-DW, CHI 0.2% and EDC 0.5) and in three subgroups according to resin cement: RelyX ARC, Panavia F 2.0 or RelyX U200. Slices were obtained, with five slices of each third submitted to the analysis of the adaptation of the adhesive interface through scores and the perimeter with gaps in confocal laser scanning microscopy and one slice of each third later evaluated qualitatively in scanning electron microscopy. The results were analyzed using with Kruskal-Wallis and Spearman correlation tests. There was no difference in adaptation for the different resin cements (p = .438). EDC presented better adaptation when compared to the groups treated with DW and CHI (p < .001), while the CHI and DW presented similar adaptation values (p = .365). No difference was observed in the perimeter referring to the gap areas for the different resin cements (p = .510). EDC showed a lower percentage of perimeters with gaps when compared to CHI (p < .001), with the percentage of perimeter with gaps of teeth treated with CHI being lower than DW (p < .001). A positive correlation coefficient equal to 0.763 was obtained between the perimeter with gaps and the adaptation data of the adhesive interface (p < .001). EDC resulted in better adaptation of the adhesive interface and a lower percentage of perimeters with gaps compared to chitosan.

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.

Long-term effect of curcuminoid treatment on resin-to-dentin bond strength

Endogenous dentin proteases contribute to the degradation of collagen fibrils in the hybrid layer. Recently, inhibition of host-derived proteases by curcuminoids has shown promising results. The aim of this study was to evaluate the effect of curcuminoid treatment on the microtensile bond strength (μTBS) after 24 h or 12 months of storage. Fifty-four extracted sound human molars were flattened to mid-coronal dentin and divided into nine groups. After phosphoric acid-etching for 15 s, the dentin was experimentally treated for 60 s using 100 μM or 200 μM of curcumin, diflourobenzocurcumin, or demethoxycurcumin dissolved in 1% and 2% dimethyl sulfoxide (DMSO)/water solutions. Untreated and DMSO-treated groups served as controls. After bonding agent application, each tooth was restored with dental composite. The molars were sectioned into 0.9 × 0.9 × 6 mm beams. The μTBS testing was performed after 24 h and 12 months of storage in artificial saliva. Data were analyzed using regression analyses. Failure patterns were evaluated using scanning electron microscopy. Dentin treatment with curcuminoids did not adversely affect 24-h μTBS compared to controls. After 12 months, the μTBS of curcuminoid groups was statistically significantly higher than the controls. This study indicates the feasibility of using curcuminoids as protease inhibitors.

In vitro evaluation of the anti-proteolytic and cross-linking effect of mussel-inspired monomer on the demineralized dentin matrix

OBJECTIVES

To evaluate the anti-proteolytic and cross-linking effect of N-(3,4-dihydroxyphenethyl)methacrylamide (DMA) on the demineralized dentin matrix in vitro.

METHODS

Four experimental solutions were selected: 50% ethanol/water solution (Control); 1, 5, and 10 mmol/L DMA dissolved in 50% ethanol/water solution. Sound human molars were sectioned to produce dentin beams with dimension of 1×1×6 mm. The dentin beams were demineralized with 10% phosphoric acid for 8 h to remove the apatite. The demineralized specimens were randomly separated into four groups and immersed in the four experimental solutions for 1 h. After the treatment, the ultimate tensile strength (UTS), loss of dry mass and the release of hydroxyproline by storing the treated specimens in 0.1 mg/mL collagenase solution for 24 h were assessed. The swelling ratio of another ten specimens from each group were evaluated. The interaction between DMA with dentin matrix was observed under Field Emission Scanning Electron Microscopy (FESEM). UTS data was analyzed by two-way ANOVA followed by Tukey test, and the other data was analyzed by one-way ANOVA followed by Tukey test (α = 0.05).

RESULTS

The two-way ANOVA factors, different solutions (p < 0.001), collagenase degradation (p < 0.001) and their interactions (p < 0.001) all significantly affected the UTS. The 10 mM DMA treatment significantly decreased the percentage of loss of dry mass, release of hydroxyproline and swelling ratio of demineralized dentin matrix compared to other treatment groups (p < 0.05). The FESEM observation depicted that with increasing concentration of DMA, the structure of dentin matrix was protected and the porosity within dentin collagen network was decreased.

