Search Results (140)

This study evaluated the influence of drying time, application mode, and agitation on the micro-tensile bond strength (μTBS) of a novel mesoporous bioactive glass-containing universal adhesive (Hi-Bond Universal). Twelve experimental groups were established according to drying time (blot-dry, 10 s dry, or 20 s dry), application mode (total-etch or self-etch), and agitation (with or without). The μTBS test and failure mode analysis were performed for each experimental group (n = 20), and an adhesive interface was observed using field-emission scanning electron microscopy. The μTBS of all experimental groups was analyzed using a three-way ANOVA and Tukey’s honestly significant difference (HSD) post hoc test (α = 0.05). The total-etch mode yielded higher μTBS than the self-etch mode in the blot-dry and 10 s dry groups (p < 0.05). Agitation also significantly increased the μTBS in the blot-dry and 10 s dry groups for both application modes (p < 0.05). However, application mode and agitation had no effect on the μTBS in the 20 s dry group (p > 0.05). FE-SEM revealed longer and more uniform resin tags after agitation in the blot-dry and 10 s dry groups for both application modes. In conclusion, total-etch mode and agitation effectively increased the bond strength of mesoporous bioactive glass-containing universal adhesives. Full article

Novel dentin bonding pretreatment using copper sulfate (CuSO₄) and dipotassium hydrogen phosphate (K₂HPO₄) may create a more hydrophobic environment for dentin bonding. Thus, this study aims to investigate the impact of a CuSO₄ + K₂HPO₄ pretreatment on dentin μTBS when bonded with a universal adhesive to conventional and CAD/CAM resin composites. Eighty recently extracted human molars (n = 80) were chosen and placed in transparent acrylic blocks to expose the crowns entirely. Nano-filled resin composite and CAD/CAM resin blocks were selected. Based on the dentin pretreatment, type of resin composite, and adhesion strategy, the teeth were randomly allocated into eight equal groups (n = 10). The microtensile bond strength (μTBS) and fracture mode were determined. A three-way analysis of variance (ANOVA) was used to analyze the μTBS data, followed by Tukey’s post hoc test. The μTBS values were not significantly affected by either the resin composite type (p > 0.05) or the adhesive strategy (p > 0.05) according to the three-way ANOVA results. Conversely, significant differences were detected between no dentin pretreatment (24.20 ± 4.54 MPa) and CuSO₄ + K₂HPO₄ pretreatment (33.66 ± 5.22 MPa) using an etch-and-rinse adhesive strategy for nano-filled composites (p < 0.001). Additionally, significant differences were detected between no dentin pretreatment (24.71 ± 4.33 MPa) and CuSO₄ + K₂HPO₄ pretreatment (32.49 ± 4.92 MPa) using an etch-and-rinse adhesive strategy for CAD/CAM resin blocks (p < 0.001). Moreover, significant differences were detected between no dentin pretreatment (21.20 ± 3.40 MPa) and CuSO₄ + K₂HPO₄ pretreatment (30.31 ± 3.87 MPa) using a self-etching adhesive strategy for nano-filled composites (p < 0.001). Also, significant differences were detected between no dentin pretreatment (23.89 ± 3.89 MPa) and CuSO₄ + K₂HPO₄ pretreatment (31.22 ± 4.71 MPa) using a self-etching adhesive strategy for CAD/CAM resin blocks (p < 0.001). In conclusion, dentin μTBS was enhanced by a copper-based treatment when used with nano-filled and CAD/CAM resin blocks. Full article

