Strength Of Resin Research Articles

Influence of different endodontic irrigants on shear bond strength of composite resin to coronal dentin: An in vitro study

Objectives: Endodontic irrigants are critical in root canal treatments, but their influence on the coronal dentin bond strength of composite restorations is a key concern for a favorable clinical prognosis. The present in vitro study explores the effect of different endodontic irrigants on shear bond strength of composite resin. Material and Methods: Fifty permanent human mandibular molars were sectioned to expose coronal dentin and divided into five groups. Each group received a specific irrigant treatment before composite resin bonding. Shear bond strength was examined using Instron Universal testing machine, and statistical analysis was conducted using post hoc Tukey’s test and analysis of variance. Results: Group A (Saline) showed a mean shear bond strength of 18.5 Megapascal (MPa). Group B [sodium hypochlorite (NaOCl)] had mean shear bond strength of 15.2 MPa. Group C [Chlorhexidine (CHX) Gluconate] exhibited mean shear bond strength of 20.3 MPa. Group D ethylenediaminetetraacetic acid (EDTA) recorded mean shear bond strength of 14.8 MPa, while Group E [citric acid (CA)] had the highest mean shear bond strength at 22.7 MPa. Conclusion: The type of endodontic irrigant used significantly affected the shear bond strength of composite restorations to coronal dentin. CHX gluconate and CA displayed superior bond strengths compared to Saline, NaOCl, and EDTA. This underscores the importance of irrigant selection in achieving successful composite restorations in endodontically treated teeth.

Understanding polyamidoamine epichlorohydrin (PAAE) retention in paper

Polyamidoamine epichlorohydrin (PAAE) is a permanent wet strength resin used in papermaking. When applied to paperboard, some amount of resin is retained in the sheet, and some is lost to the white water. The papermaker usually knows the amount of PAAE charged to the pulp but has no idea how much chemical is retained in the sheet. In addition, the influence of PAAE dosage, freeness, zeta potential, and pulp kappa number variability on PAAE retention is not well understood. Factorial design experiments using unbleached and bleached softwood (loblolly pine) kraft pulps were conducted to understand the factors that affect PAAE retention. The results revealed that PAAE retention, wet tear index, and tensile index not only depended on the PAAE charged of the pulp but also depended significantly on the pulp freeness. In lieu of freeness, zeta potential data can be used to predict PAAE retention. In addition, at similar freeness, bleached pulp has the highest retention of PAAE compared to low and high kappa unbleached kraft pulps. The results also suggest that lignin may have potential as a wet strength agent.

Molecular dynamics study on the influence of thermal aging on the mechanical properties of epoxy resins for high voltage bushing.

Thermal aging significantly deteriorates the mechanical properties and service performance of epoxy resins used for the high-voltage bushing. Current studies on the thermal aging behavior of epoxy resins mainly focus on experimental observations. However, an in-depth understanding of the mechanism of thermal aging of epoxy resins requires the monitoring of structural evolution of epoxy resins during thermal aging at the molecular level. To thoroughly analyze the intrinsic factors affecting structural evolution and the effect of thermal aging on the mechanical properties of epoxy resin for high-voltage bushing, epoxy resin models with different crosslinking degrees were established and thermal aging treatments at various temperatures and time periods were carried out by molecular dynamics simulation. It was found that the tensile strength of the epoxy resin was enhanced with the increase of the crosslinking degree, which was related to the elevation of the proportion of C-N and O-H bonds in its structure. With the increase of thermal aging temperature, the tensile strength of the epoxy resin decreased, which was related to the formation of weak bonds. At the early stage of thermal aging and after a period of high-temperature thermal aging, the strength of epoxy resin significantly decreases. The thermal aging of the epoxy resin is accelerated under external loading. In addition, the crosslinking degree and curing agent also affect the thermal aging resistance of epoxy resins. The results of this study can provide guidance for predicting and improving the thermal aging resistance of epoxy resins. Materials Studio was used to construct molecular models and complete crosslinking reactions. DGEBA and 44DDS (or 33DDS) were mixed at a ratio of 2:1, followed by crosslinking reaction. During this process, the Nose method was used to control temperature, the Berendsen method was used to control pressure, and the polymer consistent force field (PCFF) was used to control the motion and force of atoms. Isobaric-isothermal ensemble (NPT ensemble) was used to heat up epoxy resin models to various thermal aging temperatures of 400K, 500K, 600K and 700K. The models were maintained at these temperatures for different thermal aging times of 100ps, 200ps, 300ps, 400ps, 500ps, 600ps, 700ps and 800ps. Afterwards, the models were cooled down to 300K and subjected to uniaxial tensile testing at this temperature with a strain rate of 1 × 109s-1. The structural configurations and stress-strain data during the tensile process were recorded. The flow stress of the material was derived by counting the average stress in the 20-50% strain interval.

