Adhesive Bond Strength Research Articles

The effect of hemostatic agents and dentin cleansing protocols on shear bond strength of resin composite using universal adhesive: an in vitro study

BackgroundDuring restoring class II and V cavities with resin composite, hemostatic agents are frequently used to control gingival bleeding and/or gingival fluid to provide a dry field which is crucial for efficient bonding. Hemostatic agents may adversely affect the bonding procedure, thus their removal prior to bonding is essential. The current study evaluates the effect of two hemostatic agents and different dentin cleansing protocols on the shear bond strength of resin composite to dentin using a universal adhesive.MethodsNinety premolars were sectioned to expose coronal dentinal surfaces which were divided into 3 groups: control group, not treated with hemostatic agent (n = 10); a group treated with Viscostat “20% ferric sulphate” (n = 40); and a group treated with Viscostat clear “25% aluminum chloride” (n = 40). The groups treated with hemostatic agents were subdivided into 4 subgroups according to the cleansing protocol: water, phosphoric acid, katana cleaner, and air abrasion. Shear bond strength (SBS) of resin composite bonded to the treated dentin using a universal adhesive was measured after thermocycling.ResultsTwo-way ANOVA showed that hemostatic agent, cleansing protocol and their interaction has significant effect on SBS (p < 0.0001). Viscostat (10 ± 3.3 MPa) exhibited lower SBS than Viscostat Clear (16.2 ± 5.5 MPa). Acid etching (17.3 ± 7.3 MPa) showed higher SBS compared to Katana Cleaner (12.6 ± 4.7 MPa), water (12.1 ± 4.8 MPa) and air abrasion (10.8 ± 2 MPa).ConclusionThe use of hemostatic agents can adversely affect the bond strength of universal adhesives to dentin. Phosphoric acid provided the best hemostatic agent-cleansing protocol while katana cleaner and air abrasion demonstrated inferior results.

The effect of the introduction of B4C on the adhesive and cohesive properties of self-fluxing coatings

Wear and tear of technical equipment elements is a serious problem that negatively affects the productivity of production processes. The work analyzed the strength of cohesive and adhesive bonds of wear-resistant coatings obtained by detonation gas-dynamic spraying method based on a self-fluxing alloy, depending on the introduction of B4C particles into the composite composition. The chemical composition of the cohesive bonds of the resulting coatings and the effect of boron-containing elements on their strength were analyzed. The method of transverse scratching of transverse sections of thick coatings is a qualitative assessment of adhesive and cohesive properties and helps to determine the mechanisms of their destruction. The purpose of the work is to study the effect of the introduction of B4C particles on the adhesive and cohesive properties of coatings obtained by detonation gas-dynamic spraying based on self-fluxing NiCrBSi alloy. Methods for studying coating samples obtained by detonation gas-thermal method: scanning electron microscopy, energy dispersive analysis, optical metallographic microscopy, scratch testing. Previously, wear-resistant coatings based on self-fluxing NiCrBSi-B4C alloy have proven their effectiveness as protective coatings for centrifugal beet cutter knives. This study substantiates the feasibility of obtaining a composite based on such coatings with the introduction of boron carbide to improve its strength characteristics.

The influence of external and internal factors on ensuring adhesive interaction of a polymeric sealant with a substrate surface (a review)

This paper analyzes literature data on the influence of various factors affecting the strength and durability of adhesive bonds, as well as presents a characterization of the methods described in the literature for conducting relevant studies. It is shown that one of the main characteristics of adhesive joints is the interaction at the interface between the substrate and the adhesive. The adhesive capability of a sealant largely depends on the structure of the polymer component, as well as the presence of components in the sealant that enhance this property. The structure and condition of the substrate surface significantly affect the nature of the interaction between the adhesive and the substrate. Various methods are used to determine the strength of the adhesive bond, differing in the type of applied loads and the nature of the surface fracture. An important indicator is the determination of the wetting angle of the substrate by the sealant, which characterizes the surface energy. The durability of adhesive bonds is significantly influenced by environmental factors as well as operational conditions. Moisture, atmospheric oxygen, ultraviolet radiation, and microorganisms have a particularly strong effect on the properties of polymeric sealants.

