Improved Bond Strength Research Articles

Effects of Silver Diamine Fluoride and Potassium Iodide Solutions on the Anti-Caries Properties, Surface Hardness, and Bond Strength of Resin Modified Glass Ionomer in Dentin

This study evaluated the effects of silver diamine fluoride (SDF) and potassium iodide (PI) on carious dentin. The antibacterial efficacy, surface hardness, and bond strength of resin-modified glass ionomer cement (RMGI) were assessed. Dentin specimens were prepared and subjected to artificial caries formation. The antibacterial effect of SDF/PI was compared to sodium fluoride varnish using Streptococcus mutans colony counts. Surface microhardness was measured using the Vickers hardness test. Shear bond strength of RMGI to treated surfaces was evaluated after thermocycling. Results showed that SDF/PI had superior antibacterial effects compared to NaF varnish. Surface hardness significantly increased one week after SDF/PI application. While SDF/PI treatment did not immediately affect RMGI bond strength to carious dentin, delayed bonding after one week significantly improved bond strength. These findings suggest that SDF/PI is effective in arresting caries and enhancing remineralization of carious dentin. The study also indicates that delaying restoration placement for one week after SDF/PI application may be beneficial for improving bond strength. This research provides valuable insights into the clinical application of SDF/PI for caries management and subsequent restorative procedures.

Micromechanical and Tribological Characterization of Fabricated Ti–6Al–4V Alloy Using Laser Powder Bed Fusion

Abstract In the dynamic era of advanced manufacturing technology, laser powder bed fusion (L-PBF) have gained popularity in different domains due to its capability to build parts from bulk to miniature size with higher efficiency and precision. Ti–6Al–4V, a bio-inert metal alloy, possesses a unique blend of profound mechanical and biocompatibility attributes, making it highly suitable for implant applications. This study reports the fabrication of Ti–6Al–4V alloy for implant application via the L-PBF process. The objective is to enhance the micromechanical and tribological properties of the fabricated Ti–6Al–4V component by identifying the optimal processing conditions. The fabricated component exhibited a maximum hardness of 395.26 HV and a minimum frictional coefficient of 0.3193 at 195 W laser power, 900 mm/s scanning speed, and 70 μm hatching distance. The wear-rate and absorbed wear volume were measured as 1.265 × 10−5 mm3 N−1 min−1 and 0.3162 mm3, respectively, under sliding conditions. At optimal processing state, the printed surface displayed an alpha-phase morphology with homogeneous microstructural features due to uniform melting of powder particles that improved bond strength and minimized defects. This study offers an experimental insight into operational attributes, paving the way for accelerated production of Ti–6Al–4V alloy components using the L-PBF method and tailoring tribological properties to meet specific functional requirements.

Green transforming black liquors as a new HCHO scavenger in production eco urea formaldehyde-agro composites

Innovative formaldehyde (HCHO)-scavenger based on black liquor is being developed to achieve eco-friendly low toxic urea formaldehyde (UF) adhesive. This scavenger will enhance the UF adhesive in production of agro-composites, complying with the environmental requirements. The HCHO-scavenger is synthesized from black liquor-based aerogels of various types of black liquors. The performance of the prepared scavengers is assessed via adsorption of HCHO; as well as its beneficial effect on properties of UF adhesive and UF-Palm fiber-composite. In order to produce a composite with mechanical properties and free-HCHO compliance with the standard specifications, the UF-scavenger system is optimized from its behavior. The data evidence the effective behavior of all investigated scavenger to improve bond strength of UF adhesive system (from 8.4 MPa to ∼ 18 MPa); and properties of UF-palm-composites, where the enhancement in modulus of rupture (MOR) and internal bond strength (IB), water repellent, reach to 50 %, 83 % and 7.7 %, respectively. In addition to success in producing eco-composites through reducing the free-HCHO of wood sample from 30.77 to 3.0–12.7 mg/100g with reduction percentages (58.7–90.3 %) exceeded those reported in the literature when carbon and silicon scavengers were used.

