Resin Matrix Research Articles

In Vitro Evaluation of the Fracture Strength among Three Different Denture Base Materials

Failure in the form of denture fracture is commonly encountered by both removable prosthodontics wearers and dentists, it is mainly attributed to material properties, technical features, stresses while in function or due to impact as a consequence of dropping the dentures. Traditionally, Heat-Polymerized Polymethylmethacrylate (PMMA) has been the gold standard for denture bases due to its ease of processing and acceptable mechanical properties. However, newer materials, injectable flexible nylon-based resin and CAD/CAM Polyether ether Ketone (PEEK) denture bases are being introduced with claims of superior strength and durability. The aim of this study was to investigate the fracture strength of three commonly used denture base materials in Libya, which may aid in selecting the best material for a given application and predicting potential material behavior under load when holding the durability of the material in mind. A total of 36 samples were tested. These samples were divided into three groups, with 12 samples each: Group I heat polymerized acrylic resin PMMA, group II Injectable flexible nylon-based resin and group III CAD/CAM (PEEK). The fracture strength test was carried out on a universal testing machine at a crosshead speed of 5 mm/min. The results were analyzed using ANOVA, and multiple comparisons were undertaken using Tukey’s HSD test. Statistical significance was set at P ≤ 0.001. The result of this study shows there were significant differences in the fracture strength among the three groups (P< 0.001). Moreover, CAD/CAM (PEEK) denture base material exhibited significantly the highest fracture strength (234.17N ± 13.5) whereas the least fracture strength value was measured with Injectable flexible nylon-based resin denture base material (75.25N±10.5). The study concluded that, within the limitations of this study, the results demonstrate that CAD/CAM (PEEK) outperforms Injectable flexible nylon-based resin and heat polymerized acrylic denture base materials in terms of the fracture strength, supporting its potential as an advanced material for denture construction. However, further clinical studies are recommended.

Ballistic performance analysis of PBO fiber‐reinforced epoxy composites through resin matrix rigidity and toughness modulation

AbstractThe rigidity and toughness of the resin matrix significantly influence the impact resistance of ballistic composites. However, the relationship between the properties of the resin matrix and the ballistic performance of the composites remains inadequately defined. In this study, the ballistic performance of composites with various matrix resins was investigated to assess how matrix toughness affects energy absorption. A series of epoxy resins exhibiting different rigidity and toughness were combined with PBO (poly‐p‐phenyl‐2,6‐benzobisoxazole) fibers, and their quasi‐static mechanical properties were evaluated to analyze their effectiveness in resisting ballistic impacts. In ballistic test, the brittle matrix composite demonstrated concentrated fiber breakage and localized damage, while the toughened matrix composite exhibited more dispersed damage characterized by reduced fiber breakage and minimal delamination, suggesting enhanced energy absorption via deformation within the matrix. Compared with the specific energy absorption value of the brittle matrix composite material, which is only 9.28 Jm2/kg, the specific energy absorption value of the tough matrix composite material has increased by 125% to 20.88 Jm2/kg. These findings underscore the critical role that matrix toughness plays in improving ballistic‐resistant performance by facilitating better energy distribution while mitigating fiber damage.Highlights Matrix toughness significantly enhances ballistic energy absorption in composites. Toughened matrix reduces fiber breakage and delamination under ballistic impact. Toughened matrix composite achieves a 125% higher specific energy absorption. Findings offer insights for designing high‐performance ballistic‐resistant materials.

Fe3O4 modified graphene epoxy composite materials via polyether amine reduction with enhanced microwave absorption performance

Abstract The increasing complexity of electromagnetic environments demands the development of advanced absorbers with superior performance. In this study, a novel magnetic Fe3O4-modified graphene-based absorber (FARGO) is synthesized via an in-situ reduction process using polyether amine. The resulting FARGO composite exhibits excellent microwave absorption properties. When the filling content of FARGO is 5 wt% in epoxy resin, the optimal reflection loss is -23.12 dB with a thickness of 4 mm and a broad absorption bandwidth of 5.6 GHz can be achieved as the thickness changes to 2 mm. Polyether amine efficiently reduces GO to rGO, significantly improving electrical conductivity. Simultaneously, it grafts amine groups onto the graphene surface, enhancing dispersion and reactivity within the epoxy resin matrix. These synergistic effects make it a promising candidate for high-performance microwave absorbing materials.

