Adhesive Agent Research Articles

The influence of moisture and epoxy bonding agents on interfacial behavior between normal concrete substrate and ultrahigh performance concrete as a repair material: Experimental and molecular dynamics study

In this paper, moisture conditions and epoxy bonding agents on interfacial behavior between normal concrete (NC) and ultrahigh performance concrete (UHPC) were investigated by both experiment and molecular dynamics (MD) simulation methods. The NC was exposed to different moisture conditions and bonding agents prior to UHPC reparation. The bonding strength was studied by slant shear and splitting tensile tests. A quantitative analysis of backscattered electron images as well as X-ray diffraction were applied to study the microstructure of the overlay transition zone (OTZ) between NC-UHPC. In addition, molecular dynamics (MD) simulation was combined with the macro experiments to explore the bonding mechanism between calcium silicate hydrate (C-S-H) and epoxy adhesive agents. The results show that UHPC is a promising repair material for concrete structure reinforcement/reparation with excellent bonding strength. The splitting tensile strength increases with a higher area ratio of NC to UHPC under the same substrate conditions, but varies when different adhesive agents are applied. Waterborne epoxy resin (WEP) can improve the bonding property of an imperfect NC substrate, while this improvement effect decrease with a smooth NC substrate. On the other hand, bisphenol-A-type epoxy resin (E51) has a negative effect on the bonding property. Finally, NC substrate moisture has no significant influence on the microstructure of OTZ and bonding strength. The MD results show, the growth of bonding strength between C-S-H and epoxy by adhesive agent is negligible while toughness can be improved to a certain extent. This work provides multi-scale new insight for understanding the bonding mechanism on NC-UHPC.

Do Different Types of Adhesive Agents Effect Enamel Demineralization for Orthodontic Bonding? An In Vitro Study

(1) Objective: The aim of this study was to compare the demineralization around brackets bonded with different types of adhesive agents in a cariogenic suspension environment. (2) Methods: In the study, 60 extracted upper first premolar teeth were divided into three groups with 20 teeth in each group. In Group 1, Transbond XT Primer + Transbond XT Light Cure Adhesive (3M Unitek, Monrovia, CA, USA), in Group 2, GC Ortho Connect Light Cure Adhesive (GC Crop, Tokyo, Japan) and in Group 3, Transbond™ Plus Self Etching Primer + Transbond XT Light Cure Adhesive (3M Unitek, Monrovia, CA, USA) adhesive agents were used. In Group 1 and 2, buccal enamel surfaces were etched for 30 s, washed for 15 s and dried for 15 s. All groups were bonded with Gemini metal (3M Unitek, Monrovia, CA, USA) brackets. Gingival, occlusal and proximal enamel surfaces of the brackets were measured with a DIAGNOdent pen (KaVo, Biberach, Germany), and demineralization values were recorded. Measurements were performed after bracketing (T0) and after 28 days in a cariogenic environment (T1), which was renewed every 48 h. The Kolmogorov–Smirnov test was used to determine whether or not the data were homogeneously distributed, the Wilcoxon test was used for comparisons within groups, and the Mann–Whitney U and Kruskal–Wallis tests were used for comparisons between groups. (3) Results: In all groups, demineralization values on all enamel surfaces of the brackets were found to be statistically significantly higher in the T1 period than in the T0 period (p < 0.05). In the T1 period, demineralization values of occlusal enamel surfaces in Groups 1 and 2 were found to be significantly higher than in Group 3 (p < 0.05). The amount of increase in occlusal enamel surface demineralization value between T0 and T1 periods in Groups 1 and 2 was significantly higher than in Group 3 (p < 0.05). There was no statistically significant difference in demineralization values of proximal and gingival enamel surfaces between the groups in the T1 period (p > 0.05). (4) Conclusion: Significantly less occlusal enamel surface demineralization was observed in teeth in which the Transbond™ Plus Self Etching Primer adhesive agent was not applied with acid etching.

