Adhesive Resin Research Articles

Comparative evaluation of different surface pretreatment methods on the depth of penetration of adhesive resin in sandwich technique: A confocal laser scanning microscopy study.

The aim of the study was to evaluate and compare the depth of penetration of adhesive resin in resin-modified glass ionomer cement (RMGIC) after different surface pretreatment methods using a confocal laser scanning microscope (CLSM). Class I cavity preparation was done in 45 freshly extracted premolars and divided into three groups, according to the surface pretreatment of RMGIC which was placed in a thickness of 1 mm in the cavity. In the control group, no pretreatment was done, and other two groups were pretreated with acid etching and air abrasion (AA). The fifth-generation dentin bonding agent mixed with rhodamine B dye 0.1% was applied on RMGIC in all the samples and cured for 15 s. Samples were restored using composite resin and sectioned longitudinally. The depth of penetration of adhesive resin was evaluated using CLSM. Depth of penetration of adhesive resin was highest with AA (153.70 ± 10.23), followed by acid etching (122.71 ± 12.25) and control group (77.12 ± 6.37). Based on the findings of this research, AA enhances the depth of penetration of adhesive resin in the RMGIC surface. Thus, AA before placement of composite resin on the RMGIC can be effective in a clinical scenario.

Effect of surface treatment and resin cement type on the bond strength of polyetheretherketone to lithium disilicate ceramic

BackgroundThis study aims to evaluate the effect of surface treatment and resin cement on the shear bond strength (SBS) and mode of failure of polyetheretherketone (PEEK) to lithium disilicate ceramic (LDC). This is suggested to study alternative veneering of PEEK frameworks with a ceramic material.Methodseighty discs were prepared from PEEK blank and from lithium disilicate ceramic. Samples were divided into four groups according to surface treatment: Group (A) air abraded with 110 μm Al2O3, Group (AP) air abrasion and primer application, Group (S) 98% sulfuric acid etching for 60 s, Group (SP) Sulfuric acid and primer. Each group was subdivided into two subgroups based on resin cement type used for bonding LDC:1) subgroup (L) self- adhesive resin cement and 2) subgroup (B) conventional resin cement (n = 10). Thermocycling was done for all samples. The bond strength was assessed using the shear bond strength test (SBS). Failure mode analysis was done at 50X magnification with a stereomicroscope. Samples were chosen from each group for scanning electron microscope (SEM). The three-way nested ANOVA followed by Tukey’s post hoc test were used for statistical analysis of results. Comparisons of effects were done utilizing one way ANOVA and (p < 0.05).ResultsThe highest mean of shear bond strength values was demonstrated in Group of air abrasion with primer application using conventional resin cement (APB) (12.21 ± 2.14 MPa). Sulfuric acid groups showed lower shear bond strength values and the majority failed in thermocycling especially when no primer was applied. The failure mode analysis showed that the predominant failure type was adhesive failure between cement and PEEK, while the remaining was mixed failure between cement and PEEK.ConclusionThe air abrasion followed by primer application and conventional resin cement used for bonding Lithium Disilicate to PEEK achieved the best bond strength. Primer application did not have an effect when self-adhesive resin cement was used in air-abraded groups. Priming step is mandatory whenever sulfuric acid etching surface treatment is utilized for PEEK.

Filler Mixed Into Adhesives Does Not Necessarily Improve Their Mechanical Properties.

To investigate the influence of filler type/loading on the micro-tensile fracture strength (μTFS) of adhesive resins, as measured 'immediately' upon preparation and after 1-week water storage ('water-stored'). The morphology and particle-size distribution of three filler particles, referred to as 'Glass-S' (Esschem Europe), 'BioUnion' (GC), and 'CPC_Mont', were correlatively characterized by SEM, TEM, and particle-size analysis. These filler particles were incorporated into an unfilled adhesive resin ('BZF-29unfilled', GC) in different concentrations to measure the 'immediate' μTFS. After 1-week water storage, the 'water-stored' μTFS of the experimental particle-filled adhesive resins with the most optimum filler loading, specific for each filler type, was measured. In addition, the immediate and water-stored μTFS of the adhesive resins of three experimental two-step universal adhesives based on the same resin matrix but varying for filler type/loading, coded as 'BZF-21' (containing silica and bioglass), 'BZF-29' (containing solely silica), and 'BZF-29_hv' (highly viscous with a higher silica loading than BZF-29), and of the adhesive resins of the gold-standard adhesives OptiBond FL ('Opti-FL', Kerr) and Clearfil SE Bond 2 ('C-SE2', Kuraray Noritake) was measured along with that of BZF-29unfilled (GC) serving as control/reference. Statistics involved one-way and two-way ANOVA followed by post-hoc multiple comparisons (α<0.05). Glass-S, BioUnion, and CPC_Mont represent irregular fillers with an average particle size of 8.5-9.9 μm. Adding filler to BZF-29unfilled decreased μTFS regardless of filler type/loading. One-week water storage reduced μTFS of all adhesive resins except BZF-21, with the largest reduction in μTFS recorded for BZF-29unfilled. Among the three filler types, the μTFS of the 30 wt% Glass-S and 20 wt% BioUnion filled adhesive resin was not significantly different from the μTFS of BZF-29unfilled upon water storage. Adding filler particles into adhesive resin did not enhance its micro-tensile fracture strength but appeared to render it less sensitive to water storage as compared to the unfilled adhesive resin investigated.

