Silicon Mold Research Articles

In vitro evaluation of the efficacy of different protocols on calcium hydroxide dressing removal

Objective: To compare in vitro irrigation systems’ efficacy in removing calcium hydroxide paste (Ca(OH)2) in single-root teeth. Methods: Sixty permanent teeth were prepared using ProTaper® rotatory instruments, up to F3. Specimens were split longitudinally into two halves, and two grooves located in the apical and coronal zones were created. Ca(OH)2 application into the grooves was assessed by radiographic and photographic methods. After the halves were reassembled in a silicone mold, teeth were randomly divided into experimental groups (n=15), testing Ca(OH)2 removal: 1 – CanalBrush™; 2 – E1 – Irrisonic tip; 3 – manual dynamic irrigation (MDI); 4 – XP-endo Finisher® (XP). A total volume of 10 mL of 2.5% sodium hypochlorite was used in each tooth. Finally, all groups were scored regarding the Ca(OH)2 remnants using the same methods as before. Statistical analysis was conducted using the Kruskal-Wallis test followed by Mann-Whitney U tests (with Bonferroni correction). A value of p<0.05 was considered statistically significant. Results: None of the techniques demonstrated 100% efficacy in both regions. CanalBrush™ was more effective in the apical region. Overall, E1 – Irrisonic tip and CanalBrush™ removed significantly more Ca(OH)2 than MDI and XP-endo Finisher® (p<0.05). Conclusion: Globally, E1 – Irrisonic tip and CanalBrush™ were more effective, although without statistically significant differences between them.

FRACTURE RESISTANCE UNDER CYCLIC LOADING OF LITHIUM DISILICATE VONLAYS VERSUS ROSETTA VONLAYS RESTORING PREMOLARS (IN VITRO STUDY)

The aim of the study was to assess fracture resistance under cyclic loading of Rosetta®SM CAD vs. IPS e.max CAD (control) vonlays restoring maxillary premolars. According to the sample size calculation, a total of 20 samples will be selected and then divided into two equal groups; 10 sample each based on the material type: Group (A): Ten vonlays (n=10) manufactured from IPS e. max CAD blocks (control). Group ( B): Ten vonlays (n=10) manufactured from Rosetta®SM CAD blocks (intervention). A natural tooth presenting an upper first premolar was prepared in accordance with the ceramic onlay restorations preparation guidelines with an occlusal box with half of the bucco-lingual distance and a 2 mm depth from the cusp tip to pulpal floor, gingival seat with 1 mm depth from pulpal floor, occlusal reduction of 2 mm of the functional cusp with extending the preparation at the palatal surface by 2 mm in the cervical direction, occlusal reduction of 1.5 mm of non-functional cusp and 12º divergence angle. The preparation was then extended to the labial surface, with a 0.5 mm chamfer finish line. All line angles were finally rounded, and all margins were finished. For duplication of the natural tooth; the epoxy dies were constructed. Base and catalyst of the epoxy resin material were mixed as instructed by the manufacturer at a rate of 200r/min and then was poured into the silicon mould under vibration to eliminate any air voids, then was allowed to set completely following the manufacturer instructions for 24 hours, this procedure was repeated 20 times for creating 20 epoxy resin dies which replicating the prepared natural tooth. The die was then scanned by optical scanning using Medit i500 oral scanner. Milling of Vonlays was achieved using Sirona MCX5 milling machine using IPS e. max CAD blocks and Rosetta SM CAD blocks: 10 IPS e.max CAD blocks with block size C14 and 10 Rosetta®SM CAD blocks with block size C14 were used. Vonlays were then seated on their corresponding dies and cemented with dual cured self-adhesive resin cement (Variolink, Ivoclar Vivadent). Cementation procedures were performed by keeping each sample under a constant pressure of 5Kg using a custom designed cementation device for standardization the applied load during cementation process. All samples were mechanically aged (cyclic loading) to simulate 6 months of clinical use. Following that, all samples were subjected to fracture resistance testing under a compressive load to the center of their long axis using computer controlled universal testing machine with a load cell of 5 Kilo newton (K N) with a computer software used for data recording (Instron® Bluehill Lite Software). The mean values ± SDs values for e.max group were (502.39 ±102.89 N) with minimum value (338.16 N) and maximum value (721.29 N). The mean values ± SDs values. Rosetta group were (468.76 ± 67.54 N) with minimum value (367.11 N) and maximum value (648.48 N). Failure modes were determined under stereomicroscope and classified into repairable and catastrophic in both groups and showed that 60% of e.max group exhibited repairable failure while 40% of specimens showed catastrophic failure while in Rosetta group, 90% of the specimens exhibited repairable failure. Only 10% displayed catastrophic failure. Then a fractured part within each group was examined under scanning electron microscope (SEM) to reveal and compare their microstructure.