Effects of nano-SiO2 on interfacial bond performances between normal-strength concrete and high-strength concrete

This study investigates the feasibility of applying nano-SiO2 (NS) as interfacial bonding agents to realize robust bonds between normal-strength concrete and high-strength repair materials. Two nano-SiO2 application methods were experimentally investigated and compared: spraying the diluted solution and fabricating modified mortar-based adhesive agents. The effects of adopted measures and concentrations (0, 2.5, 3.75, and 5%) on interfacial bond performances were determined by slant shear, splitting bond, and water permeability tests. Finally, the underlying reinforcing mechanisms of each method were illustrated through a three-layer interface model and verified by SEM/EDS. The results demonstrated that the spray NS solution could produce compact C-S-H layers on substrate surfaces. However, the concentration should be strictly controlled (≤3.75%) to inhibit the locally over-concentrated phenomenon, which may result in porous microstructure and separation gaps at the interface. The synergetic effects between NS and mortar-based bonding agents considerably benefit interfacial cohesion and stress/deformation compatibility between overlays. Despite smooth interfaces, the optimal NS-modified mortar groups achieve equivalent slant shear strength to the surface textured samples. In addition, the failure mode of mortar groups turns into cohesive failure with the addition of NS. Compared to the control group, slant shear strength and impermeability of the S-W-3.75 and S-M-3.75 groups enhanced by 25.6%/7.5% and 118.4%/66.5%, respectively. In summary, fabricating NS-modified mortar is more effective in interface modification than spray treatments. The SEM/EDS results confirm that nano-SiO2 can diffuse in interfacial transition zones and refine the microstructure of corresponding layers. In particular, high proportions of Si atoms were also noted in the penetration layer of the substrate. Therefore, applying appropriate contents of nano-SiO2, especially incorporated into mortar-base bonding agents, is highly recommended in structural rehabilitation.

Dentin primer based on a highly functionalized gelatin-methacryloyl hydrogel.

In this study, a highly functionalized GelMA hydrogel was synthesized and assessed for degree of functionalization. As the proposed GelMA hydrogel was coupled to a visible-light photoinitiator, we hypothesized it might serve as base to formulate a model dentin primer for application in restorative dentistry. GelMA was mixed with photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), photopolymerized for 0-40s using a dental light-curing device and tested for extrudability, degree of photo-crosslinking (DPxlink), water sorption/solubility/swelling (WS/SL/SW) and apparent modulus of elasticity (AE). Model dentin primer was prepared by mixing GelMA+LAP with a primer of a commercial three-step etch-and-rinse adhesive. After application of GelMA-based primer to acid-etched dentin, samples were bonded with correspondent adhesive agent, photopolymerized and had their immediate bond strength compared to control samples primed and bonded with the same commercial material. Extrudability of hydrogel was confirmed using a microsyringe to write the acronym "CDMI". DPxlink of GelMA+LAP changed significantly as a function of photopolymerization time (20s<30s≤40s). WS, SL and SW were significantly reduced in hydrogels polymerized for 30 and 40s. AE of hydrogels varied significantly as a function of photopolymerization time (20s<30s≤40s; 20s‡40s). Bond strength of dentin primed with GelMA-based primer was lower (∼29.3MPa) but not significantly of that of control (∼34.6MPa). Optimization of a GelMA-based dentin primers can lead to the development of promising biomimetic adhesives for dentin rehabilitation.

Use of Rotary Ultrasonic Plastic Welding as a Continuous Interconnection Technology for Large-Area e-Textiles

For textile-based electronic systems with multiple contacts distributed over a large area, it is very complex to create reliable electrical and mechanical interconnections. In this work, we report for the first time on the use of rotating ultrasonic polymer welding for the continuous integration and interconnection of highly conductive ribbons with textile-integrated conductive tracks. For this purpose, the conductive ribbons are prelaminated on the bottom side with a thermoplastic film, which serves as an adhesion agent to the textile carrier, and another thermoplastic film is laminated on the top side, which serves as an electrical insulation layer. Experimental tests are used to investigate the optimum welding process parameters for each material combination. The interconnects are initially electrically measured and then tested by thermal cycling, moisture aging, buckling and washing tests, followed by electrical and optical analyses. The interconnects obtained are very low ohmic across the materials tested, with resulting contact resistances between 1 and 5 mOhm. Material-dependent results were observed in the reliability tests, with climatic and mechanical tests performing better than the wash tests for all materials. In addition, the development of a heated functional prototype demonstrates a first industrial application.

