Microstructural and Hydrophilic Properties of Polylactide Polymer Samples with Various 3D Printing Patterns.

The aim of the work is to study the effect of the 3D printing process on the microstructural and hydrophilic properties of polylactic acid (PLA) samples with various model printing patterns obtained from the black filament PLA by sequentially applying polymer layers using the FDM (fused deposition modeling) method. X-ray phase analysis revealed the partial crystallization of PLA polymer chains in the printed samples, which occurs under thermal and mechanical action on the original amorphous PLA filament during 3D printing to varying degrees, depending on the geometry of the pattern and the morphology of its surface. At the same time, IR spectroscopy data indicate the preservation of all intrastructural chemical bonds of polylactide. Measured at the original installation, the values of the wetting edge angles on the surface of the printed samples are in the range φ = 50-60°, which is significantly less than the right angle. This indicates the hydrophilic properties of the whole sample's surface. At the same time, the influence of different geometries of model drawings in printed samples was found not only on the morphology of the sample's surface according to SEM data but also on its wettability.

Application of 3D printing surgical training models in the preoperative assessment of robot-assisted partial nephrectomy.

BACKGROUND: To explore the application effect of 3D printing surgical training models in the preoperative assessment of robot-assisted partial nephrectomy. METHODS: Eighty patients who underwent robot-assisted partial nephrectomy surgery between January 2022 and December 2023 were selected and divided into two groups according to the chronological order. The control group (n = 40) received preoperative assessment with verbal and video education from January 2022 to December 2022, while the observation group (n = 40) received preoperative assessment with 3D printing surgical training models combined with verbal and video education from January 2023 to December 2023. The preoperative anxiety, information demand score, and surgical awareness were compared between the two groups. The physiological stress indicators, including interleukin-6 (IL-6), angiotensin II (AT II), adrenocorticotropic hormone (ACTH), cortisol (Cor), mean arterial pressure (MAP), and heart rate (HR), were also measured at different time points before and after surgery.They were 6:00 am on the day before surgery (T0), 6:00 am on the day of the operation (T1), 6:00 am on the first day after the operation (T2), and 6:00 am on the third day after the operation (T3).The preparation rate before surgery was compared between the two groups. RESULTS: The anxiety and surgical information demand scores were lower in the observation group than in the control group before anesthesia induction, and the difference was statistically significant (P < 0.001). Both groups had lower scores before anesthesia induction than before preoperative assessment, and the difference was statistically significant (P < 0.05). The physiological stress indicators at T1 time points were lower in the observation group than in the control group, and the difference was statistically significant (P < 0.05). The overall means of the physiological stress indicators differed significantly between the two groups (P < 0.001). Compared with the T0 time point, the T1, T2, and T3 time points in both groups were significantly lower, and the difference was statistically significant (P < 0.05). The surgical awareness and preparation rate before surgery were higher in the observation group than in the control group, and the difference was statistically significant (P < 0.05). CONCLUSION: The preoperative assessment mode using 3D printing surgical training models combined with verbal and video education can effectively reduce the psychological and physiological stress responses of surgical patients, improve their surgical awareness, and enhance the preparation rate before surgery.

Applications of three-dimensional printing in percutaneous closure of aortic-to-right ventricle fistula after transcatheter aortic valve replacement: a case report.

Background: Percutaneous closure of aortic-to-right ventricle (ARV) fistula has emerged as an alternative to surgical management in selected cases. The use of three-dimensional (3D) printing in interventional planning for structural heart disease provides a concrete understanding, and it is useful in diagnostic assessment and to guide treatment approaches and to simulate procedures. Case summary: We report a case of a 70-year-old male presenting in cardiogenic shock due to severe aortic stenosis and reduced left ventricular ejection fraction. The patient had several comorbidities and was deemed not eligible for cardiac surgery. After transcatheter aortic valve replacement (TAVR), an ARV fistula was discovered on the TTE. Due to complex anatomical considerations, a 3D printed model of the patient's anatomy was employed to supplement the decision-making process and technical planning of percutaneous ARV closure. Successful closure of the fistula with the use of the Amplatzer atrial septal occluder was subsequently performed. Discussion: Three-dimensional printing improves the understanding of complex structures of cardiac diseases, allowing for enhanced planning and simulation of the procedure. This case, demonstrating the effective percutaneous closure of a TAVR-related ARV fistula facilitated by the use of 3D printed anatomical models in the pre-procedural phase, highlights the technology's potential in advancing patient-specific treatment approaches.