Shear bond strength between dental adhesive systems and an experimental niobium-based implant material

This study aimed to investigate adhesive shear bond strength (SBS) on an ultrafine-grained niobium alloy (UFG-Nb) that is a potential dental implant material. SBS of three adhesive systems combined with three composites to UFG-Nb was compared to corresponding SBS to Ti-6Al-4V and to zirconia. Specimens of the substrates UFG-Nb, Ti-6Al-4V and zirconia with plane surfaces were sandblasted with Al2O3, cleaned and dried. Three adhesive systems (Futurabond U, Futurabond M + , Futurabond M + DCA; all VOCO GmbH, Cuxhaven, Germany) were applied each on specimens of each substrate and light cured. One composite (BifixSE, BifixQM, GrandioSO; all VOCO GmbH) was applied and light cured resulting in 27 groups (n = 10) for all substrate-adhesive-composite-combinations. SBS was measured after 24 h of storage. To simulate aging equally prepared specimens underwent 5000 thermocycles before SBS measurement. There was no significant difference in SBS within the non-aged groups. Among the artificially aged groups, GrandioSO-groups showed a greater variance of SBS than the other composites. All significant differences of corresponding UFG-Nb-, Ti-6Al-4V- and zirconia-groups with same adhesive-composite-combination (ACC) were observed between UFG-Nb and zirconia or Ti-6Al-4V and zirconia but never between the two metallic substrates. The similarity between these materials might show in their adhesive bonding behavior. As there were no differences comparing corresponding groups prior to and after artificial aging, it can be concluded that aging does not affect SBS to UFG-Nb, Ti-6Al-4V and zirconia using the tested ACCs. Adhesive bonding of established ACCs to UFG-Nb is possible resulting in SBS comparable to those on Ti-6Al-4V and zirconia surfaces.Graphical

Evaluation of Shear Bond Strength of Universal Adhesives to Dentin: in Vitro Study

Aim: Universal adhesives are widely used in restorative dentistry. The aim of this study was to evaluate the shear bond strength (SBS) of universal adhesives to dentin in different application modes. Materials and Methods: The study utilized seven universal adhesives and one total-etch adhesive. The sixty-four extracted intact human molars used in the study were embedded in acrylic blocks to the enamel-cement junction. The occlusal surface was removed to expose the dentin surface. After applying self-etch and total-etch adhesives to the dentin, flowable composite (Clearfil Majesty Flow, Kuraray) was placed in a transparent mold (2.38 mm diameter and 2 mm height) and polymerized. After thermal aging (1000 cycles), a SBS test has been carried out on a universal testing machine. The fracture types formed on the surface of the teeth were examined under a microscope. Data were analyzed by two-way analysis of variance (ANOVA) test (p&lt;0.05). Results: SBS values of universal adhesives on dentin showed statistically significant differences according to adhesive and application mode (p&lt;0.05). Total-etch application produced statistically higher SBS than self-etch application (p&lt;0.05). The two-step universal adhesive (G2 Bond Universal) had the highest SBS in both the self-etch and total-etch application modes (p&lt;0.05). When the bond surfaces of the universal adhesives were examined, fractures occurred most frequently in the adhesive type. Conclusion: The use of universal adhesives in the total-etch mode results in greater bond strength to dentin tissue. Universal adhesive type influences bond strength.

Comparative Assessment of Adhesive Bond Strength of 25% and 50% Propolis-modified Glass Ionomer Cement to Human Dentin: An In Vitro Study

Comparative Assessment of Adhesive Bond Strength of 25% and 50% Propolis-modified Glass Ionomer Cement to Human Dentin: An In Vitro Study

Comparative Evaluation of Mechanical Properties and Bond Strength of Glass Ionomer Cement reinforced with three different concentrations of Silver Nanoparticles as against Conventional Glass Ionomer Cement in Primary Teeth.