Microleakage Study of a Bulk Fill over an Uncured Adhesive System

This study aimed to evaluate and compare the microleakage of composite resin restorations under a total-etch adhesive system applied with two different techniques, with and without cure. Cavities were made on the buccal surface of twenty-six intact teeth and subsequently restored with bulk-fill flow composite resin (SDR®® flow+) and conventional resin (Spectra™ ST HV). Two experimental groups were created, one where the total-etch adhesive (Prime &amp; Bond Active®) was cured and another where the adhesive was not cured before placing the flowable resin. Two control groups were also created, negative and positive. After the restorations were finished the, teeth were submerged in a solution of sodium pertechnetate (99mTcNaO4) for 3 h to evaluate the microleakage. The results showed more infiltration of radioisotopes characterized by the highest total count values of microleakage in group 1 (cured adhesive) and in the positive control. Group 2 (noncured adhesive) and the negative control showed lower values. We therefore considered that these groups were similar since their p-value was less than 0.05, with no statistically significant difference. Group 4 showed a statistically significant increase in relation to group 3 (p = 0.027). We concluded that the method of bulk-fill composite resins with noncured adhesive agents can have a positive effect on the longevity of bond strengths, with reduced microleakage.

Effect of Different Types of Adhesive Agents on Orthodontic Bracket Shear Bond Strength: A Cyclic Loading Study.

Bracket failure is one of the most important problems encountered during fixed orthodontic treatment. For this reason, different types of adhesive agents have been developed over the years. Consequently, the aim of this study was to evaluate the shear bond strength of brackets bonded to teeth etched with a conventional acid etching method in a laboratory environment by using different types of adhesive agents and comparing the number of shear strokes. Sixty human maxillary premolars were divided into three groups and Gemini stainless steel metal brackets (3M Unitek, Monrovia, CA, USA) were bonded to all teeth. In Group 1, Transbond™ XT Primer (3M Unitek, Monrovia, CA, USA) and Transbond™ XT Light Cure Adhesive Paste composite (3M Unitek, Monrovia, CA, USA) were used. In Group 2, BracePaste® MTP Primer (American Orthodontics, Sheboygan, CA, USA) and BracePaste® Adhesive composite (American Orthodontics, Sheboygan, WI, USA) were used. In Group 3, Ortho Solo™ Primer (Ormco, Orange, CA, USA) and Grengloo™ Adhesive composite (Ormco, Brea, CA, USA) were used. The samples were subjected to a shear test with a closed-loop controlled, low-cycle fatigue machine with a capacity of 10 N and a crosshead speed of 300 mm/min. The number of shear strokes of the brackets was recorded. According to the Kruskal-Wallis and Mann-Whitney U tests performed on the data obtained, statistically significant differences were found between the groups in terms of the numbers of shear strokes (p &lt; 0.05). Significantly higher numbers of shear strokes and higher shear bond strengths were observed in Group 3 compared with Group 1 and Group 2 (p &lt; 0.05). There was no statistically significant difference between the numbers of shear strokes for Group 1 and Group 2 samples (p &gt; 0.05). To conclude the study, it was observed that the type of adhesive used had an effect on the bond strength of the bracket and that the Grengloo™ adhesive agent showed higher shear bond strength. It was observed that BracePaste® Adhesive and Transbond™ XT Light Cure Adhesive Paste adhesive agents had similar shear bond strengths.

Watered-Based Graphene Dispersion Stabilized by a Graft Co-Polymer for Electrically Conductive Screen Printing

Graphene conductive inks have attracted significant attention in recent years due to their high conductivity, corrosion resistance, and environmentally friendly nature. However, the dispersion of graphene in aqueous solution is still challenging. In this work, we synthesized an amphiphilic graft copolymer, polyvinyl alcohol-g-polyaniline (PVA-g-PANI), and studied the graphene dispersion prepared with the graft copolymer by high-speed shear dispersion. The amphiphilic graft copolymer can be used as a stabilizer and adhesive agent in graphene dispersion. Given the steric hindrance of the graft copolymer, the stability of graphene dispersion is improved by decreasing the probability of π-π stacking. PVA-g-PANI has a better stability on graphene dispersion than carboxymethylcellulose sodium (CMC-Na) and a mixture of PVA and PANI. The graft copolymer has only a slight effect on the conductivity of graphene dispersion due to the existence of conductive PANI, which is beneficial for preparing the graphene dispersion with good conductivity and adhesion. Graphene dispersion is well-adapted to screen printing and is very stable with regard to the sheet resistance bending cycle.

