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Journal of Neurosurgical Sciences Dec 2023Resection of bone infiltrating meningiomas of the sphenoid plane and the orbital walls is a highly challenging neurosurgical procedure. In this study, the authors...
BACKGROUND
Resection of bone infiltrating meningiomas of the sphenoid plane and the orbital walls is a highly challenging neurosurgical procedure. In this study, the authors present 11 cases of fronto-orbital and sphenoid wing meningioma which were subjected to tumor resection and cranioplasty using a pre-designed CAD PMMA-implant in one single staged procedure.
METHODS
Eleven cases were prospectively analyzed from January 2011 to December 2018. In all cases preoperative CT scans were performed and evaluated, in order to produce a customized PMMA-implant, fitting the osseous defect left after surgical resection of the predefined tumorous mass. Surgery was performed with standard techniques with the addition of availability of preplanned neuronavigational data as well as a matching template of the implant for intraoperative use. After tumor resection, cranioplasty followed using the predesigned PMMA implant.
RESULTS
Gross total resection was achieved in 82% (9 of 11 cases). Mean time of surgery for the combined procedure resulted in 223min±99min, with a mean blood loss of 427±192cc. Mean hospital stay for the combined procedure resulted in 11.5±3 days. In 18% of the cases (2/11), patients suffered from late onset infection of the implant and needed a surgical removal.
CONCLUSIONS
The presented data show that gross total resection and subsequent single staged bone reconstruction in osseous sphenoid wing and orbital rim meningiomas can be achieved using predesigned PMMA CAD implants with preplanned tumor resection borders with neuronavigational guidance.
Topics: Humans; Meningioma; Meningeal Neoplasms; Polymethyl Methacrylate; Treatment Outcome; Neurosurgical Procedures
PubMed: 35766207
DOI: 10.23736/S0390-5616.22.05758-7 -
BMC Oral Health Jan 2024In dentistry, there is a growing preference for computer-aided design and computer-aided manufacturing (CAD/CAM) systems over traditional laboratory procedures. However,...
BACKGROUND
In dentistry, there is a growing preference for computer-aided design and computer-aided manufacturing (CAD/CAM) systems over traditional laboratory procedures. However, there is not much literature comparing various CAD/CAM materials. Thus, this study aimed to assess and compare the color stability and hardness of gingival and tooth colored milled and 3D-printed acrylic resins.
MATERIALS AND METHODS
Four types of CAD/CAM materials were prepared: 3D-printed pink shade (PP), milled polymenthymethacrylate (PMMA) pink shade (MP), 3D-printed tooth shade (PT) and milled PMMA tooth shade (MT) (n = 6). For hardness, disc shaped samples of 15 mm × 2 mm and for color stability, bar shaped samples of 65mmx10mmx2.5 mm were prepared and polished. Vickers hardness test was performed in a microhardness tester. Color stability test was done by immersing in coffee solution and coca cola for 7 days. Day 0 and day 7 measurements were recorded using a digital spectrophotometer and the change in color was calculated. For statistical analysis, one-way ANOVA and Tukey's post hoc tests were done.
RESULTS
For color stability, milled PMMA was superior to 3D-printed resin samples. Milled pink and tooth shade samples had similar color stability, whereas 3D-printed tooth shade samples were more color stable as compared to pink shade 3D-printed samples. For hardness, milled tooth shade PMMA was the most superior one, followed by 3D-printed tooth shade, whereas pink shade milled PMMA and 3D-printed resin samples had similar hardness values and were inferior to the tooth shade CAD/CAM materials.
CONCLUSION
Color stability of milled PMMA is superior to that of 3D-printed resins. Hardness of tooth shade milled and 3D-printed resins is more than that of pink shade milled and 3D-printed resins.
Topics: Humans; Polymethyl Methacrylate; Research Design; Gingiva; Computer-Aided Design; Dental Materials; Denture, Complete
PubMed: 38200506
DOI: 10.1186/s12903-023-03708-2 -
Biomacromolecules Aug 2023A series of cellulose--diblock bottlebrush copolymer elastomers (cellulose--poly(-butyl acrylate)--poly(methyl methacrylate) (Cell--PBA--PMMA)) with short side chains...
A series of cellulose--diblock bottlebrush copolymer elastomers (cellulose--poly(-butyl acrylate)--poly(methyl methacrylate) (Cell--PBA--PMMA)) with short side chains were synthesized via successive atom transfer radical polymerization (ATRP) to study the influence of varying compositions and lengths of the graft diblock side chains on microphase morphologies and properties. The microphase-separated morphologies from misaligned spheres to cylinders were observed by atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) measurements. These bottlebrush copolymer elastomers possessed thermal stability and enhanced mechanical properties because the PMMA outer block could self-assemble into hard microdomains, which served as physical cross-links. The viscoelastic responses of these bottlebrush copolymers within the linear viscoelastic (LVE) regime were carried out by the oscillatory shear rheology. The time-temperature superposition (tTs) principle was applied to construct the master curves of the dynamic moduli, and the sequential relaxation of dense bottlebrush copolymers with different PMMA hard outer block lengths was analyzed. The rheological behaviors in this work could be utilized to build up the connection of microstructures and properties for the application of these bottlebrush copolymers as high-performance thermoplastic elastomers.
