Search Results (109)

Background: There are very few studies in literature concerning the bonding between 3D-printed resin posts and the core build-up material. This study aimed to evaluate and compare the adhesion of 3D-printed and milled resin posts to composite resin core build-up material following different surface treatments. Methods: Three types of resin posts were utilized in this study: ready-made glass-reinforced fiber post (3M ESPE, Germany), milled PEEK POST (Bredent, Germany), and 3D-printed resin post (CROWNTEC, Saremco Dental AG, Switzerland). Each type of post was categorized into three groups based on surface treatments: C: untreated surfaces; SB: Air abrasion with 50 μm aluminum oxide particles was applied to the posts’ surfaces.; HO: the posts’ surfaces were immersed in 30% H₂O₂ for 5 min. A dual-cured composite resin (Grandio DC; VOCO) was utilized for core build-up in each group to evaluate adhesion through the push-out bond strength test. The modes of failure were analyzed, and the surface morphology of the post was characterized using SEM. Data were analyzed using a two-way analysis of variance (ANOVA) along with Tukey’s test. Results: The two-way ANOVA indicated a significant effect for surface treatment (F = 583.54, p < 001), post type (F = 79.96, p < 0.001), and their interactions (F = 265.74, p < 0.001). Regarding 3D-printed resin post, 30% H₂O₂ for 5 min recorded the highest statistically significant bond strength value (13.11 ± 1.61) compared to other groups. Regarding the milled PEEK post, the air particle abrasion recorded the highest statistically significant value (23.88 ± 1.66) compared to other groups. Adhesive failure was the predominant failure type, with an occurrence rate of 70.35%. Mixed failure was noted in 24.07% of the cases, with a significant prevalence in the PEEK post within the air particle abrasion group (58.3%). Cohesive failure was noted in 5.54% of cases, with a significant prevalence in the air particle abrasion group, occurring at rates of 16.6% in the resin fiber post group and 33.3% in PEEK posts. Conclusions: Air particle abrasion significantly improved the push-out bond strength of milled PEEK posts, but it did not have a similar effect on the 3D-printed resin posts. The application of 30% H₂O₂ for 5 min to 3D-printed resin post enhanced the adhesion to core build-up material. The manufacturing method of posts, the surface treatments utilized, and their interactions affect the interfacial bond strength between posts and the composite resin core build-up material. Full article

This study evaluated the effects of mechanical agitation of Aloe vera Barbadensis Miller solution at different concentrations using passive ultrasonic irrigation (PUI), XP Endo Finisher (XPF), XP Clean (XPC), and Easy Clean (ECL), compared to conventional endodontic irrigation (CIE), on bond strength and adhesive failure patterns in the cervical, middle, and apical thirds of the root canal. Aloe vera solutions at 1%, 3%, and 5% were tested to reverse collagen fiber collapse induced by hypochlorous acid, a free radical released by 2.5% sodium hypochlorite, which impairs dentin hybridization and the light curing of resin cement. Fiberglass posts were cemented using an etch-and-rinse adhesive system (Ambar; FGM) and conventional dual resin cement (Allcem Core) in root dentin across all thirds. Human teeth underwent chemical–mechanical preparation, and the Aloe vera solution was agitated using the CIE, PUI, XPF, XPC, or ECL protocols. Slices from each root third were evaluated under a stereomicroscope at 10× magnification and subjected to the push-out test. Cytotoxicity was assessed by applying various Aloe vera concentrations to stem cells from the apical papilla (SCAPs) for 24 h, followed by analysis of cell metabolism (Alamar Blue), viability (Live/Dead), and proliferation (F-actin). Aloe vera demonstrated significant biological activity and enhanced bond strength, particularly at 3% and 5%, irrespective of the agitation method or root third. Thus, it can be concluded that using Aloe vera solution is an alternative for pre-treatment before the cementation of fiberglass posts with conventional dual-cure resin cement in endodontically treated dentin. Full article