Effect of using Polyether Ether Ketone versus Metal Mesh Reinforcement on Fracture Resistance of Maxillary Polymethyl Methacrylate Denture Bases. An In-Vitro study.

The aim of this study was to evaluate the effect of different reinforcing materials on the fracture resistance of maxillary dentures reinforced by either PEEK or metal framework meshes. The weight of reinforced dentures in both groups was also calculated. 14 reinforced complete dentures were fabricated with similar denture base thickness and same arrangement of teeth by duplication of trial denture bases through custom made stone mold and silicon mold for teeth arrangement. The dentures were divided into 2 groups. In the first group, the dentures were reinforced with metal meshes while in other group PEEK meshes of the same thickness was used for the reinforcement. Mesh reinforcement in both groups were digitally designed by EXO-CAD dental software on scanned cast, printed, and then fabricated in either of the two materials: metal or PEEK. Each denture was subjected to load from a universal testing machine using a fissure load applicator at mid palatal area at speed of 5mm/min. The load at failure manifested by sharp drop to below 50% on load-deflection curve was recorded in Newton. Before the load application, the weight of each denture in both groups was evaluated. All collected data were statistically analyzed. Fracture pattern of dentures in both groups was visually assessed. A statistically significant difference (P= 0.004) in the maximum average load the dentures could withstand before fracture was found between the two groups. Metal reinforced maxillary dentures could withstand maximum average load of 1686.63 ±325.06 N with corresponding value of 1160.22 ±197.21 (N) for PEEK reinforced dentures. Also using PEEK mesh decreased weight of denture by 26% compared to metal reinforced denture. PEEK mesh with thickness of 0.7 to 0.9 mm did not influence the fracture strength of complete dentures compared to metal mesh with the same thickness.

Fit accuracy of removable partial denture metal frameworks produced by CAD-CAM – a clinical study

Objectives: To assess the effect of a CAD-CAM protocol fabrication on the clinical fit accuracy of removable partial denture metal frameworks to abutment teeth. Methods: Fifteen patients with partial edentulism were selected to participate in this clinical study, and twenty dental arch rehabilitations were planned. For each dental arch (n=20), two cobalt-chromium frameworks were produced through two protocols: CAD-CAM production (experimental group); and conventional lost-wax casting technique (control group). Clinical fit accuracy was assessed using an indirect quantitative method to evaluate the gap between the framework occlusal rest and the corresponding rest seat. A silicone mold of that gap was obtained, digitized, and analyzed by micro-computed tomography. The two silicone molds obtained for each occlusal rest were overlapped and evaluated for thickness and volume. Data were analyzed with the paired t test for silicone thickness results and the Wilcoxon test for silicone volume results (α= 0.05). Results: Considering the two dependent variables under study, no statistically significant (p=0.441 for silicone thickness and p=0.204 for silicone volume) differences were found between groups. Conclusions: The results of this study suggest that the CAD-CAM protocol applied is a viable method for the production of removable partial denture metal frameworks. (Rev Port Estomatol Med Dent Cir Maxilofac. 2021;62

Multiscale 2D/3D microshaping and property tuning of polymer-derived SiCN ceramics

