Bond Strength Research Articles

Comparative evaluation of surface changes and bond strength of microabrasion bleached enamel before and after remineralization with nano-hydroxyapatite paste: In vitro study

Objectives: Comparative evaluation of surface changes and bond strength of Microabrasion Bleached enamel before and after Remineralization with Nano-hydroxyapatite paste, an In vitro study. Methods: Enamel samples were divided into - Group I - Conventional bleaching (HB), Group II - Conventional bleaching with remineralization (HB+N-Hp), Group III - Microabrasion-assisted bleaching (M+HB), and Group IV - Microabrasion-assisted bleaching with remineralization (M+HB+N Hp). Surface roughness was measured using a profilometer. Samples were stored in artificial saliva for two weeks, then bonded with nanofilled composite resin and subjected to shear bond strength (SBS) analysis. Results: Group IV (M+HB+N-Hp) showed higher surface roughness than Groups I (HB) and II (HB+N-Hp), while Group II had significantly lower surface roughness compared to Groups III (M+HB) and IV. In terms of shear bond strength (SBS), Group III exhibited significantly higher SBS than Group I, whereas Group II showed significantly reduced SBS compared to Group I. All values were statistically significant. Conclusions: Remineralization with N-Hp reduces the surface roughness caused by bleaching and microabrasion, potentially decreasing bacterial biofilm adherence. Despite increased surface roughness correlating with better bond strength, microabrasion-assisted bleaching followed by remineralization and direct composite veneering after two weeks is a promising minimally invasive treatment for severe tooth discolorations. Further studies should explore varying frequencies and concentrations of N-Hp application.

Interfacial interaction mechanism and theoretical bond strength model between UHPC-CA and steel bar

The bond property is the basis of the bear collectively load between the steel bar and Ultra-High Performance Concrete with Coarse Aggregate (UHPC-CA). In this paper, the theoretical calculation method of bond strength between UHPC-CA and high-strength steel bar is studied. The chemical adhesion strength, friction coefficient, and mechanical interlock process of the two were investigated respectively through the refined bond property tests. The failure model is established from the interlock failure characteristics, and the bond strength is obtained theoretically. Results show that the chemical adhesion strength and friction coefficient between UHPC-CA and steel bars are 0.07MPa and 0.5, respectively. The friction coefficient between UHPC-CA is 1.15. The interlock failure process of UHPC-CA and steel bars can be divided into three stages: uncracked stage, crack development stage, and split stage. The crack develops at an angle of 52° to the steel bar's axis and tends to stagnate at a height of 4.5 times the rib. A theoretical bond strength model is established and it is proved that the model is applicable not only to UHPC-CA but also to UHPC. This study can provide a theoretical basis for determining the anchorage length of steel bars in the design of UHPC-CA/UHPC structure, and can also provide a reference for the formulation of relevant standards.

Copper Oxide Nanoparticles Loaded in Adhesive to Carious Dentin. An In Vitro Study Assessing μTBS, Degree of Conversion, EDX, and SEM

This In Vitro study investigated the effects of incorporating copper nanoparticles (CuNPs) into an etch-and-rinse (ER) adhesive on the survival rate of Streptococcus mutans (S. mutans), micro tensile bond strength (μTBS), and degree of conversion (DC) when applied to carious dentin. Mandibular teeth with carious lesions were selected, and S. mutans was inoculated on carious-affected dentin (CAD). The samples were divided into four groups based on the concentration of CuNPs in the OptiBond FL primer: Group 1 had unmodified ER adhesive, Group 2 had 0.1 wt% CuNPs, Group 3 had 0.5 wt% CuNPs, and Group 4 had 1 wt% CuNPs. The survival rate of S. mutans was assessed, and the samples were restored to evaluate μTBS and failure modes. The DC was measured using Fourier Transform Infrared Spectroscopy (FTIR). Statistical analysis using ANOVA and Tukey tests determined significant differences across groups in antibacterial efficacy, μTBS, and DC. The results indicated that the 1 wt% CuNPs group (Group 4) exhibited the lowest bacterial survival, while the unmodified ER adhesive group (Group 1) showed the highest S. mutans survival. The highest bond strength to the CAD was observed in the 0.5 wt% CuNPs group (Group 3), with Group 1 demonstrating the lowest μTBS. These findings suggest that incorporating CuNPs into an ER adhesive system, particularly at a concentration of 0.1 wt%, can effectively provide antimicrobial properties to the adhesive interface while simultaneously enhancing bond strength and achieving a favorable degree of conversion with carious-affected substrates.