Investigation of Free Vibration Behavior for Composite Sandwich Beams with a Composite Honeycomb Core

The purpose of the current research is to determine the effect of fiber type, volume ratio, and matrix type on the vibration properties of sandwich beams made of composite face sheet and core. The typical sandwich structure consists of three layers: face sheets, core, and adhesive bonding, and in this research, the adhesive layer between the face sheets and core was abolished by preparing the overall mold with fibers inside and casting the resin to fill the face sheet and core parts. The face sheets of the composite beams are made from a polyester or epoxy matrix reinforced with glass fiber, carbon fiber, and hybrid fiber, and the core is a honeycomb consisting of random glass fibers immersed in a resin matrix (polyester or epoxy). 22 composite sandwich beams were constructed to conduct vibration testing. The vibration results obtained experimentally were compared to the ANSYS R1 2022 software, and the results were in very good agreement. Hybrid fibers and polyester matrix achieved the highest values of natural frequency for (clamped-clamped) boundary conditions, where the natural frequency value of the hybrid fiber and polyester matrix reached (2037 Hz) at a volume fraction of (23.14%) experimentally and the natural frequency reached (1804.5 Hz) at a volume fraction of (21.95%) experimentally for the simply supported boundary condition.

Wide range dielectric behavior characterization of ternary composite (Re-BT-CaO)

This article's primary objective is to investigate a ternary composite's dielectric behavior using time domain spectroscopy (TDS). A heterogeneous mixture of barium titanate (BT) and calcium oxide (CaO) in an epoxy resin matrix (RE) with a predetermined volume fraction level (70%) makes up this type of material. The remaining components (BT and CaO) are variable in increments of 07.50% and complete one another in order to achieve the final percentage, which is 30%. The different composite samples are created using the aforementioned stoichiometric ratios at room temperature and below atmospheric pressure. These mixes are put through a dielectric behavior analysis over a broad frequency range, from DC to 10 GHz. This study intends to highlight the impact of calcium oxide and barium titanate on the composite's dielectric behavior and on the form factor provided by the modified Lichtenecker equation (MLL). It follows a numerical method for optimizing of the predictive model of this law based on a better smoothing of this shape factor in order to allow a better concordance among the predicted values and practical ones. A comparison between the experimental data and the MLL values is performed in order to highlight the proposed model performance on the ternary composite dielectric permittivity estimation quality. This research's focus is on how these materials are used in micro- and nanoelectronics as well as telecommunication components fabrication.

Effect of Ammonium Polyphosphate/Silicate Content on the Postfire Mechanics of Epoxy Glass‐Fiber Composites Using Facile Chocolate Bar‐Inspired Structures

ABSTRACTThis study investigates the postfire mechanical properties of epoxy glass‐fiber reinforced composites (EP GFRCs) using increasing concentrations of ammonium polyphosphate (APP) and inorganic silicate (InSi) to modify the char and fire residue. A facile chocolate bar‐inspired structure was introduced for fire exposure and subsequent flexural testing of the GFRCs. The resin matrix used here was a diglycidyl ether of bisphenol‐A (DGEBA) resin, cured with dicyandiamide (DICY), and accelerated by Urone. The microstructures of the degraded composites after three‐point bending tests, were evaluated using scanning electron microscopy (SEM) and x‐ray computed tomography (XCT) imaging. A previous study showed that increasing the APP and InSi content significantly enhanced flame retardancy, via improved char formation under fire conditions. However, flexural properties and fire resistance were adversely affected after fire exposure, highlighting a trade‐off effect. Fiber breakage and delamination of the composites increased upon failure with increasing APP + InSi content in the composite due to unconsolidated char. The experimental values for the postfire flexural mechanics were in good agreement with the two‐layer model proposed in literature. This paper presents a preliminary basis for postfire mechanical testing of epoxy composites for use in fire‐safe structures, using a combination of standardized testing norms.