Experimental investigation on bond properties of nano-Al2O3 and hydroxypropyl methyl cellulose (HPMC) modified coated steel bar embedded in concrete

In this work, cementitious coatings incorporate nano-Al2O3 (NA) and HPMC were developed applying to the surface of steel bars to enhance bond behavior. A total of 81 pull-out specimens were prepared to evaluated bond properties of different coated steel bars embedded in ordinary performance concrete (OPC), high performance concrete (HPC) and ultra-high-performance concrete (UHPC). The mechanical properties of the cement-based coatings have also been examined. Test results show that flexural and compressive strengths of coating paste exhibited initially increasing and followed by decreasing as NA content increase. Synergistic effect of NA and HPMC results in cement-based coating exhibiting superior mechanical properties. Besides, coating microscopic morphology characterized by scanning electron microscope (SEM) technique revealed that fewer coating defects with NA and HPMC compounding. More importantly, the highest bond strength between coated steel bar and different types concretes was found at 1.0 % NA content in the coatings. Synergistic effect of 1.0 % NA and 0.12 % HPMC improved bond strength of coated steel bar embedded in OPC, HPC and UHPC. It can be obtained from bond-slip curve that, regardless of the HPMC addition to coatings, coated steel bar with 1.0 % NA content shows higher bond stiffness. With both NA and HPMC added, bond stiffness, bond toughness and bond ductility of coated steel bar are superior to those of the coating with NA alone. Moreover, as concrete strength increases, the bond strength, bond stiffness and bond toughness of coated steel bar also increase, respectively.

Comparative Analysis of Shear Bond Strength in Orthodontic Brackets Between Milled and 3D-Printed Definitive CAD/CAM Restorations

Objective: The objective of this study was to evaluate the effect of different surface treatment methods on the shear bond strength (SBS) of metal brackets bonded to two types of CAD/CAM composite restorations: milled and 3D-printed. Materials and Methods: A total of 160 flat-shaped specimens (10 × 10 × 2 mm3) were prepared from four different CAD/CAM composites; two milled (Lava Ultimate™ [LU] and Grandio™ [GR]) and two 3D-printed (Crowntec™ [CT] and C&B Permanent™ [CB]). These specimens underwent thermocycling (5000 cycles at 5–55 °C), then were categorized based on the surface treatment into four groups (n = 10): Group C (control, no surface treatment), Group HF (treated with 9.6% hydrofluoric acid), Group DB (mechanical roughening by a diamond bur), and Group SB (sandblasting using aluminum oxide). Metal brackets were bonded using Transbond XT Primer and universal adhesive, stored in artificial saliva for 24 h, then thermocycled again. Shear bond strength (SBS) was tested using a universal testing machine until bracket debonding occurred. The adhesive remnant index (ARI) was assessed using a stereomicroscope to quantify the residual adhesive following debonding. Result: Regarding material, GR and LU restorations had significantly higher SBS values compared to CT and CB, ranging from 13.90 MPa to 20.35 MPa. Regarding surface treatment, SB and HF groups showed significantly higher SBS values. The ARI scores showed different adhesive modes of failure, with higher instances of scores 0 and 1, which indicate no or minimal adhesive remaining. Conclusions: Both milled and 3D-printed materials had adequate SBS for clinical use, with milled materials showing superior results. Surface treatments like sandblasting and HF significantly improved bond strength, with adhesive failure being common.

Effect of mechanical and chemical surface treatments on the repairing of milled and 3D-printed denture bases.

Ensuring a strong bond between chairside autopolymerized acrylic resin to denture base is essential for denture repair and reline procedures. However, there is no established protocol to enhance bond strength between autopolymerizing resin and computer-aided design and computer-aided manufacturing (CAD-CAM) denture base materials. The purpose of this study was to determine shear bond strength of CAD-CAM denture bases and autopolymerizing acrylic resin after mechanical and chemical surface treatments compared with heat-polymerized acrylic resin. Heat-polymerized, milled, and 3-dimensional (3D) printed denture bases were divided into 4 surface treatment protocols: none (control), airborne-particle abrasion (APA), tetrahydrofuran, and Vitacoll application. Autopolymerizing acrylic resin cylinders were bonded to denture surface. Shear bond strength and failure modes were determined after thermocycling. Denture base surfaces were assessed for surface roughness, surface morphology, and microhardness before and after surface treatment. Data was analyzed using two-way ANOVA and multiple comparison tests. The results showed that APA significantly increased shear bond strength and surface roughness of all denture base materials. Tetrahydrofuran and Vitacoll application improved shear bond strength of heat-polymerized acrylic resin, but did not reach the level achieved by APA. Conversely, tetrahydrofuran application improved bond strength of 3D-printed denture to the level of APA. Tetrahydrofuran and Vitacoll application significantly reduced denture base hardness, compared with control and APA. In conclusion, mechanical surface treatment using APA enhances the adhesion of autopolymerizing acrylic resin to heat-polymerized and CAD-CAM denture bases. Tetrahydrofuran and Vitacoll chemical surface treatment improved adhesion to heat-polymerized acrylic resin, with only tetrahydrofuran enhancing bond strength of 3D-printed denture to the level of APA. Without surface treatment, the highest bond strength was shown in 3D-printed denture base material.