Application effect of head-mounted mixed reality device combined with 3D printing model in neurosurgery ventricular and hematoma puncture training.

BACKGROUND: The purpose of this study was to explore the applicability of application effect of head-mounted mixed reality (MR) equipment combined with a three-dimensional (3D) printed model in neurosurgical ventricular and haematoma puncture training. METHODS: Digital Imaging and Communications in Medicine (DICOM) format image data of two patients with common neurosurgical diseases (hydrocephalus and basal ganglia haemorrhage) were imported into 3D Slicer software for 3D reconstruction, saved, and printed using 3D printing to produce a 1:1-sized head model with real person characteristics. The required model (brain ventricle, haematoma, puncture path, etc.) was constructed and imported into the head-mounted MR device, HoloLens, and a risk-free, visual, and repeatable system was designed for the training of junior physicians. A total of 16 junior physicians who studied under this specialty from September 2020 to March 2022 were selected as the research participants, and the applicability of the equipment and model during training was evaluated with assessment score sheets and questionnaires after training. RESULTS: According to results of the assessment and questionnaire, the doctors trained by this system are more familiar with the localization of the lateral anterior ventricle horn puncture and the common endoscopic surgery for basal ganglia haemorrhage, as well as more confident in the mastery of these two operations than the traditional training methods. CONCLUSIONS: The use of head-mounted MR equipment combined with 3D printing models can provide an ideal platform for the operation training of young doctors. Through holographic images created from the combination of virtual and real images, operators can be better immersed in the operation process and deepen their understanding of the operation and related anatomical structures. The 3D printed model can be repeatedly reproduced so that doctors can master the technology, learn from mistakes, better achieve the purpose of teaching and training, and improve the effect of training.

Customized Multilevel 3D Printing Implant for Reconstructing Spine Tumor: A Retrospective Case Series Study in a Single Center.

OBJECTIVE: To investigate the clinical efficacy and safety of 3D printed artificial vertebral body for patients who underwent multilevel total en bloc spondylectomy (TES) and analyze whether it could reduce the incidence of implant subsidence. METHODS: This is a retrospective study. From January 2017 to May 2018, eight consecutive cases with spine tumor undergoing multilevel TES were analyzed. All patients underwent X-ray and CT examinations to evaluate the stability of internal fixation during the postoperative follow-up. Demographic, surgical details, clinical data, and perioperative complications was collected. Visual analog scale, Frankel score, and spinal instability neoplastic score (SINS) classification were also recorded. RESULTS: There were six cases of primary spinal tumor and two cases of metastatic spinal tumor. All patients achieved remarkable pain relief and improvement in neurological function. Five patients underwent operation through the posterior approach, one patient underwent operation through the anterior approach and the remaining two patients through a combined anterior and posterior approach. At the last follow-up period, X-rays showed that the 3D printed artificial vertebral body of all cases matched well, and the fixation was reliable. Hardware failure such as loosening, sinking, breaking, and displacement wasn't observed during the follow-up period. CONCLUSION: 3D printed customized artificial vertebral body can provide satisfying good clinical and radiological outcomes for patients who have undergone multilevel TES.

Case Report: Three-Dimensional Printing Model for Surgical Planning of Left Ventricular Aneurysm: Evolution Toward Tailoring Surgery.