DEVELOPMENT OF BORON-MODIFIED AMINOPLAST RESIN COATINGS FOR ENHANCED UREASE INHIBITION IN SALINE-SODIC SOILS

The melamine-formaldehyde-boron (MFB) composite was synthesized with high efficiency, achieving a 95% yield. The incorporation of boric acid into the melamine-formaldehyde resin matrix resulted in a homogeneous, physically stable polymer composite. The synthesis was characterized by FT-IR spectroscopy, revealing key functional groups such as N-H stretching (~3350 cm⁻¹) for melamine residues, C=O stretching (~1650 cm⁻¹) for formaldehyde, B-O vibrations (~1350 cm⁻¹) for boric acid integration, and C-N bending (~1250 cm⁻¹) indicative of cross-linking between melamine, formaldehyde, and boric acid. Further investigations evaluated the impact of boric acid-coated urea granules on the productivity and physicochemical properties of saline-sodic soil. Boric acid incorporation (5% coating) significantly improved soil conditions by lowering pH, reducing electrical conductivity, and increasing organic matter content. Moreover, urease activity was reduced by 75%, leading to improved nitrogen retention. The effect of boric acid on plant productivity was most pronounced at a 5% coating, with radish plant productivity showing a 44% increase, along with improvements in shoot and root biomass. These findings highlight the potential of MFB-coated urea granules to enhance soil health and plant growth, demonstrating the effectiveness of boric acid in optimizing nitrogen release and mitigating soil salinity.

Silk Fibroin‐CF Hybrid Nanofiller Endowing Epoxy Coating with Outstanding Anticorrosion and Anti‐erosion Properties

AbstractThe exceptional protective coating can extend the service life of the equipment in a severe marine environment. Carbon fibers (CFs), characterized by high tensile strength, elastic modulus, and excellent chemical resistance, serve as an appropriate filler for coating reinforcement. However, the inadequate fiber/matrix interfacial adhesion makes it difficult to prepare high performance CF‐reinforced composites. Therefore, we synthesized a kind of silk fibroin modified CF (CF─SF) as a reinforced‐additive for strengthening the corrosion resistance and anti‐erosion properties via improving the interfacial adhesion between CFs and resin matrix. The impedance value of composite coating including 1 wt% CF—SF (CF—SF/EP) was 1.65 × 108 Ωˑcm2 after immersion, which was two orders of magnitude greater than that of the pure EP coating. In addition, the erosion experiments results showed that the volume loss of EP/CF—SF coating was 132.6 mm3, which decreased by 36.4% and 17.4% compared with EP/CF and EP/CF─O, respectively. The average depth of the CF—SF/EP coating (0.27 mm) was the shallowest among the coatings. Ultimately, we examined the protective mechanism of the CF–SF/EP coating.

An Experimental Study of the Properties of Bamboo Particle Reinforced Epoxy Matrix Biocomposites

