Search Results (158)

This study aimed to develop an innovative resin composite with anti-biofouling properties, tailored to prosthesis fabrication in dentistry using a digital light processing (DLP) 3D-printing technique. The resin composite was formulated using a blend of dental monomers, with the integration of 2-methacryloyloxylethyl phosphorylcholine (MPC) with anti-biofouling behavior and γ-MPS-treated silica-zirconia powder for simultaneous mechanical reinforcement. The overall characterization of the resin composite was carried out using various contents of MPC incorporated into the resin (0–7 wt%) for examining the rheological behavior, photopolymerization, flexural strength/modulus, microstructure and anti-biofouling efficiency. The resin composite demonstrated a significant reduction in bacterial adhesion (97.4% for E. coli and 86.5% for S. aureus) and protein adsorption (reduced OD value from 1.3 ± 0.4 to 0.8 ± 0.2) with 7 wt% of MPC incorporation, without interfering with photopolymerization to demonstrate potential suitability for 3D printing without issues (p < 0.01, and p < 0.05, respectively). The incorporation and optimization of γ-MPS-treated silica-zirconia powder (10–40 vol%) enhanced mechanical properties, leading to a reasonable flexural strength (103.4 ± 6.1 MPa) and a flexural modulus (4.3 ± 0.4 GPa) at 30 vol% (n = 6). However, a further increase to 40 vol% resulted in a reduction in flexural strength and modulus; nevertheless, the results were above ISO 10477 standards for dental materials. Full article

This study aimed to develop experimental filler-reinforced resin composites for vat-photopolymerization 3D printing and to evaluate the effects of filler addition on their mechanical, physicochemical, and bonding properties for dental restorative applications. Silanized nano- and/or micro-fillers were incorporated into acrylic resin monomers to formulate photocurable resins suitable for vat-photopolymerization. The rheological behavior of these liquid-state resins was assessed through viscosity measurements. Printed resin composites were fabricated and characterized for mechanical properties—including flexural strength, flexural modulus, and Vickers hardness—both before and after 8 weeks of water immersion. Physicochemical properties, such as water sorption, water solubility, and degree of conversion, were also evaluated. Additionally, shear bond strength to a resin-based luting agent was measured before and after artificial aging via thermocycling. A commercial dental CAD-CAM resin composite served as a reference material. Filler incorporation significantly improved the mechanical properties of the printed composites. The highest performance was observed in the composite containing 60 wt% micro-fillers, with a flexural strength of 168 ± 10 MPa, flexural modulus of 6.3 ± 0.4 GPa, and Vickers hardness of 63 ± 1 VHN, while the commercial CAD-CAM composite showed values of 152 ± 8 MPa, 7.9 ± 0.3 GPa, and 66 ± 2 VHN, respectively. Filler addition did not adversely affect the degree of conversion, although the relatively low conversion led to the elution of unpolymerized monomers and increased water solubility. The shear bond strength of the optimal printed composite remained stable after aging without silanization, demonstrating superior bonding performance compared with the CAD-CAM composite. These findings suggest that the developed 3D-printed resin composite is a promising candidate for dental restorative materials. Full article

Background: Graphene oxide (GO) is widely explored as a functional additive in polymer composites; however, its simple physical dispersion in dental resins often leads to poor interfacial stability and limited long-term performance. Covalent functionalization may overcome these limitations by enabling chemical integration into the polymer matrix. This study presents the synthesis and FT-IR/Raman characterization of GRAPHYMERE^®, a novel graphene oxide-based monomer obtained through exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate. Methods: A novel GO-based monomer, GRAPHYMERE^®, was synthesized through a three-step process involving GO exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate to introduce polymerizable acrylic groups. The resulting product was characterized using FT-IR and Raman spectroscopy. Results: Spectroscopic analyses confirmed the presence of aliphatic chains and amine functionalities on the GO surface. Although some expected signals were overlapped, the data suggest successful surface modification and partial insertion of methacrylamide groups. The process is straightforward, uses low-toxicity reagents, and avoids complex reaction steps. Conclusions: GRAPHYMERE^® represents a chemically modified GO monomer potentially suitable for copolymerization within dental resin matrices. While its structural features support compatibility with radical polymerization systems, further studies are required to assess its mechanical performance and functional properties in dental resin applications. Full article