A 59-year-old woman was admitted to the emergency department for heart failure (HF), New York Heart Association (NYHA) IV, showing an anterior, evolved myocardial infarction (MI) with a wide apical left ventricular aneurysm (LVA), ejection fraction (EF) 24%, and global longitudinal strain (GLS) -5. 5% by echo. Cardiac magnetic resonance imaging (MRI) confirmed an apical LVA without thrombus, EF 20%, and a transmural delayed enhancement in the myocardium wall. Coronarography showed a three-vessel disease with occluded proximal left anterior descending (LAD) and proximal right coronary artery (RCA). Based on the cardiac CT scan, we decided to generate a three-dimensional (3D) print model of the heart, for better prediction of residual LV volumes. After LVA surgery plus complete functional revascularization, an optimal agreement was found between predicted and surgical residual LV end-diastolic (24.7 vs. 31.8 ml/m2) and end-systolic (54.1 vs. 69.4 ml/m2) volumes, with an improvement of NYHA class, from IV to I. The patient was discharged uneventfully and at 6- and 12-month follow-up, the NYHA class, and LV volumes were found unchanged. This is a second report describing the use of the 3D print model for the preoperative planning of surgical management of LVA; the first report was described by Jacobs et al. among three patients, one with a malignant tumor and the remaining two patients with LVA. This article focused on the use of the 3D print model to optimize surgical planning and individualize treatment of LVA associated with complete functional revascularization, leading to complete recovery of LV function with a favorable outcome.

The usefulness of 3D printed heart models for medical student education in congenital heart disease.

BACKGROUND: Three-dimensional (3D) printing technology enables the translation of 2-dimensional (2D) medical imaging into a physical replica of a patient's individual anatomy and may enhance the understanding of congenital heart defects (CHD). We aimed to evaluate the usefulness of a spectrum of 3D-printed models in teaching CHD to medical students. RESULTS: We performed a prospective, randomized educational procedure to teach fifth year medical students four CHDs (atrial septal defect (ASD, n = 74), ventricular septal defect (VSD, n = 50), coarctation of aorta (CoA, n = 118) and tetralogy of Fallot (ToF, n = 105)). Students were randomized into printing groups or control groups. All students received the same 20 min lecture with projected digital 2D images. The printing groups also manipulated 3D printed models during the lecture. Both groups answered an objective survey (Multiple-choice questionnaire) twice, pre- and post-test, and completed a post-lecture subjective survey. Three hundred forty-seven students were included and both teaching groups for each CHD were comparable in age, sex and pre-test score. Overall, objective knowledge improved after the lecture and was higher in the printing group compared to the control group (16.3 ± 2.6 vs 14.8 ± 2.8 out of 20, p < 0.0001). Similar results were observed for each CHD (p = 0.0001 ASD group; p = 0.002 VSD group; p = 0.0005 CoA group; p = 0.003 ToF group). Students' opinion of their understanding of CHDs was higher in the printing group compared to the control group (respectively 4.2 ± 0.5 vs 3.8 ± 0.4 out of 5, p < 0.0001). CONCLUSION: The use of 3D printed models in CHD lectures improve both objective knowledge and learner satisfaction for medical students. The practice should be mainstreamed.

Digital navigation and 3D model technology in mandibular reconstruction with fibular free flap: A comparative study.

OBJECTIVE: The low accuracy limits the use of fibular free flap (FFF). We apply digital navigation and 3D printing model technology in mandibular reconstruction to improve FFF's accuracy. METHODS: 34 patients who underwent with FFF to repair mandibular defects were divided into Navigation Group (13 cases, using digital navigation and 3D printing model) and Control Group (21 cases, only 3D printing model). We retrospectively reviewed patients' hospitalization information and evaluated patients by subjective and objective items, such as UW-Qol scale, CT data. RESULTS: The operation time of Navigation Group was higher significantly than Control Group (10.36 ± 1.87vs9.00 ± 1.34 h).There were no significant differences in early postoperative complications. The Qol score of appearance, motion, anxiety were higher significantly in Navigation Group. The CT results showed that mandibular angle deviation and chin deflection of Navigation Group were better significantly than Control Group (1.72 ± 1.29° vs 3.69 ± 1.67°, 2.45 ± 1.39 vs 5.19 ± 2.13 mm). CONCLUSIONS: The digital navigation can improve FFF's accuracy in mandibular reconstruction. It doesn't significantly increase complications. The digital navigation's installation and operation methods should be simplified to shorter operation time and expand its application.