CONCLUSIONS

The treatment by 10 mM DMA/ethanol solution for 1 hour is capable of enhancing the mechanical properties of demineralized dentin matrix against collagenase degradation and may be clinically useful to improve the durability of hybrid layer.

CLINICAL SIGNIFICANCE

The 10 mM DMA/ethanol primer may offer an alternative choice for dentists to strengthen the mechanical properties of demineralized dentin matrix and resist its degradation by collagenase.

Effect of chlorhexidine-loaded poly(amido amine) dendrimer on matrix metalloproteinase activities and remineralization in etched human dentin in vitro

To investigate the effect of chlorhexidine (CHX)-loaded carboxyl-terminated poly (amido amine) dendrimer (CHX-PAMAM-COOH) on matrix metalloproteinase (MMP) activities and remineralization in human dentin, CHX-PAMAM-COOH was prepared and characterized by Fourier-transform infrared spectroscopy. The inhibitory effects of CHX, PAMAM-COOH, and CHX-PAMAM-COOH on soluble recombinant human matrix metalloproteinase (rhMMP-2) and dentin-bound endogenous MMP activity were measured using an MMP Activity Assay Kit. In situ zymography was performed to evaluate the gelatinase activity in dentin pretreated with CHX, PAMAM-COOH, and CHX-PAMAM-COOH. The remineralization of etched dentin pretreated with CHX, PAMAM-COOH, and CHX-PAMAM-COOH was evaluated by field emission-scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) after incubation in artificial saliva for 14 days. The results of the rhMMP-2 activity assay showed that the MMP-2 activity in the CHX-PAMAM-COOH group and the CHX group decreased significantly to 5.58 ± 0.85% (P < 0.05) and 4.86 ± 1.12% (P < 0.05), respectively, but that in the PAMAM-COOH group increased significantly to 213.38 ± 0.11% (P < 0.05). The results of total MMP activity and in situ zymography showed a significant reduction in endogenous gelatinase activity in dentin in the CHX-PAMAM-COOH group and the CHX group. The SEM and EDS results showed that rod-like crystals were formed on the etched dentin surface in the PAMAM-COOH group and the CHX-PAMAM-COOH group, and their Ca/P ratios were 1.73 and 1.71, respectively. In conclusion, CHX-PAMAM-COOH can inhibit dentin-bound endogenous MMPs and induce remineralization in etched dentin simultaneously. However, it is important to note that the catalytic role of PAMAM dendrimers may have an undesired excitatory effect on MMP activity, which cannot be ignored if PAMAM dendrimers were used alone in the oral environment.

Effect of chemical cross-linkers on surface topography and microtensile bond strength of sound dentin: An in vitro study

AIM AND OBJECTIVES

The aim of the study was to investigate the effect of two different collagen cross-linking agents proanthocyanidin (Grape seed extract [GSE] and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide) on the surface topography of etched dentin and microtensile bond strength (μTBS) of resin dentin bond.

MATERIALS AND METHODS

Fifty-two sound human 3rd molars were collected, and their occlusal surfaces were ground flat to expose dentin. Dentin surfaces were etched using phosphoric acid and then teeth were randomly divided into four groups, according to the dentin treatment: Group 1: wet bonding technique, Group 2: dry bonding technique, Group 3: 6.5% proanthocyanidin, and Group 4: 0.1M carbodiimide. Scanning electron microscope analysis was done for twenty specimens (n = 5 per group) at ×10,000 and ×30,000 magnification. Remaining 32 specimens were restored with TETRIC N-Bond adhesive systems and resin composite. After 24 h, teeth were sectioned to produce a cross-sectional surface area of 1.0 mm2 and tested for μTBS.

STATISTICAL ANALYSIS

Data were statistically analyzed using ANOVA and post hoc least significant difference test (P < 0.05).