Minimizing the risk of secondary caries in dentistry is achieved by using adhesive systems that provide a strong bond between the natural hard tissue and the restorative material. Evaluating the effectiveness of these systems requires studying both their interaction with dentin and enamel and their behavior in environments with varying acidity. In this work, the interaction of a reactive monomer, 4-methacryloxyethyl trimellitic anhydride (4-META), used in adhesive systems with both dentin-like hydroxyapatite (HA) and hydroxyapatite ceramics, was investigated. Kinetic studies showed that under experimental conditions, 4-META was hydrolyzed and amorphized. Dentin-like HA possessed greater adsorption capacity to 4-META than ceramic HA. Immersion of HA into a solution of 4-META led to formation of an acidic calcium phosphate phase over time in both systems. Studies on the solubility of the synthetic nanosized hydroxyapatite and its derivative with 4-META in 0.1 mol/L lactic acid, also containing CaCl₂, Na₂HPO₄, and NaF (pH 4.5), and in distilled water (pH 6.3) indicated the occurrence of dissolution, complexation, and crystallization processes, causing changes in the liquid and solid phases. The total Ca²⁺ concentration upon dissolution of hybrid HA-4-META in a lactic acid solution was three times lower than the total Ca²⁺ concentration upon dissolution of pure HA. This suggested that 4-META-treated dentin-like surfaces demonstrate greater resistance to dissolution in acidic environments compared to untreated surfaces, highlighting the potential for these hybrids in dental applications. Full article

Diseases such are caries affect approximately 25% of the worldwide population. Such a state requires novel, antibacterial materials. This research aimed to synthesize and characterize the structures of two urethane-dimethacrylate monomers showing possible antibacterial activity for dental composite restorative materials (DCRMs). The monomers were based on isophorone diisocyanate (IPDI) and dicyclohexylmethane 4,4′-diisocyanate (CHMDI). The structures of the monomers and their key elements were confirmed with the application of spectroscopy methods. Nuclear Magnetic Resonance Spectroscopy (¹H and ¹³C NMR) and Fourier Transform Infrared Spectroscopy (FTIR) were applied. The monomers were synthesized and their structures were confirmed with the abovementioned techniques. Full article

Although dental resin composite restoratives offer a widely used direct-placement treatment option aimed at replacing the form and function of a natural tooth, there are several clinically relevant performance aspects of these materials that can be improved. The formulation of the resin matrix phase of dental composites for high-efficiency photopolymerization leading to polymers with excellent mechanical properties has always been a challenge that is addressed here through the use of structurally new and more reactive monomers as well as the formation of polymer networks that incorporate non-covalent reinforcing interactions. The purpose of this study was to validate that a set of tetraurethane diacrylates (TUDAs) with a novel configuration of their urethane linkages in coordination with acidic comonomers could be devised to obtain highly robust new composite materials. Due to the novel molecular design, this exploratory approach was conducted using reaction kinetics and three-point bend testing to assess the performance. Conversion and mechanical properties were measured to refine these formulations prior to the addition of filler. The initial formulations demonstrated outstanding dry mechanical test results that subsequently showed a major intolerance to water storage, which led to a model study using urethane diacrylate (UDA) followed by the addition of hydrophobic TUDA monomers. Once the resin formulations were optimized, silane-treated particulate filler was added to determine the effectiveness as composite materials. The final formulation used a hydrophobic, aromatic TUDA along with 4-methacryloxyethyl trimellitic anhydride (4-META) as a latent acidic comonomer and a mixture of acrylic acid (AA) and methacrylic acid (MAA). This formulation achieves a very high level of both reactivity and mechanical properties relative to current dental composite restoratives. Full article

