Search Results (387)

Microbially Induced Carbonate Precipitation (MICP) is a biochemical process that promotes the precipitation of calcium carbonate, mainly in the mineral form of calcite, using urease-producing bacteria. This method has numerous applications, particularly in the field of geotechnical engineering when it is adopted for soil improvement or for the consolidation of porous or cracked construction materials such as stone and concrete. One microfluidic platform made of polymethylmethacrylate (PMMA) was designed with multiple channels, and the minerals precipitated were visualized using an optical microscope. The precipitated mineral observed in all channels analyzed formed spherical mineral structures with a core and multiple external rings. The same spherical mineral structures were observed in the biocement layer precipitated on plates of the same material as that of the microfluidic platform and on limestone, following the same treatment protocol. SEM images of pieces of these layers, complemented with EDS and mineral analysis by XRD, have confirmed the existence of multiple layers of minerals with spherical structures, mainly vaterite, precipitated around a nucleation point. Overlapping minerals in both the confined microfluidic channels and the unconstrained plates indicate that overlap results from repeated injections rather than physical confinement. From the tests with the microfluidic devices, these studies revealed that crystallization depends on different factors, namely the size of the channels and the number of Sporosarcina pasteurii cells. The number of injections appeared to affect the number of rings precipitated around the inner core. Substrate effects on spatial distribution or adhesion may still exist but were not detectable in this study and require further investigation. The observation of similar mineralogical structures in both the microfluidic devices and the plates, particularly the limestone, demonstrates that microfluidic systems are effective tools for small-scale visualization of geological processes. Full article

Calcium phosphate–poly(methyl-methacrylate) composite layers have been synthetized on silicon substrates in magnetron sputtering discharge by adjusting the radio-frequency power. The electron energy distribution function measured at holder substrate position shifts to lower energies when the radio-frequency power applied to the magnetron source increases from 50 to 150 W and the poly(methyl-methacrylate) molecule dissociation is augmented. The optical emission spectral analysis indicated the dynamics of the excitation and ionization processes in the Ar–calcium phosphate–poly(methyl-methacrylate) plasma mixture, as well as the dissociation patterning of the polymer molecules. The Ca I, P I, and H_α atomic lines and CaO, PO, POH, CO, CH and C₂ molecular bands characteristic to the calcium phosphate and poly(methyl-methacrylate) decomposition were evidenced. At 150 W radio-frequency power a reduction in the polymer content in the composite layer volume was observed even if the α-CH₃ main chain and the C=O molecular bands are still present. More C-C/C-H, C-OH/C-O-C polymeric bonds were revealed at the layer surface, indicating the formation of plasma polymers. The Ca/P ratio changes from 1.72 to 1.9 at 50 to 150 W, respectively, maintaining the amorphous structure of the layers. In this power range, the transition of layer surface morphologies from grain-like to worm-like plasma polymer characteristics is connected to an increase in plasma ion density and layer thickness. Full article

Purpose: This study aimed to compare the clinical and radiological outcomes of treating unstable osteoporotic vertebral fractures using hybrid fixation with uncemented transpedicular screws (Group A) versus polymethylmethacrylate (PMMA) cement-augmented screws (Group B). Methods: A retrospective comparative study of 55 patients treated between 01/2017 and 03/2024. Group A included 35 patients (mean age 71.22 ± 6.12 years); Group B included 20 patients (mean age 72.9 ± 7.75 years). Clinical outcomes were compared preoperatively, 6 weeks and 1 year after surgery. For clinical evaluation, the ODI and VAS for back pain were used. Restoration of the sagittal spinal profile was evaluated using the sagittal Cobb angle and the height of the fractured vertebral body. Results: Both groups showed significant clinical improvement in ODI and VAS scores at 6 weeks and 1 year postoperatively (p < 0.001), without significant between-group differences. The ODI changed from a preoperative value of 75.07 ± 21.13 to 50.72 ± 17.7 at 6 weeks postoperatively, and to 28.83 ± 20.9 at 1 year postoperatively in Group A. In Group B, the preoperative ODI value of 66.8 ± 14.56 changed to 47.00 ± 11.72 at 6 weeks and to 19.8 ± 9.15 at 1 year postoperatively The VAS decreased from 7.55 ± 1.43 preoperatively to 3.50 ± 1.17 at 6 weeks and to 1.52 ± 1.18 at 1 year postoperatively in Group A, and from 7.53 ± 1.39 preoperatively to 2.53 ± 1.02 at 6 weeks and to 1.52 ± 1.18 at 1 year postoperatively in Group B. In Group A, preoperative Cobb angle values of 11.01 ± 13.85 improved to 7.33 ± 16.17 at 6 weeks, with subsequent loss to 12.96 ± 14.75 degrees at 1 year postoperatively. In Group B, preoperative values were 11.44 ± 17.84, corrected to 5.16 ± 8.33 at 6 weeks, and to 7.37 ± 9.28 degrees at 1 year postoperatively. Conclusions: Good clinical outcomes were achieved in both evaluated groups using uncemented or cement-augmented screws, without a statistically significant difference. Differences were noted in the radiological evaluation of the success of sagittal profile correction. While both groups showed initial radiological improvement, the uncemented screw group experienced a statistically significant loss of correction at the 1-year follow-up. Full article