Surface treatment of poly(p-phenylene sulfide) and its impact on adhesion of epoxy resin: Theoretical insights

The adhesion of epoxy resin and poly(p-phenylene sulfide) (PPS) is investigated using density functional theory. This study investigated the unoxidized and oxidized (100), (110), and (010) surfaces of PPS, with (110) and (010) surfaces having the highest and lowest adhesive strengths, respectively. Surface oxidation increased the adhesive strength, particularly that of surfaces with initially low strength. The change in surface roughness by oxidation also affected the dispersion interaction, decreasing for the (100) and (110) surfaces and increasing for the (010) surface. The contribution of both interactions resulted in comparable adhesive strength for all oxidized surfaces. These findings provide insights for adhesion to PPS materials.

Evaluation of the Effect of Different Bonding Systems and Restorative Materials on Shear Bond Strength in the Repair of High-Viscosity Glass Ionomer Cement

Aim: High viscosity glass ionomer cements have been produced to increase the mechanical properties of glass ionomer cements. The aim of this study is to determine the appropriate adhesive system and restorative material that can be used in fracture repair of high viscosity glass ionomer cements. Material and Methods: A total of 140 standard size acrylic blocks were used in the study. 14 groups were formed from randomly selected acrylic blocks, with 10 samples in each group. High viscosity glass iomomer cement was placed in the first 13 groups, and resin-modified glass ionomer cement was placed in the last group. After the thermal cycle aging process was applied to all samples, repair restorations were performed with 4 different adhesive systems, 2 different composite resins and 2 different restorative types of glass ionomer cement. After the repair restorations, thermal cycle aging was applied again and the shear bond strengths were evaluated. One-way analysis of variance and Duncan multiple comparison test were used for statistical analysis. Results: The highest shear bond strength values were obtained by the total etch adhesive system (p&lt;0.001). The lowest shear bond strength values were obtained when high-viscosity glass-iomomer cement without adhesive system was restored with high-viscosity glass iomomer cement (p&lt;0.001). Conclusion: For higher shear bond strength values in the repair of high-viscosity glass ionomer cements should use to total etch adhesive systems and composite resin.

The Effect of Using PVAc (Polyvinyl Acetate) &amp; Epoxy Resin Adhesives on the Shear Strength of Laminated Bamboo

The Effect of Using PVAc (Polyvinyl Acetate) &amp; Epoxy Resin Adhesives on the Shear Strength of Laminated Bamboo

Effects of sterilization, conditioning, and thermal aging on the retention of zirconia hybrid abutments: A laboratory study.

To investigate the effects of sterilization, conditioning method, and thermal aging on the retentive strength of two-piece zirconia abutments. In total, 128 stock zirconia abutments were divided into four groups (n = 32) according to the conditioning parameters: (A) air-abrasion using 50 μm alumina particles/1.0 bar, (B) 50 μm/2.0 bar, (C) 100 μm/1.0 bar, and (D) 100 μm/2.0 bar. All abutments were bonded onto titanium bases using DTK adhesive resin and stored in water bath (37°C) for 72 h. Each group was subdivided into two subgroups (n = 16), group 1 was disinfected, whereas group 2 followed disinfection and autoclave sterilization. Half of the specimens of each subgroup (n&amp;#x02009;=&amp;#x02009;8) was directly subjected to the axial retention test (groups N), while the other half was first subjected to 150&amp;#x02009;days of thermocycling followed by retention test (groups T). Statistical analysis was performed with three-way ANOVA, additional statistical analysis was performed by using separate one-way ANOVAs followed by the Tukey's post-hoc test for post hoc pairwise comparisons among groups. The highest median retention strength was recorded for group B2N (1390 N), whereas the lowest strength was recorded for group C1T (688 N). No significant interaction (p ≥ 0.05) was detected between the different variables; conditioning method, sterilization, and the thermal cycling regarding the effect on the resulting retention. However, the sterilization always showed a positive effect. Thermocycling presented an adversely significant effect only in the absence of sterilization (p < 0.05), with the exception of subgroups A. For the sterilized groups, thermocycling had no statistically significant effect on the retention. Steam autoclaving increased the retention of hybrid zirconia abutments. DTK adhesive resin for two-piece zirconia abutments performed well after sterilization and thermocycling.