Objectives: The widespread adoption of three-dimensional (3D)-printed resins in restorative dentistry has introduced significant challenges in establishing strong and lasting bonds with resin-based cements. Despite the development of numerous surface treatment techniques designed to improve adhesion, a clear consensus on the most effective approach remains elusive. This systematic review and meta-analysis critically examined the impact of various surface treatment protocols on the bond strength of 3D-printed resins. By comparing treated versus untreated surfaces, the study aimed to determine the most reliable strategies for enhancing adhesion, ultimately offering evidence-based guidance to inform clinical decision-making. Methods: This review identified relevant studies through a comprehensive search of MEDLINE via PubMed, Web of Science, Scielo, Scopus, and EMBASE databases, supplemented by manual reference checks, to identify in vitro studies published up to February 2025. Studies assessing the bonding of 3D-printed resins following various surface treatments and bonding protocols were included. Data on bond strength outcomes, such as shear bond strength, microtensile bond strength, and microshear bond strength, were extracted. Data extraction included study details, type of 3D-printed resin and printing technology, surface treatment protocols, bond strength testing methods, storage conditions, and results. The quality of included studies was assessed using the ROBDEMat tool. Meta-analyses were performed using the Review Manager Software (version 5.4, The Cochrane Collaboration, Copenhagen, Denmark), with statistical significance set at p < 0.05. Statistical heterogeneity among studies was evaluated using the Cochran Q test and the I² inconsistency test. Results: Nine studies met the criteria for qualitative analysis, with eight included in the meta-analysis. The findings revealed that surface treatment protocols significantly enhanced the immediate bond strength to 3D-printed resins (p = 0.01), with only sandblasting and silane demonstrating a statistically significant effect (p < 0.007). Similarly, after aging, surface treatments continued to improve bond strength (p = 0.01), with sandblasting and hydrofluoric acid being the only methods to produce a significant increase in bond strength values (p < 0.001). Conclusions: This meta-analysis underscores the importance of combining mechanical and chemical surface treatments, especially sandblasting and silane application, to achieve reliable and durable bonding to 3D-printed resins. Full article

This study investigated the effects of acid etching with grape seed extract (GSE)-modified etchants, varying phosphoric acid (PA) concentrations, on endogenous collagenolytic activity of etched dentin, adhesive–dentin (A/D) interfacial formation, and bond strength over time. Three PA concentrations (5%, 10%, and 20%) were combined with 2% GSE (5PA/GSE, 10PA/GSE, and 20PA/GSE) and compared to a control (CT) group using 32% PA gel (3M Universal Scotchbond etchant). Seventy-four caries-free human third molars were sectioned to expose dentin surfaces, which were etched and analyzed. In situ zymography with confocal laser microscopy was used to assess endogenous collagenolytic activity in etched dentin specimens. For A/D interfacial morphology and bond strength, etched dentin was bonded with Adper Single Bond Plus adhesive (3M ESPE) and composite buildup. The interfacial morphology of A/D specimens was evaluated using either Goldner’s trichrome staining under light microscopy after microtomy sectioning or scanning electron microscopy. A/D specimens were stored in either TESCA buffer or collagenase solution and tested immediately (IM) or at multiple time points over one year using the microtensile bond strength (μTBS) test. Data were analyzed by one- or three-way ANOVA followed by Games–Howell or Tukey’s tests (α = 0.05). GSE-modified etchants significantly reduced endogenous collagenolytic activity (p < 0.05). Although GSE-modified etchants resulted in thinner A/D interfaces, the bond strength remained unaffected (p > 0.05). Bond strength stability was prolonged up to one year with 5PA/GSE and 10PA/GSE (p < 0.001), while CT or 20PA/GSE showed significant degradation by 17 weeks (p < 0.01). Storage in the more aggressive collagenase solution did not further reduce the bond strength compared to TESCA buffer (p = 0.966). Acid etching with GSE-modified etchants effectively inhibits endogenous MMP-mediated collagenolytic activity. At 5% and 10% PA, this approach enhances the stability of the A/D bond strength, offering a promising modification for dentin bonding protocols. Full article