Automated repair of asphalt pavement cracks and potholes utilizing 3D printing and LiDAR scanning

This study introduces a method for automatic repair of asphalt pavement cracks and potholes using 3D printing and LiDAR scanning. A scanning method was developed to accurately detect and represent cracks and potholes in a 3D model. To address the limitations of LiDAR scanning, such as missing data points caused by the irregular shapes of cracks and potholes, the screened Poisson method was applied to reconstruct the missing data points. These models were validated through both theoretical calculations and sand test. In addition, the research focuses on optimizing key 3D printing parameters, such as printing temperature and printing speed, to enhance performance of crack repair throughout semi-circular bending test. Direct tensile strength test was employed to assess the impact of waste materials (e.g., rubber tire powder and waste glass) on the bond strength of filled sample. The results indicated a volume difference of 2–5 % between the scanning method and the sand test method, demonstrating high accuracy in detecting and reconstructing 3D cracks/potholes. Binders modified with 10 % rubber tire powder, or 20 % waste glass exhibited the highest tensile strength of 212 kPa and 207 kPa, respectively. However, using more than 30 % waste materials is not recommended due to a significant reduction in bond strength compared to conventional binders. An optimal 3D printing speed of 180 mm/min and a temperature of 117 °C are recommended for use in 3D printing in laboratory conditions. It was also noted that higher printing speeds decrease indirect tensile strength, highlighting the importance of balanced parameter settings.

Glass Ionomer Modified with Bacterial Cellulose Nanocrystals. An In Vitro Analysis Assessing Shear Bond Strength and Microleakage Scores in Deciduous Dentition

The aim of this study was to evaluate the shear bond strength (SBS) and microleakage of bacterial cellulose nanocrystals (BCNCs) incorporated into conventional glass ionomer cement (CGIC) when bonded to deciduous dentin. Sixty primary first and second molars with class I cavitated dentinal lesions were preserved and randomly allocated into two groups based on the technique used for caries removal. Group 1 utilized the conventional approach for caries removal, while Group 2 used Carie Care™ for caries removal. Each of these groups was further divided into two subgroups based on the type of restoration received. Microleakage and failure mode assessments were performed using a stereomicroscope, while SBS testing was conducted using a universal testing machine. The SBS and microleakage scores were analyzed using one-way analysis of variance (ANOVA) and Tukey post hoc test with a significance level of p=0.05. Specimens from Group 1A (conventional approach+CGIC) presented the highest scores of marginal leakage, while Group 1B (conventional approach+BCNCs-modified CGIC) demonstrated the lowest values of microleakage. Additionally, samples from Group 2B (Carie Care™+BCNCs-modified CGIC) revealed the highest bond integrity scores. The incorporation of BCNCs into CGIC had a positive impact on both shear bond strength and marginal leakage when bonded to the dentin substrate. This modification improved the performance of the glass ionomer cement, enhancing its applicability in dental restorations.

Assessment of clinical performance of universal adhesives versus other adhesive systems: A systematic review and meta-analysis of clinical trials