Production of biodegradable polymer matrix biocomposites that are cost effective, sustainable, and environmentally friendly with desirable properties using particles as discontinuous phase (filler) is a welcome development. In this study, bamboo particle reinforced epoxy resin matrix biocomposites were developed by stir casting method. Varied weight percentages (5 to 30 wt. %) of 100 µm bamboo particles were added separately and blended with an epoxy resin – hardener matrix. The blends were fed into a fabricated wooden mould and allowed to cure at room temperature. After 24 hrs, the specimens were removed from the mould and subjected to microstructural examination using a Scanning Electron Microscope (SEM). Furthermore, the physical and mechanical properties characterisation of the specimens were also carried out. The results obtained from the experiments showed the presence of pores in the microstructure of the specimens and the distribution of reinforcing particles in the epoxy matrix. The reinforced composites (S2 to S6) demonstrated an appreciable increase in density when compared with the unreinforced control specimen (C1). Specimens (S2 to S6) demonstrated lower water absorption than C1. The composites demonstrated increased ultimate tensile strength with filler addition up to 25 wt. %. Similarly, the reinforced specimens demonstrated improved hardness as the weight percent (wt. %) of bamboo particles increased up to 25 wt. %. However, the composites demonstrated a reduction in impact energy as filler content increased when compared with the control specimen. Specimen S5 formulation, which contained 25 wt. % of reinforcing particles demonstrated the best properties in terms of density, water absorption, hardness, and ultimate tensile strength. These findings highlight the effectiveness of bamboo particles in enhancing the physical and mechanical properties of the developed ecofriendly biocomposites.

Effect of surface treatments on the bond strength of resin-repaired resin matrix CAD-CAM ceramic: A Scoping review.

To evaluate the existing evidence on surface treatment techniques employed in the repair of resin matrix CAD-CAM ceramics and their effects on short- and long-term bond strength. This scoping review was conducted following the PRISMA-ScR guidelines for scoping reviews and was registered on the Open Science Framework platform. Based on the PCC concept, where P: Resin matrix CAD-CAM ceramic blocks for CAD-CAM, C: Bond strength, and C: Surface treatments, a search was conducted in the PubMed, Embase, Web of Science, Scopus, and Lilacs (grey literature) databases until October 2024, with no language or date restrictions. In vitro studies comparing mechanical and/or chemical surface treatments on the bond strength of resin composite repairs were included. A total of 47 studies were included in the qualitative analysis, of which 45 used both mechanical and chemical treatments, and 29 used chemical treatments alone. The combination of chemical and mechanical treatments is the appropriate option. Alumina blasting and silica coating are the most commonly used mechanical surface treatments, either alone or in conjunction with chemical treatments. Laser irradiation may serve as an alternative to conventional treatments. The studies revealed variability among protocols for repairing resin matrix CAD-CAM ceramics, with the combined use of chemical and mechanical treatments being the most effective approach.

Simulation and experimental study of single axis load of resin-based concrete at macro-micro scale

ABSTRACT This study focuses on resin-based concrete, a novel composite material in which resin replaces the traditional cementitious binder, forming a three-phase composite consisting of aggregate, resin matrix, and interfacial transition zones. Four random aggregate models were generated using the Monte Carlo method and their stability was verified. Subsequently, a two-dimensional micro-model was established, and the simulation results were compared with experimental data, yielding a maximum error of 8%, which validated the feasibility of the model. The findings indicate that circular aggregates exhibit lower load-bearing capacity, while irregular aggregates demonstrate higher capacity. Although the peak compressive strength is similar among different aggregate shapes, the crack propagation paths vary significantly. The load-bearing capacity of resin-based concrete increases with aggregate content up to an optimal value of approximately 80%, beyond which it decreases. At this optimal content, crack paths transition from branched to near-linear. In terms of aggregate grading, higher coarse aggregate proportions enhance load-bearing capacity and promote linear crack propagation, whereas higher fine aggregate proportions reduce capacity and result in multiple irregular crack paths. Finally, the numerical simulation results were used to guide macroscopic experiments, and orthogonal experiments were conducted to determine the optimal mixture proportions of different resin binders.