This study aimed to evaluate the physicochemical and mechanical properties of a modified adhesive system containing resveratrol by assessing its microtensile bond strength (µTBS), degree of conversion (DC), mini-flexural strength (MFS), and antibacterial activity. The modified etch-and-rinse adhesive system was prepared by resveratrol (RES) incorporation in different concentrations: adhesive with 0.5% RES (RES0.5), adhesive with 1% RES (RES1), adhesive with 2% RES (RES2), and adhesive with no RES incorporation (RES0—control group). The µTBS test was conducted on 40 human molars with dentin exposure, which were etched, bonded with the adhesives (n = 10), and restored with resin composite. Fourier Transform Infrared Spectroscopy (FTIR) measured the DC for the MFS; ten adhesive sticks were made for each group. Antibacterial activity was assessed using colony-forming unit (CFU) counts. For µTBS, no difference between the groups was found (mean ± SD): RES0.5—42.93 ± 15.49^A; RES1—42.61 ± 13.97^A and RES2—39.43 ± 9.14^A; RES0—41.01 ± 2.64^A. The DC (% ± SD) of the experimental groups was similar: RES0.5—81.02 ± 1.95^A; RES1—76.02 ± 9.00^A; RES2—58.86 ± 15.94^A; RES0—77.75 ± 3.22^A. For MFS (mean ± SD): RES0.5—33.14 ± 13.83^A; RES1—31.1 ± 12.21^A; RES2—19.72 ± 5.43^B; RES0—29.72 ± 11.95^A. For CFU (mean ± SD): RES0.5—0.67 × 10⁷ ± 0.37^B; RES1—0.68 × 10⁷ ± 0.34^B; RES2—0.60 × 10⁷ ± 0.02^C; RES0—0.75 × 10⁷ ± 0.03^A. The incorporation of resveratrol into the adhesive system at low concentrations (0.5 and 1%) does not alter the bond strength of the adhesive interface, the degree of conversion, or the flexural strength. Additionally, both concentrations exhibited antibacterial properties by reducing the colony-forming units of S. mutans. Full article

Universal adhesives can be applied in versatile bonding strategies, with selective dentin etching (SDE) emerging as a promising approach for enhancing dentin–adhesive interfaces. This study evaluated the immediate adhesive interface to dentin of two universal adhesives (Optibond^TM Universal and Futurabond M+) with an SDE strategy. Sixty human molars were randomly assigned to six experimental groups (n = 10): control (self-etch strategy), SDE, and SDE3 (SDE with three adhesive layers). After dentin exposure and smear layer simulation, adhesives were applied, followed by composite resin restoration. Microtensile bond strength in 1 mm² beams was performed in a universal testing machine (1 kN; 0.5 mm/min) after 24 h water storage. Failure modes were classified, and the adhesive interfaces were characterized by scanning electronic microscopy. SDE was higher for both adhesives compared to the control group, but was this change statistically significant in Futurabond M+ only (Mann–Whitney, p < 0.001). On the other hand, in Optibond^TM Universal, only SDE3 significantly increased bond strength (Mann–Whitney, p < 0.001). Adhesive failures predominated across all groups. Microscopy images revealed longer and more numerous resin tags in SDE and SDE3 specimens. The SDE strategy enhanced immediate bond strength of these universal adhesives, with product-specific variations, suggesting that application strategies should be tailored to each universal adhesive’s unique formulation to optimize dentin bonding effectiveness. Full article

Fluorinated ethylene propylene (FEP) films were subjected to heat, UV, and heat–UV treatments. Structural changes that occurred after these treatments were recorded via X-ray diffraction (XRD), microtensile, and laser ablation testing. XRD macromolecular orientation texture analysis revealed changes in the fraction of crystalline components and the degree of anisotropy of the FEP films after being subjected to different processing conditions. Heat treatment at 200 °C affected structural properties by rearranging the crystallites and resulting in a higher degree of anisotropy. By contrast, the UV treatment of FEP resulted in a lower degree of anisotropy. The changes in anisotropy and crystallinity of FEP films significantly affected their Young’s modulus and yield stress. The UV laser ablation threshold values were found to be lower for the heat-treated FEP films. Full article