Introduction: Restorative dental materials are defined as substances that are used to repair, replace, or enhance a patient’s teeth. Various materials used in paediatric dentistry are zinc oxide eugenol, glass ionomer cement, resin composite, calcium hydroxide, silver amalgam, giomers etc. GIC is a biocompatible material having a low thermal expansion coefficient and fluoride release property. There are still a few drawbacks of GICdue of their poor mechanical properties therefore addition of Silver Nanoparticles demonstrated improved mechanical and bactericidal capabilities. There hasn’t been much study on the quality of the bond contact between silver nanoparticles and dentin, as well as the color’s durability. Aim: To evaluate and compare the mechanical properties and bond strength of Glass ionomer cement reinforced with three different concentrations of silver nanoparticle as against conventional glass ionomer cement in primary Teeth. Materials and Method: Silver nanoparticles will be prepared using three chemicals namely, silver nitrate, sodium citrate and tannic acid. Traditional GIC (GC Fuji II, GC Corporation, Tokyo, Japan) will be purchased. Three different concentrations of silver nanoparticles will be prepared i.e., 0.2, 0.4, and 0.6%. The GIC specimens will then be divided into 4 groups: GIC without silver nanoparticles (AgNPs),0.2%,0.4% and 0.6% AgNPs. Mechanical properties will be checked such as compressive, tensile, and bond strength using Universal Testing Machine. Expected Results: GIC reinforced with silver nano particles is expected to have better mechanical strength, less microleakage and wear resistance, greater fracture resistance and adhesive bond strength. Conclusion: GIC reinforced with silver nano particles will be expected to have better mechanical and physical properties than conventional Type II GICs and is expected to be a promising material for restoration in primary teeth.

Does enamel deproteinisation with 10% papain affect shear bond strength of orthodontic adhesives: a randomised controlled trial.

To evaluate the effect of 10% papain as an enamel deproteinising agent on the shear bond strength (SBS) of three orthodontic adhesives: Transbond XT, resin-modified glass ionomer cement (RMGIC) and Biofix. Single-centre, double-blinded, split-mouth randomised controlled trial. Department of Orthodontics and Dentofacial Orthopaedics, Nair Hospital Dental College, Mumbai, India. A total of 20 participants requiring bilateral premolar extraction for fixed orthodontic treatment in both the maxillary and mandibular arches were included in this study. In total, 80 premolars from the above-mentioned participants were divided into four groups as follows: group A: Transbond XT deproteinised with 10% papain gel; group B: Biofix deproteinised with 10% papain gel; group C: RMGIC deproteinised with 10% papain gel; and group D: Transbond XT without enamel deproteinisation as a control group-bonded as instructed by the manufacturer. After deproteinisation, brackets were bonded and after a follow-up period of 28 days, the teeth were extracted. The SBS was then measured using the Universal Testing Machine. The force needed to shear the bracket was documented, and bond strengths were subsequently calculated in megapascals (MPa). The obtained results were subjected to statistical analysis and one-way ANOVA was performed to compare the mean SBS between the groups. Subsequently, pairwise comparisons were conducted using Tukey's post hoc test. There was a statistically significant difference in SBS among all groups (P = 0.002). The SBS of TransXT with deproteinisation increased significantly compared with TransXT without deproteinisation (P = 0.03). There was no statistically significant difference between the SBS of TransXT without deproteinisation and RMGIC (P = 0.47) and Biofix (P = 0.39), both with deproteinisation. The use of 10% papain for deproteinising enamel improved the SBS of all materials. Deproteinising improved the SBS of RMGIC and Biofix to the level of TransXT without deproteinisation.

Novel GSK-3 inhibitor based universal dentin bonding system: A comprehensive analysis of dentinal repair and improved bond strength