Improving bond strength and deposition efficiency of ceramic coatings via low pressure cold spraying: A study on hydroxyapatite coatings with Cu-Zn blends

This study presents Low Pressure Cold Spraying (LPCS) method for ceramic coatings, aimed at enhancing efficiency and elucidating bonding mechanisms. It focuses on the deposition of ceramic coatings using LPCS, with hydroxyapatite (HA) on 316L stainless steel (SS) as an illustrative example. Despite the advantages of LPCS, retaining HA particles has proven challenging, resulting in thin coatings (11.09 ± 2.56 μm) with low bonding strength (1.80 ± 0.19 MPa). To address this issue, a composite coating strategy was developed by blending 20 wt% Cu and Zn powder with 80 wt% HA. This approach significantly improved coating properties, achieving enhanced bonding strength (33.70 ± 1.13 MPa), deposition efficiency (27 %), and hardness (136.30 ± 2.45 HV) compared to pure Cu-Zn coatings. Numerical simulations were conducted to interpret these experimental results, indicating that blending metal with HA improves deposition efficiency, bonding strength, and hardness. In HA coatings, particles fragment into submicron grains and embed into the substrate through mechanical interlocking (MI), with shockwave-induced bonding strengthening subsequent layers. For Cu-Zn coatings, bonding occurs through MI and adiabatic shear instability (ASI). In HA-Cu-Zn coatings, high-velocity HA particles and Zn particles enhance bonding further through in-situ tamping.

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.

Does the Application of Anti-Erosive Substances on Eroded Dentin Affect Bond Strength? A Systematic Review

This systematic review evaluated whether using anti-erosive agents as a pretreatment of eroded dentin before bonding with resin composite affects the bond strength. A search was conducted by two reviewers in the PubMed, Embase, Scopus, Web of Science, and Science Direct databases in January 2023. Articles that employed artificially eroded human dentin and performed treatment prior to adhesion with anti-erosive substances were eligible. A validated tool with 12 items regarding in vitro studies was used to assess the risk of bias in the selected articles, obtaining a final score for each study. Four in vitro studies were included in this systematic review. Most studies used the microtensile bond strength test; most failures were adhesive or mixed. No tested substance negatively affected the bond strength to eroded dentin. Sodium fluoride (NaF), tin-containing fluoride (Sn/F) and silver diamine fluoride (Ag(NH₃)₂F) have been proven not to interfere with or improve bond strength to eroded dentin.

In Vitro Bond Strength of Dentin Treated with Sodium Hypochlorite: Effects of Antioxidant Solutions.

This systematic review aims to evaluate whether the application of antioxidant solutions can enhance the bond strength of resin-based materials to sodium hypochlorite (NaOCl)-treated dentin. This study follows the PICOT strategy: population (sodium hypochlorite-treated dentin), intervention (application of antioxidants), control (distilled water), outcome (bond strength), and type of studies (in vitro studies). The systematic review and meta-analysis were conducted following PRISMA guidelines. Electronic databases were searched for in vitro studies evaluating the effects of antioxidants on bond strength to sodium hypochlorite-treated dentin. Two independent reviewers screened articles, extracted data, and assessed risk of bias. Meta-analyses were performed using a random-effects model to compare standardized mean differences in bond strength between antioxidant pretreatment and control groups. Inclusion criteria consisted of in vitro studies that examined the bond strength of resin-based materials to NaOCl-treated dentin with antioxidant application, while exclusion criteria included studies with incomplete data, those not using a control group, or those that did not directly measure bond strength. From 3041 initial records, 29 studies were included in the qualitative analysis and 25 in the meta-analysis. Ascorbic acid, sodium ascorbate, grape seed extract, green tea, and rosmarinic acid significantly improved bond strength to sodium hypochlorite-treated dentin (p < 0.05). The effectiveness of grape seed extract varied with adhesive system type. Hesperidin, p-toluene sulfonic acid, and sodium thiosulfate did not significantly improve bond strength. Most studies had a high risk of bias. This suggests that the conclusions drawn from these studies should be interpreted with caution, and further research with more robust methodologies may be needed to confirm the findings. In conclusion, this systematic review implies that certain antioxidants can improve bond strength to sodium hypochlorite-treated dentin, with efficacy depending on the specific agent and adhesive system used. Further standardized studies are needed to optimize protocols and confirm these findings.