The main purpose was to evaluate the in vitro adhesion strength of direct and semi-direct composite resin restorations in dentin, when the same adhesive system is applied, using microtensile testing (μTBS) and to observe the most recurrent types of failure in the different groups. For this study, 16 intact human mandibular molars without microscopic evidence of lesions were randomly divided into two test groups, according to the restoration strategy: direct restoration (DR) and semi-direct restoration (SR). For both restorative strategies, the same adhesive system (Clearfil SE Bond 2, Kuraray, Tokyo, Japan) was applied to the dentin surface using a two-step self-etching approach with no prior conditioning of the dentin, and the same composite resin (Ceram. x Sepctra ST HV, Dentsply Sirona, Charlotte, NC, USA) was used as a restorative material. The indirect restoration was cemented using resin cement (Variolink Esthetic LC, Ivoclar Vivadent, Schaan, Liechtenstein) within the interior side of the restoration. Each specimen was sliced into sections measuring approximately 1 mm². The rods were then subjected to a microtensile bond strength test and the statistical analysis on the differences in μTBS between the groups were determined with the Mann–Whitney test. The surfaces were examined to determine the failure mode. The Chi-Square test was used to determine the association between the type of restoration and the failure mode. The DR group presented with a mean μTBS of 38.15 ± 10.75 MPa and a predominance of cohesive failures in the composite resin (69.5%). The SR group showed a mean μTBS of 25.45 ± 10.19 MPa and a predominance of adhesive failures (92.3%). There was not only a statistically significant difference in the adhesive strength of the DR and SR groups (p < 0.001), but also a statistically significant association between the type of restorative strategy and failure mode (p < 0.001). Even though Clearfil SE Bond 2 provided acceptable adhesion to the dentin, using the same two-step self-etch adhesive system, lower adhesive strength and more adhesive failures are expected in semi-direct restorations when compared to direct restorations. Full article

This study aimed to evaluate the micro-tensile bond strength (µTBS) of two types of composites for indirect restoration, luted to enamel and dentin with self-adhesive cement. Moreover, it aimed to evaluate the impact of thermocycling on bond strength. Sixteen flat enamel and dentin surfaces of human molars were cemented to equal flat specimens of the laboratory composite Signum ceramis and the CAD/CAM block Cerasmart. Half of the specimens of the group underwent thermocycling. After that, the samples were cut into 80 beams for µTBS analysis. The data were analyzed using Levene’s test and the independent sample t-test. The micro-tensile bond strength tests revealed that thermocycling significantly reduced the adhesive bond. Dentin bonds better to conventional laboratory composites. Enamel bonds are better than composite blocks for milling. Full article

Substantial tooth bonding is the defining characteristic of effective minimally invasive all-ceramic restorations. Natural and synthetic cross-linkers that could strengthen the bonding quality are currently drawing enormous interest. Thus, this study aimed to assess the microtensile bond strength and nanoleakage of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated ceramics to pretreated dentin with chlorhexidine or Salvadora persica extract, compared to no pretreatment, after thermomechanical cyclic loading. Consequently, forty-five extracted third-molar teeth (n = 45) were utilized to obtain mid-coronal dentin and assigned into three groups (n = 15) in accordance with dentin pretreatment; (group I: no dentin pretreatment (control), group II: 2% chlorhexidine, and group III: Salvadora persica extract pretreatments). Ceramic onlays were milled from lithium disilicate IPS e.max CAD/CAM blocks and cemented to prepared teeth with etch-and-rinse resin cement (Variolink Esthetic DC system kit). Microtensile bond strength and interfacial nanoleakage were accessed after thermomechanical cyclic loading. Statistical analysis was performed using one-way ANOVA, followed by Tukey’s post hoc test. Additionally, p-values < 0.05 were considered statistically significant. The chlorhexidine pretreated group showed the most favorable outcome compared to the control group. Conversely, using Salvadora persica pretreatment did not affect the bond strength and nanoleakage compared to the control group (p > 0.05). Consequently, unlike Salvadora persica extract, chlorhexidine–dentin pretreatment maintained superior bonding strength to ceramics after thermomechanical cyclic loading, facilitating minimally invasive, yet lasting, aesthetic restoration. Full article