Universal adhesives (UAs) often exhibit comparable or even superior bond strength to traditional adhesive systems, ensuring reliable and long-lasting adhesion between the resin composite and the tooth structure. Therefore, this study aimed to assess the clinical performance of UAs compared to other adhesive systems in direct resin composite restorations through a systematic review and meta-analysis. Two reviewers executed a literature search in five electronic databases: PubMed, EMBASE, Scopus, Web of Science, and Scielo. Clinical trials comparing the clinical evaluation of resin composite restorations in Class I, Class II, or Class V cavities placed with an universal adhesive (UA) system against resin composite restorations placed with another non-UA system were included in the review. An analysis was carried out using Review Manager software version 5.3.5 (London, England, United Kingdom). Standardized effect sizes with 95% confidence intervals were calculated to allow comparisons between different interventions and different outcomes. The methodological quality of each study was assessed using the Cochrane RoB2 tool for randomized clinical trials. A total of 2331 potentially relevant studies were identified. After title and abstract examination, 14 studies remained in the systematic review. From these, a total of 11 studies were included in the meta-analysis. The retention rates of resin composite restorations after 6 months showed no significant difference between total-etch (TE, p=0.83), or self-etch (SE, p=0.78) adhesives and UAs applied in TE and SE modes (p>0.05). However, UAs applied in selective-enamel etching (SEE) mode demonstrated superior clinical performance compared to other adhesives (p=0.01), particularly TE adhesives (p=0.02). Similarly, after >12 months of follow-up, there were no significant differences in retention rates among different adhesive modes (p>0.05). Additionally, the incidence of secondary caries did not significantly differ across adhesive modes at both 6-month and >12-month evaluations (p>0.05). This systematic review and meta-analysis suggested that UAs demonstrate comparable clinical performance to TE and SE adhesive systems in direct resin composite restorations, particularly in terms of restoration retention rates and the incidence of secondary caries. UAs applied in SEE mode exhibited superior clinical outcomes compared to other adhesive systems. These findings indicate that UAs can be considered a viable alternative to traditional adhesive systems in clinical practice, offering flexibility in application while maintaining comparable long-term outcomes.

Bond-slip Behavior of Lapped Sand-Coated Deformed GFRP Rebars in UHPC under Double-Row Splice Test

Novel Ultra-High-Performance-Concrete (UHPC) structures reinforced with Fiber-Reinforced Polymer (FRP) rebars are promising candidates for applications in important infrastructures under exposed environments where normal concrete and steel rebars may falter. This paper aims to assess the bond-slip behavior between lapped sand-coated deformed Glass FRP (GFRP) rebars and UHPC using double-row splice tests, with parameters including bar diameter, splice length and lap clearance. Failure modes including the pullout of GFRP rebars and the splitting of UHPC were identified. For cases of pullout failure, the average bond strengths in samples with splice lengths of 5db were reduced by 17.6-22.1% compared to those of 2.5db. Increasing the lap clearance from 0 to 1db and 2db led to 11.1% and 30.2% increases in average bond strengths. Furthermore, average bond-slip models for lapped sand-coated deformed GFRP rebars in UHPC were developed. The predicted curves matched the experimental ones, showing errors within 20% for both average bond stresses and slips. When the cover is not less than 2db, the splice length is recommended to be at least 15db for sand-coated deformed GFRP rebars with diameters of 10mm to 16mm in UHPC, approximately 1.25 times the corresponding development length proposed by the existing research.

An efficient deep learning approach for ultimate bond strength estimations of corroded bar and concrete

Abstract The corrosion behavior of the reinforced concrete structure depends heavily on the interfacial bond behavior between steel and concrete. Over the years, the deterioration of integrated reinforced steel has weakened this bond and potentially led to structural problems. Conventional methods of bond strength evaluation, such as pullout and bond beam tests, is frequently intrusive and tedious. Therefore, there is a growing need for non-intrusive, effective, and reliable forecasting algorithms capable of assessing bond deterioration caused by corrosion. Traditional algorithms for predicting bond strength make it difficult to capture the complex nature of steel-concrete bonds. The present study proposes two different deep learning algorithms, i.e., convolutional neural networks (CNN) and long short-term memory (LSTM), for predicting maximum bond strength in the presence of corrosion. The predictive model is based on a comprehensive dataset comprising 218 datasets from previous studies encompassing diverse input and output variables for predicting the models. The models were trained and tested using the given data to improve early predictions of corrosion-induced bond degradations. The predictive model’s effectiveness was assessed by applying various performance metrics. From this study, the CNN model exhibits higher accuracy and efficiency with mean absolute error, root mean square error, and mean absolute percentage error of 0.25, 0.28, and 95.72, respectively, for predicting ultimate bond strength estimations. The findings of this study provide an accurate and robust prediction model to improve the reliability and safety of the concrete structure by enhancing the residual load-bearing capacity of the concrete structure that has undergone corrosion.

Data and Molecular Fingerprint-Driven Machine Learning Approaches to Halogen Bonding.

