Search Results (368)

Background/Objectives: The application of additive manufacturing in medicine, and specifically in personalised medicine, has achieved notable development. This article aims to present the results and benefits of applying a comprehensive methodology to simulate, plan, and manufacture customised three-dimensional medical prosthetic devices for use in surgery to restore bone structures with congenital and acquired malformations. Methods: To digitally reconstruct a bone structure in three dimensions from a medical image, a segmentation process is developed to correlate the anatomical model. Then, this model is filtered using a post-processing step to generate stereolithography (STL) files, which are rendered using specialised software. The segmentation of tomographic images is achieved by the specific intensity selection, facilitating the analysis of compact and soft tissues within the anatomical region of interest. With the help of a thresholding algorithm, a three-dimensional digital model of the anatomical structure is obtained, ready for printing the required structure. Results: The described cases demonstrate that the use of anatomical test models, cutting guides, and customised prostheses reduces surgical time and hospital stay, and achieves better aesthetic and functional results. Using materials such as polylactic acid (PLA) for presurgical models, appropriate resins for cutting guides, and biocompatible materials such as polyether ether ketone (PEEK) or polymethylmethacrylate (PMMA) for prostheses, the described improvements are achieved. Conclusions: The achievements attained demonstrate the feasibility of applying these techniques, their advantages and their accessibility in Ecuador. They also reinforce the ideas of personalised medicine in the search for medical treatments and procedures tailored to the needs of each patient. Full article

Aseptic loosening (AL) represents the leading cause of long-term failure in total joint arthroplasty, often necessitating revision surgery. This review explores the complex mechanisms underlying AL, which involve a multifaceted interaction between the implanted biomaterials and the host immune response. We outline the key inflammatory mechanisms triggered by wear debris from polyethylene, polymethylmethacrylate, metal, and ceramic materials. We also examine emerging biomarkers for early detection and differentiation between stable and loosened implants, including proinflammatory cytokines, bone metabolism markers, extracellular matrix degradation products, microRNAs, and genetic polymorphisms. Lastly, we discuss current and future strategies for prevention and treatment, ranging from surgical optimization and biomaterial selection to pharmacological interventions. A comprehensive understanding of these mechanisms may help reduce the incidence of AL and improve long-term outcomes in arthroplasty patients. Full article

Background: Prosthetic cementation using the biologically oriented preparation technique (BOPT) presents challenges in removing excess cement from the gingival sulcus, due to the absence of a finishing line and the impossibility of using absolute isolation with a rubber dam. This study aimed to evaluate the effectiveness of relative isolation using polytetrafluoroethylene (PTFE) tape in reducing cement retention during BOPT cementation. Methods: Fifteen 3D-printed resin models were created from an intraoral scan of a patient restored with BOPT in both upper central incisors. Each model included removable gingiva. Splinted polymethylmethacrylate (PMMA) provisional crowns were fabricated and cemented with temporary cement. One central incisor was isolated with PTFE (0.1 mm or 0.2 mm), while the contralateral tooth was left unisolated as a control. After debonding, digital scanning and volumetric analysis using root mean square (RMS) deviation were performed to quantify retained cement. Paired t-tests were applied to compare groups. Results: The mean RMS for the PTFE group was 0.1248 ± 0.0519 mm, compared to 0.1973 ± 0.0361 mm in the non-isolated group (p < 0.001). No significant difference was found between PTFE thicknesses of 0.1 mm and 0.2 mm (p = 0.388). Conclusions: PTFE tape is effective for relative isolation when rubber dam placement is not feasible in BOPT restorations. Further clinical studies are recommended to confirm these findings in vivo. Full article