Long-term hybrid stability and matrix metalloproteinase inhibition by fucosterol in resin-dentin bonding biomechanics

Fucosterols have been widely studied for their antioxidant, anticancer, and anti-inflammatory properties. However, they have not yet been studied in the field of dentistry. This study aimed to determine whether pretreatment of dentin with fucosterol before resin restoration enhances bond stability in resin-dentin hybrid layers. After applying 0.1, 0.5, and 1.0 wt% fucosterol to demineralized dentin, microtensile bond strength (MTBS) and nanoleakage tests were performed before and after collagenase aging, and the surface was observed using scanning electron microscope (SEM). The fucosterol-treated group showed better bond strength and less nanoleakage both before and after collagenase aging, and the corresponding structures were confirmed using SEM. MMP zymography confirmed that the activity of MMPs was relatively low along the concentration gradient of fucosterol, and the FTIR analysis confirmed the production of collagen crosslinks. In addition, fucosterol exhibits cytotoxicity against Streptococcus mutans, the main cause of dental decay. The results of this study suggest that fucosterol pretreatment improves bond strength and reduces nanoleakage at the resin-dentin interface, possibly through a mechanism involving collagen cross-link formation via the inhibition of endogenous and exogenous MMP activity. This study demonstrates the potential of fucosterol as an MMP inhibitor in dentin, which contributes to long-term resin-dentin bond stability and can be used as a restorative material.

Assessing the impact of different Urushiol primer solvents on dentin remineralization and bond strength.

To investigate urushiol's potential as a dentin cross-linking agent, promoting remineralization of etched dentin and preventing activation of endogenous proteases causing collagen degradation within the hybrid layer. The goal is to improve bond strength and durability at the resin-dentin interface. Urushiol primers with varying concentrations were prepared using ethanol and dimethyl sulfoxide (DMSO) as solvents. Dentin from healthy molars underwent grinding and acid etching for 15s, followed by a 1min application of urushiol primer. After 14 and 28days of remineralization incubation and remineralization were usedtoassessby Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR), Micro-Raman spectroscopy, X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Vickers Hardness, Scanning Electron Microscopy (SEM), and Energy X-ray dispersive spectroscopy (EDS). The overall performance of urushiol primers as dentin adhesives was observed by microtensile bond strength (μTBS) testing and nanoleakage assessment. Investigated the inhibitory properties of the urushiol primers on endogenous metalloproteinases (MMPs) utilizing in situ zymography, and the cytotoxicity of the primers was tested. Based on ATR-FTIR, Raman, XRD, EM-EDS and Vickers hardness analyses, the 0.7%-Ethanol group significantly enhanced dentin mineral content and improved mechanical properties the most. Pretreatment notably increased the μTBS of restorations, promoted the stability of the mixed layer, and reduced nanoleakage and MMPs activity after 28days. The urushiol primer facilitates remineralization in demineralized dentin, enhancing remineralization in etched dentin, effectively improving the bonding interface stability, with optimal performance observed at a 0.7 wt% concentration of the urushiol primer.

Effect of silver diamine fluoride and potassium iodide on shear bond strength for glass ionomer cement to primary dentine.

Silver diamine fluoride (SDF) is a highly effective topical fluoride for halting dental caries; however, it darkens both teeth and restorations. Therefore, it is of interest to assess the shear bond strength (SBS) of glass ionomer cement (GIC) to caries-affected dentin treated with SDF alone and SDF followed by KI. Forty primary molar samples were prepared to reveal a flat dentin surface and were randomly assigned to two groups. In group A, the dentin surfaces were pre-treated with 38% SDF, while in group B, the dentin was treated first with SDF and then with KI before being restored with GIC. The SBS was measured using a universal testing machine. The results show that teeth pre-treated with both SDF and KI demonstrated significantly improved bond strength of GIC to dentin compared to SDF treatment alone.