Purpose: The aim of this in vitro study was to investigate the adhesive bond strength of glass fiber posts when cemented with universal resin cement in two different adhesion modes: adhesive and self-adhesive. Methods: A total of 20 extracted single-root teeth were endodontically treated, decoronated and prepared to receive glass fiber posts (GFPs) with a diameter of 1.6 mm (RelyX fiber post 3D). Specimens were randomly divided into two groups: (G1) GFPs were cemented using RelyX Universal cement in self-adhesive mode, and (G2) GFPs were cemented using Scotch Bond Universal Plus and RelyX Universal cement (adhesive mode). Afterwards, the specimens were sliced at three root levels: coronal, middle and apical. Bond strength was measured using a push-out test. Data were analyzed with a two-way analysis of variance (ANOVA) test and independent sample T-test. Results: Bond strength was significantly influenced by the adhesive strategy (p < 0.025) and the position of the root third (p < 0.007). Microscopic analysis of failure mode revealed a higher prevalence of adhesive failures (cement–dentine). Conclusions: Glass fiber posts cemented with universal resin cement applied in adhesive mode showed significantly higher push-out bond strength than when applied in self-adhesive mode. In both study groups, the apical root regions exhibited the highest retention values, followed by the middle and coronal regions. Full article

The calcium silicate-based sealers currently available on the market have different compositions and formulations, which is why their physical and chemical properties may vary. (1) The aim of the study was to measure the physico-chemical properties of calcium silicate-based sealers and their push-out bond strength to root dentine, comparing two push-out testing protocols. (2) Standardized specimens of EndoSequence BC, BioRoot RCS, MTA Fillapex, and AH Plus (control) were subjected to pH measurements over 28 days. Radiopacity was measured using a CCD sensor, and flexural strength was assessed using a three-point bending setup. Push-out bond strength was measured in coronal, middle, and apical sections of 40 single-root teeth (conventional method), and cylindrical cavities were prepared for all sealers on the same root dentine disks in 11 third molars (disk method). (3) EndoSequence BC exhibited a higher pH than MTA Fillapex and the highest radiopacity (p < 0.05). The highest flexural and push-out bond strengths were found for AH Plus. The push-out bond strength of EndoSequence BC and BioRoot RCS was higher than MTA Fillapex (p < 0.05). The conventional and disk methods exhibited similar push-out bond strength results, but the data were more homogeneously distributed in the disk method. (4) All calcium silicate-based sealers exhibited a higher pH than AH Plus. MTA Fillapex did not meet the ISO standard. Calcium silicate-based sealers showed weaker performance in terms of physical properties compared to AH Plus. Full article

Background/Objectives: The primary purpose of the study is to investigate the bond strength of apical fillings following retreatment in teeth with failed apical resection. Methods: After the preparation and obturation of the 120 human upper central and canine teeth, apical 3 mm was resected and separated into two main groups to prepare retrograde cavities using tungsten carbide burs or ultrasonic retro-tips. Each main group was separated into three subgroups according to retrograde filling material (Glass ionomer cement, MTA and Biodentine), and each subgroup was divided according to placement technique: manual condensation and indirect ultrasonic vibration. After the retrograde filling, retreatment procedures were performed, and 2 mm sections were removed from the apical filling and analyzed for push-out test. A Kolmogorov–Smirnov test was used to check the normal distribution of the data while Levene’s test was used to check the homogenity of group variances. The data were analyzed using three-way ANOVA. Results: The analysis of variance demonstrated a significant difference between cavities prepared with tungsten carbide and ultrasonic retro tips in push-out bond strength. Conclusions: There was no effect on the bond strength of the retrograde filling material and the placement technique of the material. Full article