The Various Silane Agents in Universal Adhesives on Repair Strength of Resin Composite to Resin Composite

The aim of this investigation was to examine the bonding efficacy of a universal adhesive containing various silane agents to repair aged resin composite with new resin composite. Ninety resin composite specimens were created with nanofilled resin composite and aged for 5000 cycles in a thermocycler. The specimens were sorted into nine groups (n = 10) at random based on the methods used to treat the surfaces with/without silane agent (Si), and adhesive agents (Single bond universal, SU; Single bond universal plus, SUP; Clearfil Tri-S bond universal, CFU; and Single bond 2, SB2). A template was placed on the treated surface of the aged resin composite, and then the resin composite was filled into the template. The shear bond strength (SBS) test was conducted using a universal tester and failure patterns were determined. The statistical analysis was performed using a one-way ANOVA and a Tukey’s test. The lowest SBS values were exhibited in the no surface treatment group (7.69 ± 2.57 MPa). The highest SBS values were exhibited in Si + SUP group (28.04 ± 1.62 MPa), with a significant difference compared to SUP group (22.69 ± 2.21 MPa), Si + SU group (22.08 ± 1.83 MPa), Si + CFU group (21.98 ± 1.54 MPa), and Si + SB2 group (21.85 ± 2.18 MPa). The experimental group demonstrated a predominance of adhesive failure at the junctions between the aged resin composite and the new resin composite. In conclusion, The SUP, which incorporates 3-(aminopropyl)triethoxysilane (APTES) and 3-methacryloxypropyltriethoxysilane (3-MPTES), has a positive effect on the repaired shear bond strength of resin composite to resin composite both with and without the use of a silane agent prior to the use of the SUP when compared with a conventional adhesive agent (SB2) and other universal adhesives (SU and CFU). Moreover, an additional silane agent used prior to the SUP application has the highest shear bond strength.

Mussel-Inspired Two-Dimensional Halide Perovskite Facilitated Dopamine Polymerization and Self-Adhesive Photoelectric Coating.

Polydopamine (PDA) is a good adhesion agent for lots of gels inspired by the mussel, whereas hybrid organic-inorganic perovskites (HOIPs) usually exhibit extraordinary optoelectronic performance. Herein, mussel-inspired chemistry has been integrated with two-dimensional HOIPs first, leading to the preparation of new crystal (HDA)2PbBr4 (1) (DA = dopamine). The organic cation dopamine can be introduced into PDA resulting in a thin film of (HPDA)2PbBr4 (PDA-1). The dissolved inorganic components of layered perovskite in DMF solution together with H2O2 addition can facilitate DA polymerization greatly. More importantly, PDA-1 can inherit an excellent semiconductor property of HOIPs and robust adhesion of the PDA hydrogel resulting in a self-adhesive photoelectric coating on various interfaces.

Investigation of shear bond strength of different adhesive agents to demineralized enamel with or without resin ınfiltration

Investigation of shear bond strength of different adhesive agents to demineralized enamel with or without resin ınfiltration

A cyanoacrylate/triethyl citrate/nanosilica-based closure glue with wet-adhesion capability for treatment of superficial varicose veins.

Varicose veins in legs are common in clinics. Currently, medical adhesive-based, minimally invasive endovenous occlusion is used to treat them. However, the most common cyanoacrylate medical adhesives do not perform well when used under blood/wet conditions. In particular, poor adhesion, short curing time, and high heat release greatly limit their clinical use. In this paper, we demonstrate the use of a composite system composed of butyl-cyanoacrylate, triethyl citrate, and nanosilica that exhibits a blood/wet-adhesion capability to serve as a new sealing glue. Hydrophobic triethyl citrate groups displace boundary waters while also protecting cyanoacrylate monomers from undergoing rapid polymerization. Nanosilica increases viscosity, which contributes to in situ extrusion molding and retention. An optimal formulation, FAL-006, exhibited good physical and chemical properties in vitro. The performed additional safety assays indicated that FAL-006 has good biocompatibility. The closure efficiency of FAL-006 in vivo was evaluated in both a rat abdominal aortic closure model and in a sheep lower limb venous closure model. Taken together, these results indicate that FAL-006 exhibits promising potential for use in clinical applications. Furthermore, this study provides a new strategy for designing underwater adhesive agents for additional clinical applications, and a strategy for constructing other biomaterials needed for use under wet conditions.

The Effect of Morpholine on Composite-to-Composite Repair Strength Contaminated with Saliva.

