Parametric Optimization of 3D Printed Hydrogel-Based Cardiovascular Stent.

PURPOSE: This study aimed to develop personalized biodegradable stent (BDS) for the treatment of coronary heart disease. Three-dimensional (3D) printing technique has offered easy and fast fabrication of BDS with enhanced reproducibility and efficacy. METHODS: A variety of BDS were printed with 3 types of hydrogel (~5 ml) resources (10%w/v sodium alginate (SA), 10%w/v cysteine-sodium alginate (SA-CYS), and 10%w/v cysteine-sodium alginate with 0.4%w/v PLA-nanofibers (SA-CYS-NF)) dispersed from an 22G print head nozzle attached to the BD-syringe. The printability of hydrogels into 3D structures was examined based on such variables as hydrogel's viscosity, printing distance, printing speed and the nozzle size. RESULTS: It was demonstrated that alginate composition (10%w/v) offered BDS with sufficient viscosity that defined the thickness and swelling ratio of the stent struts. The thickness of the strut was found to be 338.7 ± 29.3 µm, 262.5 ± 14.7 µm and 237.1 ± 14.7 µm for stents made of SA, SA-CYS and SA-CYS-NF, respectively. SA-CYS-NF stent displayed the highest swelling ratio of 38.8 ± 2.9% at the initial 30 min, whereas stents made of SA and SA-CYS had 23.1 ± 2.4% and 22.0 ± 2.4%, respectively. CONCLUSION: The printed stents had sufficient mechanical strength and were stable against pseudo-physiological wall shear stress. An addition of nanofibers to alginate hydrogel significantly enhanced the biodegradation rates of the stents. In vitro cell culture studies revealed that stents had no cytotoxic effects on human umbilical vein endothelial cells (HUVECs) and Raw 264.7 cells (i.e., Monocyte/macrophage-like cells), supporting that stents are biocompatible and can be explored for future clinical applications.

Three-dimensional-printed intercalary prosthesis for the reconstruction of large bone defect after joint-preserving tumor resection.

BACKGROUND: Joint-preserving intercalary tumor resection can result in better proprioception and a more normal joint function after reconstruction. However, most reported reconstruction techniques are usually associated with frequent complications. Therefore, the approach of reconstruction following joint-preserving tumor resection warrants further study. METHODS: Between September 2016 and October 2018, 12 patients with metaphyseal malignant bone tumors around the knee joint were treated by joint-preserving intercalary resections with the aid of three-dimensional (3D)-printed osteotomy guide plates and reconstructions using 3D-printed intercalary prostheses. We assessed the accuracy of the resection by comparing the cross sections at the resection plane with 3D-printed matching surface of the prostheses. The functional outcomes, complications and oncological status were also evaluated. RESULTS: All patients were observed for 7 to 32 months with an average follow-up of 22.5 months. The achieved resection was accurate, with accurate matching between the residual bone and prosthesis. The mean MSTS score was 28 (range, 26-30). Superficial infection occurred in two patients. Local recurrence was observed in one patient, while pulmonary metastasis was identified in one patient. CONCLUSIONS: The personalized osteotomy guide plate and prosthesis based on 3D printing technique facilitate joint-preserving tumor resection and functional reconstruction. However, longer follow-up and larger sample size are required to clarify its long-term outcomes. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Three-dimensional printing technology for localised thoracoscopic segmental resection for lung cancer: a quasi-randomised clinical trial.

BACKGROUND: Three-dimensional (3D) computed tomography (CT) reconstruction technology has gained attention owing to its potential in locating ground glass nodules in the lung. The 3D printing technology additionally allows the visualisation of the surrounding anatomical structure and variations. However, the clinical utility of these techniques is unknown. This study aimed to establish a lung tumour and an anatomical lung model using 3D printing and 3D chest CT reconstruction and to evaluate the clinical potential of 3D printing technology in uniportal video-assisted thoracoscopic segmentectomy. METHODS: Eighty-nine patients with ground glass nodules who underwent uniportal video-assisted thoracoscopic segmentectomy were classified into the following groups: group A, lung models for pre-positioning and simulated surgery that were performed with 3D chest CT reconstruction and 3D printing, and group B, patients who underwent chest CT scans with image enhancement for 3D reconstruction. The differences in the surgery approach transfer rate, surgical method conversion rate, operative time, intraoperative blood loss, and postoperative complication rate were compared between the two groups. RESULTS: Between groups A and B, there were significant differences in the approach transfer rate (0% vs.10.5%, p = 0.030), operative time (2.07 ± 0.24 h vs. 2.55 ± 0.41 h, p < 0.001), intraoperative blood loss volume (43.25 ± 13.63 mL vs. 96.68 ± 32.82 mL, p < 0.001) and the rate of surgical method conversion to lobectomy (0% vs. 10.5%, p < 0.030). In contrast, there was an insignificant difference in the postoperative complication rate between groups A and B (3.9% vs. 13.2%, p = 0.132). CONCLUSIONS: 3D printing technology facilitates a more accurate location of nodules by surgeons, as it is based on two-dimensional and 3D image-based findings, and therefore, it can improve surgical accuracy and safety. This technique is worth applying in clinical practice.