Polymer blending techniques enable the tailoring of desired properties for diverse applications. This study investigates the effect of PMMA content on the thermomechanical, chemical, mechanical, and fatigue life properties of PC/ABS/PMMA (polycarbonate/acrylonitrile–butadiene–styrene/polymethylmethacrylate) ternary blends. To this end, various characterization analyses, as well as tensile, impact, and fatigue tests, were conducted. The results indicate that the viscoelastic modulus improves with increasing PMMA content in ternary blends. Furthermore, PC/ABS/PMMA blends exhibit an immiscible phase morphology. The elastic modulus, yield strength, and tensile strength increase with higher PMMA content, while the elongation at break and impact strength decrease. Fatigue strength and the fatigue strength exponent were found to vary nonlinearly with PMMA content. Compared to PC/ABS blends, PC/ABS/PMMA blends demonstrated improvements of approximately 12% to 58% and 26% to 117% in hysteresis energy and the dynamic elastic modulus, respectively. Additionally, fatigue life cycles improved by 5% to 11% at low stress amplitudes. This experimental study provides comprehensive insight into the complex interplay among the chemical, thermomechanical, mechanical, and fatigue properties of ternary PC/ABS/PMMA blends, highlighting their potential for applications requiring balanced or tailored structural and material characteristics. Full article

Due to the need for reproducible, scalable, and environmentally friendly nanomaterial synthesis methods, an increasing amount of scientific interest revolves around microfluidic technologies. In this context, the present paper proposes a new three-dimensional (3D) spiral microfluidic platform designed and tested for the simultaneous synthesis and surface functionalization of magnetite (Fe₃O₄) nanoparticles with salicylic acid (SA). The microreactor was fabricated from overlaid polymethylmethacrylate (PMMA) sheets and assembled into a compact, reusable chip architecture, allowing continuous reagent mixing and enhanced hydrodynamic control. The performed physicochemical analyses confirmed that on-chip synthesized Fe₃O₄@SA NPs exhibit crystallinity, a uniform spherical morphology, a narrow size distribution, excellent colloidal stability, and successful surface functionalization. In vitro cytotoxicity assays using MRC-5 lung fibroblasts and HaCaT keratinocytes revealed a concentration-dependent response, identifying a safe dose range below 610 µg/mL. The integrated design, efficient synthesis, and favorable biocompatibility profile position this 3D microfluidic platform as a promising tool for scalable nanomaterial production in biomedical and environmental applications. Full article

Background: Reconstructing maxillofacial defects is important in dentistry, so efforts are being made to develop materials that promote cell migration and repair. Graphene oxide (GO) is used to enhance the biocompatibility of polymethylmethacrylate (PMMA) due to its nanostructure. Objective: to assess cytotoxicity, cell proliferation, and differentiation of human dental pulp stem cells (hDPSC) in response to a conventional PMMA (PMMA) and polymer enriched with GO (PMMA+GO). Methods: Experiments were carried out with primary hDPSC subcultures. The PMMA and PMMA+GO were tested in direct and indirect contact. Cytotoxicity (1 day) and proliferation (3, 7, and 14 days) were evaluated with an MTT bioassay. The osteogenic, adipogenic, and chondrogenic aspects were determinate with alizarin red, oil red, and safranine. Mean values, standard deviation, and percentages were calculated; data were analyzed with Shapiro–Wilks normality and Student’s t-test. Results: The cell viability of PMMA and PMMA+GO in direct contact correspond to 90.8 ± 6.2, 149.6 ± 14.5 (1 day); 99.9 ± 7.0, 95.7 ± 6.1 (3 days); 120.2 ± 14.6, 172.9 ± 16.2 (7 days); and 102.9 ± 17.3, 95.4 ± 22.8 (14 days). For indirect contact, 77.2 ± 8.4, 99 ± 21.4 (1 day); 64.8 ± 21.6, 67.0 ± 9.6 (3 days); 91.4 ± 16.5, 142 ± 18.7 (7 days); and 63 ± 15.8, 79.1 ± 3.1 (14 days). PMMA+GO samples showed enhanced adipogenic, chondrogenic, and osteogenic aspects. Conclusions: The integration of GO into PMMA biopolymers stimulates cell proliferation and differentiation, holding great promise for future applications in the field of biomedicine. Full article