Topics: Elastomers; Cellulose; Polymethyl Methacrylate; Scattering, Small Angle; X-Ray Diffraction; Polymers; Nanostructures; Rheology
PubMed: 37462907
DOI: 10.1021/acs.biomac.3c00386 -
BMC Ophthalmology Mar 2024To measure the dislocation forces in relation to haptic material, flange size and needle used.
PURPOSE
To measure the dislocation forces in relation to haptic material, flange size and needle used.
SETTING
Hanusch Hospital, Vienna, Austria.
DESIGN
Laboratory Investigation.
METHODS, MAIN OUTCOME MEASURES
30 G (gauge) thin wall and 27 G standard needles were used for a 2 mm tangential scleral tunnel in combination with different PVDF (polyvinylidene fluoride) and PMMA (polymethylmethacrylate haptics). Flanges were created by heating 1 mm of the haptic end, non-forceps assisted in PVDF and forceps assisted in PMMA haptics. The dislocation force was measured in non-preserved cadaver sclera using a tensiometer device.
RESULTS
PVDF flanges achieved were of a mushroom-like shape and PMMA flanges were of a conic shape. For 30 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 1.58 ± 0.68 N (n = 10) and 0.70 ± 0.14 N (n = 9) (p = 0.003) respectively. For 27 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 0.31 ± 0.35 N (n = 3) and 0.0 N (n = 4), respectively. The flange size correlated with the occurring dislocation force in experiments with 30 G needle tunnels (r = 0.92), when flanges were bigger than 384 micrometres.
CONCLUSIONS
The highest dislocation forces were found for PVDF haptic flanges and their characteristic mushroom-like shape for 30 G thin wall needle scleral tunnels. Forceps assisted flange creation in PMMA haptics did not compensate the disadvantage of PMMA haptics with their characteristic conic shape flange.
Topics: Humans; Haptic Technology; Polymethyl Methacrylate; Sclera; Lenses, Intraocular; Fluorocarbon Polymers; Polyvinyls
PubMed: 38443841
DOI: 10.1186/s12886-024-03369-x -
ACS Biomaterials Science & Engineering Apr 2024Poly(methyl methacrylate) (PMMA) is commonly used for dental dentures, but it has the drawback of promoting oral health risks due to oral bacterial adhesion. Recently,...
Poly(methyl methacrylate) (PMMA) is commonly used for dental dentures, but it has the drawback of promoting oral health risks due to oral bacterial adhesion. Recently, various nanoparticles have been incorporated into PMMA to tackle these issues. This study aims to investigate the mechanophysical and antimicrobial adhesive properties of a denture resin by incorporating of nanoclay into PMMA. Specimens were prepared by adding 0, 1, 2, and 4 wt % surface-modified nanoclay (Sigma) to self-polymerizing PMMA denture resin. These specimens were then evaluated using FTIR, TGA/DTG, and FE-SEM with EDS. Various mechanical and surface physical properties, including nanoindentation, were measured and compared with those of pure PMMA. Antiadhesion experiments were conducted by applying a (ATCC 11006) suspension to the surface of the specimens. The antiadhesion activity of was confirmed through a yeast-wall component (mannan) and mRNA-seq analysis. The bulk mechanical properties of nanoclay-PMMA composites were decreased compared to those of pure PMMA, while the flexural strength and modulus met the ISO 20795-1 requirement. However, there were no significant differences in the nanoindentation hardness and elastic modulus. The surface energy revealed a significant decrease at 4 wt % nanoclay-PMMA. The antiadhesion effect of was evident along with nanoclay content in the nanocomposites and confirmed by the reduced attachment of mannan on nanoclay-PMMA composites. mRNA-seq analysis supported overall transcriptome changes in altering attachment and metabolism behaviors on the surface. The nanoclay-PMMA materials showed a lower surface energy as the content increased, leading to an antiadhesion effect against . These findings indicate that incorporating nanoclay into PMMA surfaces could be a valuable strategy for preventing the fungal biofilm formation of denture base materials.
Topics: Polymethyl Methacrylate; Adhesives; Mannans; Materials Testing; Dentures; RNA, Messenger
PubMed: 38453640
DOI: 10.1021/acsbiomaterials.3c01817 -
International Journal of Pharmaceutics Oct 2023The pH-responsive drug release approach in combination with three-dimensional (3D) printing for colon-specific oral drug administration can address the limitations of...