Use of 3D-printing cerebral aneurysm model assisting microcatheter shaping in neurovascular intervention technique training.

BACKGROUND: Microcatheter shaping plays a vital role in coil embolization of cerebral aneurysms, while the complicated method and insufficient training opportunities make it difficult for junior neurovascular clinicians to master this technique. In this program, we constructed a novel training method and assessment system for microcatheter shaping in coil embolization of cerebral aneurysms with 3D technique, and evaluated its efficacy for microcatheter shaping training in junior neurovascular clinicians. METHODS: Patient-specific models for cerebral aneurysms in different locations and with different morphologies were selected by experienced senior neurovascular clinicians. The solid polylactic acid model and the soft hollow crystal silicone model of intracranial aneurysms were then made separately for shaping reference and assessment in the training course. Twelve residents without prior experience of microcatheter shaping and 25 neurovascular clinicians who have in vivo experience of microcatheter shaping on 3-5 occasions were selected for this training program and randomly divided into the traditional training group and the experimental training group. Four senior neurovascular clinicians assisted and guided the trainees in two groups and evaluated the time and accuracy of microcatheter shaping. RESULTS: Eighteen trainees were assigned to the traditional training group, among which 4 had prior experience in microcatheter shaping. The other 19 were assigned to the experimental training group, including 8 with prior experience. No statistical difference in the distribution of experienced students between the two groups was noted(P = 0.295). After the training session, the shaping time was found shorter in the experimental training group than that in the traditional training group (40.3.5 ± 16.2 s vs. 54.2 ± 16.4 s, P = 0.014), while the shaping score was found higher in the experimental training group than that in the traditional training group (4.4 ± 0.5 vs. 2.6 ± 1.2, P < 0.001). Specifically, for the trainees without prior experience, the experimental training group also showed less time consumption and higher score (Time: 52.7 ± 7.7 vs. 61.5 ± 9.5, P = 0.02; Score 4.1 ± 0.5 vs. 2.3 ± 1.1, P < 0.01). Meanwhile, for the trainees with prior experience, the advantage was noted in shaping score (4.7 ± 0.3 vs. 3.9 ± 0.6, P < 0.01) but not in time consumption (23.3 ± 4.4 vs. 28.5 ± 3.9, P = 0.07). CONCLUSION: This training program is quite effective at teaching junior neurovascular physicians the essential surgical abilities required for coiling cerebral aneurysms.

Oral Bioavailability and Pharmacokinetics of Sildenafil Orally Disintegrating Tablets under Various Gastric pH Levels Following Administration of Omeprazole in Rats.

Sildenafil citrate, an oral drug used to treat erectile dysfunction, has low water solubility and oral bioavailability. The solubility is greatly influenced by the pH, changing from 37.25 mg/mL to 0.22 mg/mL with a change in pH from 1.2 to 8.0. This indicates that the absorption may decrease in patients who use drugs, such as proton pump inhibitors (PPIs), for gastroesophageal reflux disease. To improve the absorption of sildenafil citrate at various gastric pH levels, a sildenafil citrate orally disintegrating tablet (ODT), which has a rapid disintegration feature, was produced by a 3D printing technique. Our study investigated the pharmacokinetic parameters of the sildenafil citrate ODT in rats after oral administration and compared the absorption of the sildenafil citrate ODT and sildenafil citrate commercial tablet (RLD), with and without PPI treatment. The LC/MS/MS analysis of the plasma sildenafil concentration revealed that the area under curve from time 0 to infinity (AUC0-∞) of sildenafil in the sildenafil citrate ODT group was significantly higher than in the sildenafil citrate RLD group whether it was in combination with the PPI or not (274.8% and 144%, respectively; p < 0.05). The relative systemic bioavailability of sildenafil citrate RLD significantly decreased with the PPI, but that of sildenafil citrate ODT was not affected by the PPI. These results indicate that the relative systemic bioavailability of sildenafil citrate ODT was increased when it was prepared using the 3D printing technique and the absorption of this formulation was not affected by the PPI.