The number of resin cements marketed for fiber post cementation has increased significantly. This study compared the push-out bond strength (PBS) of self-adhesive and universal resin cements used to lute fiber posts at 24 h and after 6 months of aging in artificial saliva. Fiber posts were luted to eighty human roots endodontically treated with four self-adhesive/one-step resin cements, with one of them also used in combination with its appropriate tooth primer; one universal resin cement, applied as one-step or together with its corresponding universal adhesive (multi-step); and one adhesive/multi-step resin cement, as a control. After storage (24 h or 6 months), the interfaces were subjected to PBS tests and the data were analyzed by two-way ANOVA and Tukey and Student’s t-tests (p < 0.05 defined as statistical significance). The results showed that Scotchbond Universal Plus + RelyX Universal attained statistically higher values at 24 h and 6 months. At 24 h, all resin cements yielded similar PBS to root dentin, while at 6 months, NormoCem obtained the lowest PBS. Storage for 6 months significantly decreased PBS for NormoCem and Multilink Automix. Root section did not influence PBS regardless of storage time. It was concluded that PBS is resin cement dependent. The universal resin cement, RelyX Universal, applied in combination with Scotchbond Universal Plus adhesive, obtained a higher and more stable PBS than the other resin cements tested. Full article

Strengthening reinforced concrete (RC) buildings is a critical challenge in the construction industry, pushed by the necessity to address aging infrastructure, environmental degradation, and growing use requirements. Ultra-high-performance fiber-reinforced concrete (UHPFRC) is one of the advanced materials that present a viable solution owing to its exceptional durability and mechanical characteristics, which encompass higher compressive and tensile strengths, low permeability, and resilience against intense environmental as chloride ingress, cycles of freeze–thaw, and chemical assaults. This literature review comprehensively examines UHPFRC as a rehabilitation or strengthening mix material for the RC slabs and beams. Experimental key subjects include the influence of bonding techniques, strengthening configurations, steel fiber ratios, UHPFRC thickness, and reinforcing steel within the UHPFRC layer. In addition, the existing numerical and analytical approaches for forecasting the flexural or shear capability of reinforcing concrete structures retrofitted with UHPFRC were examined and critically assessed. Despite the improvements in the RC structures achieved through experiments utilizing UHPFRC as a reinforcement layer, this study highlights some deficiencies in the existing knowledge, such as the absence of effective ways to address debonding, insufficient research on cyclic loading, and the necessity for economical and sustainable strengthening techniques. This review establishes a basis for future research, intending to create an innovative UHPFRC-based strengthening system that mitigates current limits and improves the overall efficacy, performance, and durability of RC structures. Full article

Background: The optimum bond strength of glass fiber posts can be compromised; it has not yet been established which final irrigant, when used in combination with luting cement, can improve this bond strength. Objectives: This study assessed the effectiveness of 2% chitosan as a final irrigant in combination with different types of luting cement used to improve the bond strength of glass fiber posts bonded to root canal-treated teeth. Methods: Thirty single-rooted anterior teeth were collected and sectioned 2 mm above the most incisal point of the cementoenamel junction. After root canal filling, post spaces were prepared and irrigated in Group I using 17% EDTA for 3 min and in Group II using 2% chitosan for 3 min. Each group was divided into three subgroups: Fiber posts were cemented in subgroup A with Fuji II Cement (resin-reinforced glass ionomer cement), in subgroup B with RelyX Unicem (self-adhesive resin cement), and in subgroup C with Metacem Refill (total-etch resin cement). Push-out bond strength (N) for each sample was measured using a universal testing machine, and the failure mode was assessed with a stereomicroscope at 30× magnification. The fiber post’s morphological structure was analyzed through scanning electron microscopy. Statistical analysis included one-way ANOVA followed by Tukey’s post hoc test in the case of significant differences between the groups. p-Values less than 0.05 were considered statistically significant. Results: This study found no statistically significant difference between using 17% EDTA and 2% chitosan as the final irrigant before post placement (p > 0.05). RelyX Unicem cement showed significant bonding strength when used with 2% chitosan in the coronal, middle, and apical thirds (p = 0.009, p = 0.02, p = 0.01, respectively). Conclusions: Chitosan at 2% can be considered a good alternative to 17% EDTA when used as a final irrigant for the post space. Full article