The ability to predict the strength of halogen bonds and properties of halogen bond (XB) donors has significant utility for medicinal chemistry and materials science. XBs are typically calculated through expensive ab initio methods. Thus, the development of tools and techniques for fast, accurate, and efficient property predictions has become increasingly more important. Herein, we employ three machine learning models to classify the XB donors and complexes by their principal halogen atom as well as predict the values of the maximum point on the electrostatic potential surface (VS,max) and interaction strength of the XB complexes through a molecular fingerprint and data-based analysis. The fingerprint analysis produces a root-mean-square error of ca. 7.5 and ca. 5.5 kcal mol-1 while predicting the VS,max for the halobenzene and haloethynylbenzene systems, respectively. However, the prediction of the binding energy between the XB donors and ammonia acceptor is shown to be within 1 kcal mol-1 of the density functional theory (DFT)-calculated energy. More accurate predictions can be made from the precalculated DFT data when compared to the fingerprint analysis.

Analysis of the Impact and Mechanism of Polyacrylate-Based Composite Paste on the Performance of Recycled Aggregate

This study developed three composite slurries for coating recycled aggregate by incorporating polyacrylate emulsion, fly ash, and gypsum into a cement-based mixture. The filling and pozzolanic effects of fly ash help to improve microcracks in the recycled aggregates. The polyacrylate emulsion forms a strong bonding layer between the cement matrix and the aggregates, enhancing the interfacial bond strength. Based on relevant studies, the following mix designs were developed: Slurry 1 consists of pure cement paste; Slurry 2 contains 15% fly ash and 3% gypsum added to the cement paste; Slurry 3 adds 22% polyacrylate emulsion to the slurry. The study first compared the effects of the three composite slurries on the crushing value and water absorption of recycled aggregates, and then analyzed their impact on the mechanical properties, permeability, and drying shrinkage of concrete. Finally, the mechanisms behind the enhancement were investigated using the Vickers Hardness Test (HV), Mercury Intrusion Porosimetry (MIP), and scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS). The results showed that the polyacrylate emulsion composite slurry had the most significant improvement effect. For recycled aggregate AL, the crushing value decreased from 28.8% to 22.5% and the saturated surface–dry water absorption decreased from 15.1% to 13.8% after cement slurry modification. After coating with the composite slurry, the crushing value further dropped to 18.2% and the water absorption to 9.5%. Two aspects of the performance of recycled aggregates are enhanced with the polymer composite slurry: first, fly ash provides nucleation sites for CH, reducing the tendency for directional CH alignment. Second, the long chains of PAE (polyacrylic ester) encapsulate cementitious particles, effectively filling surface defects on the recycled aggregates, improving the bonding strength at the new-to-old interface, and significantly enhancing the performance of both recycled aggregates and recycled concrete.

Research Progress of Human Biomimetic Self-Healing Materials.

Humans can heal themselves after injury, which inspires researchers to develop bionic self-healing materials. Such materials not only equipped with the self-repair capacities akin to those of the human body, but also emulate the mechanical properties of human organs, including the tensile resilience of muscles, the fatigue resistance of skin, and the elevated modulus typical of cartilage. Based on the design concept of imitating the structure of human organs, the bionic self-healing material perfectly solves the problem of poor mechanical properties of self-healing materials caused by weak bond energy and inter-chain flow. This review discusses various organ-inspired self-healing materials in detail, summarizes their synthetic principles and introduces their fascinating mechanical properties. Finally, the application prospects of bionic self-healing polymer materials, such as bio-strain sensors, self-healing anticorrosive coatings, biomedical detection, etc., are outlined. Considering the excellent comprehensive performance and multi-functions of human biomimetic self-healing polymers, more outstanding sustainable materials will be developed, accelerating research progress in self-healing materials and realizing environmentally friendly products in multiple fields.

Bond strength of resin-based restorative materials to fast-setting calcium silicate cement using different resin adhesive systems.