Mitigation of Fiber Print-Through During Replication of Carbon Fiber-Reinforced Polymer Mirrors

Aiming at the phenomenon of fiber print-through (FPT) during the curing process of carbon fiber-reinforced polymer (CFRP) mirrors, this paper effectively mitigates FPT by improving the replication technique. This paper simulates and analyzes the causes of FPT generation and then improves the replication technique based on multiple explorations of the replication process. In the improved replication technique, a mold is designed to assist in the curing process of the mirrors and to further suppress the FPT on the surface by applying pressure during the curing process. In addition, the layup method, resin matrix, and curing equipment are also optimized and improved. The surface roughness of the CFRP mirrors before and after the process improvement is measured using an optical surface profilometer, and the roughness parameters such as the arithmetic average deviation, root mean square error, and maximum height are obtained. Measurement results show that the improved replication technique effectively mitigates FPT, the surface of the obtained CFRP mirror is smoother, and the application of pressure during curing can further reduce the roughness of the mirror surface.

Flexural Strength, Fatigue Behavior, and Microhardness of Three-Dimensional (3D)-Printed Resin Material for Indirect Restorations: A Systematic Review

The purpose of this systematic review was to evaluate three mechanical properties of 3D-printed resins for indirect restorations according to published scientific evidence. This systematic review was conducted according to the PRISMA statement (preferred reporting elements for systematic reviews and meta-analyses). The search was performed by two investigators, (DD) and (VB), and a third (AC) resolved disagreements. Articles were searched in four digital databases: PubMed, EBSCO, Lilacs, and Science Direct, starting on 18 February 2024. As 3D-printing technology has shown significant advances in the last 5 years, the review was conducted with a publication year range between 2019 and 2024, in English language and included in vitro articles on the mechanical properties of flexural strength, fatigue behavior, and microhardness of 3D-printed materials for temporary or definitive restorations. MeSH terms and free terms were used for the titles and abstracts of each article. Finally, the QUIN tool was used to assess the risk of bias. In the main search, 227 articles were found, of which 20 duplicates were excluded, leaving 207 articles; of these, titles and abstracts were read, and 181 that did not meet the eligibility criteria were eliminated; of the remaining 26 articles, 1 article was eliminated for not presenting quantitative results. Regarding publication bias, 6 of the 25 articles had a low risk of bias, 18 had a medium risk of bias, and 1 had a high risk of bias. It may be concluded that 3D-printed resins have lower flexural strength, fatigue behavior, and microhardness than other resin types used for the fabrication of temporary and permanent restorations. The type of 3D printer and polymerization time could be factors that significantly affect the flexural strength, fatigue behavior and microhardness of 3D-printed resins. Based on existing evidence, it should be considered that additive technology has promising future prospects for temporary and permanent dental restorations.

Two‐dimensional layered MoS2/lignin as additives for epoxy composites with improved mechanical and tribological properties

AbstractThe MoS2/lignin hybrid material was successfully synthesized and incorporated into an epoxy resin to fabricate composite coatings. The results demonstrate that MoS2 is uniformly attached to the surface of lignin sheets. Compared to adding lignin alone, the MoS2/lignin hybrid‐epoxy resin (EP) composite coatings exhibited enhanced friction‐reducing and wear‐resistant properties. Specifically, the 1 wt% MoS2/lignin hybrid displayed excellent dispersion and high interfacial compatibility within the resin matrix, leading to a 66.7% increase in Vickers hardness, a 27.5% increase in tensile strength, and a 73.9% improvement in char yield. Furthermore, the friction coefficient and wear rate were reduced by 63.2% and 75.8%, respectively. As a uniformly dispersed hybrid structure, the MoS2/lignin material can endure higher loads, autonomously repair defects, and form a stable and complete transfer film on the worn surface, demonstrating synergistic friction‐reducing and wear‐resistant effects within the epoxy resin matrix. Integrating MoS2 into a two‐dimensional material can provide a practical reference for designing polymer‐based hybrid materials with outstanding comprehensive properties.Highlights The MoS2/lignin hybrid material was successfully synthesized. MoS2 is uniformly attached to the surface of lignin sheets. The hybrid significantly enhances friction‐reducing and wear‐resistant properties. Vickers hardness increased by 66.7%, and tensile strength increased by 27.5%. The friction coefficient was reduced by 63.2%, and the wear rate was reduced by 75.8%.