The aim of this study was to specifically explore the effects of morpholine on chemical surface treatments of aged resin composites contaminated with saliva to new resin composite repair strength. One hundred and thirty five resin composite specimens were fabricated and thermocycled to replicate an aged resin composite. These aged resin composites were randomly separated into nine groups (n = 15) depending on the various surface contaminants and surface treatment techniques. These groups were as follows: group 1-no surface treatment; group 2-no saliva + adhesive agent; group 3-no saliva + morpholine + adhesive agent; group 4-no saliva + morpholine; group 5-saliva; group 6-saliva + adhesive agent; group 7-saliva + morpholine + adhesive agent; group 8-saliva + morpholine; and group 9-saliva + phosphoric acid + adhesive agent. A mold was covered on the top of the specimen center and then filled with resin composite. The shear bond strengths and failure modes were examined. The collected data was analyzed using one-way ANOVA, and the significance level was determined using Tukey's test. Group 5 (3.31 ± 0.95 MPa) and group 6 (4.05 ± 0.93 MPa) showed the lowest bond strength statistically, while group 3 (23.66 ± 1.35 MPa) and group 7 (22.88 ± 1.96 MPa) showed the most significantly high bond strength. The bond strength in group 2 (16.41 ± 1.22 MPa) was significantly different from that in group 1 (9.83 ± 1.13 MPa), group 4 (10.71 ± 0.81 MPa), and group 8 (10.36 ± 1.53 MPa), while group 9's (17.31 ± 1.48 MPa) SBS was not significantly different. In conclusion, the application of morpholine on aged resin composite with or without contamination with saliva prior to the application of the adhesive agent increased the bond strength of aged resin composite repaired with new resin composite (p &lt; 0.05).

Changes in the Oral Microbiocenosis in the Process of Different Adhesive Agents Use for Fixation of Complete Removable Laminar Dentures

The use of adhesives to improve the fixation of complete removable laminar dentures, along with numerous benefits for the patient, creates additional risks of imbalance in some representatives of the oral microflora and, consequently, may cause or maintain the development of prosthetic stomatitis and worsen oral hygiene. Therefore, it is important to study the prevention of disorders of the normobiocenosis of the oral cavity due to the differentiated choice of adhesives based on their antimicrobial activity. The study represents the peculiarities of changes in the oral normomicrobiocenosis in the process of the prescribed adhesives’ use for fixing complete removable laminar dentures.&#x0D; The aim of the study – is to study the changes in the oral microbiocenosis in the process of adhesives use for fixing complete removable laminar dentures and to assess the effectiveness of their choice based on the results.&#x0D; Materials and methods of the study. There were examined 120 people, who used full removable laminar dentures, 90 of them used adhesive means prescribed by a dentist for three weeks to improve fixation. All patients were sampled for bacteriological examination. Based on the analysis of culture results for microorganisms in each Group, the constancy index was determined – sowing frequency in percent and population level – colonization mass in lg CFU/ml.&#x0D; Results of the study. In comparison with persons who did not use adhesives to improve the fixation of removable dentures and data before the study it was determined that the adhesive “Corega” had a preservative effect on the normoflora, reduced the population level of pathogenic coccal microflora, yeasts; adhesive “Laсalut” had an inhibitive effect on all representatives of the normal microflora, reduced sowing frequency and population level of β-hemolytic streptococci, but did not affect the pathogenic activity of Staphylococcus aureus, yeasts and gram-negative bacteria; adhesive “Protefix” had a suppressive effect on the normoflora, did not affect the population level of pathogenic microorganisms and even increased the massiveness of colonization by gram-negative bacteria.&#x0D; Conclusions. Taking into account the determined changes in the oral microbiocenosis in persons who used adhesives to improve the fixation of complete removable laminar dentures, we can talk about the effectiveness of the adhesive “Сorega” for long-term use in the absence of complications in prosthetic bed tissues and with proper hygienic care of the oral cavity; adhesives “Laсalut” and “Protefix” in patients with existing dysbiotic disorders and with subsequent control of the impact on the resident microflora of the oral cavity.