This study assessed the bond strength of resin-based restorative materials to fast-setting calcium silicate cement (Aarhus Uinversity, Denmark) when treated with each of two one-bottle universal adhesive systems. The cement surface (N=256) was treated with a self-priming adhesive and a self-etch phosphate monomer-containing adhesive with and without etching of the cement surface. Specimens then received either resin composite or compomer restorative materials (n=32). The bond strength was measured after 1 day and 1500 thermocycles (n=16). The failure type was visually inspected. The cement-adhesive-restorative material interface was visualized using scanning electron microscopy (SEM). The data were analyzed using multiple linear regression. Restorative material type, resin adhesive system, and thermocycling had a statistically significant effect on the bond strength. Compomer restorative material and self-etch universal adhesive system demonstrated statistically significantly higher bond strength values to fast-setting calcium silicate cement, predominantly exhibiting cement cohesive failure. Etching the cement surface enhanced the bond strength of the self-priming universal adhesive. Thermocycling significantly reduced the bond strength. SEM showed self-etch universal adhesive seemingly diffused over the etched cement surface compared to other groups. Self-etch phosphate monomer-containing universal adhesive and compomer resulted in the highest bond strength to fast-setting calcium silicate cement.

The Effect of Silver Nanoparticles on Bond Strength of Calcium Silicate-Based Sealer: An In Vitro Study

The aim of this study was to evaluate the bond strength of the calcium silicate-based sealer (CSS) modified with the silver nanoparticles (AgNPs) using the single-cone technique (SC) and the continuous wave condensation (CWC) technique, measured by a universal testing machine. The AgNPs and the modified sealers were characterized by scanning electron microscopy and transmission electron microscopy. One hundred single-rooted extracted human permanent teeth with a single root canal were cleaned and shaped with a Protaper Next system. The teeth were randomly divided into four groups (n = 25) as follows: Group 1, canals were obturated using the SC technique with TotalFill® BC Sealer. Group 2, canals were obturated using the SC technique with TotalFill® BC Sealer mixed with AgNPs. Group 3, canals were obturated using the CWC technique with TotalFill® HiFlow BC Sealer. Group 4, canals were obturated using the CWC technique with TotalFill® HiFlow BC Sealer mixed with AgNPs. After two weeks, 1 mm-thick dentin slices were cut and exposed to a push-out bond strength test using a universal testing machine. Specimens were examined under a digital microscope to determine the mode of failure. Statistical analysis was performed using ANOVA and Tukey multiple comparison tests (p < 0.05). The nanoparticle characterization revealed a spherical morphology with no obvious aggregations. The results showed that group 4 had the highest dislodgement resistance compared to all groups (p < 0.05). Group 4 was significantly higher in push-out bond strength value than group 1 (p < 0.001) and group 3 (p < 0.003), but not significantly higher than group 2. Cohesive failure was the most prevalent failure mode among all groups. It can be concluded that the incorporation of silver nanoparticles into the calcium silicate-based sealer significantly increased the bond strength. The warm obturation approach demonstrated significantly higher resistance to dislodgment as compared to the single-cone technique.

Development of Biodegradable and Recyclable FRLM Composites Incorporating Cork Aggregates for Sustainable Construction Practices

Reducing energy consumption in the building sector has driven the search for more sustainable construction methods. This study explores the potential of cork-modified mortars reinforced with basalt fabric, focusing on optimizing both mechanical and hygroscopic properties. Six mortar mixtures were produced using a breathable structural mortar made from pure natural hydraulic lime, incorporating varying percentages (0–3%) of cork granules (Quercus suber) as lightweight aggregates. Micro-computed tomography was first used to assess the homogeneity of the mixtures, followed by flow tests to evaluate workability. The mixtures were then tested for water absorption, compressive strength, and adhesion to tuff and clay brick surfaces. Adhesion was measured through pull-off tests, to evaluate internal bonding strength. Additionally, this study examined the relationship between surface roughness and bond strength in FRLM composites, revealing that rougher surfaces significantly improved adhesion to clay and tuff bricks. These findings suggest that cork-reinforced mortars offer promising potential for sustainable construction, achieving improved hygroscopic performance, sufficient mechanical strength, internal bonding, and optimized surface adhesion.