The pH-responsive drug release approach in combination with three-dimensional (3D) printing for colon-specific oral drug administration can address the limitations of current treatments such as orally administered solid tablets. Such existing treatments fail to effectively deliver the right drug dosage to the colon. In order to achieve targeted drug release profiles, this work aimed at designing and producing 3D printed tablet shells using Eudragit® FS100 and polylactic acid (PLA) where the core was filled with 100 µl of N-acetylglucosamine (GlcNAc)-loaded methyl cellulose (MC) hydrogel. To meet the requirements of such tablets, the effects of polymer blending ratios and MC concentrations on physical, thermal, and material properties of various components of the tablets and most importantly in vitro drug release kinetics were investigated. The tablets with 80/20 wt% of Eudragit® FS100/PLA and the drug-loaded hydrogel with 30 mg/ml GlcNAc and 3% w/v MC showed the most promising results having the best printability, processability, and drug release kinetics besides being non-cytotoxic. Manufacturing of these tablets will be the first milestone in shifting from the conventional "one size fits all" approach to personalized medicine where different dosages and various combinations of drugs can be effectively delivered to the inflammation site.
Topics: Acetylglucosamine; Methylcellulose; Hydrogels; Tablets; Drug Liberation; Polyesters; Printing, Three-Dimensional; Colon; Hydrogen-Ion Concentration; Technology, Pharmaceutical
PubMed: 37669729
DOI: 10.1016/j.ijpharm.2023.123366 -
BMC Musculoskeletal Disorders Nov 2023Long bone defects resulting from primary trauma or secondary to debridement of fracture-related infection (FRI) remain a major clinical challenge. One approach often...
BACKGROUND
Long bone defects resulting from primary trauma or secondary to debridement of fracture-related infection (FRI) remain a major clinical challenge. One approach often used is the induced membrane technique (IMT). The effectiveness of the IMT in infected versus non-infected settings remains to be definitively established. In this study we present a new rabbit humerus model and compare the IMT approach between animals with prior infection and non-infected equivalents.
METHODS
A 5 mm defect was created in the humerus of New Zealand White rabbits (n = 53) and fixed with a 2.5 mm stainless steel plate. In the non-infected groups, the defect was either left empty (n = 6) or treated using the IMT procedure (PMMA spacer for 3 weeks, n = 6). Additionally, both approaches were applied in animals that were inoculated with Staphylococcus aureus 4 weeks prior to defect creation (n = 5 and n = 6, respectively). At the first and second revision surgeries, infected and necrotic tissues were debrided and processed for bacteriological quantification. In the IMT groups, the PMMA spacer was removed 3 weeks post implantation and replaced with a beta-tricalcium phosphate scaffold and bone healing observed for a further 10 weeks. Infected groups also received systemic antibiotic therapy. The differences in bone healing between the groups were evaluated radiographically using a modification of the radiographic union score for tibial fractures (RUST) and by semiquantitative histopathology on Giemsa-Eosin-stained sections.
RESULTS
The presence of S. aureus infection at revision surgery was required for inclusion to the second stage. At the second revision surgery all collected samples were culture negative confirming successful treatment. In the empty defect group, bone healing was increased in the previously infected animals compared with non-infected controls as revealed by radiography with significantly higher RUST values at 6 weeks (p = 0.0281) and at the end of the study (p = 0.0411) and by histopathology with increased cortical bridging (80% and 100% in cis and trans cortical bridging in infected animals compared to 17% and 67% in the non-infected animals). With the IMT approach, both infected and non-infected animals had positive healing assessments.
CONCLUSION
We successfully developed an in vivo model of bone defect healing with IMT with and without infection. Bone defects can heal after an infection with even better outcomes compared to the non-infected setting, although in both cases, the IMT achieved better healing.
Topics: Rabbits; Animals; Fracture Healing; Polymethyl Methacrylate; Staphylococcus aureus; Tibial Fractures; Humerus
PubMed: 37964215
DOI: 10.1186/s12891-023-07031-3 -
Scientific Reports Oct 2023Total en bloc spondylectomy (TES) effectively treats spinal tumors. The surgery requires a vertebral body replacement (VBR), for which several solutions were developed,...