Bond performance and constitutive model of steel bar in G-UHPC under cyclic loading

The increasing embrace of the low-carbon and environmentally sustainable construction approach has opened exciting opportunities for using environmentally friendly geopolymer based ultra-high-performance concrete (G-UHPC) in engineering structures, drawing significant attention to its performance. Seismic performance is a crucial factor in structural design, and it is greatly affected by the bond behavior between steel bar and concrete. As a result, a thorough understanding of the bond behavior of steel bars to G-UHPC provides essentially theoretical support for the structural design and nonlinear finite element analysis of G-UHPC structures, which is vital for their widespread implementation in earthquake engineering. This study tested 54 specimens from 18 groups to examine the bond performance of G-UHPC and steel bars under cyclic loading. The influence of concrete and steel bar types, protective layer thickness, bond length, and steel fiber on critical bond performance indicators were evaluated, and the bond stress-slip hysteretic and skeleton curves were analyzed. Subsequently, based on the experimental data, a constitutive model was proposed to predict the bond stress-slip relationship of steel bars and G-UHPC under cyclic loading. The results indicated that the steel bars exhibited superior bond performance with G-UHPC as compared to NSC. The bond and residual strength between steel rebars and G-UHPC was approximately 1.73 times and 3 times greater, respectively, in comparison with that between NSC and steel rebars. Increasing the strength of steel bars only resulted in a limited 2 % improvement in bond strength. The steel bar diameter, protective layer thickness, bond length, and the dosage and length of steel fibers in G-UHPC significantly influenced the bond performance. The addition of irregular-shaped steel fibers to G-UHPC has demonstrated potential in improving energy consumption, with the most remarkable enhancement observed for the inclusion of twisted steel fibers. Specifically, the incorporation of twisted steel fibers signally enhanced the energy consumption to approximately 1.3 times the energy dissipation as compared to straight steel fibers with the same dosage and aspect ratio. In addition, the accuracy of the proposed constitutive model has been validated.

Investigating the impact of surface treatments on tensile bond strength between pediatric prefabricated zirconia crowns and primary maxillary incisors with various types of luting cement: an in vitro study.

This study aimed to evaluate the effects of two surface treatments on the tensile bond strength of prefabricated zirconia crowns (PZCs) using bioactive and resin cements. Forty extracted human primary maxillary incisors were prepared and divided into four groups based on surface treatment and cement type: (1) sandblast with bioactive cement, (2) sandblast with resin cement, (3) 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) with bioactive cement, and (4) 10-MDP with resin cement. After 24h of cementation, specimens underwent 5000 thermocycling cycles between 5°C and 55°C. Tensile bond strengths were measured using a universal testing machine. The data were analyzed using two-way ANOVA and Tukey's post hoc test, with significance set at p < 0.05. The mean tensile bond strengths observed were 2.25 ± 1.27MPa for sandblast with bioactive cement, 1.39 ± 0.95MPa for sandblast with resin cement, 2.45 ± 1.15MPa for 10-MDP with bioactive cement, and 1.68 ± 1.03MPa for 10-MDP with resin cement. Significant improvements in bond strength were observed in the bioactive cement group treated with 10-MDP compared to those treated with sandblasting (p < 0.05). The 10-MDP treatment did not enhance bond strength for the resin cement compared to sandblasting. Bioactive cement generally provides a higher tensile bond strength than resin cement. While 10-MDP treatment enhances bond strength when used with bioactive cement, it does not show a similar enhancement when used with resin cement compared to sandblasting, indicating its effectiveness is selective based on the type of cement used.