Color Alterations, Flexural Strength, and Microhardness of 3DPrinted Resins Treated in Different Coloring Agents.

Purpose This study evaluated the color alterations, flexural strength and microhardness properties of two different 3D-printed permanent crown resins. Materials and Methods Samples were produced from two different 3D Print permanent crown resins: Group 1 (Saremco Crowntec; Saremco, Switzerland), Group 2 (P-crown Version 2; Senertek, Turkey). Color changes (ΔE values), flexural strenght and vickers hardness number of the samples were calculated. Data were analyzed with Shapiro-Wilk normality test, Independent-t test, and Mann Whitney-U tests. Significance level was accepted as P<0.05. Results ΔE values for red wine were found to be significantly higher in Group 1 (6.43Å}2.26; P<0.001). The flexural strength values (MPa) of Group 1 were significantly higher than Group 2 in all three solutions (P<0.001). There was no significant difference between the VHN values of the samples kept in wine and coffee solutions (P= 0.271; 0.827). Conclusion 3D printing resins are affected at different levels by coloring solutions. Microhardness and flexural strength of 3D print samples kept in different coloring agents are different.In the use of 3D printing resins, product selection should be made by taking into account the individual factors such as the eating and drinking habits of the patients and the physical properties expected from the sample.

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.

Effect of Chitosan Nanoparticle as an Antioxidant Material on Shear Bond Strength of Composite Resin to Enamel after External Bleaching

Effect of Chitosan Nanoparticle as an Antioxidant Material on Shear Bond Strength of Composite Resin to Enamel after External Bleaching

Striving for Sustainable Solutions: Optimizing Utility Properties of Recycled Paper with the Addition of Wet Strength Resin

Paper producers are increasingly challenged to meet customer demands for high-quality sanitary papers amidst rising price pressures and diminishing quality of recycled fibers. One promising avenue for enhancing paper quality involves augmenting wet strength. For this purpose, synthetic wet strength resins are used, among other things. This study explores the efficacy of utilizing a polyamide-epichlorohydrin resin-based agent for the internal sizing of white wastepaper. Such chemicals, when added to cellulosic fibers in proper amounts before the paper is made, can not only improve water resistance and air permeability of the finished product but also significantly affect both the dry and wet strength paper, which is a crucial aspect for sanitary papers. This study shows that the appropriate addition of resin allows the wetted recycled paper to retain even more than 30% of its dry strength, while in the dry state, the breaking strength of the paper is improved by approximately 46%. As the demand for more sustainable and resistant paper products continues to grow, the use of wet strength agents is expected to increase in the coming years, as well as the need for research in this field. This research therefore undoubtedly contributes to advancing sustainable practices within the paper industry, aligning with the principles of circular economy by optimizing the utility of recycled fibers while maintaining product quality.

Shear Strength of Adhesively Bonded Joint with Toughened Epoxy Mussel Powder

Synthetic fillers were usually used to improve the shear strength of epoxy resin, but dependency on mineral-derived substances may increase the greenhouse effect. To surmount the problem, biofiller from household wastes mussel shells is proposed to improve the mechanical properties of epoxy due to its high calcium carbonate content. In this paper, the physical properties (X-ray diffraction test)and shear strength of toughened epoxy with mussel shell powder (TEMP) were investigated. Single lap joints (SLJ) specimens were tested for shear strength with incorporation of various TEMP volume fractions and over-lap length. The testing series includes TEMP volume fractions from 0% to 10% (by 2.5% increment) and overlap length ranging from 12.7 to 50.8 mm. The results demonstrated that the longest overlap length and 7.5% TEMP volume fractions exhibited a significant effect on the ultimate joint strength. From scanning electron microscopy (S EM), 10% TEMP was prone to particle agglomerations and gave less joint strength. The joint strength with 7.5% mussel shell powder was stronger compared with other volume fractions, with strength enhancement from 103.7% to 169.6% for the studied overlap lengths.