This study evaluated the effects of incorporating silk fibroin nanoparticles into self-curing polymethyl methacrylate (PMMA) on the mechanical and Candida albicans responses of provisional dental prostheses. Rectangular specimens (64 × 10 × 3 mm) were fabricated and assigned to three groups (n = 10): G1 (control), PMMA without reinforcement; G2, PMMA with 0.5% silk nanoparticles; and G3, PMMA with 1% silk nanoparticleScheme4. 4 × 6 mm) were prepared. Scanning electron microscopy (SEM) was used to assess nanoparticle incorporation within the polymer matrix. No significant differences were observed in surface roughness (G1 = 0.4118 ± 0.100; G2 = 0.3245 ± 0.072; G3 = 0.3269 ± 0.076) or microhardness (G1 = 12.21 ± 0.351; G2 = 12.72 ± 0.213; G3 = 12.53 ± 0.177). Flexural strength differed significantly among the groups (p = 0.009), with higher values in nanoparticle-reinforced specimens (G1 = 79.142 ± 3.202; G2 = 87.089 ± 2.756; G3 = 92.412 ± 1.963). None of the tested concentrations exhibited antifungal activity against C. albicans. In conclusion, the incorporation of silk fibroin nanoparticles enhanced the flexural strength of self-curing PMMA without adversely affecting surface roughness or microhardness, although no antifungal effect was detected at the evaluated concentrations. Full article

Driven by environmental concerns, the packaging industry is shifting toward high-performance and bio-based coating alternatives. In this research, poly(methylmethacrylate) (PMMA) and modified cellulose nanocrystal (m-CNC) were employed as reinforcing agents to develop sustainable poly (lactic acid)-based coatings for packaging applications. Various formulations, influenced by polymer matrix blends and m-CNC loadings (1–5%), were prepared using solvent and applied as protective coating on cardboard paper substrates. The grammage of polymeric coatings (CG) on paper was also investigated using various wet film thicknesses (i.e., 150–250 μm). Accordingly, key parameters including water contact angle, thermal behavior, mechanical performances and barrier properties were systematically evaluated to assess the effectiveness of the developed nanocomposite coatings. As a result, nonylphenol ethoxylate surfactant-modified cellulose nanocrystals exhibited good dispersion and stable suspension in chloroform for one hour, improving compatibility and interaction of polymer–CNC fillers. The water vapor permeability (WVP) of PLA-coated papers was significantly reduced by blending PMMA and increasing the content of m-CNC nanofillers. Furthermore, CNC incorporation enhanced the oil resistance of PLA/PMMA-coated cardboard. Pronounced improvements in barrier properties were observed for paper substrates coated with dry coat weight or CG of ~20 g/m² (corresponding to 250 μm wet film thickness). Coatings based on blended polymer—particularly those reinforced with nanofillers—markedly enhanced the hydrophobicity of the cardboard papers. SEM-microscopy confirmed the structural integrity and morphology of the nanocomposite coatings. Regarding mechanical properties, the upgraded nanocomposite copolymer (PLA-75%/PMMA-25%/m-CNC3%) exhibited the highest bending test and tensile strength, achieved on coated papers and free-standing polymeric films, respectively. Based on DSC analysis, the thermal characteristics of the PLA matrix were influenced to some extent by the presence of PMMA and m-CNC. Overall, PLA/PMMA blends with an optimal amount of CNC nanofillers offer promising sustainable coatings for the packaging applications. Full article