The evolution of adhesive dentistry: a review of materials and techniques

Adhesive dentistry has undergone remarkable advancements since its inception, fundamentally transforming restorative dental care. Initially marked by the development of early resins and etching techniques, adhesive dentistry has evolved to incorporate sophisticated materials and innovative techniques that significantly enhance clinical outcomes. The introduction of Bis-GMA resins in the 1960s improved mechanical properties and reduced polymerization shrinkage, paving the way for modern composite resins. These composites, enhanced by nanotechnology and advanced filler technology, provide superior strength, wear resistance, and esthetic qualities. Techniques such as selective enamel etching and multi-layering of adhesive systems have further improved bond strength and reduced technique sensitivity. The clinical applications of adhesive dentistry are extensive, ranging from direct and indirect restorations to cosmetic procedures and preventive measures. Direct composite restorations offer minimally invasive solutions with excellent esthetics, while indirect restorations such as inlays, onlays, and veneers benefit from strong, reliable bonds and improved durability. Cosmetic procedures, including veneers, achieve dramatic esthetic improvements with long-lasting results. Preventive applications, such as sealants, effectively protect against caries, especially in pediatric and high-caries-risk patients. The continuous refinement of materials and techniques has led to better clinical outcomes, increased patient satisfaction, and reduced need for invasive procedures. Advances in adhesive materials and methods have ensured that restorations not only mimic natural tooth structures but also maintain their integrity under functional forces. As research and development in adhesive dentistry continue to progress, the field is poised to offer even more innovative and effective solutions, further enhancing the quality of dental care. Overall, the evolution of adhesive dentistry underscores its pivotal role in modern dental practice, providing durable, esthetic, and reliable restorative options that meet the diverse needs of patients.

Adhesive Performance of Pit and Fissure Sealants on Deproteinized Enamel with Different Proteolytic Agents: In Vitro Study.

The objective of this work was to assess the efficacy of different proteolytic agents on the bond strength of pit and fissure sealants to bovine enamel. Eighty-four bovine enamel specimens were randomly assigned in groups according to the pit and fissure sealant applied (HelioSeal F or Dyad Flow). Then, the specimens were subdivided according to the proteolytic agent used (n = 7): Group 1, distilled water (control); Group 2, 10 wt.% Tergazyme®; Group 3, 10 wt.% ZYME®; Group 4, 10% papain gel; Group 5, 10% bromelain gel; and Group 6, 5.25 wt.% sodium hypochlorite. The cell viability of the proteolytic solutions was assessed through the MTT assay. The proteolytic agents were applied on the enamel surface prior to the acid-etching procedure; then, the pit and fissure sealants were placed. The micro-shear bond strength was evaluated after 24 h or 6 months of water storing at 37 °C. Representative SEM images were taken for each experimental group. The bond strength data were statistically analyzed by a three-way ANOVA test using a significance level of α = 0.05. Bromelain and papain proteolytic solutions did not exert any cytotoxic effect on the human dental pulp cells. After 24 h and 6 months of aging, for both pit and fissure sealants, sodium hypochlorite, papain, bromelain, and Tergazyme® achieved statistically significant higher bond strength values (p < 0.05). Irrespective of the deproteinizing agent used, Dyad Flow resulted in a better bond strength after 6 months of aging. The type 1 etching pattern was identified for sodium hypochlorite, papain, and bromelain. Tergazyme®, papain, and bromelain demonstrated efficacy in deproteinizing enamel surfaces prior to acid etching, leading to the improved bond strength of pit and fissure sealants. Clinically, this suggests that these proteolytic agents can be considered viable alternatives to traditional methods for enhancing sealant retention and longevity. Utilizing these agents in dental practice could potentially reduce sealant failures.

Evaluation of the Effectiveness of Semolina in Improving the Bond Strength of Metal Alloys and Acrylic Resins for the Fabrication of Hybrid Prostheses for Implant Restoration: An In Vitro Study.

Introduction Fixed prosthodontic solutions for restorations of multiple implants are often done using acrylic-metal hybrid prosthesis. These restorations have a high failure rate due to poor bond strength between metal and acrylic, despite using digital attachments and primers. This study has been done to demonstrate an economical yet effective method of increasing shear bond strength between acrylic and metal. Materials and methods Disc specimens of 10 mm diameter and 2 mm thickness were designed using the Meshmixer version 3.5 software (Autodesk Inc., San Rafael, USA). The standard tessellation (STL) file was imported and sent for direct metal laser sintering (DMLS) in cobalt-chromium (CoCr),titanium (Ti), and wax milling. The groups were defined. Ten samples were included in each group. Group 1: Conventional Casting in CoCr; Group 2: Conventional Casting with Opaquer (CoCr); Group 3: DMLS CoCr; Group 4: DMLS CoCr with Opaquer; Group 5: DMLS Ti; Group 6: DMLS Tiwith Opaquer; Group 7: Casting with Semolina (CoCr); and Group 8: Casting with Semolina and Opaquer (CoCr). Wax-up was performed using double wax sheet thickness of modeling wax. Flasking and acrylization were done using the injection moulding technique. A universal testing machine was used for shear bond strength. Results were tabulated and statistical analysis was done usingIBM SPSSStatistics for Windows (IBM Corp., Armonk, USA). The Shapiro-Wilk test was done to confirm the normality of the data, followed by the one-way analysis of variance (ANOVA) test to compare the shear bond strength between metal alloys and heat cure acrylic resin. Results The one-way ANOVA results reveal significant differences in bond strengths among the various groups. Conventional Casting with Opaquer showed no significant difference (p=0.335), but there were notable improvements in bond strength when compared to DMLS CoCr, DMLS CoCr with Opaquer, DMLS Ti, DMLS Ti with Opaquer, Semolina, and Semolina with Opaquer, with DMLS Ti having the largest mean difference (3.368). Conventional Casting with Opaquer significantly outperformed all groups, especially Semolina, which showed the highest mean difference (7.558). Similar trends were seen with DMLS CoCr and DMLS Ti, where Semolina consistently demonstrated superior bond strength. Overall, Semolina produced the highest bond strengths across all conditions. These results underscore the importance of material selection and treatment in enhancing bond strength. Conclusion Semolina can be used as an economicaland reliable method to increase the shear bond strength between acrylic and metal bonding. Its ability to burn out during dewaxing without any remains or remnants in mould deems it a useful material for increasing mechanical bonding.