This study presents an evaluation of the microtensile bond strength (µTBS) and microleakage (ML) of a bulk-fill (BF) composite, Ormocer, and Alkasite in comparison to the conventional composite bonded to caries-affected dentin (CAD) in deciduous dentition. Eighty-four human primary molars displaying carious lesions involving the middle third of dentin were included. CAD was exposed, and the teeth were randomly assigned to four groups based on the type of restorative material used: Group 1 (conventional composite), Group 2 (BF composite), Group 3 (Alkasite), and Group 4 (Ormocer). Sample storage and artificial aging were performed. Dye penetration, a universal testing machine, and a stereomicroscope were used for microleakage, µTBS, and failure mode assessment. The interface was evaluated by scanning electron microscopy (SEM). µTBS and ML results were analyzed using a one-way analysis of variance (ANOVA) and Tukey’s post hoc tests (p < 0.05). Group 1 (conventional composite) exhibited the highest microleakage and lowest bond strength. The minimum ML and maximum μTBS values were demonstrated by Group 4 (Ormocer). Ormocer and Alkasite proved to be better alternatives to conventional composites in terms of ML and bond strength in deciduous dentition. Full article

Miniaturized components for enhanced integrated functionality or thin sheets for lightweight applications often consist of face-centered cubic metals. They exhibit good strength, corrosion resistance, formability and recyclability. Microfabrication technologies, however, may introduce cold work or detrimental heat-induced lattice defects into the material, with consequences for the mechanical properties. Austenitic stainless steels (1.4310, 1.4301) and aluminum alloys (EN AW-5005-H24, EN AW-6082-T6) were selected for this study. The influence of pulsed fiber laser cutting, microwaterjet cutting, and annealing on the strain–stress behavior was investigated. The micro-tensile test setup comprised a flex-structure force sensor, a laser extensometer, and a dedicated sample holder. Fiber laser cut 1.4310 samples exhibited early failure at low fracture strain in narrow shear band zones. The shear band zones were detectable on the sample surface, in the laser extensometer images, in the horizontal sections of the stress–strain curves, and in the microstructure. Inside the shear band zones, grains were strongly elongated and exhibited numerous parallel planar defects. Heat-induced chromium carbides, in combination with low stacking fault energy (SFE) and elevated carbon content, favored shear band zone formation in 1.4310. In contrast, microwaterjet cut high SFE materials EN AW-5005-H24 and EN AW-6082-T6, as well as low-carbon austenitic stainless steel 1.4301, exhibited uniform plastic deformation. Full article

Friction surfacing (FS) is increasingly recognized as an advanced technique for coating similar and dissimilar materials, enabling superior joint quality through plastic deformation and grain refinement. This study investigates the deposition of AA6082-T651 alloy on a medium-carbon steel EN14B substrate using FS, with process parameters optimized, and the effect of axial load, rotational speed, and traverse speed on coating integrity. The optimal sample was subjected to heat treatment (HT) at 550 °C for 24, 36, and 48 h to further enhance mechanical properties. Comprehensive microstructural and mechanical analyses were performed on both heat-treated and non-heat-treated samples using optical microscopy (OM), field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), microhardness testing, and micro-tensile techniques. The optimized sample was processed with a 6 kN axial load, a rotational speed of 2700 rpm, and a traverse speed of 400 mm/min, and demonstrated superior bond quality and enhanced mechanical properties. The highest interfacial hardness values, 138 HV0.1 were achieved for the sample annealed for 48 h, under an axial load of 6 kN. Annealing for 48 h significantly improved atomic bonding at the aluminum–steel interface, confirmed by the formation of Fe₃Al intermetallic compounds detected via FESEM-EDS and XRD. These compounds were the primary reason for the enhancement in the mechanical properties of the FS deposit. Furthermore, the interrelationship between process and thermal parameters revealed that a peak temperature of 422 °C, heat input of 1.1 kJ/mm, and an axial load of 6 kN are critical for achieving optimal mechanical interlocking and superior coating quality. The findings highlight that optimized FS parameters and post-heat treatment are critical in achieving high-quality, durable coatings, with improved interfacial bonding and hardness, making the process suitable for structural applications. Full article