Application of flipped classroom teaching mode supported by 3D printing model in embryology experiment teaching / 解剖学报

Objective To explore the teaching effect of flipped classroom teaching mode supported by the 3D printing model in the embryology experiment. Methods Totally 76 students from class 2016 were randomly divided into two groups: the experimental group previewed the embryo 3D models before class and taught other students in class, while the control group did not preview the embryo 3D models before class. An embryo knowledge test and a questionnaire survey were carried out before and after the experimental class to compare the differences of knowledge mastery and self-evaluation between the two groups. Results In the aspect of self-evaluation, the self-evaluation of the experimental group students in explaining the causes and explaining the process of development was significantly improved after the lecture (P<0.05), while the self-evaluation of the control group students in identifying the structure, understanding knowledge, telling the causes and explaining the process of development was significantly improved (P< 0.05). In terms of knowledge test scores, the scores of students in the experimental group and the control group after teaching were higher than those before teaching (P < 0.05). The improvement of the knowledge test in the control group was significantly higher than that in the experimental group (P<0.05). The experiment group' s grades of knowledge test were significantly higher than the control group in the second experiment. 70.27% of the students thought that they were still lack of knowledge in the introspection of the causes of wrong answers. The misunderstanding of English nouns (15.54%), psychological factors (5.41%) and other factors (8.78%) also caused the students to lose points in the knowledge tests. Conclusion The combination of the 3D printing model and the flipped classroom teaching mode can effectively improve the teaching effect, which should be paid attention to in the reform of embryology experimental teaching.

Simulation and navigation of living donor hepatectomy using a unique three-dimensional printed liver model with soft and transparent parenchyma.

Three-dimensional printed liver models have been used for preoperative simulation. Unlike the standard three-dimensional system on a monitor, the three-dimensional printed model can be observed from any angle manually; therefore, surgeons can obtain a clear image directly from the model. We herein report the use of a unique three-dimensional liver model with a soft and transparent liver parenchyma. Through the parenchyma, the surgeons can observe the intrahepatic vessels and perform incisions in the model as a preoperative simulation. In this study, we applied this model to donor hepatectomy, which under most circumstances requires meticulous attention to detail. The actual processes and uses of a three-dimensional liver model in clinical surgery for liver transplantation are presented.

Patient-Specific Three-Dimensional Model for a Safe Surgical Pathway in Sacral Chondrosarcoma.

Sacral tumors are amongst the most challenging procedures to treat because of the complex anatomy. This study determined whether patient-specific models change preoperative planning decisions made in preparation for en bloc resection of complex sacral mass surgical procedures. Imaging showed a big encapsulated mass at the S2-3 level involving the neural foramina and obscuring the nerve roots. High-resolution images were acquired and utilized to generate a patient-specific 3D tumor model. The visual and tactile inspection of 3D models allowed the best anatomical understanding, with faster and clearer comprehension of the surgical anatomy. The 3D sacral model was for observation of previously unapparent anatomical details; with this new technology, surgeon can observe their planned surgical intervention, explore the patient-specific anatomy and extension of the tumor, and sharpen their procedure choices. Moreover, multiple planes showed how far the angles on the plane would extend for osteotomy of the sacrum. Another result was identifying correct guides and safe venture landmarks. The study helped to establish safe osteotomy line wherever the nerve roots were retained and enabled osteotomy by preserving bilaterally the S1 and S2 nerve roots for wide excision of wide excision of primary sacral tumor to get adequate bowel and bladder functions. Finally, it helped to determine whether or not the remaining bone in the sacrum is sufficient for spinopelvic stability and needed fixation. It was decided spinopelvic fixation was not necessary for this case. Surgical intervention of sacral tumors varies depending on the tumor, its size, extension, and location. Surgery can have profound risks including unnecessary nerve root resection spinopelvic instability and suboptimal oncological resection. 3D models help to transfer complex anatomical information to clinicians and provide guidance in the preoperative planning stage, for intraoperative navigation and for surgical training purposes.