Total en bloc spondylectomy (TES) effectively treats spinal tumors. The surgery requires a vertebral body replacement (VBR), for which several solutions were developed, whereas the biomechanical differences between these devices still need to be completely understood. This study aimed to compare a femur graft, a polyetheretherketone implant (PEEK-IMP-C), a titan mesh cage (MESH-C), and a polymethylmethacrylate replacement (PMMA-C) using a finite element model of the lumbar spine after a TES of L3. Several biomechanical parameters (rotational stiffness, segmental range of motion (ROM), and von Mises stress) were assessed to compare the VBRs. All models provided adequate initial stability by increasing the rotational stiffness and decreasing the ROM between L2 and L4. The PMMA-C had the highest stiffness for flexion-extension, lateral bending, and axial rotation (215%, 216%, and 170% of intact model), and it had the lowest segmental ROM in the instrumented segment (0.2°, 0.5°, and 0.7°, respectively). Maximum endplate stress was similar for PMMA-C and PEEK-IMP-C but lower for both compared to MESH-C across all loading directions. These results suggest that PMMA-C had similar or better primary spinal stability than other VBRs, which may be related to the larger contact surface and the potential to adapt to the patient's anatomy.
Topics: Humans; Finite Element Analysis; Polymethyl Methacrylate; Lumbar Vertebrae; Range of Motion, Articular; Biomechanical Phenomena; Spinal Fusion
PubMed: 37907570
DOI: 10.1038/s41598-023-45736-6 -
Journal of the Mechanical Behavior of... Aug 2023To investigate the wear resistance of conventional, CAD-milled and 3D-printed denture teeth in vitro with simulated aging. To use the collected data to train single time...
OBJECTIVES
To investigate the wear resistance of conventional, CAD-milled and 3D-printed denture teeth in vitro with simulated aging. To use the collected data to train single time series sample model LSTM and provide proof of concept.
METHODS
Six denture teeth materials (Three Conventional; Double-cross linked PMMA (G1), Nanohybrid composite (G2), PMMA with microfillers (G3), CAD-milled (G4), two 3D-printed teeth (G5, G6) (Total n = 60) underwent simulation for 24 and 48 months of linear reciprocating wear using a universal testing machine (UFW200, NeoPlus) under 49 N load, 1 Hz and linear stroke of 2 mm in an artificial saliva medium. Single samples were parsed through Long Short-Term Memory (LSTM) neural network model using Python. To determine minimal simulation times, multiple data splits for training were trialled (10/20/30/40%). Scanning electron microscopy (SEM) was performed for material surface evaluation.
RESULTS
3D printed tooth material (G5) had the lowest wear resistance (59 ± 35.71 μm) whereas conventional PMMA with microfillers (G3) shown the highest wear rate (303 ± 0.06 μm) after 48 months of simulation. The LSTM model successfully predicted up to 48 months wear using 30% of the collected data. Compared with the actual data, the model had a root-mean-square error range between 6.23 and 88.56 μm, mean-absolute-percentage-error 12.43-23.02% and mean-absolute-error 7.47-70.71 μm. SEM images revealed additional plastic deformations and chipping of materials, that may have introduced data artifacts.
CONCLUSIONS
3D printed denture teeth materials showed the lowest wear out of all studied for 48 months simulation. LSTM model was successfully developed to predict wear of various denture teeth. The developed LSTM model has the potential to reduce simulation duration and specimen number for wear testing of various dental materials, while potentially improving the accuracy and reliability of wear testing predictions. This work paves the way for generalized multi-sample models enhanced with empirical information.
Topics: Polymethyl Methacrylate; Materials Testing; Reproducibility of Results; Surface Properties; Neural Networks, Computer; Dentures
PubMed: 37392604
DOI: 10.1016/j.jmbbm.2023.105984 -
Biosensors Sep 2023In recent years, innovative cell-based biosensing systems have been developed, showing impact in healthcare and life science research. Now, there is a need to design...
In recent years, innovative cell-based biosensing systems have been developed, showing impact in healthcare and life science research. Now, there is a need to design mass-production processes to enable their commercialization and reach society. However, current protocols for their fabrication employ materials that are not optimal for industrial production, and their preparation requires several chemical coating steps, resulting in cumbersome protocols. We have developed a simplified two-step method for generating controlled cell patterns on PMMA, a durable and transparent material frequently employed in the mass manufacturing of microfluidic devices. It involves air plasma and microcontact printing. This approach allows the formation of well-defined cell arrays on PMMA without the need for blocking agents to define the patterns. Patterns of various adherent cell types in dozens of individual cell cultures, allowing the regulation of cell-material and cell-cell interactions, were developed. These cell patterns were integrated into a microfluidic device, and their viability for more than 20 h under controlled flow conditions was demonstrated. This work demonstrated the potential to adapt polymeric cytophobic materials to simple fabrication protocols of cell-based microsystems, leveraging the possibilities for commercialization.
Topics: Microfluidic Analytical Techniques; Polymethyl Methacrylate; Printing; Lab-On-A-Chip Devices
PubMed: 37887097
DOI: 10.3390/bios13100904