Shear bond strength of ultraviolet-polymerized resin to 3D-printed denture materials: Effects of post-polymerization, surface treatments, and thermocycling.

The purpose of this study is to compare the shear bond strength of ultraviolet (UV)-polymerized resin to 3D-printed denture materials, both with and without post-polymerization. Moreover, the effects of surface treatment and thermocycling on shear bond strength after post-polymerization were investigated. Cylindrical 3D-printed denture bases and teeth specimens were prepared. The specimens are subjected to two tests. For Test 1, the specimens were bonded without any surface treatment or thermal stress for comparison with and without post-polymerization. In Test 2, specimens underwent five surface treatments: untreated (CON), ethyl acetate (EA), airborne particle abrasion (APA) with 50 μm (50-APA) and 110 μm alumina (110-APA), and tribochemical silica coating (TSC). A UV-polymerized resin was used for bonding. Half of the Test 2 specimens were thermocycled for 10,000 cycles. Shear bond strength was measured and analyzed using Kruskal-Wallis and Steel-Dwass tests (n = 8). In Test 1, post-polymerization significantly reduced shear bond strength of both 3D-printed denture materials (P < 0.05). No notable difference was observed between the denture teeth and the bases (P > 0.05). In Test 2, before thermocycling, the CON and EA groups exhibited low bond strengths, while the 50-APA, 110-APA, and TSC groups exhibited higher bond strengths. Thermocycling did not reduce bond strength in the latter groups, but significantly reduced bond strength in the EA group (P < 0.001). Post-polymerization can significantly reduce the shear bond strength of 3D-printed denture materials. Surface treatments, particularly APA and TSC, maintained bond strength even after thermocycling.

Polyurethane‐based cross‐linked nano spheres and their application in toughening epoxy resin

AbstractToughening thermo‐setting resins with both high impact strength and tensile strength is a challenging issue. In this study, a novel cross‐linked polyurethane nano spheres for toughening epoxy resin were prepared by self‐emulsification method with hexamethylene diisocyanate trimer (HDI trimer) and diethylene triamine (DETA) as the crosslinkers. The structure, morphology and particle size of cross‐linked polyurethane nano spheres were investigated by infrared spectroscopy, laser particle size analyzer and scanning electron microscopy. Results showed that the prepared cross‐linked polyurethane nano spheres showed spherical shape and had the size in the range from 40 to 258 nm. The application of cross‐linked polyurethane nano spheres in toughing epoxy resin was investigated. The results showed that cross‐linked polyurethane nano spheres can be uniformly dispersed in epoxy resin and no obvious aggregation phenomenon was observed. And the tensile strength and impact strength of epoxy resin can be increased simultaneously when the cross‐linked polyurethane nano spheres were used in toughening epoxy resin. With the increase of the amount of polyurethane nano spheres in epoxy resin, both the tensile strength and impact strength of epoxy resin had the trend of first increase and then decrease. The amount of HDI trimer in the microspheres had a great impact on their toughening effect on epoxy resin. When the cross‐linked polyurethane nano spheres contained HDI trimer content of 12 wt% and the amount of the nano spheres in epoxy resin was 8 wt%, the impact strength of the epoxy resin can reach as high as 23 kJ/m2, which was 4.33 times that of pristine epoxy resin. And the tensile strength of toughened epoxy resin was 50.7 MPa, which was at same level of that of pristine epoxy resin. The results of this study indicate that the cross‐linked polyurethane nano spheres have a great potential in toughening thermo setting resins, such as epoxy resin.

Prohibiting pure and saline water infiltration into organic-nano-coated calcium silicate hydrates surface: A nanoscale mechanisms analysis

Extend the lifetime of coated cement paste under severe environment is a big challenge and the most crucial problems are related the degradation in the interface between coating and cement paste. This work is devoted to an in-depth investigation under aggressive environment of the deterioration process between epoxy coating and nano-granular Calcium-Silicate-Hydrate (CSH) paste. Further, a depth analyze of what properties make an organic-coating (epoxy and rubber) impermeable is established by means of Molecular Dynamics simulations (MD). Results indicate that the chlorine ions are responsible to attack the epoxy resins coating and CSH surface. Non-fully epoxy coating is detached more distorted in salty solution (4 wt% of NaCl) than in pure water solution. The Casurface-Oepoxy and Casurface-NMPD are the two bonds responsible for the bonding strength of epoxy resins coating and CSH surface. It is found that both the pore structure and the big surface roughness in organic-coating could accelerate the degradation in the interface. The water sorption in the permeable epoxy coating is increasing within time, in agreement with experimental investigations. Nevertheless, a continuous well-distributed rubber nano-coating is capable to make CSH impermeable under harsh environment. The obtained diffusion coefficient is decreased by 12.26 % in 4 wt% of NaCl solution.