Multidisciplinary Assessment of Planning and Resection of Complex Bone Tumor Using Patient-Specific 3D Model.

Oncological interventions in thoracic cavity have some important problems such as choice of correct operative approaches depending on the tumor, size, extension, and location. In sarcoma surgery, wide resection should be aimed for the curative surgery. Purpose of this study was to evaluate pre-operative planning of patient-specific thoracic cavity model made by multidisciplinary surgeon team for complex tumor mass for oncological procedures. Patient's scans showed a large mass encroaching on the mediastinum and heart, with erosion of the adjacent ribs and vertebral column. Individual model of this case with thoracic tumor was reconstructed from the DICOM file of the CT data. Surgical team including six interdisciplinary surgeons explained their surgical experience of the use of 3D life-size individual model for guiding surgical treatment. Before patients consented to surgery, each surgeon explained the surgical procedure and perioperative risks to her. A questionnaire was applied to 10 surgical residents to evaluate the 3D model's perception. 3D model scans were useful in determining the site of the lesion, the exact size, extension, attachment to the surrounding structures such as lung, aorta, vertebral column, or vascular involvement, the number of involved ribs, whether the diaphragm was involved also in which order surgeons in the team enter the surgery. 3D model's perception was detected statistical significance as < 0.05. Viewing thoracic cavity with tumor model was more efficient than CT imaging. This case was surgically difficult as it included vital structures such as the mediastinal vessels, aorta, ribs, sternum, and vertebral bodies. A difficult pathology for which 3D model has already been explored to assist anatomic visualization was mediastinal osteosarcoma of the chest wall, diaphragm, and the vertebral column. The study helped to establish safe surgical line wherever the healthy tissue was retained and enabled osteotomy of the affected spinal corpus vertically with posterior-anterior direction by preserving the spinal cord and the spinal nerves above and distal the tumor. 3D tumor model helps to transfer complex anatomical information to surgeons, provide guidance in the pre-operative planning stage, for intra-operative navigation and for surgical collaboration purposes. Total radical excision of the bone tumor and reconstructions of remaining structures using life-size model was the key for successful treatment and better outcomes. The recent explosion in popularity of 3D printing is a testament to the promise of this technology and its profound utility in orthopedic oncological surgery.

Clinical application and effect of individual 3D printing model on pedicle screw placement for upper cervical spine fracture / 中华创伤杂志