Spinning waste as reinforcement for epoxy composites: mechanical performance

The present research work studies the feasibility of using waste cotton fibres from carding machines as a reinforcing material in epoxy resin matrix for composite fabrication. Waste cotton fibres were utilized to produced thick paper with an areal density of 150 g/m2. The physico-chemical properties of the produced papers were evaluated by X-ray diffraction methods, chemically and tensile testing. Composites samples were prepared using modified paper with epoxy resin, maintaining with different fibre content (20%, 30% and 40 wt%). The mechanical properties of the composite were evaluated by the tensile, flexural and interlaminar shear test. The tensile fracture behavior of the composites was investigated by scanning electron microscopy (SEM). The tensile strength, flexural strength and inter laminar shear strength (ILSS) of 40% fibre content composite in the machine direction were found to be 48, 54 and 6.1 MPa respectively. The results indicate that waste cotton fibers can be an excellent reinforcing material for composite production.

Three-Dimensional-Printed Photopolymer Resin Materials: A Narrative Review on Their Production Techniques and Applications in Dentistry

Additive manufacturing (3D printing) has transformed dentistry by providing solutions with high precision and accuracy achieved through digital workflows, which facilitate the creation of intricate and personalized structures. Additionally, 3D printing promotes cost efficiency by reducing material waste and errors while enabling on-demand production, minimizing the need for extensive inventories. Recent advancements in 3D-printed resin materials have enhanced their clinical applications by improving mechanical strength, biocompatibility, esthetics, and durability. These innovations have facilitated the fabrication of complex and patient-specific structures, such as dental prostheses, surgical guides, and orthodontic appliances, while significantly reducing production time and material waste. Ongoing research and innovation are expected to strengthen resin properties, including strength, translucency, and durability, broadening their clinical applications. The ongoing evolution of 3D printing technology is poised to play a critical role in driving personalized treatments, streamlining clinical workflows, and shaping the future of dental care. This narrative review comprehensively examines the production techniques and clinical applications of 3D-printed photopolymer resins across various dental specialties, including prosthodontics, orthodontics, pediatric dentistry, maxillofacial surgery, periodontology, endodontics, and conservative dentistry. Additionally, the review provides insight into the transformative impact of these technologies on patient care, highlights existing challenges, and suggests future directions for advancing resin properties and their integration into routine dental practice.

Thermal activation and dynamic mechanical characterization of glass-reinforced shape memory polymer composites for medical applications

Thermally activated shape memory polymers are of increasing interest nowadays. Their incorporation in textile-based preforms reinforced composites is being focused on, owing to some functional applications of medical textiles, e.g., posture support of joints after fracture surgery where gradual healing of fractures requires the joints to be moved slightly, which is not possible with conventional supports. Hence, this study was aimed at the development and characterization of thermally activated shape memory composites having woven glass fiber reinforcements for such applications. Three different stackings or laminates were developed (single-, double-, and triple-layered composites), solely using glass fiber, whereas resin material induced shape memory function. The glass transition temperature of the engineered specimens was determined, and the shape memory function was evaluated at three different temperatures, namely, below, at, and above the glass transition temperature (45°C, 65°C, and 85°C). Increasing the characterization temperature decreased the shape recovery time by 75%, owing to softening and better polymer chain mobility at higher temperatures. The shape recovery velocity also increased with increasing temperature. Increasing the number of glass fabric layers compromised the shape memory function; however, the interlaminar shear strength was improved.

Zr-doped mesoporous silica (Zr-MSS) for improved mechanical stability and biocompatibility of dental composite resins.