The efficacy of Er,Cr:YSGG laser and contemporary universal adhesive systems on composite resin repair bond strength: an in vitro study.

The aim of this study is to investigate the repair bond strength of composite resin following three different surface treatments (bur-grinding, silanization, and Er,Cr:YSGG laser irradiation) using various universal adhesives. A total of 160 resin composite specimens, produced in cylindrical form (6 × 2mm) with a nanohybrid composite resin within metal molds, were subjected to 5000 cycles of aging in a thermocycler. The aged samples were categorized into four groups based on surface treatments: control, bur, silane, and Er,Cr:YSGG laser. Following surface treatments, the specimens underwent repair using the same resin composite and four different adhesive systems: Tokuyama Universal Bond (TUB), Prime Bond Universal (PBU), Gluma Bond Universal (GBU), and Clearfil SE Bond (CSB). Subsequently, the specimens were subjected to shear forces, and statistical analysis was performed using two-way ANOVA and Tukey tests (p < 0.05). The failure modes were examined using a stereomicroscope, and the surface topography of the roughened resin composite was assessed through scanning electron microscopy (SEM). Results indicated that silane + GBU exhibited the highest shear bond strength (SBS) (15.61MPa) while control + TUB showed the lowest SBS (7.63MPa). Silane demonstrated significantly higher SBS values (p ≤ 0.05), with no significant difference observed between bur and laser methods (p = 0.998). It is recommended to include an additional silanization step before applying universal adhesive, as it effectively enhances the bond strength of the repaired composite.

A basket of materials for 3D printed prostheses in digital dentistry

Objective: This literature review's objective is to identify feasible materials that can be 3D printed and is utilised to create removable dentures. The review includes an overview of the properties, advantages, and limitations of different 3D printing materials, including polymers, metals, resins, ceramics, and composites. Methods: In the era of digital dentistry, additive manufacturing, or 3D printing, is taking the place of subtractive manufacturing, or milling. For example, pre polymerised PMMA (polymethylmethacrylate) used for subtractive manufacturing leads to more wastage of material (block) compared to additive manufacturing. Traditionally 3D printing has its roots in rapid prototyping (RP), which the name is given to the rapid production of models using additive layer manufacturing. Result: The study showed that the addition of CNCs and AgNPs to the PMMA resin resulted in a significant improvement in the mechanical properties of the printed parts. The flexural strength of the composite resin increased by up to 31.6% with the addition of 0.1 wt% AgNPs and 1 wt% CNCs. The impact strength of the composite resin also increased by up to 24.2% with the addition of 0.1 wt% AgNPs and 1 wt% CNCs. The researchers attributed the improvement in mechanical properties to the synergistic effect of CNCs and AgNPs, which enhanced the interfacial adhesion between the polymer matrix and the reinforcement particles. Conclusion: Additive manufacturing describes technologies that can be used anywhere throughout the product life cycle from pre-production (i.e. rapid prototyping) to full scale production (also known as mass production).

Comparative Evaluation of Various Antioxidants on the Shear Bond Strength of Composite Resin to Bleached Enamel - An In Vitro Study.

To evaluate and compare the effect of various antioxidants on the shear bond strength of composite resin to bleached enamel. Labial enamel surfaces of 90 extracted human maxillary central incisors were randomly divided into five groups based on the antioxidant used as follows: Group I ( n = 20): Bleaching with 40% hydrogen peroxide gel for 10 min, without the use of an antioxidant; Group II ( n = 20): Bleaching followed by the use of 10% sodium ascorbate solution; Group III ( n = 20): Bleaching followed by the use of 5% grape seed extract solution; Group IV ( n =20): Bleaching followed by the use of 5% pine bark extract solution; and Group V ( n =20): Control group in which no bleaching was done. Groups I-IV were further subdivided into two subgroups of 10 teeth each, whether the antioxidant application and composite build-up was done immediately (subgroup A) or after 2 weeks of postbleaching (subgroup B). Shear bond strength of the specimens was tested under a universal testing machine. One-way analysis of variance followed by Mann-Tukey posthoc multiple comparison test was used to analyse the data. The level of significance was established at P < 0.05. Within the limitations of this study, it was observed that the use of antioxidants effectively reversed the compromised bond strength of bleached enamel. Among the antioxidants, 5% pine bark extract application after bleaching showed better bond strength.