Objective@#To investigate the accuracy and feasibility of individual 3D printing model for pedicle screw placement in treating patients with upper cervical spine fracture.@*Methods@#A retrospective case control study was conducted to analyze the clinical data of 30 patients with upper cervical spine fracture admitted to Ningbo No.6 Hospital from August 2013 to December 2018. There were 19 males and 11 females, aged 45-67 years with an average age of 53.5 years. The 15 patients in the study group were treated with pedicle screw fixation and another 15 patients in the control group were treated with traditional freehand screw fixation. A total of 120 pedicle screws were implanted, with 60 screws in each group. The operation time, intraoperative blood loss, preoperative and postoperative visual analogue score (VAS), Japan Orthopedic Association (JOA) score were recorded. The position and grade of screws were evaluated according to Kawaguchi's evaluation method of screw grade after operation. The patients took monthly reexamination for the first three months after discharge. In the first two months after discharge, the patients took X-ray examination for observation of screw loosening or rupture of internal fixation. At the third month after operation, the patients took CT of cervical spine for observation of bone healing and fusion.@*Results@#The mean follow-up duration was 17.8 months (range, 13-21 months). The study group had shorter operation time (99.13±3.04)minutes compared with the control group (107.00±6.92) minutes (P<0.01). There were no significant differences in intraoperative blood loss, preoperative VAS, JOA scores before operation and 1 year after operation between the two groups (P>0.05), but the VAS in study group was significantly lower than that in control group (P<0.05). In the study group, the VAS score 1 year after operation [(2.3±0.5)points] was lower than that before the operation [(7.7±0.7)points], and the JOA score [(16.8±0.4)points] was significantly higher than that before the operation [(15.9±0.7)points](P<0.01). In the control group, the VAS 1 year after operation [(2.5±0.5)points] was significantly lower than that before operation [(7.5±0.5)points] (P<0.01), and the JOA score [(16.5±0.5)points] was significantly higher than that before operation [(15.9±0.8)points] (P<0.05). In the study group, according to the CT results, there were 28 atlas pedicle screws of grade 0 (93.3%), two of grade 1 (6.7%), 0 of grade 2, 0 of grade 3, and there were 27 axial pedicle screws of grade 0 (90.0%), three of grade 1 (10.0%), 0 of grade 2, and 0 of grade 3. In the control group, there were 25 atlas pedicle screws of grade 0 (83.3%), four of grade 1 (13.3%), one of grade 2 (3.4%), 0 of grade 3, and there were 27 axial pedical screws of grade 0 (90.0%), three of grade 1 (10.0%), 0 of grade 2, and 0 of grade 3. There was no significant difference in the accuracy of pedicle screw placement between the two groups (P>0.05). No serious complications such as spinal cord or vertebral artery injury occurred. At 3 months after operation, CT showed that the fracture of cervical vertebra healed.@*Conclusion@#Individualized 3D printed cervical spine model can guide the pedicle screw placement for upper cervical spine fracture, which can shorten the operation time, reduce the postoperative pain of patients, improve the accuracy of screw placement, and reduce the risks related to operation.

Clinical application and effect of individual 3D printing model on pedicle screw placement for upper cervical spine fracture / 中华创伤杂志

Objective To investigate the accuracy and feasibility of individual 3D printing model for pedicle screw placement in treating patients with upper cervical spine fracture.Methods A retrospective case control study was conducted to analyze the clinical data of 30 patients with upper cervical spine fracture admitted to Ningbo No.6 Hospital from August 2013 to December 2018.There were 19 males and 11 females,aged 45-67 years with an average age of 53.5 years.The 15 patients in the study group were treated with pedicle screw fixation and another 15 patients in the control group were treated with traditional freehand screw fixation.A total of 120 pedicle screws were implanted,with 60 screws in each group.The operation time,intraoperative blood loss,preoperative and postoperative visual analogue score (VAS),Japan Orthopedic Association (JOA) score were recorded.The position and grade of screws were evaluated according to Kawaguchi's evaluation method of screw grade after operation.The patients took monthly reexamination for the first three months after discharge.In the first two months after discharge,the patients took X-ray examination for observation of screw loosening or rupture of internal fixation.At the third month after operation,the patients took CT of cervical spine for observation of bone healing and fusion.Results The mean follow-up duration was 17.8 months (range,13-21 months).The study group had shorter operation time (99.13 ± 3.04)minutes compared with the control group (107.00 ± 6.92) minutes (P ＜ 0.01).There were no significant differences in intraoperative blood loss,preoperative VAS,JOA scores before operation and 1 year after operation between the two groups (P ＞ 0.05),but the VAS in study group was significantly lower than that in control group (P ＜ 0.05).In the study group,the VAS score 1 year after operation [(2.3 ± 0.5) points] was lower than that before the operation [(7.7 ± 0.7) points],and the JOA score [(16.8 ± 0.4) points] was significantly higher than that before the operation [(15.9 ± 0.7) points] (P ＜ 0.01).In the control group,the VAS 1 year after operation [(2.5 ± 0.5) points] was significantly lower than that before operation [(7.5 ±0.5)points] (P ＜0.01),and the JOA score [(16.5 ±0.5)points] was significantly higher than that before operation [(15.9 ± 0.8)points] (P ＜ 0.05).In the study group,according to the CT results,there were 28 atlas pedicle screws of grade 0 (93.3％),two of grade 1 (6.7％),0 of grade 2,0 of grade 3,and there were 27 axial pedicle screws of grade 0 (90.0％),three of grade 1 (10.0％),0 of grade 2,and 0 of grade 3.In the control group,there were 25 atlas pedicle screws of grade 0 (83.3％),four of grade 1 (13.3％),one of grade 2 (3.4％),0 of grade 3,and there were 27 axial pedical screws of grade 0 (90.0％),three of grade 1 (10.0％),0 of grade 2,and 0 of grade 3.There was no significant difference in the accuracy of pedicle screw placement between the two groups (P ＞ 0.05).No serious complications such as spinal cord or vertebral artery injury occurred.At 3 months after operation,CT showed that the fracture of cervical vertebra healed.Conclusion Individualized 3D printed cervical spine model can guide the pedicle screw placement for upper cervical spine fracture,which can shorten the operation time,reduce the postoperative pain of patients,improve the accuracy of screw placement,and reduce the risks related to operation.