Biopolymer-based dermal fillers have gained attention in facial aesthetics due to their biocompatibility, gel-forming properties, and capacity to stimulate tissue regeneration. However, evidence regarding their clinical performance remains scattered and inconsistent. This systematic review evaluates the current scientific literature on the effectiveness and safety of injectable biopolymers used in facial aesthetic procedures. A systematic search was conducted in PubMed, MEDLINE, and Embase databases for studies published between 2016 and 2024. Only human studies in English assessing clinical efficacy, safety, adverse events, and patient satisfaction were included. Of the 280 articles initially identified, 9 met the inclusion criteria. The selected studies showed improvements in facial volume and wrinkle reduction with gel-based biopolymers such as poly-L-lactic acid (PLLA), polycaprolactone (PCL), and polymethylmethacrylate (PMMA). Most studies reported high patient satisfaction and a low incidence of serious adverse effects. However, methodological heterogeneity and limited long-term data reduced the strength of the evidence. While injectable biopolymers appear to be effective and generally safe, current evidence is limited and variable. Further multicenter randomized trials with standardized protocols and longer follow-up periods are needed. Clinicians should apply these materials with caution, ensuring individualized treatment planning and careful risk assessment. Full article

The increasing demand for orthopedic and neurosurgical implants has driven advancements in biomaterials, additive manufacturing, and antimicrobial strategies. With an increasingly aging population, and a high incidence of orthopedic trauma in developing countries, the need for effective, biocompatible, and infection-resistant implants is more critical than ever. This review explores the role of polymers in 3D printing for medical applications, focusing on their use in orthopedic and neurosurgical implants. Polylactic acid (PLA), polycaprolactone (PCL), and polyetheretherketone (PEEK) have gained attention due to their biocompatibility, mechanical properties, and potential for antimicrobial modifications. A major challenge in implantology is the risk of periprosthetic joint infections (PJI) and surgical site infections (SSI). Current strategies, such as antibiotic-loaded polymethylmethacrylate (PMMA) spacers and bioactive coatings, aim to reduce infection rates, but limitations remain. Additive manufacturing enables the creation of customized implants with tailored porosity for enhanced osseointegration while allowing for the incorporation of antimicrobial agents. Future perspectives include the integration of artificial intelligence for implant design, nanotechnology for smart coatings, and bioresorbable scaffolds for improved bone regeneration. Advancing these technologies will lead to more efficient, cost-effective, and patient-specific solutions, ultimately reducing infection rates and improving long-term clinical outcomes. Full article

This paper investigates the dual effects of slope variation and flame interaction on counter-directional flame propagation through numerical simulations of polymethylmethacrylate (PMMA) plates. Critical flame propagation parameters, including flame morphology, flame spread speed, mass loss rate, and radiative heat flux density, were analyzed using the Fire Dynamics Simulator (FDS v6.7.5) software. By comparing counter-directional flames and unilateral flames under varying slope conditions, we evaluated how flame interactions influence flame spread speed and mass loss rate, as well as the role of the view factor in radiative heat flux distribution. Numerical results revealed that the counter-directional fire propagation process on slopes could be divided into four distinct stages based on variations in flame spread rate and mass loss rate. Moreover, we propose a novel method to quantify flame interaction intensity on slopes using flame spread time. These findings enhance the mechanistic understanding of slope-dependent counter-directional flame propagation. Full article