Comparative Evaluation of Candida Albicans Adherence, Flexural strength and Water Sorption of Orthodontic Self-Cure Acrylic Resin Modified with 2-Methacryloyloxyethyl Phosphorylcholine by Two Different Techniques: in-vitro Study

Comparative Evaluation of Candida Albicans Adherence, Flexural strength and Water Sorption of Orthodontic Self-Cure Acrylic Resin Modified with 2-Methacryloyloxyethyl Phosphorylcholine by Two Different Techniques: in-vitro Study

The impact of artificial aging using chewing simulator on micro-shear bond strength and micro-leakage of alkasite and bioactive resin based composites: an in-vitro comparative study

Objective The current study was conducted to assess and compare the impact of artificial aging using chewing simulator on the novel bulk fill restorative materials (Cention N) and Bioactive Resin Based Composites (ACTIVA) regarding, micro-shear bond strength and micro-leakage. Tetric N ceram bulk fill composite was used as control. Patients and methods For micro-shear bond strength testing, thirty recently extracted molars were collected, then their occlusal surfaces were cut horizontally using low-speed diamond saw under coolant exposing flat dentin surfaces. Tetric N-Bond adhesive was applied to the dentin surface, then Tygon tubes (three for each tooth) with height 1 mm and internal diameter 1 mm were placed on the flat surfaces, followed by light curing, then the restorative material (10 specimens for each material) was condensed inside the tubes. Half of the specimens is subjected to artificial aging (thermal and dynamic loading using Chewing Simulator). The specimens were mounted in blocks of stones, then placed horizontally in the universal testing machine. The load was applied using a knife-edge chisel till debonding of the composite cylinders from dentin surface. Fifteen extracted human molars were utilized for the purpose of evaluating micro-leakage. A total of thirty class II cavities were meticulously constructed on the mesial and distal surfaces of the teeth. The evaluation of micro-leakage was conducted using a dye penetration test, employing a scoring system ranging from 0 to 4. Results The nonaged specimens of the tested materials did not show significant differences regarding micro-shear bond strength, and micro-leakage. Aging had no significant effect on all of the tested properties in the three tested materials. Conclusion Short-term thermomechaical aging used in this study did not deteriorate micro-shear bond strength and micro-leakage of the tested materials. Alkasite (Cention N) and ACTIVA Bioactive Resin Based Composites are promising materials with physico-mechanical properties comparable to conventional bulk-fill composites. However, further in vitro and in vivo studies are needed to assess the properties of these recently introduced materials.

Repair bond strength of a new self-adhesive composite resin to three different resin-matrix ceramic CAD-CAM materials.

This study aimed to evaluate the shear bond strength of two flowable composite resins to resin-matrix ceramic CAD-CAM materials.Fifty-four plates obtained from Lava Ultimate (LU), Cerasmart (CS), and Vita Enamic (VE) CAD-CAM blocks were assigned to nine groups: N0: Nova Compo SF (NCSF), N1: Silane/Single Bond Universal (SBU)/NCSF, N2: SBU/NCSF, N3: Silane/G-Premio Bond (GPB)/NCSF, N4: GPB/NCSF, G1: Silane/SBU/G-aenial Universal Injectable Composite (GUIC), G2: SBU/GUIC, G3: Silane/GPB/GUIC, G4: GPB/GUIC. After the repair procedures, shear bond strength values were analyzed. Silane pre-application decreased bond strength in most LU and CS groups but increased it in VE. NCSF performed better than GUIC in all CAD-CAM's with similar adhesive protocols. SBU in combination with NSCF had the highest bond strength among all repair procedures in LU and CS. Silane-containing universal adhesives in combination with self-adhesive resin composites should be used to repair resin-matrix ceramic materials.