A novel surgical treatment approach for the vertical root fracture of posterior teeth: a case report with 24-month review

Background Up to 25% of the tooth extraction after root canal treatment could be attributed to the vertical root fracture (VRF). The treatment choice for teeth with VRF would mostly be the extraction despite some repairing methods were also reported. The repairing treatment result of VRF would mostly depend on the fixation strength and the bioactivity of the repairing materials, especially for the posterior teeth with high masticating stresses. This case report designed a novel surgical treatment approach for the VRF of posterior teeth.Methodsa maxillary premolar with buccal-palatal complete VRF was treated with a new dual-layered repairing approach using adhesive resin + iRoot BP Plus bioceramic cement to fill the modified fracture line with retention forms through the intentional replantation.ResultsAt the 24-month review, the tooth showed desirable periodontal healing and normal function.ConclusionsThis case report indicated that the dual-layered repairing approach might be effective for saving the posterior teeth with VRF. Nevertheless, further clinical trials are needed for its long-term result.

Influence of titanium dioxide nanotubes with alkyl ammonium alkyl bromide on the physicochemical properties and adhesion of experimental adhesive resins to dentin

ObjectiveThis study evaluated the effect of the incorporation of titanium dioxide nanotubes with alkyl trimethyl ammonium bromide (ntTiO2/ATAB) into experimental adhesive resins on their physicochemical properties and adhesion to dentin. Materials & methodsThe experimental adhesive resins were formulated with 66.66 wt% Bis-GMA and 33.33 wt% HEMA, photoinitiator with addition of ntTiO2/ATAB (1:1) in different concentrations: G1%, G2.5%, and G5%. One groups with no ntTiO2/ATAB addition was used as control (G0%). An optical tensiometer was used to analyze the contact angle (COA) by the sessile drop method (distilled water and α-bromonaphthalene) (n = 5), while the surface free energy (SFE) was calculated using Owens-Wendt-Rabel-Kaelble method. Flexural strength (FS) test (three-point bending) of polymerized adhesive samples was performed according to ISO 4049:2019 (n = 10) after 24 h or one year of water storage at 37 °C, as well as for the microtensile bond strength (μTBS) test, in which a commercial adhesive (GSBMP) was also used as control (n = 10). The adhesive-dentin interfaces were evaluated by scanning electron microscopy and X-ray spectrometry (n = 5). Data were analyzed by one-way (COA and SFE), two-way (FLE and μTBS) ANOVA and Tukey's test (α = 0.05). ResultsG5% showed the highest COA with nonpolar liquid and higher SFE than G0%. The G5% showed decreased FS compared to G0%. The μTBS of both controls (G0% and GSBMP) decreased after one year. TiO2/ATAB-containing adhesives to dentin showed no significant decrease after one year. All adhesives formed hybrid layer and the resin tags inside the dentinal tubules. ConclusionsThe incorporation of 1 and 2.5% of ntTiO2/ATAB into experimental adhesive resins did not impar the SFE. After one year, any concentration of ntTiO2/ATAB reduced the FS compared with control, but did not impair the μTBS.

Controlling the stability and adhesion performance of cold-setting phenol–resorcinol–formaldehyde resin adhesives through methanol addition