This study evaluated the effect of resin cements and post-space irrigation solutions on the push-out bond strength of diabetic and non-diabetic dentin. A total of 160 human central teeth (80 diabetic, 80 non-diabetic) were prepared using X5 files and obturated with AH Plus sealer and X5 gutta-percha. Post spaces were prepared, and teeth were divided into eight groups based on resin cements (Variolink N, Panavia SA Universal) and irrigation protocols (saline, saline + 2% CHX). A 1 mm slice from each tooth’s middle third was tested for push-out bond strength. Statistical analysis was performed using three-way ANOVA and Tukey HSD tests. In non-diabetic dentin, saline + CHX with Variolink N achieved the highest bond strength. In diabetic dentin, saline with Panavia SA Universal resulted in the lowest bond strength (p < 0.05). The dentin type, resin cement, and irrigation solution significantly impacted fiber post bond strength, and CHX irrigation improved it. Full article

Background: The aim of this study was to investigate the effects of retro-cavity preconditioning with or without 17% ethylenediaminetetraacetic acid (EDTA) solution on root surface pH as well as dislodgement resistance of NeoMTA2 and MTA Flow retro-fills. Methods: Forty-eight single-rooted human incisors were selected. After completion of endodontic treatment, root-end resections were performed, and retro-cavities were prepared. The samples were randomly divided into two groups of A and B (n = 24 each). In group A, retro-cavities were preconditioned with 2.5% NaOCl, followed by 17% EDTA solution, whereas in group B, preconditioning was performed using 2.5% NaOCl before final irrigation with normal saline. Samples in each group were randomly subdivided into two subgroups of 1 and 2. Retro-fillings in the A1 and B1 subgroups were performed with MTA Flow, and in the A2 and B2 subgroups, they were performed with NeoMTA2. Root surface pH was measured in each sample at three different stages: before preparation of retro-cavities (pH0), after retro-cavity preconditioning (pH1), and three days after retro-filling (pH2). Subsequently, the push-out bond strength (PBS) of the retro-filling materials was measured by a universal testing machine, and their failure modes were visualized under 64× magnification. Results: Preconditioning with EDTA caused a significant increase in PBS for both NeoMTA2 and MTA Flow (p < 0.001). There was no significant difference between the average bond strength of MTA Flow and Neo MTA2 (p = 0.271). There was a significant increase in the average pH2 compared to pH1 and pH0 across all groups (p < 0.001). Specifically, the use of EDTA led to a notable increase in the average pH2 in the MTA Flow group compared to the Neo MTA2 group (p = 0.027). Groups preconditioned with EDTA more frequently indicated a cohesive failure mode. Conclusions: The use of EDTA significantly increased the push-out bond strength of retro-fill materials to dentin. However, it did not prevent the ultimate alkalinity of retro-filled cavities. Full article

The lifecycle of wind turbine blades is around 20–25 years. This makes studies on the reuse of dismantled blades an urgent need for our generation; however, their recycling is very difficult due to the specific makeup of their composite material. In this study, the authors determined a concept for the reuse of turbine blade sections filled with concrete for geotechnical structures, retaining the walls, piles, or parts of their foundations. Working out detailed structural solutions to the above problem should be preceded by the identification of material parameters. In particular, getting to know the interface stress-strain characteristics is crucial. Therefore, this research focuses on the cooperation between recycled FRP composites and concrete in load-carrying, including experiments and numerical analyses. Regarding the two types of destructive stress, which may occur at the interface under both compression and bending, two types of tests were executed: the ‘push-out test’, modelling the interface’s answer to shear stress, and the ‘pull-off test’, demonstrating the interface’s reaction to normal stress. Additionally, the strength parameters of the materials used were tested. The numerical model for the push-out process was calibrated on the basis of the tests, and this way the shear bond strength and the coefficient of friction between the concrete and the recycled FRP laminate were assessed. Full article