Flexible Bonding of Polymer Substrates By Microwave Heating of Carbon Nanotubes

Recently, as research on developing electronic devices for simultaneous implementation of flexibility and conductivity has been continuously conducted, ensuring stable and high reliability of devices in preparation for various mechanical deformation is becoming important. When a physical force such as bending, twisting, or folding is applied, the bonding area between two substrates should ensure stability due to high stress generation. Epoxy resin materials used as standard adhesive agents have brittleness due to the nature of the material, and are weak in terms of flexibility due to increased bonding thickness due to high temperature hardening. In addition, it is difficult to apply as a bonding material in consideration of thermal deformation of the polymer substrate exposed to high temperatures during the process. To improve both flexibility and durability against fatigue deformation, Flexible bonding process is required without adhesive such as epoxy resin with poor brittleness. Surface activation bonding technologies by ion beams and vacuum ultraviolet rays have been developed in previous studies, bonding between plastic substrates by activating thin metal films surface of adhesive layer with ion beam or improving adhesive force by direct-UV radiation on the surface of the polymer substrate. In this study, a flexible bonding process between polymer substrates was developed by heating carbon nanotubes (CNTs) through microwave irradiation. High microwave absorption properties of CNT lead to heat dissipation behavior and light emission characteristics. Heat transfer mechanism of CNT applied to CNT-polymer composites, CNT electrodes fields and has been microwave assisted purification. By utilizing the microwave heating effect, we selected CNT materials for flexible substrates. Multi-walled carbon nanotubes (MWNTs) were coated on a bonded PET polymer substrate and then local heating was performed by microwaves to induce mechanical entanglement between the CNTs and the PET. In the bonding process, the output power of the microwave was adjusted to 600,800 and 1000 Watt, and the bonding strength was evaluated by quantifying the bonding strength was evaluated. For the analysis of the bonding mechanism in the area where mechanical entanglement took place, the CNT-PET bonding interface was analyzed through electron scanning microscope (SEM) measurement, and further analysis was performed for each process condition. In addition, a fracture mechanism analysis that occurred at the junction was performed after the overlapping shear strength test. Acknowledgments This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020M3H4A3106413, Development of Evaluation Method for Mechanical Deformation of Micro-joints in Micro-LED Module) Figure 1

The Effect of Multiple Applications of Phosphate-Containing Primer on Shear Bond Strength between Zirconia and Resin Composite.

Occasional chipping can still occur with zirconia material despite its high strength. Emergency repairs can be accomplished using zirconia primer, adhesive agent, and resin composite when the fracture of zirconia exposes the zirconia framework. Phosphate-containing primers play an important role in zirconia surface treatment. The objective of this investigation was to evaluate the effect of multiple applications of phosphate-containing primer on shear bond strength between zirconia and resin composite. In this case, 78 zirconia discs were sandblasted by alumina particles; the zirconia was then randomized into six groups for single application and multiple applications of phosphate-containing primer according follows; group 1: no application, group 2: one application, group 3: two applications, group 4: three applications, group 5: four applications, and group 6: five applications. Adhesive was applied on the zirconia surface and the resin composite was bonded. Shear bond strength was assessed using a universal testing machine. The de-bonded surface was examined using a stereomicroscope. The shear bond strengths were statistically analyzed with one-way ANOVA and Bonferroni. Group 1 had the lowest shear bond strength with a significant difference compared to groups 2–6, whereas group 4 had the highest shear bond strength, with no significant difference compared to groups 5–6. The failure mode revealed 100% adhesive failure in all groups. In conclusion, to maximize shear bond strength at zirconia and resin composite interfaces, sandblasted zirconia surfaces should be treated with three applications of phosphate-containing primer prior to the adhesive agent.

Comparative Evaluation of the Effect of Degree of Convergence and Surface Area on the Retentive Force of Titanium Crowns Cemented with Various Adhesive Luting Agents on Extracted Human Teeth – A Laboratory Study

Introduction: The retention of base metal crowns and noble metal crowns cemented with various luting agents is well documented. However, little emphasis was given to the degree of convergence and surface area of tooth preparation. Aim and Objective: A study was planned to analyze the effect of the degree of convergence and surface area of the tooth preparation on the retention of titanium crowns with various adhesive luting agents. Materials and Methods: Forty-five caries-free extracted human premolars were obtained. They were divided into three groups according to the degree of convergence and further subdivided based on the type of luting agents used. The teeth were prepared with an angle of convergence of 5°, 10°, and 15° with a flat occlusal surface using K9 crown finishing installation, complete. Light body copper band impressions were made to determine the surface area. Titanium crowns thus obtained were sandblasted, ultrasonically cleaned, and cemented using Panavia F, Calibra, and Glass Ionomer Cement. Results: Results showed that Panavia F was the best luting agent exhibiting maximum retentive force to dislodge the crown in a vertical direction using the universal tensile testing machine at a cross-head speed of 1 mm/min. Conclusion: The force required to dislodge the titanium crown from the prepared tooth was maximum for Panavia F on 5°, 10°, and 15° angle of convergence at 65.23 kgf, 48.52 kgf, and 40.14 kgf. Retentive force values drastically reduced as the degree of convergence increased. There was a reduction in the surface area due to an increase in the taper.