Comparison of microtensile bond strength of prepared teeth treated with proanthocyanidin, Camellia sinensis - Polyphenols, and metal crowns luted with resin-modified glass ionomer cement: An in vitro study.

The aim of this study was to evaluate the effect of proanthocyanidin and C. sinensis-polyphenols on microtensile bonding properties of prepared teeth with resin-modified glass ionomer cement (GIC). This was an in vitro study. Seventy-eight maxillary premolars were selected and mounted into auto-polymerizing acrylic resin blocks. The samples were prepared and metal crowns were fabricated. The samples were randomly divided into three groups. Samples under Group 1 were not treated with any of the extracts and followed conventional bonding protocol. Samples under Group 2 and Group 3 were treated with proanthocyanidin and C. sinensis-polyphenols, respectively. After dentin treatment, these samples were luted to metal crowns using resin-modified GIC. Universal testing machine was used to measure the load at which the crowns were debonded and microtensile bond strength in MPa was calculated. The results were statistically analyzed using one-way ANOVA and post hoc Tukey HSD. Samples treated with C. sinensis polyphenols (Group 3) had maximum bond strength followed by Group 2, where the samples were treated with proanthocyanidin. C. sinensis polyphenols due to their anti-proteolytic and antioxidant properties showed improved bond strength compared to proanthocyanidin, a cross-linking agent, followed by conventional bonding protocol.

Evaluation of Shear Bond Strengths of 3D Printed Materials for Permanent Restorations with Different Surface Treatments.

The development of high-filled 3D printing resin necessitates a bonding protocol for dental indirect restorations to achieve optimal bond strength after cementation. This study evaluates shear bond strengths of high-filler 3D printed materials for permanent restorations with various surface treatments. Rodin Sculpture 1.0 (50% lithium disilicate fillers) and 2.0 Ceramic Nanohybrid (>60% zirconia and lithium disilicate fillers) were tested, with Aelite All-Purpose Body composite resin as control. Samples were prepared, post-cured, and sandblasted with alumina (25 µm). Surface roughness was analyzed using an optical profilometer. Two bonding protocols were compared. First, groups were treated with lithium disilicate silane (Porcelain Primer) or zirconia primer (Z-Prime Plus) or left untreated without a bonding agent. Beam-shaped resin cement (DuoLink Universal) specimens were bonded and stored in a 37 °C water bath. Second, additional sets of materials were coated with a bonding agent (All-Bond Universal), either followed by silane application or left untreated. These sets were then similarly stored alongside resin cement specimens. Shear bond tests were performed after 24 h. SEM images were taken after debonding. One-Way ANOVA and post hoc Duncan were performed for the statistical analysis. Rodin 1.0 exhibited increased adhesive failure with silane or zirconia primer coating, but significantly improved bond strengths with bonding agent application. Rodin 2.0 showed consistent bond strengths regardless of bonding agent application, but cohesive failure rates increased with bonding agent and filler coating. In all groups, except for Rodin 1.0 without bonding agent, silane coating increased cohesive failure rate. In conclusion, optimal shear bond strength for high-filler 3D printing materials can be achieved with silane coating and bonding agent application.