Polymer-derived ceramics exhibit excellent properties and are compatible with many shaping techniques due to their liquid precursors. We present a fast and pressureless process for the fabrication of SiCN. Using varied amounts of the filler divinyl benzene, defect-free monolithic disc samples are obtained at high yields. Their electrical conductivity is adjustable across 10 orders of magnitude, flexural strength is improved up to 1.7 GPa, and cytocompatibility is demonstrated. This processing route is applied to a new multiscale microshaping method combining the advantages of two-photon polymerization and casting. The parts’ general shape is defined by KOH-etched silicon molds whereas individual freeform microfeatures like a 3D QR code are implemented through sacrificial 2PP photoresin microstructures added to the mold. The green body is pyrolyzed directly in the mold, whereby the photoresin decomposes and the ceramic part with the submicrometer resolution features imprinted releases itself from the mold undamaged due to ∼30% shrinkage.

Articular Eminence Morphology of American Historic and Contemporary Populations.

ObjectivesThis study was performed to determine the values of the articular eminence inclination (AEI), the articular eminence height (AEH), and the length of the articular eminence curved line (AEL) among American prehistoric and contemporary populations.Materials and methodsThe study was carried out on 120 human dry skulls divided into 4 groups: Illinois group (IP), Kentucky group (KP), African Americans group (AAP) and American Caucasians group (ACP). Each group comprised 30 human dry skulls. Measurements of AEI (by two methods), AEH and AEL were performed using computer software on 5 sagittal sections through silicone molds of the articular eminence. The obtained results were statistically analyzed at significance level of p < 0.05.ResultsNo statistically significant differences of AEI, AEH and AEL values were obtained among American populations (IP, KP, AAP, ACP) neither by body side, sex and age (p > 0.05). The mean AEI M1 values ranged from 31.56° to 38.72°, the mean AEI M2 values ranged from 44.14° to 58.37°, the mean AEH ranged from 5.82 to 6.86 mm, and the mean AEL values ranged from 11.57 to 12.73 mm.ConclusionsAEI, AEH, AEL values are variables, but they did not differ significantly among American populations. Left-right differences as the result of natural body asymmetry were not statistically significant. Sex and age did not significantly affect the articular eminence morphology.

In vitro fragmentation performance of a novel, pulsed Thulium solid-state laser compared to a Thulium fibre laser and standard Ho:YAG laser

The aim of this work was to compare the fragmentation efficiency of a novel, pulsed Thulium solid-state laser (p-Tm:YAG) to that of a chopped Thulium fibre laser (TFL) and a pulsed Holmium solid-state laser (Ho:YAG). During the fragmentation process, we used a silicone mould to fixate the hemispherical stone models under water in a jar filled with room-temperature water. Each laser device registered the total energy applied to the stone model to determine fragmentation efficiency. Our study examined laser settings with single pulse energies ranging from 0.6 to 6 J and pulse frequencies ranging from 5 to 15 Hz. Similar laser settings were applied to explicitly compare the fragmentation efficiency of all three devices. We experimented with additional laser settings to see which of the three devices would perform best. The fragmentation performance of the three laser devices differed statistically significantly (p < 0.05). The average total energy required to fragment the stone model was 345.96 J for Ho:YAG, 372.43 J for p-Tm:YAG and 483.90 J for TFL. To fragment the stone models, both Ho:YAG and p-Tm:YAG needed similar total energy (p = 0.97). TFL’s fragmentation efficiency is significantly lower than that of Ho:YAG and p-Tm:YAG. Furthermore, we found the novel p-Tm:YAG’s fragmentation efficiency to closely resemble that of Ho:YAG. The fragmentation efficiency is thought to be influenced by the pulse duration. TFL’s shortest possible pulse duration was considerably longer than that of Ho:YAG and p-Tm:YAG, resulting in Ho:YAG and p-Tm:YAG exhibiting better fragmenting efficiency.