Polymethylmethacrylate (PMMA) bone cement is widely used in orthopedics, accounting for approximately 80% of knee joint replacements in the United States. While prosthesis designs and materials have evolved to improve performance and durability, PMMA cement has undergone minimal compositional changes. Carbon-based nanomaterials, particularly graphene oxide (GO), have attracted interest for their ability to enhance the mechanical and thermal properties of orthopedic cements. This study evaluated the effects of incorporating different GO concentrations into PMMA bone cement on its mechanical properties, cytocompatibility, and antibacterial activity. PMMA was modified with GO at 0.1, 0.25, and 0.5 weight percent (wt%) for mechanical and antibacterial tests, and at 1.0 wt% for cytocompatibility. Mechanical performance was assessed via four-point bending tests. Cytocompatibility was evaluated using mouse embryonic fibroblasts (NIH/3T3), and antibacterial activity was tested against Staphylococcus aureus using a modified direct contact assay. GO incorporation significantly increased Young’s modulus (0.1% and 0.25%, p = 0.009) and improved tensile strength (p = 0.0015) and flexural strength (p = 0.025) at 0.1%. Cytocompatibility remained comparable to the control (p = 0.873). Antibacterial activity was concentration dependent, with 0.25% and 0.5% GO maintaining significant bacterial inhibition up to 48 h, whereas 0.1% showed no sustained effect. Overall, 0.25 wt% GO provided the most suitable balance between mechanical integrity and antibacterial performance, indicating that PMMA–GO bone cements with this composition can combine enhanced mechanical properties with relevant antibacterial activity without compromising biocompatibility, and are therefore promising candidates for orthopedic applications. Full article

Orthognathic surgery restores functional balance and facial esthetics in patients with dentofacial deformities. The use of adjunctive facial implants—made from materials such as porous polyethylene, titanium, or polyetheretherketone (PEEK)—has increased to enhance contour and projection, although standardized guidelines for their selection and integration remain scarce. Following PRISMA-ScR guidelines, a systematic search of PubMed, Scopus, Embase, and LILACS identified studies reporting facial implants placed concomitantly with orthognathic surgery. Eligible studies included case reports, case series, observational studies, clinical trials, and reviews involving human patients, without language or date restrictions. Seventeen studies published between 1998 and 2025 met the inclusion criteria, comprising retrospective and prospective designs, case series, and one technical note. Implants were used in the malar, infraorbital, paranasal, chin, mandibular body, and angle regions. Materials included PEEK, porous polyethylene, silicone, hydroxyapatite, polymethylmethacrylate, and titanium. PEEK was mainly used for patient-specific implants, while porous polyethylene was commonly used as stock implants. Follow-up time, outcome reporting, and study design varied widely, reflecting substantial methodological heterogeneity and predominantly observational evidence. As a result, outcomes were primarily reported qualitatively, limiting comparative assessment and long-term inference. Overall, the available literature suggests that alloplastic facial implants may serve as useful adjuncts to orthognathic surgery for contour enhancement, with outcomes influenced by implant design, surgical expertise, fixation, and soft tissue conditions. However, the current evidence base remains limited, underscoring the need for standardized outcome measures, comparative studies, and longer follow-up to better inform clinical decision-making and future research. Full article