Natural Alternatives to Non-biodegradable Polymers in 3D Printing of Pharmaceuticals.

BACKGROUND: Due to potential toxicity, non-biodegradable polymers used in 3D (3-dimensional) printing of drugs could be dangerous for patient safety and the environment. OBJECTIVE: This review aims to investigate the toxicity of non-biodegradable polymers and investigate the use of natural materials as an alternative in 3D printing medicines. The study evaluates the dangers connected to 3D printing. METHODS: A review of the literature on various 3D printing processes, such as inkjet printing, fused filament manufacturing, and extrusion-related 3DP systems, was done for this study. Also, the use of cellulose derivatives and natural materials in 3D printing and their potential as active excipients was proposed. RESULTS: The review identified potential toxicity risks linked to non-biodegradable polymers used in drug 3D printing. As a potential fix for this issue, the use of natural materials with improved mechanical and thermal properties was explored. The use of cellulose derivatives as an alternative to non-biodegradable polymers in 3D printing pharmaceuticals was also investigated in the study. CONCLUSION: This study emphasises the significance of evaluating the risks connected to drug 3D printing and recommends using natural materials as an alternative to non-biodegradable polymers. More study is required to create secure and reliable 3D printing processes for pharmaceuticals.

Three-Dimensional Open Water Microchannel Transpiration Mimetics.

The key problem that hinders the water transportation performance and application of microchannels is the annoying gaslock. Realizing liquid transport without the gaslock requires a specially designed pump and a channel system, as well as the reduction of gas concentration in liquids. In nature, to eat viscous nectar with high efficiency, hummingbirds use their open geometric tongue for nectar-sucking. Inspired by hummingbirds' tongue, we report a bionic open microchannel that discharges unwanted gas inside the microchannel from the opening without influencing its fluidic performance. The opening can also be used for extrusion of oil droplets in microchannels, indicating great potential applications in oil-water separation and chemical slow release, especially for bubble discharge in microchannels. Most significantly, a mimicked "leaf" with our bionic open microchannnels exhibits marvelous "transpiration" performance when irradiated by a laser. Our work provides a new strategy for the fabrication of open microchannels and sheds light on potential applications of multiphase phenomena in microchannels including oil-water separation, phase change heat and mass transfer, solar vapor generation, and precisely controllable drug delivery.

3D printed miniature atomic emission detector coupling with gas chromatography: A sensitive and cost-effective strategy for the determination of volatile methylsiloxanes in municipal sewage.

The determination of volatile methylsiloxanes (VMSs) in municipal sewage has attracted great attention. Gas chromatography-mass spectrometry (GC-MS) is the most mature detection technique for VMSs, however, its instrumentation and operation cost are unfavorable in low- and middle-income countries. Herein, a novel and cost-effective strategy by using a 3D printed miniature microplasma optical emission detector (µAED) as an alternative to MS detector, was developed to detect VMSs in municipal sewage by GC after preconcentration by a laboratory-built automatic purge and trap (P&T) system. Two types of µAEDs have been fabricated and their analytical performances were compared. The one using two tungsten rods as electrodes shows better performance and was thus selected as the detecting system for real sample analysis. Under the optimized conditions, the P&T-GC-µAED system provided limits of detection of 3.6 ng L-1 to 15.5 ng L-1 of Si for tested VMSs. Relative standard deviations were better than 3.0% and good recoveries ranging from 82.4% to 102.8% were obtained for all analytes. The applicability of this system was demonstrated via the measurement of VMSs in the influents and effluents from 10 wastewater treatment plants (WWTPs) in Chengdu, China.

Effect of 3D-Printed PLA Structure on Sound Reflection Properties.