The study aims to assess the effect of printing orientation on surface roughness and gloss of resins for 3D printing of aligners. Squared specimens (14 × 14 × 4 mm) were printed using Dental LT Clear (Formlabs, Somerville, MA, USA; LT) or Tera Harz TC-85 DAC (Graphy, Seoul, Republic of Korea; TC) with different orientations: 0° (horizontal), 90° (vertical), and as per the manufacturer’s recommendation (40° for LT, 60° for TC). A profilometer was used to measure roughness (Ra) in µm, while gloss was recorded in gloss units (GU) with a glossmeter. The collected data were statistically analyzed. Material type did not significantly influence roughness, while print orientation was an influential factor, with the orientation recommended by the manufacturer yielding the roughest specimens. Vertical printing resulted in significantly higher roughness than horizontal. Material type was a significant factor for gloss, with TC exhibiting significantly higher gloss than LT. Print direction significantly influenced gloss, with vertical printing resulting in the highest gloss. The finding of higher roughness for vertical prints can be explained by the presence of a greater number of layers. The superior gloss exhibited by TC regardless of print angulation could be related to the effective cleaning of uncured resin by centrifugation and to the high degree of monomer conversion in nitrogen atmosphere. Full article

Photocurable materials offer a rapid transition from a liquid to a solid state, and have recently received great interest in the medical field. However, while dental resins are very popular, only a few materials have been developed for soft tissue repair. This study aims to synthesize a difunctional methacrylate monomer using a dibutyltin dilaurate which is suitable for the photocuring of soft materials. These soft materials were compared with PhotoBioCure^® (Szczecin, Poland) material with a similar molecular weight, of Mn ~7000 g/mol on average. Infrared spectroscopy was used to monitor the two-step synthesis catalyzed with dibutyltin dilaurate, while spectroscopic and chromatographic methods were used to determine the chemical structure and molecular weight of the monomers. Photopolymerization kinetics under varying light intensities were explored in a nitrogen atmosphere for representative difunctional monomers. The mechanical testing of the resulting elastomeric films confirmed tensile strength and modulus values consistent with soft tissue parameters in the range of 3–4 MPa. The 3D printability of the macromonomers was also assessed. Additionally, cytotoxicity assessments using cultured cells showed a high cell viability (97%) for all new materials. Overall, we demonstrate that difunctional methacrylate monomers converted to flexible solids during photopolymerization show great potential for biomedical applications. Full article

In the latter part of the 20th century, remarkable developments in new dental materials and technologies were achieved. However, regarding the impact of dental resin-based materials 3D-printed on cellular responses, there have been a limited number of published studies recently. The biocompatibility of dental restorative materials is a controversial topic, especially when discussing modern manufacturing technologies. Three-dimensional printing generates the release of residual monomers due to incomplete polymerization of materials and involves the use of potentially toxic substances in post-printing processes that cannot be completely eliminated. Considering the issue of biocompatibility, this article aims to establish an overview of this aspect, summarizing the different types of biocompatibility tests performed on materials used in 3D printing in dentistry. In order to create this comprehensive review, articles dealing with the issue of 3D printing in dentistry were analysed by accessing the main specialized search engines using specific keywords. Relevant data referring to types of materials used in 3DP to manufacture various dental devices, polymerization methods, factors affecting monomer release, cytotoxicity of unreacted products or post-curing treatments, and methods for assessing biocompatibility were analysed. Although the introduction of new restorative materials used in dental treatments is subject to national and international regulations and standards, it is necessary to investigate them regarding biocompatibility in order to support or deny the manufacturers’ statements regarding this aspect. Full article