Phenol–resorcinol–formaldehyde (PRF) resin adhesives are commonly used in the manufacture of laminated timber products, and they are cold-set at room temperature rather than hot-pressed to generate a three-dimensional polymer structure in the products. However, their excellent reactivity often leads to poor storage stability and a short pot life. This study examines the influence of methanol addition on the stability and adhesion performance of PRF resins. These resins were synthesized by various levels of methanol addition (5 %, 10 %, and 15 %), and their structures were investigated using Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. Furthermore, differential scanning calorimetry (DSC) was used to analyze their thermal behavior, and their cure kinetics were analyzed with two isoconversional analyses: Kissinger–Akahira–Sunose (KAS) and Vyazovkin (VYZ) method. The adhesion performances of PRF resins were evaluated for glue-laminated timber (GLT). The results demonstrated that the viscosity and solids content of PRF resins decreased while their gelation time increased as the methanol addition level increased. Methanol addition has also improved the resin stability over time. The chemical structure of PRF resins did not change considerably with an increase in the methanol level. However, methanol interaction with formalin in a hardener presumably hindered the reactivity of PRF resins. This was supported with an increase in the apparent activation energy of the curing process of PRF resins as the methanol level increased. In addition, decreasing the methanol levels from 15 % to 5 % enhanced the adhesion performance of GLT bonded with PRF resins. The results indicated that adding methanol to PRF resins improved its stability while simultaneously weakened its performance. However, 5 % methanol level is recommended for PRF resins.

Antibacterial Properties of an Experimental Dental Resin Loaded with Gold Nanoshells for Photothermal Therapy Applications.

This study explored the chemical and antibacterial properties of a dental resin loaded with gold nanoshells (AuNPs) in conjunction with photothermal therapy (PTT) as a novel method against Streptococcus mutans (S. mutans) to prevent secondary caries. First, a 20-h minimum inhibitory concentration (MIC) assay was performed on solutions of AuNPs with planktonic S. mutans under an LED device and laser at 660 nm. Next, resin blends containing 0, 1 × 1010, or 2 × 1010 AuNPs/mL were fabricated, and the degree of conversion (DC) was measured using an FTIR spectroscopy. Lastly, a colony forming unit (CFU) count was performed following 24 h growth of S. mutans on 6 mm diameter resin disks with different light treatments of an LED device and a laser at 660 nm. The MIC results only showed a reduction in S. mutans at AuNP concentrations less than 3.12 µg/mL under a laser illumination level of 95.5 J/cm2 compared to the dark treatment (p < 0.010 for each). CFU and DC results showed no significant dependence on any light treatment studied. The AuNPs expressed antibacterial effects following PPT against planktonic S. mutans but not in a polymerized dental adhesive resin. Future studies should focus on different shapes, structure, and concentrations of AuNPs loaded in a resin blend.

Color stability and marginal adaptation of ceramic veneers cemented using different composite resins.

The purpose of this study was to compare the color stability and marginal adaption of lithium disilicate veneers before and after thermocycling using various resin composite materials employed as cement. Laminate veneer preparation was done on an acrylic tooth according to standardized procedures. The veneer preparations were duplicated into twenty-one dies. The veneers were fabricated from lithium disilicate using the CEREC in Lab system. According to the cement type, the twenty-one die specimens were randomly divided into three equal groups: group I, with light cured adhesive resin cement (N.=7), group II, with flowable light cured composite, and group III, with preheated nano filled composite. The cemented specimens underwent 5000 thermocycling cycles. Color was assessed using a reflective spectrophotometer. The vertical marginal gap, following cementation and thermocycling, was measured using a digital microscope. One-way ANOVA followed by Tukey's post-hoc test was used to statistically assess the data. After thermocycling, there was no statistically significant difference in ΔE among cement type groups for color stability (P=0.369). However, the preheated composite showed the lowest ΔE mean values. Within adhesive resin cement and flowable composite groups, marginal gap means values recorded after thermocycling were significantly higher than those after cementation (P=0.013 and P<0.001, respectively). Although preheated composite cement showed the highest marginal discrepancy, it would be the best choice regarding color stability.

Preparation of biomimetic reinforced modified carbon fiber composites and study of their friction properties

Because aluminum-based parts cannot be used for long-term applications in large load-wear environments, nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites were successfully prepared in this study for that purpose. By adjusting the plating solution ratio, nickel–tungsten was used as a carrier to introduce molybdenum disulfide nanoparticles, forming a nickel–tungsten/molybdenum disulfide composite coating on the surface of carbon fibers. To enhance the interfacial bonding strength between the carbon fiber and aluminum matrix, a laser was employed to induce the formation of a honeycomb-like structure on the surface of the aluminum base. This increased the contact area between the carbon fiber, aluminum matrix, and epoxy resin adhesives, forming a nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material. The performance of this composite material was tested and analyzed. The results demonstrated that compared with the carbon fiber/aluminum composite material, the shear strength of the nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material was increased by 129.7 %, and the friction coefficient and wear rate were reduced by 54.8 % and 83 %, respectively. Next, investigation of the mechanism underlying the honeycomb structure's contribution to the adhesive strength of the composites and their resistance to shear load revealed that the wear-resistant mechanism of molybdenum disulfide nanoparticles reinforced the nickel–tungsten composite coatings. The preparation and study of nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites provide a reference for expanding the applications of aluminum-based composite materials to meet the service requirements of complex environments.