The widespread implementation of new CAD/CAM materials has led to the necessity of establishing an adequate luting protocol. The aim of this study was to evaluate the microtensile bond strength (μTBS) and the film thickness of different luting methods on CAD/CAM resin blocks. Five Brilliant Crios CAD/CAM blocks (Coltene/Whaledent) were sequentially sectioned into two halves, air abraded with 50 µm aluminum oxide, and luted according to five different cementation protocols: Brilliant EverGlow (BEG), Brilliant EverGlow with ultrasound application (BEG-US), preheated Brilliant EverGlow (BEG-H), Brilliant EverGlow Flow (BEGF), and Duo Cem^® Trans (DC). Subsequently, the blocks were sectioned to obtain rods, which were then submitted to a microtensile bond strength test (n = 20). The surfaces were examined with optical microscopy to determine the failure mode and the bonding interface was assessed with scanning electron microscope (SEM) analysis. Bond strength values were analyzed using one-way ANOVA and Tukey’s post hoc tests (α = 0.05). The bond strength values varied with the different cementation protocols (p < 0.001): BEG (45.48 ± 18.14 MPa), BEG-US (42.15 ± 14.90 MPa), BEG-H (41.23 ± 15.15 MPa), BEGF (58.38 ± 15.65 MPa), and DC (81.07 ± 8.75 MPa). Regarding bond strength, DC presented significantly higher values than all other experimental groups (p < 0.050), whereas all luting methods using BEG presented similar values (p = 0.894). Adhesive failures were the predominant type. On SEM evaluation, all the luting materials presented a tight and homogeneous cement–block interface with variable film thicknesses. In conclusion, among the cementation protocols, the resin cement (DC) rendered the highest bond strength values. SEM analysis revealed that the lowest film thickness was associated with the flowable composite (BEGF). Full article

Background/Objectives: This study aimed to investigate the microtensile bond strength (µTBS) of composite-based (Cerasmart), polymer-infiltrated (Vita Enamic), and feldspathic (Cerec) CAD/CAM blocks luted to dentin using a dual-cure resin cement (LinkForce), as well as micro-hybrid (G-aenial) and flowable composites (G-aenial Universal Flo), and evaluate the microhardness (HV) of luting materials through the CAD/CAM blocks. Methods: Cerasmart, Enamic, and Cerec were luted to dentin using three luting materials; LinkForce, G-aenial, and Universal Flo (n = 5). For HV, 117 disk-shaped specimens from LinkForce, G-aenial, and Universal Flo (n = 13) were polymerized through 3 mm thick CAD/CAM. Thirty-nine light-cured specimens without CAD/CAM were used as control. Following 24 h storage, the µTBS and HV were evaluated. Data were analyzed using the two-way ANOVA and post hoc Tukey tests (p < 0.05). Results: The µTBS to dentin and HV were significantly influenced by the type of luting material and CAD/CAM material. With all the CAD/CAM materials, LinkForce and Universal Flo exhibited a significantly similar µTBS to that of dentin (p > 0.05). Compared with the control group, all the HV values of the luting materials decreased significantly (p < 0.05). Conclusions: Heavily filled flowable composites exhibit a bonding effectiveness similar to that of dual-cure resin cements. All the luting materials showed similar HV when polymerized through the polymer-infiltrated CAD/CAM material. Full article