3D printing technique is currently one of the promising emerging technologies. It is used in many areas of human activity, including acoustic applications. This paper focuses on studying the sound reflection behavior of four different types of 3D-printed open-porous polylactic acid (PLA) material structures, namely cartesian, octagonal, rhomboid and starlit structures. Sound reflection properties were evaluated by means of the normal incidence sound reflection coefficient based on the transfer function method using an acoustic impedance tube. In this study, various factors affecting the sound reflection performance of the investigated PLA samples were evaluated. It can be concluded that the sound reflection behavior of the tested PLA specimens was strongly affected by different factors. It was influenced, not only by the type of 3D-printed open-porous material structure, but also by the excitation frequency, the total volume porosity, the specimen thickness, and the air gap size behind the tested specimen inside the acoustic impedance tube.

A Universal Spinning-Coordinating Strategy to Construct Continuous Metal-Nitrogen-Carbon Heterointerface with Boosted Lithium Polysulfides Immobilization for 3D-Printed LiS Batteries.

Constructing intimate coupling between transition metal and carbon nanomaterials is an effective means to achieve strong immobilization of lithium polysulfides (LiPSs) in the applications of lithium-sulfur (LiS) batteries. Herein, a universal spinning-coordinating strategy of constructing continuous metal-nitrogen-carbon (MNC, M = Co, Fe, Ni) heterointerface is reported to covalently bond metal nanoparticles with nitrogen-doped porous carbon fibers (denoted as M/MN@NPCF). Guided by theoretical simulations, the Co/CoN@NPCF hybrid is synthesized as a proof of concept and used as an efficient sulfur host material. The polarized CoNC bridging bonds can induce rapid electron transfer from Co nanoparticles to the NPCF skeleton, promoting the chemical anchoring of LiPSs to improve sulfur utilization. Hence, the as-assembled LiS battery presents a remarkable capacity of 781 mAh g-1 at 2.0 C and a prominent cycling lifespan with a low decay rate of only 0.032% per cycle. Additionally, a well-designed Co/CoN@NPCF-S electrode with a high sulfur loading of 7.1 mg cm-2 is further achieved by 3D printing technique, which demonstrates an excellent areal capacity of 6.4 mAh cm-2 at 0.2 C under a lean-electrolyte condition. The acquired insights into strongly coupled continuous heterointerface in this work pave the way for rational designs of host materials in LiS systems.

The effect of enhanced bone marrow in conjunction with 3D-printed PLA-HA in the repair of critical-sized bone defects in a rabbit model.

BACKGROUND: Traditionally, the iliac crest has been the most common harvesting site for autologous bone grafts; however, it has some limitations, including poor bone availability and donor-site morbidity. This study sought to explore the effect of enhanced bone marrow (eBM) in conjunction with three-dimensional (3D)-printed polylactide-hydroxyapatite (PLA-HA) scaffolds in the repair of critical-sized bone defects in a rabbit model. METHODS: First, 3D-printed PLA-HA scaffolds were fabricated and evaluated using micro-computed tomography (µCT) and scanning electron microscopy (SEM). Twenty-seven New Zealand white rabbits were randomly divided into 3 groups (n=9 per group), and the defects were treated using 3D-printed PLA-HA scaffolds (the PLA-HA group) or eBM in conjunction with 3D-printed PLA-HA scaffolds (the PLA-HA/eBM group), or were left untreated (the control group). Radiographic, µCT, and histological analyses were performed to evaluate bone regeneration in the different groups. RESULTS: The 3D-printed PLA-HA scaffolds were cylindrical, and had a mean pore size of 500±47.1 µm and 60%±3.5% porosity. At 4 and 8 weeks, the lane-sandhu X-ray score in the PLA-HA/eBM group was significantly higher than that in the PLA-HA group and the control group (P<0.01). At 8 weeks, the µCT analysis showed that the bone volume (BV) and bone volume/tissue volume (BV/TV) in the PLA-HA/eBM group were significantly higher than those in the PLA-HA group and the control group (P<0.01). Hematoxylin and eosin staining indicated that the new bone area in the PLA-HA/eBM group was significantly higher than that in the PLA-HA group and the control group (P<0.01). CONCLUSIONS: The group that was treated with eBM in conjunction with 3D-printed PLA-HA showed enhanced bone repair compared to the other 2 groups. PLA-HA/eBM scaffolds represent a promising way to treat critical-sized bone defects.

Biomaterials and 3D printing techniques used in the medical field.