Resin Cements in Dentistry

Even though the GIC has undergone many advances, its chemistry is fundamentally different from that of modern resin based composite direct filling products, which feature a silica or glass particle filled polymer matrix that enhances repair retention. When the restoration is etched or air abraded after the tooth has been conditioned with an adhesive resin and etched, retention becomes "micromechanical," ensuring the resin cement's high tensile strength. Cementation of the extraoral fabricated restoration is very important for the longevity of the restoration. The bond strength of resin cement to ceramic and fibre post is better than conventional cements. This article discusses about the various types of resin cements and there uses for luting indirect restorations such crowns, veneers, inlays, and onlays, etc.

Influence of screw channel angulation on reverse torque value and fracture resistance in monolithic zirconia restorations after thermomechanical cycling: an in-vitro study

BackgroundWhile the concept of angled screw channels has gained popularity, there remains a scarcity of research concerning the torque loss and fracture strength of monolithic zirconia restorations with various screw channel angulations when exposed to thermomechanical cycling. This in-vitro study aimed to evaluate the reverse torque value and fracture resistance of one-piece screw-retained hybrid monolithic zirconia restorations with angulated screw channels after thermomechanical cycling.MethodsOne-piece monolithic zirconia restorations, with angulated screw channels set at 0°, 15°, and 25° (n = 6 per angulation) were fabricated and bonded to titanium inserts using a dual-cure adhesive resin cement. These assemblies were then screwed to implant fixtures embedded in acrylic resin using an omnigrip screwdriver, and reverse torque values were recorded before and after thermomechanical cycles. Additionally, fracture modes were assessed subsequent to the application of compressive load. One-way ANOVA and Bonferroni post hoc test were used to compare the groups (α = 0.05).ResultsThe study groups were significantly different regarding the fracture resistance (P = 0.0015), but only insignificantly different in the mean percentage torque loss (P = 0.4400). Specifically, the fracture resistance of the 15° group was insignificantly higher compared to the 0° group (P = 0.9037), but significantly higher compared to the 25° group (P = 0.0051). Furthermore, the fracture resistance of the 0° group was significantly higher than that of the 25° group (P = 0.0114).ConclusionsOne-piece hybrid monolithic zirconia restorations with angulated screw channels can be considered an acceptable choice for angulated implants in esthetic areas, providing satisfactory fracture strength and torque loss.

Molecular Understanding of the Distinction between Adhesive Failure and Cohesive Failure in Adhesive Bonds with Epoxy Resin Adhesives.

In the development of adhesives, an understanding of the fracture behavior of the bonded joints is inevitable. Two typical failure modes are known: adhesive failure and cohesive failure. However, a molecular understanding of the cohesive failure process is not as advanced as that of the adhesive failure process. In this study, research was developed to establish a molecular understanding of cohesive failure using the example of a system in which epoxy resin is bonded to a hydroxyl-terminated self-assembled monolayer (SAM) surface. Adhesive failure was modeled as a process in which an epoxy molecule is pulled away from the SAM surface. Cohesive failure, on the other hand, was modeled as the process of an epoxy molecule separating from another epoxy molecule on the SAM surface or breaking of a covalent bond within the epoxy resin. The results of the simulations based on the models described above showed that the results of the calculations using the model of cohesive failure based on the breakdown of intermolecular interactions agreed well with the experimental results in the literature. Therefore, it was suggested that the cohesive failure of epoxy resin adhesives is most likely due to the breakdown of intermolecular interactions between adhesive molecules. We further analyzed the interactions at the adhesive failure and cohesive failure interfaces and found that the interactions at the cohesive failure interface are mainly accounted for by dispersion forces, whereas the interactions at the adhesive failure interface involve not only dispersion forces but also various chemical interactions, including hydrogen bonds. The selectivity between adhesive failure and cohesive failure was explained by the fact that varying the functional group density affected the chemical interactions but not the dispersion forces.