CONCLUSION

When acid-etched dentin is treated by 6.5% proanthocyanidin (GSE) and 0.1M carbodiimide, followed by application of adhesives, it results in increased μTBS due to cross-linking of collagen fibrils.

Evaluation of effect of two different functionalized nanoparticle photodynamic therapy on nanohardness of root dentin-An in vitro study

INTRODUCTION

The aim of this study was to evaluate the effect of functionalized nanoparticle photodynamic therapy on Nano hardness of root dentin METHODOLOGY: Fifty single rooted lower premolars were decoronated and sectioned into two halves. Then the samples were embedded horizontally in to the acrylic resin to expose the dentin surface. Baseline nanohardness was done at midroot level using a Nanohardness tester. Exposed dentin surfaces were immersed in the following irrigating solutions Post treatment nanohardness testing was done and results were analyzed statistically RESULTS: In general, all the samples in their respective groups had significant change in nanohardness following immersion in irrigant solutions except in NaOCl + EDTA and saline group. CSRB-np and PLGA-MBnp showed increased nanohardness (P = 0.005 and P = 0.007 respectively). Whereas NaOCl + EDTA + CHX showed decrease in nanohardness (P = 0.04). With regards to Modulus of elasticity (MOE), CSRB-np showed significant difference (P = 0.002) compared to the other groups. MOE increased in CSRB-np and PLGA-MBnp while it decreased in all the other groups.

CONCLUSION

In this study, the improvement of nanohardness and modulus of elasticity following the immersion of root dentin in CSRB-np solution was demonstrated.

Effect of carbodiimide and chlorhexidine on the bond strength longevity of resin cement to root dentine after radiation therapy

AIM

To evaluate the effect of carbodiimide (EDC) and chlorhexidine (CHX) on the bond strength (BS) of resin cement to root dentine of teeth submitted to radiotherapy.

METHODOLOGY

One hundred and twenty extracted maxillary canines were selected and assigned to 2 groups (n = 60): nonirradiated and irradiated (30 cycles of 2 Gy, total 60 Gy). Roots lengths were standardized, and canals were prepared and filled. Post spaces were then prepared, and the samples were redistributed according to dentine treatment (n = 20): saline solution (SF); CHX 2%; or EDC 0.5M. After drying the post space, fibreglass posts were cemented. Cross-sectioned slices were obtained, and in half of the specimens of each subgroup (n = 10), the analysis was performed immediately; the others (n = 10) were stored for 10 months before analyses. The most cervical slice of each third was subjected to a push-out test and failure pattern analysis (n = 10), and the most apical slice submitted to the analysis of the adhesive interface by SEM (n = 5). The bond strength data were submitted to anova and Tukey tests, the adhesive interface adaptation was submitted to Kruskal-Wallis and Dunn's tests, and the Chi-square test was used to evaluate the type of failure.

RESULTS

The irradiated specimens had significantly lower bond strength (13.8 ± 4.3) than the nonirradiated (18.1 ± 3.1; P < 0.001). For the irradiated teeth, the bond strengths were significantly lower in the SF and CHX groups (P < 0.001). Also, the bond strengths reduced significantly after 10 months in the SF and CHX groups (P < 0.001). Cohesive failures occurred in dentine for irradiated specimens. Poorer interface adaptation, dentine fractures and microfractures were observed in irradiated specimens, and better adaptation was observed for specimens after EDC treatment.

CONCLUSIONS

Radiotherapy was associated with lower bond strength and worse interface adaptation. Dentine treatment with EDC contributed to adhesive interface longevity during the cementation of glass fibre posts in nonirradiated and irradiated teeth.