A scanning electron microscopy study of projectile entry fractures in cortical bone; genesis and microarchitectural features

The present paper presents a scanning electron microscope (SEM) analysis of the genesis and microarchitecture of experimentally induced cortical entry fractures in porcine scapulae impacted at velocities ranging from 54 to 897 m/s. SEM observation was conducted on polyurethane replicas cast from negative silicone moulds. Analysis of the sequence of fracture processes operative during projectile impact revealed the presence of ring cracks at the site of impact, confirming that penetration in sandwich bones is achieved by cone crack propagation. Despite impulsive loading, two forms of plastic deformation were identified in the cortical bone surrounding the entry fracture up to a maximum velocity of 871 m/s. Microscopic radial and concentric cracks were associated with projectile impact, and the role of pores and pits as stress concentrators was captured. Possible underlying mechanisms for the observed plastic deformation are described, and the diagnostic utility of SEM analysis is presented.

Influence of resin cement and thermocycling on milled lithium disilicate ceramic microshear bond strength.

The aim of this study was to compare the microshear bond strength of different resin cements to CAD/CAM-created lithium disilicate ceramics after 24 hours and after 1 year (10,000 thermocycles). Forty (40) ceramic bars were subjected to pretreatment comprising airborne abrasion with aluminum oxide particles, etching with 10% hydrofluoric acid and Monobond N application. Bars were divided into 4 groups (n = 10), based on cement type: light-cured Variolink Esthetic LC (VLC) and dual-cured Variolink N (VN) at two different times: after 24 hours and after 1 year. Silicone molds were used to prepare cement cylinders on a ceramic surface. The set was stored in distilled water at 37ºC, for 24 hours or subjected to 10,000 thermocycles. The molds were removed and microshear bond strength was tested. Data were submitted to two-way analysis of variance and Tukey's test (α = 0.05). Based on the comparison between cement values at different aging times (p = 0.035), VN after 24 hours (27.10 ± 0.92) and after 1 year (20.62 ± 1.25) presented significantly higher values than VLC after 24 hours (14.79 ± 0.76) and after 1 year (6.61 ± 0.81). Bond strength recorded for both cements after 24 hours (VN: 27.10 ± 0.92 and VLC: 14.79 ± 0.76) was significantly higher than the one recorded after 1 year (VN: 20.62 ± 1.25 and VLC: 6.61 ± 0.81). The thermocycling reduced the values observed for both investigated cements; bond strength was greater for dual-cure resin cement than for light-cured resin cement.

Patient specific Polymethyl methacrylate customised cranioplasty using 3D printed silicone moulds: Technical note.

IntroductionCranioplasty after decompressive craniectomy can be performed with several techniques and materials. With the common use of 3D printing, custom cranioplasty can be produced at affordable cost. Aim of this technical note is to describe our technique for producing patient specific Polymethyl methacrylate (PMMA) cranioplasty using 3D printed silicone moulds.Materials and MethodsWe enrolled seven patients from January 2020 to June 2021 who required surgery for cranioplasty. The 3D printing was used to produce silicone moulds for defining the exact shape of the PMMA cranioplasty, according to the CT scan of the patient.ResultsWe performed seven procedures. The mean time of the surgery was 80 min. All cranioplasties perfectly matched the patient specific anatomy. No complications occurred.ConclusionsUsing 3D printed patient specific silicone moulds and PMMA resulted to be effective, with affordable costs and ensuring a good cosmetic result.

Lithographically Defined Micropost Arrays for Programmable Actuation and Interfacial Hydrodynamics

Magnetically actuating surface-attached post (ASAP) arrays have great potential in microfluidic flow control, including mixing and pumping. Both passive (nonactuating) and active (actuating) micropillar arrays can also be used to control pressure-driven flow and the motion of microscopic particles carried by the fluid through microfluidic channels. Molding techniques are popular for generating these microstructures. However, fabricating high aspect ratio elastomeric microstructures over large surface areas suffers from practical problems such as damage incurred in the demolding process. Here, we report on a fabrication protocol that generates ASAP with an aspect ratio as high as 23:1 and a cross-sectional area less than 1 μm2 using straightforward photolithography processes. We generated 50 unique ASAP arrays, each occupying an area of 1 mm2 on a silicon mold; these arrays have varied cross-sectional shape and size, aspect ratio, and spacings between neighboring posts. Our protocol also controls the level of magnetic material in the ASAP tips with a centrifugation step. Using a herringbone pattern ASAP array, we have demonstrated control over the relative phase of actuation between neighboring posts. Such ASAP serve as an experimental platform to test current models predicting that reciprocal actuators in close proximity can successfully drive flow in a low Reynolds (Re) number environment.