Mesoporous silica particles are of great interest in the field of dental composites as functional inorganic fillers due to their unique interconnected pores which can form micromechanical interlocking at the filler-resin interfaces. However, the degradation of mesoporous silica is fast in wet environments, leading to the poor mechanical stability of dental composites. Here, we synthesized Zr-doped mesoporous silica spheres (Zr-MSS) to increase the chemical stability of the particles. The particles were formulated with dental resins (Bisphenol A glycerolate dimethacrylate/triethylene glycol dimethacrylate, 50/50, wt%) to evaluate the performance of dental composites. Dental composites filled with different amount of Zr-MSS (15, 20, 25 and 30wt%) and their bimodal fillers with nonporous silica spheres (NSS) at a total filler loading of 60wt% (mass ratios of Zr-MSS: NSS=10:50) were prepared. Neat resin matrix and samples filled with mesoporous silica spheres (MSS) were used as control. The results showed that the decrease percentage of flexural strength of dental resins with Zr-MSS was the lowest, which was between 3.4 and 6.8%. It was between 20.8 and 35.5% for those with MSS. Further studies revealed that the incorporation of Zr into mesoporous fillers did not affect their light curing ability of dental composites. Not only that, cell proliferation on the dental composites with Zr-MSS was promoted, suggesting improved biocompatibility of the restorations. These indicated that the prepared Zr-MSS would be promising functional fillers for dental composite resins.

Preparation of magnetic‐oriented electronic packaging composite materials with improved thermal conductivity and insulating properties by filling magnetic BN@Fe3O4 core‐shell particles into epoxy

AbstractEpoxy resin (EP), as a resin material with excellent insulation performance, has been widely applied in fields such as electronics, coatings, ships etc. However, epoxy resins generally have poor thermal conductivity, which limits their application in the field of new generation of electronic packaging. To address the key issues mentioned above, the BN@Fe3O4 particles with positive out‐of‐plane thermal conductivity were successfully prepared in this study, having a core‐shell structure with rough surfaces as well. As a thermal conductive powder, the disadvantage of hexagonal boron nitride being easily agglomerated in resin has been improved. By applying an external magnetic field, three‐dimensional thermal conduction pathways were constructed in the matrix. The physical and chemical properties of the BN@Fe3O4 powder and its composite materials were analysed and tested. The experiment indicates that the thermal conductive magnetic powder BN@Fe3O4 had been successfully prepared. When the filling amount of BN@Fe3O4 reached 27.5 vol%, the out‐of‐plane thermal conductivity of the composite material was 1.758 W m−1 K−1, which was 982.12% that of pure EP. At this point, the mechanical behaviour and insulation performance of EP composite materials can be effectively guaranteed at the same order of magnitude as pure EP performance.

Impact of Fabrication Techniques and Polishing Procedures on Surface Roughness of Denture Base Resins.

This study aimed to assess the impact of various fabrication techniques and polishing procedures on the surface roughness (Ra) of resin-based materials used in the fabrication of complete dentures. A total of 90 specimens were produced from three different resin materials: heat-polymerized polymethyl methacrylate (PMMA) resin, CAD-CAM milled PMMA resin, and 3D-printed resin (n = 30). Each specimen measured 10 mm in diameter and 2 mm in height. The surface roughness (Ra) values of the specimens were initially determined using a contact profilometer following fabrication. Subsequently, each group of specimens was polished with 600-, 800-, and 1000-grit silicon carbide abrasive papers under running water. A second measurement of the surface roughness (Ra) values was then performed. The data were analyzed statistically using the Kruskal-Wallis test, Mann-Whitney U test, Wilcoxon signed-rank test, and paired samples t-test (p = 0.05). A statistically significant difference was identified between the groups in terms of surface roughness (Ra) prior to the polishing process (p < 0.001). However, no statistically significant difference was observed between the milled and heat-polymerized PMMA base materials following the polishing process. The 3D-printed specimens showed the most notable improvement in surface roughness due to the polishing process. Nevertheless, their surface roughness remained statistically significantly higher compared to the other samples, both before and after polishing (p < 0.001). The fabrication method of complete denture base materials was observed to influence surface roughness. The surface roughness values of the base materials fabricated using the 3D printing method were higher compared to those fabricated with milled and heat-polymerized PMMA resin, both before and after polishing.