Caries removal with Er:YAG laser followed by dentin biomodification with carbodiimide and chitosan: Wettability and surface morphology analysis

This study aimed to investigate dentin wettability and surface morphology after selective removal of carious lesion by erbium-doped yttrium aluminum garnet (Er:YAG) laser, followed by dentin biomodification with carbodiimide (EDC) and chitosan (CHI). Seventy-eight bovine dentin specimens were submitted to caries induction. Specimens were distributed according to methods of carious removal (n = 39): bur at low-speed (40,000 rpm) or Er:YAG laser (noncontact mode, 250 mJ/pulse and 4Hz). All specimens were etched with 35% phosphoric acid, and subdivided according to dentin biomodification (n = 13): Control (no biomodification), EDC or CHI. The contact angle (n = 10) between adhesive system (3M ESPE) and dentin surface was measured by a goniometer. Eighteen specimens (n = 3) were analyzed by scanning electron microscopy. Data were analyzed by two-way ANOVA and Tukey's test (α = .05). The method used to remove carious lesion did not influence the wettability of dentinal surface (p = .748). The angles produced on the remaining dentin after biomodification were influenced (p = .007). CHI promoted higher contact angles (p = .007) and EDC did not differ from the control group (p = .586). In the bur-treated group, most tubules were open, regardless of which biomodifier was used. Laser modified the organic matrix layer. CHI promoted partially closed tubules in some areas while EDC exposed dentinal tubules. Regardless of which method was used for selective removal of carious lesion, biomodification with EDC did not affect the dentin wettability, whereas CHI changed the wettability of remaining dentin. Both biomodifiers promoted a slight change on dentin morphology.

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

This study investigated the effect of SnCl₂/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl₂/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl₂/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl₂/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

Recent Advances in Adhesive Bonding - The Role of Biomolecules, Nanocompounds, and Bonding Strategies in Enhancing Resin Bonding to Dental Substrates

PURPOSE OF REVIEW

To present an overview on the main agents (i.e., biomolecules and nanocompounds) and/or strategies currently available to amplify or stabilize resin-dentin bonding.

RECENT FINDINGS

According to studies retrieved for full text reading (2014-2017), there are currently six major strategies available to overcome resin-dentin bond degradation: (i) use of collagen crosslinking agents, which may form stable covalent bonds with collagen fibrils, thus strengthening the hybrid layer; (ii) use of antioxidants, which may allow further polymerization reactions over time; (iii) use of protease inhibitors, which may inhibit or inactivate metalloproteinases; (iv) modification of the bonding procedure, which may be performed by using the ethanol wet-bonding technique or by applying an additional adhesive (hydrophobic) coating, thereby strengthening the hybrid layer; (v) laser treatment of the substrate prior to bonding, which may cause specific topographic changes in the surface of dental substrates, increasing bonding efficacy; and (vi) reinforcement of the resin matrix with inorganic fillers and/or remineralizing agents, which may positively enhance physico-mechanical properties of the hybrid layer.

SUMMARY

With the present review, we contributed to the better understanding of adhesion concepts and mechanisms of resin-dentin bond degradation, showing the current prospects available to solve that problematic. Also, adhesively-bonded restorations may be benefited by the use of some biomolecules, nanocompounds or alternative bonding strategies in order to minimize bond strength degradation.

miR-137 acts as a tumor suppressor via inhibiting CXCL12 in human glioblastoma

Up to date, miR-137 has been demonstrated as a tumor suppressor in many kinds of human malignancies. In the present study, we conducted transfection, western blot and RT-PCR to explore the role of miR-137 in the development of human glioblastoma (GBM). Here, we found that miR-137 expression was obviously down-regulated in GBM tissues and cells rather than matched non-tumor tissues and NHA cells. However, the expression of C-X-C motif ligand 12 (CXCL12) mRNA and protein were up-regulated in GBM tissues and cells. In vitro, miR-137 mimics inhibited GBM cell proliferation, migration and invasion, and the 3′-untranslated regions (3′-UTR) of CXCL12 were a direct target of miR-137. In addition, miR-137 mimics also inhibited the expression of EGFR, Bcl-2 and MMP2/9 proteins, but increased the expression of Bax protein. Notably, CXCL12 over-expression attenuated miR-137-inhibited cell proliferation and invasion, while CXCL12 siRNAs promoted miR-137 inhibition effects. In vivo, miR-137 mimics also suppressed tumor growth in nude mice xenograft model. In conclusion, miR-137 serves as a tumor suppressor by inhibition of CXCL12 in human GBM. Thus, miR-137-CXCL12 can be recommended as a useful and effective target for treatment of GBM.