Construction of silver-epoxy adhesive with suppressed silver migration rate based on thiol-silver interaction

The silver migration limits the application of silver based conductive adhesives in wet environment. The existing methods for inhibiting silver migration in epoxy conductive silver adhesives involve one or more issues such as cost, complexity, and inhibition of conductivity. Moreover, there is currently a lack of strategies that can suppress the silver migration effect while ensuring good dispersion of silver fillers in the matrix and constructing a good filler matrix interface. Herein, a facile method was reported suppressing the silver migration in silver-epoxy conductive adhesive. Tetrafunctional thiopentaerythritol tetramercaptoacetate (PERTMA) was introduced into 1,4-cyclohexanedimethanol diglycidyl ether (CHDMGE) epoxy resin as the curing agent. This method utilized the strong interaction between silver and thiols, including coordination and covalent bonding, to achieve good compatibility between filler and matrix. By tightly combining silver with the resin system, the content of free silver atoms was reduced, capturing and inhibiting the hydrolysis of silver atoms and their migration with current, and the conductivity of the conductive silver adhesive was not greatly degraded due to the silver-thiol interaction. At the same time, the introducing of PERTMA was able to reduce the surface hydrophilicity of epoxy resin, which also helped suppressing the silver migration effect under humid circumstances. The interaction between silver and thiol was characterized, and the influence of silver content on the curing behavior, material mechanical performance, conductivity, resistivity on silver migration and flexibility was explored. The CHDMGE/PERTMA/Ag conductive adhesive based on strong thiol-silver interaction had excellent resistance to silver migration, which occurred after 3500s, which was 10.67 times longer than the control group. In addition, the silver filler enhanced the tensile strength of the matrix resin by this thiol-silver interaction. This study will provide new ideas for the design and development of silver migration resistant conductive adhesives based on matrix filler interaction.

Assessment of the correlation between the tensile and diametrical compression strengths of 3D-printed denture base resin reinforced with ZrO2 nanoparticles

Background: The mechanical properties of 3D-printed denture base resins are crucial factors for determining the quality and performance of dentures inside a patient’s mouth. Tensile strength and diametral compressive strength are two properties that could play significant roles in assessing the suitability of a material. Although they measure different aspects of material behavior, a conceptual link exists between them in terms of overall material strength and resilience. Aim: This study aims to investigate the correlation between tensile strength and diametral compressive strength after incorporating 2% ZrO2 nanoparticles (NPs) by weight into 3D-printed denture base resin. Methods: A total of 40 specimens (20 dumbbell-shaped and 20 disc-shaped) were produced via 3D printing and divided into two groups (n = 10): (1) 3D-printed denture base resin without NPs and (2) the resin was strengthened with 2% by weight ZrO2 NPs. Tensile strength and diametral compressive strength were assessed using a universal testing machine. Results: A detrimental relationship was observed between the tensile strength and diametral compressive strength of 3D-printed denture base resin after the addition of NPs. Conclusion: The enhancement of one property does not necessarily mean the enhancement of another. Caution should be taken to not endanger the quality of a material.

Effect of Silica Nanoparticles On Flexural Strength And Surface Hardness Of Heat Polymerized Acrylic Resin.

Statement of problem. Various studies are present to increase the strength and surface hardness of heat polymerized acrylic resin by addition of material or surface treatments. The present study to evaluate an effect of silica nanoparticles on flexural strength and surface hardness of heat polymerized acrylic resin. Purpose. The purpose of this study was effect of silica nanoparticles, incorporated into Polymethyl Methacrylate, on flexural strength and surface hardness. The present study compared the effect of silanated and non silanated silica nanoparticles on the flexural strength and surface hardness of heat polymerized acrylic resin. Material and Methods. A total of 270 acrylic bars were fabricated, in two batches of 135 each, for testing flexural strength by universal testing machine and surface hardness determined using a digital micro Vickers hardness tester. The control group and subgroups had a sample size of 15 each with varied concentrations of nanoparticles by weight. The fabricated samples were tested for flexural strength and surface hardness. Results. Flexural strength was highest for PMMA (Polymethyl methacrylate) with 0.5% silanated silica nano particles as fillers. In both the groups, the flexural strength decreased with increase in filler concentration. Surface hardness was highest in the PMMA group with non-silanated nano particles as fillers at 5% concentration. In both groups the surface hardness improved with an increase in filler concentration. ANOVA and TUKEY’s HSD test were used. P&lt;0.05 was considered statistically significant. Conclusion. Lower concentrations of surface-treated silica nanoparticles should be used as fillers to enhance the flexural strength of commercially available heat polymerized acrylic resin. Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S79-S86