An implants' effectiveness depends upon the form of biomaterial used in its manufacture. A suitable material for implants should be biocompatible, sterile, mechanically stable and simple to shape. 3D printing technologies have been breaking new ground in the medical and medical industries in order to build patient-specific devices embedded in bioactive drugs, cells and proteins. Widespread use in medical 3D printing is a broad range of biomaterials including metals, ceramics, polymers and composites. Continuous work and developments in biomaterials used in 3D printing have contributed to significant growth of 3D printing applications in the production of personalised joints, prostheses, medication delivery system and 3D tissue engineering and regenerative medicine scaffolds. The present analysis focuses on the biomaterials used for therapeutic applications in different 3D printing technologies. Many specific forms of medical 3D printing technology are explored in depth, including fused deposition modelling, extrusion-based bioprinting, inkjet and poly-jet printing processes, their therapeutic uses, various types of biomaterial used today and the major shortcoming , are being studied in depth.

A Novel Rat Tail Needle Minimally Invasive Puncture Model Using Three-Dimensional Printing for Disk Degeneration and Progressive Osteogenesis Research.

Many studies focused on the annulus fibrosus (AF) injury in rodent tail model for the intervertebral disk degeneration (IDD) research. However, previous studies caused tremendous injury of intervertebral disk (IVD) by penetrating whole disk. This study aimed to build a progressive IDD rodent tail model by a novel device for precise and minimally invasive puncture in AF. A precise puncture device was customized by 3D Printing Technique. 40 rodent tail IVDs were randomly grouped as follows: group A, non-puncture; group B, annulus needle puncture (ANP) for 4 week; group C, ANP for 8 week; and group D, ANP for 12 week. Pre- and post-puncture IVD height on radiographs and IVD signal intensity on T2 magnetic resonance imaging (MRI) were measured. Average bone density (ABD) on the end of coccygeal vertebrae between punctured disk was measured on the radiographs. Hematoxylin and eosin, TUNEL staining methods, immunofluorescence for cleaved-caspas3 and immunohistochemistry for aggrecan and collagen II were performed. Progressively and significantly increasing IVD height loss and degenerative grade were observed following the time points. The ABD was respectively, 81.20 ± 4.63 in group A, 83.93±3.18 in group B, 92.65 ± 4.32 in group C, 98.87 ± 6.69 in group D. In both group C and group D, there were significant differences with group A. In histology, increasing number of AF cells was noted in group B. In both group C and D, the fissures in AF were obviously observed, and a marked reduction of AF cells were also observed. In all ANP groups, there were significant decrease in number of NP cells, as well as aggrecan and collagen II contents. TUNEL assay showed cellular apoptosis were stimulated in all puncture group, especially in group D. A progressive IDD rat model could be standardly established by the micro-injury IVD puncture using a novel 3D printing device. This animal model provided a potential application for research of progressive hyperosteogeny following IDD development.

Three-dimension correction of Charcot ankle deformity with a titanium implant.

BACKGROUND: Charcot neuroarthropathy of the ankle is an extremely challenging clinical dilemma, and its surgical management can be highly complicated. The goal of Charcot ankle treatment is to to restore a plantigrade and stable foot, and thus to avoid ulceration with subsequent infection. This report aims to introduce a method of correcting ankle deformity using a novel 3D printing technique. PATIENT AND METHODS: One patient with Charcot ankle deformity was operated in this study. The ankle deformity of this patient was quantified in three dimensions through computed tomography. On the basis of the computed tomography scans, a new titanium implant was designed and manufactured using 3D printing. The implant was applied in the surgery of tibio-talo-calcaneal arthrodesis to restore local anatomy of the affected ankle of the patient with Charcot neuroarthropathy. RESULTS: Evaluation of the post-operative radiography indicated union in the affected ankle. After surgery, the planar foot in this patient was restored. The patient was satisfied with the post-operative course, and joint fusion was successful as indicated by 2-year post-operative evaluation. The results of post-operative follow-up showed that the lower limb length of the patient with Charcot neuroarthropathy was salvaged, and the patient retained the plantigrade foot. CONCLUSION: Three-dimensional printing technique combined with tibio-talo-calcaneal arthrodesis may help to correct ankle deformity in patients with Charcot neuroarthropathy.

Effect of the Pore Shape and Size of 3D-Printed Open-Porous ABS Materials on Sound Absorption Performance.