RAPID MATERIALIZATION OF A SMALL SERIES OF BONE STRUCTURE REPLICATIONS FROM A DIGITALIZED MODEL, CREATED BY COMPUTER TOMOGRAPHY

The recreation of bone structures from the human body has very complex geometry and a lack of symmetry. A small series of vertebrae replications, digitized by computed tomography, could serve in exercises for medical students to help them perform operational planning for inserting implant structures, cage type implants, or screws and rods implants. Additionally, these replications could be used in the planning of extraordinary clinical cases, for example complex vertebrae deformities. The replicated structure could be fulfilled in a 1:1 ratio or scaled. For the selection of an appropriate production technology a block diagram is followed which considers suitable technologies for the production of polymer parts, compared to the series size and the complexity of the geometry. Both criteria must be taken into account when considering which technology should be used in the production of polymer parts. Comparing the advantages and disadvantages of additive technologies and replication in silicone mold, the best choice for technology is set to be replication in silicone mold. The initial preparation for the manufacture of the silicone mold includes a detailed analysis of the geometry of the model for replication. The first step includes defining the runner place as well as mounting the runner to the model. To ensure the mold is completely filled while casting, positive-shaped vents in the mold are defined. Because of the complex shapes of the spinal vertebrae and the need to take out elements in many directions, the mold is divided into multiple parts. A block-diagram that summarizes the entire manufacturing cycle for replication in a silicone mold is developed.

Impact of Endodontic Kinematics on Stress Distribution During Root Canal Treatment: Analysis of Photoelastic Stress

IntroductionStructural defects created by endodontic treatment are the most common cause of major dental failures. This study analyzed levels of stress produced by endodontic instruments during the root canal treatment by photoelastic analysis of stress. MethodsTwenty-four human premolars were randomly divided into 4 groups (n = 6) according to instrumentation protocol: ProTaper Next (GPT), One Shape (GOS), Wave One Gold (GWO), and TF Adaptive (GTF). The evaluation of the photoelastic model was performed at 4 dental zones: dental-crown region, cervical third of root, middle third of root, and apical third of root. Silicone molds were prepared (2 × 15 mm), and pinjets were used inside the root canals to fixate teeth. Photoelastic resin (2:1 ratio) was poured into the silicone molds to form photoelastic models. A transmission polariscope was used to analyze the positions of interest and recorded with a digital camera. Tardy’s method was used to quantify the fringe order (n) and calculate the maximum stress value (τ) at each selected point. Data were analyzed with two-way analysis of variance, Tukey test (P < .05), fringe descriptive analysis. ResultsAll groups showed a significant increase in the level of stress created during biomechanical preparation of the root canals. In the quantitative analysis, there was no statistically significant difference among the groups (P > .05). In the qualitative analysis, GPT and GTF instruments achieved greater levels of stresses compared with GWO and GOS instruments. At the beginning of instrumentation, stresses were concentrated at the coronary level and the end of instrumentation at the middle and apical root level. ConclusionsAll endodontic systems resulted in accumulation of stress along the dental structure. Stress was found in different concentrations along the tooth and at different levels.

Evaluation of the Effect of Addition of Poly Vinyl Pyrrolidone on, Dimensional Changes of Heat Cured Acrylic Resin Denture Base Material

The most common materials used for fabrication of denture bases are poly methyl methacrylate (PMMA). Preparation of modified heat cured denture base acrylic resin was carried out by preparing of (PMMA)(80%) and poly vinyl pyrrolidon (PVP)(20%) and the liquid part composed of methyl methacrylate (MMA) monomer. A(10) specimens for each experimental group were tested . All specimens were cured by using short curing cycle (90 min.at 74C° followed by 30 min .at 100C°).Evaluation was made by measuring dimensional stability and accuracy of the prepared denture base material in comparison with the control denture base material . The dimensional accuracy of acrylic resin denture base is the main necessity ,where it effects the retention and stability of the denture .A silicon mold was used to prepare a(40) stone mandibular master casts (control and experimental). Acrylic dough was prepared and packed for processing ,the flask were closed with pressure technique and placed in clamps after final closure .Distances were measured between (3) points marked on denture bases before and after thermocycling for both control and experimental groups. For AB and BC distances the PVP had improved the dimensional stability and accuracy before and after thermocycling while for AC distance the control group material before and after thermocycling improved the dimensional stability and accuracy.