Composite materials based on polymethylmethacrylate (PMMA) and carbon nanoparticles are used in aviation, construction, medical and other fields of activity. Carbon nanotubes and carbon nano-dots are mainly used as carbon nanoparticles. Both carbon nanotube and carbon nano-dots are difficult to obtain materials with considerable cost. Amorphous carbon nanoparticles, on the contrary, are easy to obtain and have a low cost. The purpose of this work is to study the physico-chemical and biological characteristics of polymethylmethacrylate modified with amorphous carbon nanoparticles. Laser ablation was used to obtain the nanoparticles. Dynamic light scattering, measurement of the electrokinetic potential, TEM, AFM, and Raman microscopy are used to characterize nanoparticles. FTIR, MIM, AFM, UV-visual diagnostics, ROS tests, and biopolymer regeneration tests were used to analyze the combined sensors. The bacteriostatic effect was evaluated using turbodimetry, and the antibacterial effect was evaluated using precision cytofluorometry. Mammalian cells were examined using fluorescence microscopy. Carbon nanoparticles (CNPs) have been obtained and characterized. A protocol has been developed for the introduction of CNPs into photolithographic resin. Printed samples of complex geometry. It is shown that the printed samples are amenable to polishing, have pro-oxidant properties, and are able to prevent damage to biopolymers. Printed samples inhibit the development of bacteria and cause loss of viability. At the same time, the printed samples do not affect the development of mammalian cells. The obtained resins based on PMMA with CNPs can potentially serve as the basis for the creation of non-toxic materials in biomedicine and pharmacology. Full article

Background: Antibiotic-loaded bone cement (ALBC) is widely used for local antibiotic delivery in joint arthroplasty to prevent and treat prosthetic joint infections (PJIs). In this study, we evaluated the efficacy of cemented Kirschner (K)-wires coated with various ALBC formulations using a Galleria mellonella infection model against multidrug-resistant (MDR) Staphylococcus aureus and Enterococcus faecalis. Methods: We tested commercially available bone cements, including gentamicin-only formulations (PALACOS R+G) and dual-antibiotic formulations, combining gentamicin with either clindamycin (COPAL G+C) or vancomycin (COPAL G+V), alongside an antibiotic-free control (PALACOS R). In vitro assays—including minimum inhibitory/bactericidal concentration (MIC/MBC) determination, antibiotic release kinetics, agar diffusion, and antibiofilm evaluations—demonstrated effective antibiotic release and significant antimicrobial activity against both planktonic and biofilm-associated bacteria. Results: In vivo, ALBC-coated K-wires were well tolerated in G. mellonella and significantly protected the larvae from S. aureus infection compared to controls. Notably, dual-antibiotic formulations provided superior protection, correlating with substantial reductions in bacterial colonisation on implant surfaces and in surrounding tissues. Conclusions: These findings support the utility of the G. mellonella model as a high-throughput, cost-effective platform for the preclinical evaluation of antimicrobial strategies to prevent and treat PJIs and further demonstrate the effectiveness of dual-loaded ALBC against multidrug-resistant bacteria. Full article

Background and Objectives: Osteoporotic vertebral compression fractures (OVCFs) are a major cause of morbidity, disability, and loss of independence in the elderly population. The optimal management of these fractures remains debated, especially regarding the balance between conservative treatment and minimally invasive surgical techniques such as percutaneous vertebroplasty (VP). This study aimed to compare clinical and radiological outcomes of VP and conservative management in patients with acute OVCFs. Materials and methods: A retrospective observational cohort study was conducted on 120 patients with acute OVCFs treated either conservatively or through percutaneous VP using polymethylmethacrylate (PMMA) cement. Clinical outcomes were assessed using the Visual Analogue Scale (VAS) for pain, Roland–Morris Disability Questionnaire (RMDQ), and Oswestry Disability Index (ODI). Evaluations were performed at baseline and at 1, 3, 6, and 12 months post-treatment. Radiological follow-up assessed fracture healing and new vertebral fractures. Results: Patients treated with VP experienced significantly faster pain relief and functional improvement than those managed conservatively, with marked differences in VAS, RMDQ, and ODI scores within the first month (p < 0.01). By 12 months, outcomes converged between groups, with comparable pain and functional levels. No major complications were reported; cement leakage was asymptomatic, and no neurological or systemic adverse events occurred. Radiological healing was satisfactory in both groups, without increased risk of adjacent fractures in the VP group. Conclusions: Percutaneous vertebroplasty resulted in faster short-term improvement compared with conservative treatment, while functional outcomes converged over time. The retrospective, non-randomized design limits causal inference. Full article