A 3D Robust and Microporous B←N Framework with 8‐connected Sandwich Nodes for Efficient Separation of Hexane Isomers

Recently B←N organic frameworks (BNFs) have gained substantial attention owing to their unique dative bond energy, which imparts them with specialized functionalities across a broad spectrum of applications. Despite previous reports on BNFs with permanent porosity, research endeavors towards three‐dimensional (3D) BNFs with similar properties are scarce, with no report of robust 3D BNFs featuring permanent porosity to date. Herein, electrostatic complementarystrategy is proposed to construct the first example of 3D robust and microporous BNF, BNF‐100, featuring a reo topology with 8‐connected sandwich nodes assembled via dative B←N bonds. The activated form BNF‐100a exhibits excellent chemical stability and permanent porosity with Langmuir surface area of 645.9 m2 g−1 and pore volume of 0.23 cm3 g−1. BNF‐100a can efficiently separate hexane isomers through sieving mechanisms, as confirmed by vapor adsorption experiments and dynamic breakthrough tests, surpassing the performance of most MOF materials. Finally, we achieved the purification of different branched hexane isomers using a single breakthrough column in a combined breakthrough and purging experiment, which is the first reported instance in the literature on hexane isomer separation.

A 3D Robust and Microporous B←N Framework with 8-connected Sandwich Nodes for Efficient Separation of Hexane Isomers.

Recently B←N organic frameworks (BNFs) have gained substantial attention owing to their unique dative bond energy, which imparts them with specialized functionalities across a broad spectrum of applications. Despite previous reports on BNFs with permanent porosity, research endeavors towards three-dimensional (3D) BNFs with similar properties are scarce, with no report of robust 3D BNFs featuring permanent porosity to date.Herein,electrostatic complementarystrategyisproposedto constructthe first example of3Drobust and microporousBNF,BNF-100, featuring areotopology with 8-connected sandwich nodes assembled via dative B←N bonds. The activated formBNF-100aexhibits excellent chemical stability and permanent porosity with Langmuir surface area of 645.9 m2g-1and pore volume of 0.23 cm3 g-1.BNF-100acan efficiently separate hexane isomers through sieving mechanisms, as confirmed by vapor adsorption experiments and dynamic breakthrough tests, surpassing the performance of most MOF materials.Finally, we achieved the purification of different branched hexane isomers using a single breakthrough column in a combined breakthrough and purging experiment, which is the first reported instance in the literature on hexane isomer separation.

Ce-Doped Iron Oxide Anticorrosive Coatings: Effect of c(Ce4+):c(Fe3+) Ratio on Structure, Morphology, and Coating Anticorrosion Performance

Utilizing hydrothermal methods, Ce-doped iron oxide nanoparticles were synthesized from precursor solutions under different c(Ce4:c(Fe3+) precursor solutions. The effects of the c(Ce4+):c(Fe3+) ratio in the precursor solutions on the nanoparticle morphology and nanoparticle structure of the Ce-doped iron oxide were investigated using X-Ray diffraction, transmission electron microscopy, and scanning electron microscopy. Fourier transform infrared spectroscopy (FTIR) was used to examine the bond energy strength of the Ce-doped iron oxide nanoparticles. The electrochemical properties of the Ce-doped iron oxide nanoparticles were tested using an electrochemical workstation and a saltwater immersion resistance test. The corrosion resistance of Ce-doped iron oxide coatings at different c(Ce4+):c(Fe3+) ratios was systematically analyzed, uncovering corrosion resistance mechanisms and self-healing capabilities. The results show that as the c(Ce4+):c(Fe3+) ratio decreases, the lattice constants of the samples increase along with the average grain size. Both smaller and larger c(Ce4+):c(Fe3+) ratios are detrimental to lattice distortion in α-Fe2O3. The reduced number of valence electrons provided by cerium ions in Ce-doped iron oxide hinders the generation of holes and exerts a minor influence on the crystal band structure, leading to weaker electrochemical stability. The Ce-doped iron oxide coating prepared at a c(Ce4+):c(Fe3+) ratio of 1:60 readily generates a higher number of reactive hydroxyl radicals during corrosion, thus exhibiting enhanced self-healing capabilities and corrosion resistance.

Acid-etching protocol for bioceramic cements: Evaluation of bond strength, compression and morphology.