The aim of the study was to describe the formulation of a novel universal adhesive system, based on a GSK-3 (glycogen synthetase kinase-3) inhibitor (Tideglusib®), and to evaluate its bond strength and dentinal repair capability. Tideglusib® was added to Ultradent Peak Universal Dentin Bonding Agent to make experimental adhesives (0.5 %, 1 %, 2 % final concentration). They were applied to teeth which were sectioned, stored for 24 h, or 2 years then bond strengths measured. Baseline stiffness of bonded dentin beams was tested using the three-point bending test. Animal experiments were performed to provide specimens for microcomputed tomography imaging after adhesive application. Collagen matrix was evaluated using transmission electron microscopy. The cytotoxicity of the modified adhesives was determined using fibroblastic cells. Molecular modelling evaluated binding of the Tideglusib® molecule to active sites on collagen and the adhesive components. TGFβ-1/and BMP-2 in human dentin matrices were measured and interfaces were scanned using SkyScan 2211. Adhesives’ stability tests were done. ResultsRMSD (root mean square deviation) analysis indicated simulation has equilibrated with changes for globular proteins (p < 0.05). Specimens from 0.5 %, and 1 % Tideglusib® groups displayed adhesive penetration with Micro-CT imaging and a significant increase in dentin density was seen. Specimens from the same groups showed cells with large masses of cytoplasm with focal adhesion points. Bond strength decreased significantly (p < 0.05) with increased storage time. Gradual release (p < 0.05) of both TGFβ-1 and BMP-2 from hTDMs with 0.5 % and 1 % Tideglusib® groups occurred and higher elastic moduli (p < 0.05). Collagen-based amide and proline Raman bands were seen in the Tideglusib® groups. ConclusionIncorporation of Tideglusib® in experimental Universal Adhesive System at 1 % improved adhesive bond strength and promoted dentinal repair. Application of Tideglusib® based adhesive conserve mechanical properties of the tooth structure and promote regenerative capability so can be expected to extend the service life of adhesive restorations in clinical situations.

The Effect of Dimethyl Sulfoxide on the Microtensile Bond Strength of Universal Adhesives to Dentin.

Objectives: The goal of this investigation was to see how a dentin pretreatment with 5% DMSO affected the microtensile bond strength (μTBS) of universal adhesives. Materials and Methods: In terms of adhesive kind and etching procedure, 32 healthy third human molars were randomly separated into eight groups. Three universal adhesives with etch-and-rinse and self-etch strategies (G-Premio Bond: GPB.ER/SE, All-Bond Universal: ABU.ER/SE, Prime & Bond Elect: PBE.ER/SE), one two-stage self-etch adhesive (Clearfil SE Bond: CSB), and one two-stage etch-and-rinse adhesive (Adper Single Bond 2: ASB) were employed in with and without DMSO modes (group/N=16). Dentin pretreatment was conducted with 50 μl of 5% DMSO, followed by the use of an adhesive. The μTBS of samples was tested. The influence of adhesive type and DMSO application on bond strength was evaluated using a two-way analysis of variance (ANOVA) ( =0.05). Results: The dentin-adhesive μTBS was significantly affected by DMSO administration (P=0.003), type of adhesive (P=0.001), and the combination of DMSO application and type of adhesive (P=0.027). In the DMSO application mode, the average bond strength of universal adhesives with etch and rinse mode was significantly higher than in the non-application mode, but in the self-etch technique, there was no significant difference pattern between DMSO applications and non-application modes in terms of adhesive bond strength. Conclusion: The use of DMSO in an etch-and-rinse technique can dramatically enhance the universal adhesive-dentin μTBS and has promise benefits for clinicians in terms of enhancing dentin bond performance.

Effects of temperature and loading rate on the shear performance of GFRP-steel single-lap joints

This research examines how the shear properties of glass fiber-reinforced polymer (GFRP) and steel single-lap joints react under various temperatures (−25, 0, 25, 50, and 100℃) and loading speeds (0.625, 1.25, 2.5, and 5.0 m/s). The GFRP sheets, aligned unidirectionally, were produced using vacuum-assisted resin transfer molding and were then adhesively attached to steel plates with epoxy resin. The assemblies were subjected to a high-speed servo-hydraulic testing apparatus for evaluation. The results indicate that the joint's performance is relatively unaffected by changes in the loading speed, but the overall toughness tends to decrease at higher speeds. However, the adhesive bond strength increases when temperatures are between −25 and 50℃ but diminishes as temperatures rise from 50 to 100℃. Most samples exhibited debonding at the steel-adhesive interface under varied speeds and colder temperatures, whereas debonding at the GFRP-adhesive interface was more prevalent at elevated temperatures. These insights are vital for both theoretical analyses and practical implementations of GFRP-steel single-lap joints in environments subject to extreme loading conditions and temperatures.