Denture stomatitis is a common issue among denture users, primarily caused by pathogenic microorganisms such as Candida albicans that adhere to and multiply on the denture surface. While previous approaches have focused on incorporating antimicrobial agents into denture base resins, this study introduces a novel surface coating strategy for polymethyl-methacrylate (PMMA) using hinokitiol—a natural antibacterial and antifungal compound derived from Hiba. This method enables the formation of a uniform silica–resin layer containing hinokitiol, achieved through a simple immersion process. Using X-ray and neutron reflectivity techniques, we discovered that a uniform silica–resin layer could form on PMMA with significant amounts of hinokitiol present. Time-dependent neutron reflectivity analysis revealed the presence of the following two types of hinokitiol molecules within the silica–resin layer: one type desorbs rapidly with weak capture near the surface, and the other desorbs slowly with strong capture near the PMMA interface, facilitated by hydrogen bonding in the silica–resin nanopores. These findings demonstrate a new mechanism for controlled release of antimicrobial agents from denture surfaces and highlight the potential of this coating technique as a practical and effective strategy for preventing denture-related infections. Full article

The management of severely comminuted acetabular posterior wall fractures in young, active patients presents a significant surgical challenge. When anatomical open reduction and internal fixation (ORIF) is not feasible, primary total hip arthroplasty (THA) is often considered but is a suboptimal solution due to concerns over long-term implant survivorship and the inevitability of revision surgery. This single-patient technical note presents a novel joint-preserving technique for managing unreconstructible acetabular posterior wall fractures using with cement-augmented screw fixation via the Kocher–Langenbeck approach. A 28-year-old male sustained a left posterior hip dislocation with a comminuted acetabular posterior wall fracture involving >30% of the articular surface, alongside a tibial shaft fracture, following a high-energy motorcycle collision. Intraoperative assessment confirmed the posterior wall was unreconstructible, with six non-viable osteochondral fragments. A joint-preserving salvage procedure was performed. After debridement, a stable metallic framework was created using three screws anchored in the posterior column. Polymethylmethacrylate (PMMA) bone cement was then applied over this framework in its doughy phase, meticulously contoured to reconstruct the articular surface. The hip was reduced, and the tibia was fixed with an intramedullary nail. The patient was mobilized with weight-bearing as tolerated on postoperative day 3. At the 21-month follow-up, the patient reported no pain during daily activities and only mild discomfort during deep squatting. Radiographic and CT evaluations demonstrated a stable hip joint, concentric reduction, well-maintained joint space, and no evidence of implant loosening or osteolysis. Level of Evidence: V (Technical Note/single-patient Case report). For unreconstructible, comminuted fractures of the non-weight-bearing portion of the acetabular posterior wall in young patients, cement-augmented screw fixation offers a viable joint-preserving alternative to primary THA. This technique provides immediate stability, facilitates early mobilization, and preserves bone stock. While long-term outcomes require further study, this case demonstrates excellent functional and radiographic results at 21 months, presenting a promising new option for managing these complex injuries. Full article

This study examines the chemical recycling of polymethylmethacrylate (PMMA) dental waste in semi-batch fixed-bed reactors via pyrolysis, aiming to convert this waste into the valuable monomer methyl methacrylate (MMA). First, the effect of temperature is analyzed in a laboratory-scale (30 g) semi-batch reactor at 350, 400 and 450 °C. In order to visualize the combined effect of temperature and increase in bed volume, experiments conducted at 350 °C in the laboratory (30 g) and on a pilot scale (20 kg) are compared. Experiments conducted at 475°C on technical and pilot scales are also compared to elucidate this behavior. A detailed process analysis is presented, considering different experiments conducted in a semi-batch technical-scale reactor. Experiments were conducted in a 2 L reactor at temperatures of 425 °C, 450 °C and 475 °C to understand the effects of heating rate and temperature on product yield and composition. The results show that at 425 °C, MMA was the primary liquid component, with minimal by-products, suggesting that lower temperatures enhance monomer recovery. Higher temperatures, however, increased gas yields and reduced MMA yield due to intensified thermal cracking. This study also highlights that char formation and non-condensable gases increase with the reactor scale, indicating that heat transfer limitations can influence MMA purity and yield. These findings emphasize that for effective MMA recovery, lower temperatures and controlled heating rates are optimal, especially in larger reactors where heat transfer issues are more prominent. This research study contributes to scaling up PMMA recycling processes, supporting industrial applications to achieve efficient monomer recovery from waste. Full article