A bifunctional lithium polysilicate as highly efficient adhesion agent and anchoring host for long-lifespan Li-S battery

The development of Li-S battery has been seriously hindered by the shuttle effect of polysulfides and the mechanical instability of the sulfur electrode during cycling. Constructing strong-affinity oxide hosts is an effective way to anchor the polysulfides. And then the oxide hosts with sulfur active materials need additional binder to adhere them to the current collector, and they also possess poor ability to suppress the volume change of sulfur cathode. Herein, a bifunctional lithium polysilicate (Li2O·nSiO2, LSO) as highly efficient adhesion agent and anchoring host has been exploited for long-lifespan Li-S battery. Like other oxide hosts, density functional theory (DFT) calculations reveal that LSO also displays strong chemisorption effect towards polysulfides. Specially, the LSO shows impressive adhesive property and mechanical strength, which make it act as a robust binder to improve the mechanical stability of the sulfur electrode. The sulfur cathode with LSO as the highly efficient adhesion agent and anchoring host can give an excellent cycling stability with ∼ 0.076 % capacity decay per cycle at 0.5C for 500 cycles. This work lights a new way to improve the chemical and mechanical stability of sulfur cathodes.

Effect of Different Surface Treatments on the Long-Term Repair Bond Strength of Aged Methacrylate-Based Resin Composite Restorations: A Systematic Review and Network Meta-analysis.

This systematic review and network meta-analysis is aimed at investigating the effect of common surface treatments on the long-term repair bond strength of aged resin composite restorations and to rank and compare these surface treatments. In vitro studies evaluating the methacrylate-based resin composites subjected to rigorous aging protocols before and after being repaired with a new composite were included. A frequentist network meta-analysis was carried out using a random effects model. P scores were used to rank the efficacy of the surface treatments. Also, the global and node-split inconsistencies were evaluated. Web of Science, PubMed/Medline, Scopus, and Embase databases were searched until July 07, 2022. Twenty-six studies were included in the meta-analysis. The results showed that the application of silane and a total-etch (shear MD 32.35 MPa, 95% CI: 18.25 to 46.40, P score 0.95; tensile MD 33.25 MPa, 95% CI: 25.07 to 41.44; P score 0.77) or a self-etch (shear MD 38.87 MPa, 95% CI: 21.60 to 56.14, P score 0.99; tensile MD 32.52 MPa, 95% CI: 23.74 to 41.29; P score 0.73) adhesion protocol subsequent to the roughening with diamond bur produced the highest (micro)tensile and (micro)shear bond strengths compared to diamond bur alone as the control group. There was no difference between self- and total-etch adhesive protocols. Mechanical surface treatments yielded greater bond strength when used alongside the chemical adhesive agents. Further, it is possible to achieve acceptable repair bond strength using common dental clinic equipment. Therefore, clinicians could consider repairing old resin composites rather than replacing them.

Influence of Surface Conditioning on Bonding Polyetherketoneketone to Dental Ceramic

This study researched the effects of different surface conditioning techniques on the bond strength of polyetherketoneketone (PEKK) with lithium disilicate glass-ceramic material. Total of 105 test specimens were prepared from PEKK discs and randomly distributed into 5 experimental groups (n = 21) to which different surface conditioning techniques were applied. [Group A: sandblasting + SR Connect adhesive agent (SRC), Group B: dichloromethane (DCM) + SRC, Group C: methyl methacrylate (MMA) and DCM mixture + SRC, Group D: sandblasting + DCM + SRC, Group E (control): sandblasting + Pekk Bond adhesive agent (PB).] Surface roughness values of PEKK test specimens were measured. They were bonded to lithium disilicate glass-ceramic test specimens with resin cement. Half of them were subjected to thermomechanical aging. Shear bond strength measurements were made. Among the A, B, C, D, and E groups, a statistically significant difference was observed in terms of the surface roughness values (p < 0.001). Statistically significant differences were obtained among the thermomechanical aging groups (p < 0.001) and among the non-thermomechanical aging groups (p = 0.012) in terms of shear bond strength. Group D and Group E demonstrated clinically acceptable bond strength values when bonding PEKK material with lithium disilicate glass-ceramic material.