Noise has a negative impact on our environment and human health. For this reason, it is necessary to eliminate excessive noise levels. This paper is focused on the study of the sound absorption properties of materials with open-porous structures, which were made of acrylonitrile butadiene styrene (ABS) material using additive technology. Four types of structures (Cartesian, octagonal, rhomboid, and Starlit) were evaluated in this work, and every structure was prepared in three different volume ratios of the porosity and three different thicknesses. The sound absorption properties of the investigated ABS specimens were examined utilizing the normal incidence sound absorption and noise reduction coefficients, which were experimentally determined by the transfer function method using a two-microphone acoustic impedance tube. This work deals with various factors that influence the sound absorption performance of four different types of investigated ABS material's structures. It was found, in this study, that the sound absorption performance of the investigated ABS specimens is strongly affected by different factors, specifically by the structure geometry, material volume ratio, excitation frequency of an acoustic wave, material´s thickness, and air space size behind the tested sound-absorbing materials.

Clinical feasibility and application value of computer virtual reduction combined with 3D printing technique in complex acetabular fractures.

This study investigated the clinical feasibility and application value of computer virtual reduction combined with three-dimensional (3D) printing technique in patients with complex acetabular fracture. Ninety-six patients diagnosed with complex acetabular fracture in the Orthopedics Department in The Second Affiliated Hospital of Luohe Medical College from January 2016 to June 2017 were selected and randomly divided into the routine operation group (n=48) and the 3D model group (n=48) according to the admission number of the patients. In the 3D model group, computed tomography (CT) scan was performed preoperatively, and the model was made using the virtual technique and 3D printing technique. The surgical scheme was designed according to the model. Patients in the routine operation group were diagnosed with the conventional CT scan without using the computer virtual technique and 3D printing technique. During operation, the operation time, amount of intraoperative bleeding and times of intraoperative fluoroscopy were recorded in both groups. After operation, the incidence rate of such complications as inflammatory response, iatrogenic neurological symptoms and loss of reduction were recorded in both groups. Moreover, the reduction quality of acetabular fracture was evaluated according to the Matta imaging score at 3 days after operation, and the hip joint function was evaluated based on the Hariss score at 6 months after operation. In the 3D model group, the operation time was significantly shorter than that in the control group, the amount of intraoperative bleeding and times of intraoperative fluoroscopy were significantly less than those in the routine operation group, and the incidence rate of postoperative complications was obviously lower than that in the routine operation group (P<0.05). In conclusion, computer virtual reduction combined with the 3D printing technique can significantly reduce the operation time, amount of intraoperative bleeding, times of intraoperative fluoroscopy and incidence rate of postoperative complications without adverse effects on the reduction quality of acetabular fracture and hip joint function of patients, which has a higher clinical application value and greater social significance.

Customized anterior craniocervical reconstruction via a modified high-cervical retropharyngeal approach following resection of a spinal tumor involving C1-2/C1-3.

OBJECTIVE: The surgical treatment of an upper cervical spinal tumor (UCST) at C1-2/C1-3 is challenging due to anterior exposure and reconstruction. Limited information has been published concerning the effective approach and reconstruction for an anterior procedure after C1-2/C1-3 UCST resection. The authors attempted to introduce a novel, customized, anterior craniocervical reconstruction between the occipital condyles and inferior vertebrae through a modified high-cervical retropharyngeal approach (mHCRA) in addressing C1-2/C1-3 spinal tumors. METHODS: Seven consecutive patients underwent 2-stage UCST resection with circumferential reconstruction. Posterior decompression and occiput-cervical instrumentation was conducted at the stage 1 operation, and anterior craniocervical reconstruction using a 3D-printed implant was performed between the occipital condyles and inferior vertebrae via an mHCRA. The clinical characteristics, perioperative complications, and radiological outcomes were reviewed, and the rationale for anterior craniocervical reconstruction was also clarified. RESULTS: The mean age of the 7 patients in the study was 47.6 ± 19.0 years (range 12-72 years) when referred to the authors' center. Six patients (85.7%) had recurrent tumor status, and the interval from primary to recurrence status was 53.0 ± 33.7 months (range 24-105 months). Four patients (57.1%) were diagnosed with a spinal tumor involving C1-3, and 3 patients (42.9%) with a C1-2 tumor. For the anterior procedure, the mean surgical duration and average blood loss were 4.1 ± 0.9 hours (range 3.0-6.0 hours) and 558.3 ± 400.5 ml (range 100-1300 ml), respectively. No severe perioperative complications occurred, except 1 patient with transient dysphagia. The mean pre- and postoperative visual analog scale scores were 8.0 ± 0.8 (range 7-9) and 2.4 ± 0.5 (range 2.0-3.0; p < 0.001), respectively, and the mean improvement rate of cervical spinal cord function was 54.7% ± 13.8% (range 42.9%-83.3%) based on the modified Japanese Orthopaedic Association scale score (p < 0.001). Circumferential instrumentation was in good position and no evidence of disease was found at the mean follow-up of 14.8 months (range 7.3-24.2 months). CONCLUSIONS: The mHCRA provides optimal access to the surgical field at the C0-3 level. Customized anterior craniocervical fixation between the occipital condyles and inferior vertebrae can be feasible and effective in managing anterior reconstruction after UCST resection.