Background: Late sternocutaneous fistulas (SCFs), secondary to chronic sternal osteomyelitis, are uncommon sequelae of median sternotomy and present significant therapeutic challenges. They are frequently linked to low-virulence microorganisms forming biofilms on retained foreign materials. While antibiotic-impregnated polymethylmethacrylate (PMMA) beads are established in managing chronic osteomyelitis in other anatomical locations, reports describing their use for post-sternotomy SCFs are limited to two early postoperative cases. Case Presentation: We describe a 62-year-old man with a history of triple-vessel coronary artery disease who underwent coronary artery bypass grafting via median sternotomy. Two months postoperatively, he developed an SCF in the upper sternum, initially treated with wire removal, negative pressure wound therapy, and intravenous vancomycin. Recurrence occurred one month later without systemic signs of infection. Imaging revealed inflammatory changes at the level of the manubriosternal junction. Definitive surgery included extensive sternal and costosternal debridement, bilateral anterior arthrolysis of the second ribs, and pulse lavage with 10 L of Microdacyn. The remaining defect was filled with vancomycin- and gentamicin-loaded PMMA beads. The patient had an uneventful recovery with no recurrence at six months. Conclusions: This case suggests that local antibiotic delivery via PMMA beads can be a valuable adjunct in the surgical management of recurrent, late-presenting SCFs after cardiac surgery. Full article

In the marine environment, plastic fragments are constantly engaged in a complex degradation process under exposure to various physical and chemical factors, one of which is ultraviolet (UV) radiation. These processes result in the formation of smaller micro- and nano-sized plastic particles, which are highly bioavailable to marine organisms. To clarify the toxicological effects of the exposure of degraded plastic on the marine organisms, the model used in this study was the Pacific mussel Mytilus trossulus and polymethylmethacrylate (PMMA), which is commonly found in marine debris. Using molecular and biochemical markers (DNA damage, lysosomal membrane stability, integral antiradical activity (IAA) of biological samples, and malondialdehyde (MDA) as a product of lipid peroxidation), the toxicity of pristine PMMA and photoaged (PMMA-UV) particles was assessed. Using Fourier transform infrared spectroscopy, the characteristics of the macromolecular changes in the chemical structure of PMMA-UV were obtained, with an oxidation index of 6.83 ± 0.46, compared to the pristine PMMA of 5.15 ± 0.54. Using a laser analyzer, the sizes of PMMA particles were determined, and it was found that after UV irradiation, the ratio of size groups changed—the proportion of particles with sizes of 500–1000 μm decreased, and the number of particles with sizes of 50–125 μm increased twofold. Analysis of mussel cell viability showed that after exposure to both types of PMMA microparticles, there was a decrease in the ability to retain neutral red dye in lysosomes: PMMA and PMMA-UV had a similar effect on hemocytes, reducing dye retention in cells to 55.2 ± 3.24% and 61.1 ± 1.99%, respectively. In gill and digestive gland cells, PMMA-UV particles reduced the stability of lysosomal membranes to a greater extent than PMMA. After PMMA and PMMA-UV particle exposure, the levels of DNA damage were as follows: in hemocytes, 10.1 ± 1.4% and 12.7 ± 0.8%, respectively; in gills, 7.8 ± 1.1% and 14.4 ± 2.9%, respectively; and in the digestive gland, 19.0 ± 1.3% and 21.9 ± 2.8%, respectively, according to the control values 3.6 ± 1.3%, 4.6 ± 1.1%, 5.1 ± 1.5%, respectively. According to the results of biochemical markers, the reaction of mussels to the presence of PMMA and PMMA-UV particles in the environment was tissue-specific: in the cells of the digestive gland, the level of IAA increased by 2 and 1.3 times compared to the control group of mussels (76.22 ± 6.77 nmol trolox/g wet weight and 52.43 ± 2.36 nmol trolox/g wet, respectively), while in the gill cells, the non-significant increase in antiradical activity was noted. An increase in MDA content was also observed in gill cells (255.8 ± 9.12 nmol MDA/g wet weight and 263.46 ± 9.45 nmol MDA/g wet weight, respectively) compared with the control group. This study showed that UV irradiation of PMMA microparticles increases their bioavailability and toxicity to M. trossulus. Full article