Waterborne epoxy composite coating containing N,S-doped carbon dots for enhancing corrosion resistance

In order to construct waterborne epoxy composite coating with enhanced anti-corrosive performance, the development of efficient additives with good compatibility with adhesive resin and good interaction with steel matrix is of significance. Herein, we adapted two heteroatom (N and S) doped carbon quantum dots, namely ACDs and LCDs, as eco-friendly anti-corrosion components to mix with water-based epoxy resin (WP) to prepare the CDs/WP composite coating. Compared with the ACDs/WP composite, the LCDs/WP composite exhibited a better performance because it contained more functional groups such as carboxyl and hydroxyl on the surface of LCDs, which not only made the system denser but also facilitated the multi-anchor coordination and adsorption on carbon steel. Following immersing in a 3.5 wt% NaCl solution for 28 d, the impedance modulus of LCDs/WP surpassed 109 Ω cm2, exhibiting approximately three orders of magnitude higher values compared to pure WP coatings. The inhibition efficiency was improved by 96.9%. The facile synthesis of LCDs coupled with excellent anti-corrosive properties of LCDs/WP composites, provides a new way for developing anti-corrosion coating materials.

Influence of different immediate dentin sealing strategies on bond strength of indirect resin nanoceramic restorations.

In this study, we evaluated the effect of four different strategies for bonding a CAD/CAM resin nanoceramic restoration (Lava Ultimate, 3M) to the dentin surface using a universal adhesive (Scotch Bond Universal, 3M) and adhesive resin cement (RelyX Ultimate, 3M) on the shear bond strength (SBS) and failure mode. The strategies comprised: (i) immediate sealing, immediate bonding; (ii) immediate sealing, bonding after 2weeks with provisional restoration; (iii) immediate sealing with flowable resin composite reinforcement and bonding after 2weeks with provisional restoration; and (iv) no immediate sealing, and bonding after 2weeks with provisional restoration. After bonding, all the specimens were thermocycled, shear tests were performed using a universal testing machine, and failure modes were determined using stereomicroscope and scanning electron microscopy. The highest mean SBS was recorded with immediate sealing, immediate bonding strategy. Most adhesive failures with exposed dentinal tubules were noted in specimens exposed to bonding after 2weeks with no immediate sealing, which was associated with the lowest SBS. Mixed failures predominated in all immediate dentin sealing groups. Immediate sealing with universal adhesives improves SBS, particularly in the single-visit approach, which has shown significantly better performance, whereas the provisional phase has a negative effect.

Evaluation of Microvoid and Microleakage Potential of Bulk-Fill Resin Composites in MOD Restorations

Background: Polymerization shrinkage and microvoid formation has been a significant problem giving way to resin composite failure. The aim of this study was to evaluate the microvoid potential and microleakage of two bulk-fill and a microhybrid resin composite applied with different adhesive materials. Materials and Methods: MOD cavities were prepared in 60 endodontically treated maxillary premolars. The teeth were divided into six different groups (n = 10) according to adhesive systems (Gluma (Kulzer), OptiBond FL (Kerr) and resin composite materials EverX Posterior (GC) and Filtek One Bulk Fill (3M ESPE). An aging procedure with 5000 cycles of thermal cycling was applied. All teeth were individually scanned with micro-computed tomography. A Shapiro–Wilk test, two-way MANOVA, and Bonferroni analysis were used for statistical tests. Results: Self-etch groups showed more microleakage than total-etch groups. Minimum microleakage was observed in Filtek One Bulk Fill groups, whereas G-aenial Posterior groups showed maximum microleakage. Conclusions: Filtek One Bulk Fill (3M ESPE) resin composite was found to be more effective in reducing microvoid formation in MOD cavities when applied with total-etch adhesive systems. However, EverX Posterior (GC) and G-aenial Posterior (GC) showed less microvoid formation with self-etch adhesive systems.

Tougher Bioadhesives through Dual Stimulation Strategies.

Carbene-based bioadhesives have favourable attributes for tissue adhesion, including non-specific bonding to wet and dry tissues, but suffer from relatively weak fracture strength after photocuring. Light irradiation of carbene-precursor (diazirine) also creates inert side products that are absent under thermal activation. Herein, a dual activation method combines light irradiation at elevated temperatures for the evaluation of diazirine depletion and effects on cohesive properties. A customized photo/thermal-rheometer evaluates viscoelastic properties, correlated to the kinetics of carbene:diazoalkane ratios via 19F NMR). The latter exploits the sensitive -CF3 functional group to determine joule-based light/temperature kinetics on trifluoroaryl diazirine consumption. The combination of heat and photoactivation produced bioadhesives that are 3× tougher compared to control. Dual thermal/light irradiation may be a strategy to improve viscoelastic dissipation and toughness of photo-activated adhesive resins.