Background: Adhesion within endodontic obturation material and root canal walls improves the efficacy of the endodontic treatment by establishing a barrier that inhibits reinfection and entombs residual bacteria. This study evaluates the push-out bond strength (POBS) of calcium silicate sealers compared to an epoxy-resin-based sealer. Methods: A total of 36 extracted mono-radicular teeth were prepared with Pro Taper Ultimate and irrigated with 5.25% sodium hypochlorite and 17% EDTA. The specimens were randomly split into three groups (n = 12) according to the endodontic sealer and filling technique used as follows: Ah Plus with the continuous wave condensation technique (CWC), Ah Bioceramic (Ah Bio) with the single-cone technique, and Total Fill Hi-Flow (FKG Hi-Flow) with the CWC technique. The material was allowed to set for 4 weeks, and afterwards, the roots were placed in acrylic resin and sectioned into 1 mm transverse slices. A POBS test was conducted using a universal testing machine, and the mode of bond failure was assessed at 4× magnification using a stereomicroscope. Six specimens from each group were selected for SEM-EDX examination to evaluate dentinal tubule penetration. The data were analysed using analysis of variance and Tukey and Bonferroni post hoc tests. Results: The POBS tests revealed higher values for Ah Plus in comparison to both calcium silicate sealers (p < 0.001), while FKG Hi-Flow showed superior results to Ah Bio (p < 0.001). The cohesive mode of failure was prevalent in all three groups. Conclusions: In conclusion, the resin-based sealer showed higher bond strength and better dentinal tubule penetration than the two calcium silicate sealers tested, while FKG Hi-Flow outperformed AH Bio. Full article

The bond-slip behavior between cold-formed thin-walled steel (CTS) and foamed concrete (FC) is a critical issue in the mechanical performance of FC-filled CTS composite wall structures. Thus, this study provides experimental and theoretical research on the bond-slip behavior between CTS and FC. A total of eleven specimens were tested using push-out configurations, considering the number of web holes, foamed concrete (FC) strength, anchorage length, and CTS section splice form. A constitutive model for bond-slip was proposed, and the regression formulas for accurately predicting the characteristic bond strength between CTS and foamed concrete were established. A finite element model was developed to investigate the bond-slip mechanism at the interface between CTS and FC. The bond-slip constitutive model accurately fits the experimental and finite element results. The results indicate that the ultimate bond strength of the specimens increases with the number of web holes; when the number of web holes reaches two, the ultimate bond strength is 155.4% of that of the non-perforated specimens. As the concrete strength increases from 3.43 MPa to 11.26 MPa, the ultimate bond strength of specimens with two web holes improves by 23.1%, while non-perforated specimens have a 54.7% enhancement. When the anchorage length is extended from 200 mm to 400 mm, the ultimate bond strength decreases by 29.3%. Additionally, when steel sections are joined in a double-span I form, the bond strength increases by 91.6% and 95.8% compared to the single-span form and the double-span box form, respectively. Full article

The aim of this study was to evaluate the effects of mechanized final irrigation protocols (XPE, XP-Endo Finisher; XPC, XP-Clean; and ECL, Easy Clean) compared to PUI (passive ultrasonic irrigation) on the debris incidence and open dentinal tubules, and their effects on the adhesion interface after 48 h and 6 months. One hundred twenty maxillary central incisors were submitted to chemical–mechanical preparation using a rotary instrument and 2.5% sodium hypochlorite. Specimens were distributed in 4 groups (n = 30) in accordance with the mechanized final irrigation protocol: XPE, XPC, ECL, or PUI. Forty specimens (n = 10/group) were submitted to SEM analysis to evaluate the residue incidence and dentin open tubules. The other specimens were obturated using Bio-C Sealer and submitted to push-out bond strength and adhesive failure mode evaluations in the cervical, middle, and apical thirds after 48 h or 6 months (n = 10/group). Only in the apical third, ECL presented the highest residue incidence and fewer open dentinal tubules when compared to the XPE, XPC, and PUI groups (p < 0.05). In the cervical and middle root thirds, no significant differences were observed regardless of the group evaluated (p > 0.05). After 48 h, ECL resulted in the lowest bond strength only in the apical third (p < 0.05), while the XPE, XPC, and PUI groups remained similar in the cervical and middle thirds (p > 0.05). At 6 months, all groups showed lower bond strength values regardless of the root third evaluated, but ECL showed the lowest bond strength in the apical and middle root thirds when compared to the other groups (p < 0.05). The ECL protocol did not provide adequate residue removal on the apical radicular third and negatively affected the longevity of endodontic obturation using a calcium silicate-based sealer. Full article

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. Full article