Estimation of the effect of acetone- or ethanol-based solvents on shear bond strength of composite resin using air- and blot-dry techniques.

An adequate amount of water is necessary to maintain the shape of collagen fibrils while excess water hampers dentin-resin bonding. Air-drying lacks control while blot-drying displaces water in a controlled manner. Solvents in adhesives affect the configuration of collagen fibrils. Thus, the present study aimed to compare the influence of air- or blot-drying methods on shear bond strength (SBS) of acetone- and ethanol-based adhesives. Thirty-six extracted noncarious third molars with similar crown heights were selected. Teeth were decoronated and randomly divided into two groups: after acid etching, Group I was treated with acetone-based adhesives and Group II with ethanol-based adhesives. They were again subdivided into subgroups A (blot-dried) and B (air-dried) containing nine samples each. Dentin surfaces were etched and rinsed. After the respective drying method, adhesive application and composite buildup were done. SBS was measured. The data were subjected to statistical analysis. Acetone-based adhesive showed the highest SBS in both drying methods. Further, blot-dried dentin produced significantly higher SBS than air-dried dentin. Solvent type and drying methods have an effect on the bond strength of total-etch adhesives to dentin. Acetone-based adhesives used with blot-drying techniques showed the best results.

Comprehensive evaluation of early shear bond strength and antimicrobial activity in orthodontic adhesives enhanced with salvadora persica oil.

This study investigates the mechanical properties and antimicrobial efficiency of orthodontic adhesive modified with Salvadora persica (SP) oil, including adhesive remnant index (ARI) and shear bond strength (SBS), specifically antimicrobial efficacy against Streptococcus mutans. Forty freshly extracted human premolars were recruited. They were classified into four groups according to the concentration of SP oil added to Heliosit orthodontic adhesive where the control group was with no adhesive modification, alongside three experimental groups, wherein SP oil was integrated into the adhesive at concentrations of 1%, 3%, and 5% weight/weight, respectively. The tooth buccal surface was etched by phosphoric acid gel (37%). The orthodontic brackets utilized were standard stainless steel edgewise 22". The brackets were bonded with Heliosit by Woodpecker LED light cure for 20 sec. The SBS was assessed using a universal testing machine, and ARI was inspected by a stereomicroscope at 20X magnification power. The antimicrobial activity against Streptococcus mutans was evaluated. The statistical analyses, analysis of variance (ANOVA), and Kruskal-Wallis and Duncan were performed where P ≤ 0.05. The findings indicated that among the experimental groups, the 3% SP oil group exhibited the highest mean SBS value, following closely behind the control group. Conversely, the mean SBS was lowest for the SP group with a 5% concentration. However, ANOVA and Kruskal-Wallis tests revealed no significant differences between groups (P ≥ 0.275, 0.069), respectively. Antimicrobial tests demonstrated a concentration-dependent antibacterial effect, the 5% group exhibiting the highest efficacy. Orthodontic adhesive modified with SP oil maintains favorable SBS while demonstrating antimicrobial effects against Streptococcus mutans.

Adhesive Bond Strength of Glass Ionomer Cement Modified with Chitosan at Different Concentrations: An In Vitro Comparative Evaluation

Adhesive Bond Strength of Glass Ionomer Cement Modified with Chitosan at Different Concentrations: An In Vitro Comparative Evaluation

Experimental Investigation of Processing Temperature Effect on Adhesive Bond Strength Between Engineering Thermoplastics in the Plastic Injection Molding Process

Abstract Multicomponent injection molding industry is experiencing a growth due to its ability to reduce production costs and streamline processes. However, compared to single injection, multicomponent injection molding introduces interface regions where multiple engineering polymers meet. Consequently, it is essential to comprehend and enhance the adhesive bonding strength properties of these polymers. This study investigates the adhesive bond strength of polymer–polymer multimaterial molding using two-shot bi-injection and overmolding techniques. The research also emphasizes the influence of injection molding process parameters of mold temperature and melt temperature on the adhesive bond strength of polycarbonate (PC), polycarbonate–acrylonitrile butadiene styrene (PC–ABS), acrylonitrile butadiene styrene (ABS), and styrene ethylene butadiene styrene (SEBS). Tensile strength results revealed that the bi-injection method yields the highest interface strength, approximately 10 MPa lower than the reference value for single-material hard–hard plastics. Results from overmolded samples for both injection sequences are presented, indicating that material with low melting temperature was found to be the first injected part for better adhesion strength. Empirical equations for estimating adhesion strength were derived as a function of interface temperature obtained from CAE numerical simulations and polymer glass transition temperatures. The proposed equation achieved R2 values greater than 0.96. This empirically derived equation will serve as a guide for multi-injection manufacturing processes.