To establish an acid-etching protocol for Biodentine and Cimmo DTA, evaluating compressive strength, bond strength, surface morphology in scanning electron microscope and failure modes after different etching times. Two test specimens were prepared for each cement and divided into four groups (n = 12) according to the acid-etching time (0, 5, 10 and 15 s). Compressive strength was tested using a universal testing machine, while bond strength was evaluated after bonding with Filtek Bulk Flow resin using Universal ESPE Single Bond adhesive. Failures were classified as surface-adhesive, cement-cohesive, resin-cohesive and mixed. Biodentine showed significantly higher compressive strength than Cimmo DTA (p < 0.001), regardless of acid etch time (p < 0.001). Different acid-etching strategies are required for Biodentine and Cimmo DTA, with Biodentine requiring selective etching and Cimmo DTA requiring a full 15-s etch to optimise bond strength properties.

Fiber post cemented using different adhesive strategies to root canal dentin obturated with calcium silicate-based sealer

BackgroundCalcium silicate-based sealer has favorable properties for root canal filling, including hydroxyapatite formation during the setting process. However, this process can cause difficulty during post space preparation when the sealer is set. Additionally, the remaining sealer could interfere with the bond strength of fiber post to root canal dentin. The different adhesive strategies and fiber post cementation time may affect the bond strength of the fiber post. Thus, the objective of this study was to evaluate the effect of etching modes of Scotchbond™ Universal Plus adhesive and post cementation time on the push-out bond strength of a fiber post cemented in root canals obturated with calcium silicate-based sealer.MethodsFifty-four teeth were randomly allocated to 6 groups (n = 9) based on etching modes: self-etch (SE) or etch-and-rinse (ER); post space preparation and cementation time: immediate (Im) or 7-day delayed (De): Im-Im, Im-De, and De-De. The root canals were obturated with calcium silicate-based sealer and the post space preparation was performed. The fiber post was cemented using RelyX™ Universal resin cement according to each group’s design. For the push-out bond strength test, 1-mm slices of the coronal, middle, and apical regions were tested using a universal testing machine. The failure mode analysis was determined using a stereomicroscope. The data was analyzed with three-way analysis of variance.ResultsNo negative effects of etching modes, post space preparation or cementation time on push-out bond strength were detected (p > 0.05). Additionally, the root canal region also did not significantly affect the bond strength (p > 0.05).ConclusionNo significant differences were observed between the etching modes, post space preparation and cementation time and among root canal regions.Clinical relevanceThe different etching modes of adhesive and post cementation time did not affect the bond strength of fiber post in calcium silicate filled-root canal.

Effectiveness of self-etching bonding systems on dentin after radiotherapy: perspectives on microtensile and microshear bond strength.

Self-etching dental adhesives bond with dentin through chemical reactions with calcium. This study assessed bond strength (BS) using microtensile (µTBS) and microshear (µSBS) tests on sound and post-radiotherapy dentin, with dental adhesives containing different functional monomers. Sound dentin (SD) and post-radiotherapy irradiated dentin (ID) were tested with two adhesive systems: Clearfil SE Bond (SE, 10-MDP-based) and FL Bond II (FL, containing carboxylic and phosphonic monomers with S-PRG bioactive particles). The tests occurred initially (24h) and six months later; fracture mode was also analyzed (40x). Ninety-six human molars were randomly assigned (n = 12), and half were irradiated with a 70Gy radiation dose. ForµTBS test, teeth were bonded,restored and sectioned them into beams (0.64 mm2). The µSBS test used filled transparent cylindrical matrices with resin composite and light-cured them after dental adhesive applications. Three-way ANOVA and Tukey's test (p < 0.05) analyzed the data. µTBS showed a significant substrate x adhesive interaction (p < 0.001), while µSBS was significant for all factors (p = 0.006). SE and FL performed better on SD and ID, respectively, in the µTBS test. As for µSBS, SE showed higher values on ID (p < 0.05). Lower BS values occurred for SD-FL and ID-SE after six months. Dental adhesive performance varied based on substrate type and test method. FL was more stable for ID in µTBS, while SE excelled in µSBS. As post-radiotherapy irradiated dentin becomes more vulnerable, self-etching systems based on functional monomer and bioactive ingredients may exhibit appropriate bonding to this altered substrate.