Objective: Trauma is a leading cause of enophthalmos, typically resulting from an increase in the volume of the bony orbit. The general consensus is that post-traumatic primary deformity repair should aim to restore the premorbid volume, shape, and cosmesis of the orbitozygomatic complex (OZC). This study aims to utilise novel three-dimensional (3D) printed patient-specific moulds to intraoperatively fabricate enophthalmos wedges and onlays using polymethylmethacrylate (PMMA) bone cement to reconstruct the OZC. Methods: A total of seven patients underwent digital surgical planning using Freeform software to virtually correct orbitozygomatic complex deformities guided by a design algorithm. Three-dimensionally printed nylon patient-specific moulds were used intraoperatively to fabricate enophthalmos wedges and/or onlays using an industry-standard PMMA bone cement. Clinical examination and application of the proposed design algorithm determined that enophthalmos wedges were indicated for four patients, with one also requiring an onlay; and periorbital onlays were required for the three remaining patients. Results: Hertel exophthalmometry at a mean follow-up of 19.1 months demonstrated good outcomes in the correction of post-traumatic enophthalmos and hypoglobus and with patients reporting good subjective cosmetic results. Patients 5 and 7 had follow-up three-dimensional computed tomography (3D-CT) to confirm correct placement. Conclusion: The use of patient-specific PMMA wedges and onlays, fabricated intraoperatively with the aid of 3D-printed moulds, offers a reliable and effective approach for correcting post-traumatic enophthalmos and hypoglobus. This method allows for the restoration of orbital volume and anatomical contours, addressing both functional and aesthetic concerns. Our results demonstrate that this technique yields favourable outcomes. Full article

Nanoplastics (NPs) pose a significant environmental threat due to their small sizes, widespread distribution, and bioavailability, enabling interactions with marine organisms from pelagic to benthic species. In this study, the effects of 10 days of exposure to waterborne poly(methyl)methacrylate (PMMA) NPs were evaluated in the crab Carcinus maenas by assessing behavioral and biochemical endpoints (in gills, hepatopancreas, muscle, and hemolymph). Behavioral assessments using an open field test revealed that exposure to PMMA NPs resulted in an increase in distance walked (from 73.662 ± 17.137 cm in control to 248.560 ± 25.462 cm in the highest PMMA NPs concentration) and in random movement patterns. Muscle acetylcholinesterase (AChE) activity decreased from 10.83 ± 0.73 to 6.75 ± 0.45 nmol/min/mg of protein with PMMA NPs concentration increase, which, combined with behavioral responses, suggests neurological incapacities. In the gills and hepatopancreas, defense and detoxification mechanisms were activated, with a significant increase in superoxide dismutase (SOD) activity (at 20 µg/L in gills and 80 µg/L in hepatopancreas) and glutathione S-transferases (GSTs) activity (all PMMA NPs concentrations in gills and 20 and 320 µg/L in hepatopancreas). Despite these activations, oxidative damage was observed, with a significant increase in protein carbonylation (PC) levels (20, 80, and 320 µg/L in gills and 5, 20, and 80 µg/L in hepatopancreas) and lipid peroxidation (LPO) (80 and 320 µg/L in gills and 80 µg/L in hepatopancreas). Effects on hemolymph followed a pattern similar to those reported for gills and hepatopancreas. An increase in SOD hemolymph activity was observed in organisms exposed to 5 and 80 µg/L, and GSTs activity increased in crabs exposed to 80 µg/L. Oxidative damage in hemolymph was only detected through LPO at 5 and 320 µg/L. Overall, this study showed that PMMA NPs induce biochemical alterations and damage in different tissues of C. maenas and affect its behavior with potential impacts at a population level. Full article

To promote environmental sustainability, this research investigated the potential of utilizing recycled polymethylmethacrylate (PMMA) as raw material in material extrusion (MEX) additive manufacturing (AM). To enhance its mechanical response, carbon black (CB) was employed as the filler in nanocomposite formation. Filament extrusion of the mixture at different concentrations produced printable feedstocks for MEX AM. Rheological analysis (viscosity and material flow rate) showed that the CB introduction to the matrix was beneficial for consistent layer deposition, while differential scanning calorimetry and thermogravimetric analyses verified the thermal stability of the nanocomposites during processing. Mechanical properties were optimized, with increases in modulus (27.8% and 25.8%, respectively, in tensile and bending loadings) and tensile strength at optimal CB loadings. Dynamic mechanical analysis revealed the viscoelastic response of the nanocomposites. Raman and energy dispersive spectroscopy provided element-related insights. Surface morphology and parts structure were observed employing scanning electron microscopy and micro-computed tomography, respectively, revealing a positive impact on the AM parts due to the CB presence in the nanocomposites. The 4 wt.% in CB content nanocomposite was the optimum one. This research pioneers the development of new sustainable nanocomposite filaments and highlights the potential of next-generation MEX-based AM. Full article