Evaluation of the marginal and internal fit of a single crown fabricated based on a three-dimensional printed model.

PURPOSE: To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS: A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the "Best-fit alignment" method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (α=.05). Tukey's HSD was used for post-hoc analysis. RESULTS: One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P<.001) and between areas (P<.001) were further revealed by 2-way ANOVA. CONCLUSION: Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range (<120 µm).

3D phase contrast MRI in models of human airways: Validation of computational fluid dynamics simulations of steady inspiratory flow.

BACKGROUND: Knowledge of airflow patterns in the large airways is of interest in obstructive airways disease and in the development of inhaled therapies. Computational fluid dynamics (CFD) simulations are used to study airflow in realistic airway models but usually need experimental validation. PURPOSE: To develop MRI-based methods to study airway flow in realistic 3D-printed models. STUDY TYPE: Case control. PHANTOM: Two 3D-printed lung models. FIELD STRENGTH/SEQUENCE: 1.5-3T, flow MRI. ASSESSMENT: Two human airway models, respectively including and excluding the oral cavity and upper airways derived from MR and CT imaging, were 3D-printed. 3D flow MRI was performed at different flow conditions corresponding to slow and steady airflow inhalation rates. Water was used as the working fluid to mimic airflow. Dynamic acquisition of 1D velocity profiles was also performed at different locations in the trachea to observe variability during nonsteady conditions. STATISTICAL TESTS: Linear regression analysis to compare both flow velocity fields and local flow rates from CFD simulations and experimental measurement with flow MRI. RESULTS: A good agreement was obtained between 3D velocity maps measured with flow MRI and predicted by CFD simulations, with linear regression R-squared values ranging from 0.39 to 0.94 when performing a pixel-by-pixel comparison of each velocity component. The flow distribution inside the lung models was also similar, with average slope and R-squared values of 0.96 and 0.99, respectively, when comparing local flow rates assessed at different branching locations. In the model including the upper airways, a turbulent laryngeal jet flow was observed with both methods and affected remarkably the velocity profiles in the trachea. DATA CONCLUSION: We propose flow MRI using water as a surrogate fluid to air, as a validation tool for CFD simulations of airflow in geometrically realistic models of the human airways. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1400-1409.

Investigations into in situ Enterococcus faecalis biofilm removal by passive and active sodium hypochlorite irrigation delivered into the lateral canal of a simulated root canal model.