[Fabrication and accuracy research on 3D printing dental model based on cone beam computed tomography digital modeling].

OBJECTIVE: The aim of this study is to build a digital dental model with cone beam computed tomography (CBCT), to fabricate a virtual model via 3D printing, and to determine the accuracy of 3D printing dental model by comparing the result with a traditional dental cast. METHODS: CBCT of orthodontic patients was obtained to build a digital dental model by using Mimics 10.01 and Geomagic studio software. The 3D virtual models were fabricated via fused deposition modeling technique (FDM). The 3D virtual models were compared with the traditional cast models by using a Vernier caliper. The measurements used for comparison included the width of each tooth, the length and width of the maxillary and mandibular arches, and the length of the posterior dental crest. RESULTS: 3D printing models had higher accuracy compared with the traditional cast models. The results of the paired t-test of all data showed that no statistically significant difference was observed between the two groups (P>0.05). CONCLUSIONS: Dental digital models built with CBCT realize the digital storage of patients' dental condition. The virtual dental model fabricated via 3D printing avoids traditional impression and simplifies the clinical examination process. The 3D printing dental models produced via FDM show a high degree of accuracy. Thus, these models are appropriate for clinical practice.

Three dimensionally printed pearl powder/poly-caprolactone composite scaffolds for bone regeneration.

Pearl has great potential as a natural biomaterial for bone tissue engineering, but it suffers from low porosity, difficulty in molding, and poor anti-buckling property. In this study, we used the 3-D printing technique to fabricate original pearl powder and PCL composite scaffolds with different concentrations of pearl powder. The four groups of scaffolds were termed PCL, 30% Pearl/PCL, 50% Pearl/PCL and 80% Pearl/PCL scaffolds according to the proportion of pearl powder. The samples were systematically investigated by scanning electron microscopy (SEM), wide-angle XRD, liquid substitution, Zwick static materials testing, and energy dispersive X-ray analysis. Biological characterization included SEM, fluorescent staining using calcein-AM, cell counting kit-8 assay, alkaline phosphatase and qRT-PCR analysis. The results show that the pore size and the pore morphology of the scaffolds are closely controlled via 3-D printing. This is very beneficial for tissue growth and nutrition transmission. The regular and uniform square macropore structure ensured that the pearl powder/PCL scaffolds had favorable mechanical strength. As the concentration of pearl powder in the scaffolds increase, the compressive strength and apatite formation increase as well as cell adhesion, proliferation, and osteogenic differentiation. These results show that pearl powder/PCL scaffolds fit the requirements of bone tissue engineering. The structures as well as physicochemical and biological properties of pearl powder/PCL composite scaffolds are positively associated with pearl powder concentrations.

Insight into the microbial community and its succession of a coupling anaerobic-aerobic biofilm on semi-suspended bio-carriers.

This work aims at establishing a coupling anaerobic-aerobic biofilm within a single bioreactor and revealing its microbial community and succession. By using a semi-suspended bio-carrier fabricated with 3D printing technique, an obvious DO gradient was gradually created within the biofilm, which demonstrated that a coupling anaerobic-aerobic biofilm was successfully established on the surface of bio-carriers. The results of metagenomic analysis revealed that the microbial community on the bio-carriers experienced a continuous succession in its structure and dominant species along with the operational time. The formed coupling biofilm created suitable micro multi-habitats for the co-existence of these microorganisms, including nitrifying and denitrifying bacteria, which were beneficial to the removing of organic pollutants and converting nutrients. Along with the succession, the microbial community was gradually dominated by several functional microorganisms. Overall, the results presented an approach to improve the microbial biodiversity by constructing a new structure and floating status of bio-carriers.