A Flat Embedding Method to Orient Gravistimulated Root Samples for Sectioning.

Microscopy is an important tool used for biological research and has played a crucial role toward understanding of cellular mechanisms and protein function. However, specific steps in processing of biological samples for microscopy warrant improvements to consistently generate data that can more reliably help in explaining mechanisms underlying complex biological phenomenon. Due to their small and fragile nature, some biological specimens such as Arabidopsis thaliana roots are vulnerable to damage during long sample preparation steps. Moreover, when specimens with a small diameter (typically less than 100μm) are embedded in conventional silicone mold or capsule embedding, it is not only difficult to locate their orientation inside the capsule, but also a challenge to obtain good median longitudinal sections. Specimen orientation in particular is crucial because understanding certain plant biological processes such as gravitropism rely on precisely knowing spatial information of cells and tissues of the plant organ being studied. Here, we present a simple embedding technique to properly orient small plant organs such as roots so that the desired sectioning plane is achieved. This method is inexpensive and can be accomplished with minimal equipment and supplies.

Direct-drive implosion experiment of diamond capsules fabricated with hot filament chemical vapor deposition technique

Diamond is a promising alternative capsule material for direct-drive inertial confinement fusion. Previous investigations suggest that the stiffness and higher density of diamond can mitigate laser imprinting, which is an initial perturbation on the ablation surface caused by non-uniform laser irradiation. We conduct diamond capsule fabrication using the hot filament chemical vapor deposition (HF-CVD) technique. This technique is the most suitable diamond deposition method in terms of mass production, since the deposition area can be easily extended just by increasing the number of hot filaments. This paper presents the first direct-drive implosion experiment concerning diamond capsules fabricated using the HF-CVD technique. The compression of thin diamond capsules, with an inner capsule diameter of 482 μm and a shell thickness of 1.6 μm, is successfully achieved, and the implosion trajectory of diamond capsules, with the same diameter and thickness, is consistent with 1D radiation hydrodynamic simulation calculations. However, for diamond capsules with an inner diameter of 482 μm and a shell thickness of 2.4 μm, asymmetry of the implosion trajectory and unexpected x-ray emission are observed. This is attributed to the remaining silicon (Si) mold inside the capsule left over from the fabrication process, revealing that the etching method of Si in diamond capsules should be improved.

Chest Wall Reconstruction Using 3-Dimensional Printing: Functional and Mechanical Results

BackgroundTumors involving the chest wall may require extensive resection and reconstruction. This study aims to evaluate functional, cosmetic results, and quality of life (QoL) in patients who had a reconstruction based on patient-specific 3-dimensional (3D) printing. MethodsThe patient-specific chest wall prosthesis was created for 10 patients. The anatomical models were 3D printed and used to produce a silicone mold that was filled with methyl methacrylate to create the customized prosthesis. Evaluation of the reconstruction was completed with a QoL assessment and postoperative tracking of patients’ chest motion, using infrared markers. The distance between plot points representing markers on the operated and contralateral sides was measured to assess symmetrical motion. ResultsTwenty-three consecutive patients were enrolled, with the median age of 64 years. Thirteen patients underwent a nonrigid reconstruction, and 10 had a patient-specific rigid reconstruction with methyl methacrylate. The median number of ribs resected was 3. No postoperative complications or morbidity related to the prostheses were reported. The median hospital stay in the nonrigid reconstruction group was 8.5 days compared with 7.5 days (p = .167) in the rigid reconstruction group. Postoperatively, most patients had low levels of symptoms, with 82% experiencing chest pain and 53% experiencing dyspnea. Rigid reconstruction patients demonstrated more symmetrical breathing motion compared with nonrigid reconstruction patients. The mean distances were 2.32 ± 2.18 and 7.28 ± 5.87 (P < .00001), respectively. ConclusionsThis study shows that a 3D patient-specific prosthesis is feasible and safe, suggesting a possible trend toward improved breathing mechanics, QoL, and cosmetic results.