Effect of multi-layer applications of self-etch universal bonding agents on the adhesion of resin composite to enamel.

To evaluate the effect of adhesive coats application on the enamel microtensile bond strength (µTBS) of universal adhesives, morphological etching pattern and their chemical interaction with hydroxyapatite (HA). Two universal adhesives were investigated: Scotchbond Universal (SBU, 3M) and Prime&Bond Universal (PBU, Dentsply). The adhesives were applied in self-etching mode on bovine enamel (n = 8) in one (1L), two (2L) or three coats (3L) and light-cured as per manufacturers' instructions. As controls adhesives were applied to etched enamel (H3PO4-37% phosphoric acid). Bonded specimens were cut into sticks that were stored in deionized water for 24h or 6months prior to µTBS testing. Two-way ANOVA and Tukey's test were used for statistical analysis of bond strength with α = 5%. For morphological SEM analysis, enamel surfaces were treated as aforementioned and immediately rinsed with acetone. The intensity of monomer-calcium salt formation from each treatment was measured via infrared spectroscopy (ATR-FTIR). All treatments presented no significant reduction on µTBS after aging (p > 0.05). However, SBU attained highest µTBS when applied in 3L. PBU showed higher µTBS when applied to H3PO4 etched enamel than 1L or 2L. Etching pattern was enhanced by 3L application, particularly with PBU. Chemical interaction was notably higher for SBU than PBU, with no relevant differences with more layers or prior H3PO4-etching. The application of three adhesive coats of universal adhesives in self-etch mode using may enhance the bonding performance and etching pattern to enamel, surpassing the H3PO4-etched enamel bond for SBU. The chemical interaction with calcium from enamel is not affected by number of coats or prior phosphoric acid etching.

Effect of the percentage of MUF adhesive coverage on shear strength when bonding different wood species

Due to climate changes, it is necessary to consider the use of other wood species to replace currently used woods. This work deals with the determination of the shear strength of bonded veneers (eight European wood species: spruce, larch, pine, beech, oak, poplar, birch, and alder) with Silekol® 311 melamine-urea-formaldehyde adhesive (MUF) with a variable coverage on the surface of the samples: 10, 15, 20, 25, 30, 50, 75, and 100%. The Automated Bonding Evaluation System (ABES) was used to evaluate and compare adhesive bond strengths. The larch, beech, and oak samples exhibited greater single-lap shear strength than the control samples from spruce. There was no statistically significant difference in shear strength regarding the adhesive coverage from 100% to 20% on the surface of the samples, for almost all wood species. The results of the project provide basic information about the bonding strengths with different coverage in the adhesive layer, comparing non-commonly used wood species in wood-based composites such as oriented strand board and particleboard.

Effects of Endodontic Irrigants on Shear Bond Strength of Mild Universal Adhesives to Dentin

PurposeThe objective of this in vitro study was to evaluate the shear bond strength (SBS) of several universal adhesives to dentin treated with sodium hypochlorite (NaOCl), and NaOCl followed by ethylenediaminetetraacetic acid (EDTA). Materials and MethodsAdhese Universal, Scotchbond Universal, Prime & Bond Elect, Prime & Bond Active, and Optibond XTR were included in the study. SBS values were determined in self-etch mode with no pretreatment of the dentin, after a 20-minute exposure of the dentin to 6% NaOCl, and after a 20-minute exposure to NaOCl followed by a one-minute exposure to 17% EDTA. Experimental groups were repeated using a total-etch technique (except Optibond XTR). ResultsAdhesives in self-etch mode had significantly reduced SBS following dentin exposure to NaOCl (P < .05), while with a total-etch technique, only Prime & Bond Active was affected (P < .05). SBS in self-etch mode when NaOCl exposure was followed by EDTA were equal to or higher than negative control values (P < .05). For total-etch groups, Adhese Universal was negatively affected by NaOCl + EDTA exposure (P < .05). Prime & Bond Elect exhibited lower SBS following NaOCl + EDTA exposure when compared to just NaOCl exposure but was not different from the negative control (P < .05). ConclusionFor the adhesives tested, the use of 17% EDTA following NaOCl exposure negated the negative effects of NaOCl on SBS in self-etch mode. When used in total-etch mode, results varied significantly, with some adhesives performing better or worse depending on the specific testing condition.