AIM: To investigate in situ Enterococcus faecalis biofilm removal from the lateral canal of a simulated root canal system using passive or active irrigation protocols. METHODOLOGY: Root canal models (n = 43) were manufactured from transparent resin materials using 3D printing. Each canal was created with an 18 mm length, apical size 30, a .06 taper and a lateral canal of 3 mm length, with 0.3 mm diameter. Biofilms were grown in the lateral canal and apical 3 mm of the main canal for 10 days. Three models from each group were examined for residual biofilm using SEM. The other forty models were divided into four groups (n = 10). The models were observed under a fluorescence microscope. Following 60 s of 9 mL of 2.5% NaOCl irrigation using syringe and needle, the irrigant was either left stagnant in the canal or activated using gutta-percha, sonic or ultrasonic methods for 30 s. Images were then captured every second using an external camera. The residual biofilm percentages were measured using image analysis software. The data were analysed using generalized linear mixed models. A significance level of 0.05 was used throughout. RESULTS: The greatest level of biofilm removal was obtained with ultrasonic agitation (66.76%) followed by sonic (45.49%), manual agitation (43.97%) and passive irrigation groups (38.67%), respectively. The differences were significant between the residual biofilm in the passive irrigation and both sonic and ultrasonic groups (P = 0.001). CONCLUSION: Agitation resulted in better penetration of 2.5% NaOCl into the lateral canal of an artificial root canal model. Ultrasonic agitation of NaOCl improved the removal of biofilm.

Development of Life-Size Patient-Specific 3D-Printed Dural Venous Models for Preoperative Planning.

BACKGROUND: Despite significant improvement in clinical care, operative strategies, and technology, neurosurgery is still risky, and optimal preoperative planning and anatomical assessment are necessary to minimize the risks of serious complications. Our purpose was to document the dural venous sinuses (DVS) and their variations identified during routine 3-dimensional (3D) venography created through 3D models for the teaching of complex cerebral anatomy. METHODS: 3D models of the DVS networks were printed. Compared with the controls, cases with cortical venous thrombosis have altered venous anatomy, which has not been previously compared. RESULTS: Geometrical changes between the neighboring DVS could be easily manipulated and explored from different angles. Modeling helped to conduct the examination in detail with reference to geometrical features of DVS, degree of asymmetry, its extension, location, and presence of hypoplasia/atresia channels. Challenging DVS anatomy was exposed with models of adverse anatomical variations of the DVS network, including highly angulated, asymmetrical view, narrowed lumens, and hypoplasia and atresia structures. It assisted us in comprehending spatial anatomy configuration of life-like models. CONCLUSIONS: Patient-specific models of DVS geometry could provide an improved understanding of the complex brain anatomy and better navigation in difficult areas and allow surgeons to anticipate anatomical issues that might arise during the operation. Such models offer opportunities to accelerate the development of expertise with respect to new and novel procedures as well as new surgical approaches and innovations, thus allowing novice neurosurgeons to gain valuable experience in surgical techniques without exposing patients to risk of harm.

Evaluation of the marginal and internal fit of a single crown fabricated based on a three-dimensional printed model

PURPOSE: To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS: A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the “Best-fit alignment” method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (α=.05). Tukey's HSD was used for post-hoc analysis. RESULTS: One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P < .001) and between areas (P < .001) were further revealed by 2-way ANOVA. CONCLUSION: Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range ( < 120 µm).

3D printing model of the intrahepatic vessels for navigation during anatomical resection of hepatocellular carcinoma.

INTRODUCTION: The 3D printing model of the intrahepatic vessels and regional anatomy are often used for navigation surgery. Here, we report the use of the model for anatomical resection of hepatocellular carcinoma. PRESENTATION OF CASE: Case 1: A tumor, 31mm in diameter, was located in segment 7 of the liver. Using the 3D model, we identified the regional Glissonian pedicle and performed resection of segment 7. Case 2: The tumor was located in segment 4/8 and involved the middle hepatic vein. Radical resection of segment 4 and of the ventral area of the right anterior section was performed using the 3D model. DISCUSSION: The positional relationship between the intrahepatic vessels and liver tumors is the most important factor for anatomical resection for hepatocellular carcinoma. Therefore our simplified 3D model of intrahepatic vessels without liver parenchyma is sufficient for effective guidance during surgery and has the advantage of being feasible to use for all HCC surgeries. CONCLUSION: Use of 3D printed models might have many merits and contribute to the great improvement of the surgical quality.