Cold-Injection Molded Gentamicin-Impregnated Polymethyl Methacrylate Implants for Cranioplasty.

Cranioplasty can be carried out using either fresh, frozen autologous bone or synthetic substitutes. Ordering artificial 3 dimensional (3D) implants is challenging and time consuming depending on geographical location. In this article, we share our experience using a streamlined process of producing 3D computer-assisted design (CAD) implants using commercially available 3D printers and silicone molds that can be easily replicated with consistent results and are associated with good outcomes. To develop patient-specific implants for patients with cranial defects that are accurate, consistent, low cost, and easy to replicate while reducing operator-dependent factors. We present data from 15 patients who underwent cranioplasty with 3D CAD-designed gentamicin-impregnated bone cement implants that were molded using the cold injection technique. The technique was consistent in result production, required little postdemolding manipulation, and showed no dimensional variation in design. Postoperative computed tomography scans showed excellent implant fit, and patients had a low complication rate. We have demonstrated a technique of mold preparation that is efficient and that produces a reliable result. Polymethyl methacrylate implants molded using this technique showed better reproducibility, higher accuracy, and precision than other types of implants and required minimal postdemolding clean-up.

Investigation of mid-infrared rapid heating of a carbide-bonded graphene coating and its applications in precision optical molding.

Graphene interacts with electromagnetic waves strongly in a wide range from ultra-violet to far-infrared, making the graphene coating suitable for a variety of applications. In this study, a novel localized rapid heating technique utilizing micro-patterned silicon stampers with carbide-bonded graphene coating, which directly heats up by absorbing mid-infrared light radiation, is implemented in rapid precision optical molding. The graphene network, as a functional coating to obtain thermal energy and improve the anti-adhesion of the mold surface, can heat up the mold surface rapidly (up to 18.16 K/s) and evenly above glass transition temperature over a large area within several seconds. Since the graphene coating was around tens of nanometers (∼45 nm) thick, the rapid precision surface molding process can be shortened into tens of seconds. Furthermore, the thermal response and repeatability of the graphene coated silicon wafer is investigated by repeated thermal cycling. This novel rapid precision surface molding technique is successfully tested to replicate grating structures and periodic patterns from silicon molds to thermoplastic substrates with high accuracy. Compared with conventional methods, this new approach can achieve much higher replication fidelity with a shorter cycle time and lower energy consumption.

Clinical outcomes of two-stage revision total knee arthroplasty in infected cases with antibiotic-loaded cement spacers produced using a handmade silicone mold

PurposeThis study assessed the clinical outcomes of periprosthetic joint infection patients who underwent two-stage revision total knee arthroplasty with antibiotic-loaded cement spacers fabricated using a handmade silicone mold.Materials and methodsThis study included seven patients (average age 77 years, average follow-up time 54 months) who underwent surgery at our hospital between 2009 and 2013. Clinical outcomes including knee scores, function scores, knee range of motion, and walking ability at the final observation, period from the primary total knee arthroplasty to implant removal, period from implant removal to revision total knee arthroplasty, and follow-up period after revision total knee arthroplasty were investigated.ResultsAt the final follow-up, the average knee range of motion was 99°, with no significant differences at each stage; average knee and function scores were 84 and 77, respectively. With cement spacers, five patients were able to walk with a t-cane. No recurrence of infection was observed.ConclusionsThe clinical outcomes of the current case series demonstrated good knee function with preserved walking ability, without any recurrence of periprosthetic joint infection. This study suggests that using a handmade silicone mold could be an effective option for periprosthetic joint infection after a total knee arthroplasty.