Background: Cement leakage remains a significant challenge in percutaneous vertebroplasty (PVP). Leakage can lead to serious complications, including spinal cord compression, pulmonary embolism, and nerve root irritation. While several techniques have been proposed to minimize leakage, an effective and simple solution is still needed. This study investigates the impact of pre-washing vertebral bodies with cold saline before cement injection as a potential method to reduce leakage. Methods: A retrospective analysis was conducted on patients who underwent PVP for osteoporotic vertebral compression fractures. Patients were divided into three groups: (1) conventional PVP, (2) PVP with room-temperature saline pre-injection, and (3) PVP with cold saline (4 °C) pre-injection. Cement leakage was assessed using intraoperative fluoroscopy and postoperative computed tomography (CT), categorized into paravertebral, intervertebral, retrograde, spinal canal, and distant venous leakage. Statistical analysis was performed to compare leakage rates among the groups. Results: A total of 262 patients with 461 treated vertebrae were analyzed. Cold saline pre-treatment significantly reduced cement leakage rates compared to conventional PVP and room-temperature saline pre-injection (p < 0.05). CT imaging detected significantly more cement extravasation than fluoroscopy (p < 0.01). The incidence of spinal canal and intervertebral leakage was lowest in the cold saline group, suggesting improved cement containment and distribution. Conclusions: Pre-washing vertebral bodies with cold saline before cement injection in PVP significantly reduces cement leakage, particularly in the spinal canal and intervertebral spaces. This simple and cost-effective approach may enhance surgical safety and improve patient outcomes. Full article

The antifouling performance of a zwitterionic sulfobetaine-hydroxyethyl-containing polymethylmethacrylate ter-co-polymer (PSBM) is evaluated against three photosynthetic strains, namely Chlorella sp., Nannochloropsis sp., and Arthrospira maxima. PSBM-coated polymethylmethacrylate (PMMA) surfaces displayed a significantly reduced propensity for biofilm formation compared to rough and untreated controls, leaving clean surfaces after 7 days of exposure. A tribological approach was adopted to estimate the long-term durability of the PSBM coating. Repeated cycles of exposure to Chlorella sp., Nannochloropsis sp., and A. maxima biomass subject the coating to stress and continuous biofilm challenges. After several cycles, the PSBM coating maintains a higher antifouling efficacy than the untreated PMMA surface, suggesting stability and high potential in photobioreactor applications. Full article

Microfluidic technology is an emerging interdisciplinary field that uses micropipes to handle or manipulate tiny fluids in chemistry, fluid physics, and biomedical engineering. As one of the rapid prototyping methods, the three-dimensional (3D) printing technique, which is rapid and cost-effective and has integrated molding characteristics, has become an important manufacturing technology for microfluidic chips. Polymethyl-methacrylate (PMMA), as an exceptional thermoplastic material, has found widespread application in the field of microfluidics. This paper presents a comprehensive process study on the fabrication of fused deposition modeling (FDM) 3D-printed PMMA microfluidic chips (chips), encompassing finite element numerical analysis studies, orthogonal process parameter optimization experiments, and the application of 3D-printed integrated microfluidic reactors in the reaction between copper ions and ammonium hydroxide. In this work, a thermal stress finite element model shows that the printing platform temperature was a significant printing parameter to prevent warping and delamination in the 3D printing process. A single printing molding technique is employed to fabricate microfluidic chips with square cross-sectional dimensions reduced to 200 μm, and the microchannels exhibited no clogging or leakage. The orthogonal experimental method of 3D-printed PMMA microchannels was carried out, and the optimized printing parameter resulted in a reduction in the microchannel profile to Ra 1.077 μm. Finally, a set of chemical reaction experiments of copper ions and ammonium hydroxide are performed in a 3D-printed microreactor. Furthermore, a color data graph of copper hydroxide is obtained. This study provides a cheap and high-quality research method for future research in water quality detection and chemical engineering. Full article