This project intends to develop restorative dental nanomaterial composites that are light-curable and show minimal shrinkage. Such nanocomposites are improved via employing 2,2-bis[4(2-hydroxy-3-methacryloylpropyloxy) phenyl] propane (Bis-GMA) with the unsaturated monomers bisphenol A dimethacrylate, N,N-dimethylacetamide (DMA), ethylene glycol (EG), and methacrylic acid (MAA) and loading them with SiO₂, ZrO₂, or hydroxyapatite (HA) as nanofillers of 10–30 nm. The first step was to create and characterize these novel dental materials. 1,6-hexanediol methacrylate (HDOMA) was used as a cross-linking agent. The composites based on Bis-GMA and HDOMA with a mass ratio of 40/20 were loaded with 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 wt.% of the fillers mentioned above. Photopolymerization was induced by a system of photoinitiation based on Camphorquinone/2- (Diethyl amino) ethyl acrylate (CQ/DMAEMA). The nanofillers were treated with 3-(methacryloyloxy) propyltrimethoxysilane (MPTMS) at a ratio of 1.5, 2.5, as well as 3.5%wt. compared to the filler) and a silane coupling agent to increase bonding between the phases and reduce the tendency of agglomerations. SEM images displayed the adhesion between the matrix and the three functionalized nanofillers. FTIR was used to prove the functionalization of the nanofillers by silanization with MPTMS. According to the polymer matrix, two different series of dental nanocomposites were obtained. The compressive strength of dental nanocomposites treated with 2.5 wt.% MPTMS was considerably more significant than those treated with 1.5 and 3.5%wt. MPTMS. Compressive strength (CS) and volumetric shrinkage (VS) were examined as examples of physicochemical properties. This improved nanocomposite was tested for its suitability as a dental restorative material and found to have low shrinkage and high strength. Full article

Polymethyl methacrylate (PMMA) bone cement has been a transformative material in orthopedics since its introduction in the mid-20th century. Originally used in dental medicine, PMMA was adopted for orthopedic applications by Sir John Charnley in the 1950s, significantly enhancing joint replacement surgeries. The primary appeal of PMMA lies in its biocompatibility, mechanical strength, and ease of handling, making it a favored choice for various orthopedic procedures, including arthroplasties and limb-salvage surgeries. However, the exothermic polymerization process of PMMA poses a risk of thermal necrosis in the surrounding bone tissue, as local temperatures can exceed 70 °C, causing damage to osteocytes. Research has sought to mitigate these risks by optimizing mixing techniques, reducing cement mantle thickness, and incorporating cooling methods. Recent advancements, such as the use of phase-change materials (PCMs) and alternative monomers, have shown promise in lowering the exothermic peak during polymerization. Other strategies include pre-cooling the cement and prosthetic components and using composite cement. Despite these innovations, managing the balance between minimizing heat generation and maintaining mechanical properties remains a challenge. The impact of thermal necrosis is significant, compromising implant stability and osseointegration. Understanding the complex interactions between PMMA’s thermal properties and its clinical outcomes is essential for improving orthopedic surgical practices and patient recovery. Full article

Billions of patients struggle with dental diseases every year. These mainly comprise caries and related diseases. This results in an extremely high demand for innovative, polymer composite filling materials that meet a number of dental requirements. The aim of the study was to modify the light-cured composition of permanent dental fillings by changing the composition of the liquid organic matrix. New photoinitiators (DQ1-DQ5) based on a quinoline or quinoxaline skeleton and a co-initiator-(phenylthio)acetic acid (PhTAA) were used. In addition, monomers that have been traditionally used in dental materials were replaced by trimethylolpropane triacrylate (TMPTA). The neutral dental glass IDG functioned as an inorganic filler. The influence of the storage conditions of the developed composites in solutions simulating the natural oral environment during the consumption of different meals on sorption, solubility, and mass changes was assessed. For the tests, fifty-four cylindrical composite samples were prepared according to ISO 4049 guidelines and stored in different solutions. Distilled water, artificial saliva, heptane, 10% ethanol, and 3% acetic acid, as well as solutions containing pigments such as coffee, tea, red wine, and Coca-Cola, were used for the studies. The samples were stored in these solutions for 7, 14, 28, 35, 42, 49, 56, and 63 days at 37 °C. The sorption, solubility, and mass changes in the tested samples were determined, and the trend of these changes as a function of storage time was presented. The results were analyzed considering the nature of the solution used, i.e., aqueous, hydrophobic, and acidic. The properties evaluated changed in a different way, characteristic for each of the abovementioned solution groups. It was found that the type of solution simulating the natural environment of the oral cavity has the greatest influence on the sorption, solubility, and changes in the mass of the tested material. Full article