Erosive Influence of Amazonian Tucupi on Microshear Bond Strength to Enamel and Dentin.

The scientific literature has studies that assess the influence of erosive challenges with citric acidic drinks and substances on the adhesive bond strength to enamel and dentin, but does not contain information about the influence of regional components of an acidic diet on this process. Thus, this study evaluated the erosive influence of Amazonian tucupi on enamel and dentin microshear bond strength. One hundred and sixty-eight healthy bovine incisors teeth were used, divided into 12 groups (n = 14). For erosive cycling, distilled water (negative control), cola-based soft drink (positive control), or tucupi were used, followed by adhesive strategies of (1) etch-and-rinse (conventional) (Adper™ Single Bond 2) and (2) self-etching (Clearfil SE Bond). All specimens were subjected to erosive cycling for 5 days and, after 24 h, composite resin cylinders were built up for the microshear bond strength test. The data showed normal distribution and were analyzed by two-way ANOVA, followed by the Tukey post and test (P ≤ 0.05). There were no significant differences in enamel (P > 0.05). In dentin, only the groups exposed to cola-based soft drink showed significant differences (P < 0.01). The failure mode showed that Type II (mixed) was predominant (95%). The erosive challenge with tucupi did not influence the bond strength to enamel and dentin, regardless of the adhesive strategy used.

Microtensile bond strength and nanoleakage of self-etching adhesives containing different concentrations of 45S5 bioactive glass in caries-affected dentin

ObjectiveTo evaluate microtensile bond strength (μTBS) and nanoleakage (NL%) of self-etching adhesive systems containing different concentrations of bioactive particles when applied to caries-affected dentin: immediately and after 1 year of storage. Materials and methodsThree experimental self-etching adhesive systems were developed: (1) Experimental control adhesive (without glass), (2) adhesive containing 5 % 45S5 glass (45S5 5 %), and (3) adhesive containing 20 % 45S5 glass (45S5 20 %). Sound human molars were used (n = 7). The dentin surface was exposed, and half of the specimens were subjected to artificial caries induction, followed by partial removal of the carious tissue. Adhesives were applied to the dentin surface, and teeth were restored with composite resin and sectioned. Specimens undertook microtensile bond strength tests in a universal testing machine (Instron 3342) at 24-h and 1-year. Interfaces of the sectioned specimens were observed under a stereomicroscope to obtain the fracture mode. For nanoleakage test, specimens were infiltrated with silver nitrate and the interface was analyzed using a Scanning Electron Microscope (SEM) at 24-h and 1-year. Data were subjected to ANOVA test (three-way) and Holm-Sidak post-hoc (α = 0.05). ResultsFor μTBS (p = 0.574) and NL (p = 0.334) tests, there was no interaction between the 3 main factors (Material vs. Substrate vs. Time). There was an interaction between dentin and material for μTBS (p < 0.001) and NL (p = 0.005) tests. Bioactive adhesives with 5 % and 20 % concentration were not influenced by the type of dentin (p < 0.05). There was a reduction in μTBS values and an increase in NL values for the adhesive without bioactive glass in dentin affected by caries (p > 0.05). ConclusionBioactive glasses had therapeutic action on dentin. The bond strength values of bioactive adhesives were maintained in caries-affected dentin and had low nanoleakage values. Clinical significanceSelf-etching adhesives containing 45S5 bioactive glass have the potential to preserve the dentin substrate and improve the longevity of restorations with composite resins.