Dental caries are treated using dental composite restorative materials (DCRM). However, commercial DCRMs lack antibacterial activity. This research aimed to analyze the in vitro antibacterial activity of a series of copolymers consisting of a urethane–dimethacrylate monomer (UDMA), bisphenol A glycerolate dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA) and urethane–dimethacrylate monomer with two quaternary ammonium groups and a 1,3-bis(1-isocyanate-1-methylethyl)benzene core (QAn+TMXDI, where n = 8, 10, or 12 is the number of carbon atoms in the N-alkyl substituent). QAn+TMXDI contents in copolymers were 20 and 40 wt.%. The results of the Staphylococcus aureus and Escherichia coli adhesion test demonstrated that the logCFU/mL decreased as the length of the N-alkyl chain decreased and QAn+TMXDI content increased. The copolymers of QA8+TMXDI 40 wt.%, Bis-GMA 40 wt.%, and TEGDMA 20 wt.% showed the highest antibacterial activity, with a logCFU/mL of 2.39 for S. aureus and no viable E. coli cells. Full article

Provisional crowns are often used in dentistry for prolonged periods, but bacterial attachment and dental plaque often lead to gingival inflammation and secondary caries. The aims of this research were to develop a novel resin-based antibacterial provisional crown coating to prevent secondary caries and investigate the physical properties and antibacterial efficacy. The resin-based coating was prepared by addition of triethylene glycoldivinylbenzyl ether and urethane dimethacrylate, with the antibacterial monomer dimethylaminododecyl methacrylate (DMADDM) incorporated at different mass fractions. Surface characteristics including surface roughness and contact angle were assessed. The antibacterial effects were evaluated by 48 h biofilms of Streptococcus mutans (S. mutans) on provisional crowns coated with the resin-based coating. No statistically significant difference was observed in surface roughness across all groups (p > 0.05), showing that adding DMADDM did not have a negative impact on surface roughness. The contact angle results revealed a significant difference in hydrophilicity between different concentrations of DMADDM (p < 0.01), but overall hydrophilicity did not negatively affect the performance of the coating. The incorporation of 5% DMADDM demonstrated a significant antibiofilm effect on S. mutans biofilm CFU with a 4-log reduction compared to controls (p < 0.01). Significant reductions of 4–5 folds were observed in biofilm metabolic activity and lactic acid production (p < 0.01). The findings suggest that the novel coating material could enhance the long-term performance and clinical outcomes of provisional crowns, contributing to better patient oral health. Full article

Aim: Polyurethane-based aligners, created through photoinitiated free-radical polymerization, have been the subject of numerous studies focusing solely on their mechanical properties. In contrast, we investigate their thermomechanical properties, which are crucial for their efficacy. This paper aims to investigate the effects of different UV light exposure durations on the complex modulus of elasticity, tan delta, glass transition temperature, and the degree of conversion (DC). Methods: Aligners were printed using Tera Harz TC-85 and NextDent Ortho Flex resin with specific exposure times (2, 2.4, 3, 4, and 4.5 s for Tera Harz; 5, 6, 7, and 8 s for NextDent) and processed per manufacturer guidelines. The degree of conversion was analyzed using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, while Dynamic Mechanical Analysis (DMA) characterized the mechanical properties (complex modulus and tan delta) and the glass transition. Results: Tera Harz TC-85 showed a higher degree of conversion (90.29–94.54%), suggesting fewer residual monomers, which is potentially healthier for patients. However, its lower glass transition temperature (35.60–38.74 °C) might cause it to become rubbery in the mouth. NextDent Orto Flex, with a higher storage modulus (641.85–794.55 MPa) and Tg (49.36–50.98 °C), offers greater rigidity and stability at higher temperatures (greater than temperature in the oral cavity), ideal for orthodontic forces, though its lower degree of conversion raises health concerns. Conclusions: Tera Harz TC 85 generally achieves higher DC and more stable polymerization across different UV exposure times than NextDent Orto Flex. Optimal polymerization times significantly impact both the mechanical and thermal properties of these dental resins, with NextDent showing optimal properties at 7 s and Tera Harz benefiting from both very short and extended exposure times. Full article