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Objective:To explore the feasibility and accuracy of three-dimensional (3D) modeling methods based on ultrasound imaging data for normal and abnormal fetal cardiac structures, and to construct a methodology system for 3D printing of fetal heart based on ultrasound.Methods:A total of 93 fetuses examined in Tangdu Hospital of Air Force Military Medical University from January to December 2019 were selected. Fetal echocardiography was obtained using spatio-temporal image correlation (STIC). Ninety-three hearts were 3D modeled by blood flow modeling, blood pool modeling and cavity modeling, and printed by stereolithography technique. The data measured on the 3D digital models and 3D printed solid models were compared with the corresponding fetal echocardiographic images respectively in order to evaluate the accuracy of the modeling methods.Results:The fetal cardiac blood flow models based on Doppler flow image data showed the malformation and trend of small blood vessels. The fetal cardiac structure models printed based on blood pool modeling displayed the malformation of heart and large blood vessels. Models printed based on cavity modeling method accurately displayed valve and structural defects.For 83 normal fetal hearts, the long diameters of left and right ventricles measured on echocardiography [(15.3±1.9)mm, (13.2±1.9)mm] were compared with those measured on digital models [(15.1±1.9)mm, (12.9±1.9)mm] and 3D printed models[(15.1±1.9)mm, (13.0±1.9)mm], respectively, and there were no significant differences between any two groups of them ( P>0.05). Bland-Altman showed good consistency for all measurements within and between operators. Conclusions:The three modeling methods, including blood flow modeling, blood pool modeling and cavity modeling, have their own advantages in displaying different types of fetal heart malformations. Appropriate modeling methods should be selected for 3D modeling and printing to make up for the limitations of single modeling method. The consistency between measurements on 3D models and those on echocardiography is high, and the repeatability between operators is good.
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Objective To design a space crawl training device.This device could achieve oval movement by rotating the wheel to drive the handle of the upper limb.At the same time,the leg support is driven to rotate about 30 degrees to 0 de-grees,which can assist the user to complete the entire crawling. Methods The structure of the device was modeled using SolidWorks.Then the whole device was simulated by using SolidWorks Motion,and the dynamic analysis was completed by calculation.Finally,the main force components from SolidWorks were imported into ANSYS Workbench for static analysis. Results and Conclusion The designed space trajectory crawling training device can assist the user to complete the scheduled crawling movement,and the strength checking of the key components meets the strength requirements.
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BACKGROUND: In order to obtain a deeper understanding of an incident, it needs to be investigated to “peel back the layers” and examine both immediate and underlying failures that contributed to the event itself. One of the key elements of an effective accident investigation is recording the scene for future reference. In recent years, however, there have been major advances in survey technology, which have provided the ability to capture scenes in three dimension to an unprecedented level of detail, using laser scanners. METHODS: A case study involving a fatal incident was surveyed using three-dimensional laser scanning, and subsequently recreated through virtual and physical models. The created models were then utilized in both accident investigation and legal process, to explore the technologies used in this setting. RESULTS: Benefits include explanation of the event and environment, incident reconstruction, preservation of evidence, reducing the need for site visits, and testing of theories. Drawbacks include limited technology within courtrooms, confusion caused by models, cost, and personal interpretation and acceptance in the data. CONCLUSION: Laser scanning surveys can be of considerable use in jury trials, for example, in case the location supports the use of a high-definition survey, or an object has to be altered after the accident and it has a specific influence on the case and needs to be recorded. However, consideration has to be made in its application and to ensure a fair trial, with emphasis being placed on the facts of the case and personal interpretation controlled.
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Humans , Accidents, OccupationalABSTRACT
Objective To investigate the effects of gastrocnemius muscle forces on biomechanical mechanism of heel pain. Methods The finite element model of the foot including foot bone, soft tissues, ligaments and plantar fascia was reconstructed based foot CT images by Mimics software. The gastrocnemius force applied on the foot was 40%-90% of half-body weight（320 N） with increment of 5% of half-body weight（16 N）. The plantar surface pressure distribution and peak pressure as well as the plantar fascia stress were calculated. Results The plantar surface pressure distribution was mainly concentrated on the heel and metatarsal head. With the increase of gastrocnemius force, the peak plantar pressure at the heel decreased, while the peak pressure at the front of the foot decreased at first and then increased, which reached the minimum value with the load of 224 N. The plantar fascia stress increased with the gastrocnemius force increasing. Conclusions Gastrocnemius force applied on the foot has a significant influence on the plantar pressure distribution. Finite element analysis can contribute to understanding etiology and pathology of foot diseases, predicting the biomechanical results of the treatment and provide theoretical reference for treatments.
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Three-dimensional (3D) reconstruction of cone-beam computed tomography (CBCT) scans appears to be a valuable method for assessing pulp canal configuration. The aim of this report is to describe endodontic treatment of a mandibular second premolar with aberrant pulp canal morphology detected by CBCT and confirmed by 3D modeling. An accessory canal was suspected during endodontic treatment of the mandibular left second premolar in a 21 year-old woman with a chief complaint of pulsating pain. Axial cross-sectional CBCT scans revealed that the pulp canal divided into mesiobuccal, lingual, and buccal canals in the middle third and ended as four separate foramina. 3D modeling confirmed the anomalous configuration of the fused root with a deep lingual groove. Endodontic treatment of the tooth was completed in two appointments. The root canals were obturated using lateral compaction of gutta-percha and root canal sealer. The tooth remained asymptomatic and did not develop periapical pathology until 12 months postoperatively. CBCT and 3D modeling enable preoperative evaluation of aberrant root canal systems and facilitate endodontic treatment.
Subject(s)
Female , Humans , Appointments and Schedules , Bicuspid , Cone-Beam Computed Tomography , Dental Pulp Cavity , Gutta-Percha , Pathology , ToothABSTRACT
Three-dimensional (3D) reconstruction of cone-beam computed tomography (CBCT) scans appears to be a valuable method for assessing pulp canal configuration. The aim of this report is to describe endodontic treatment of a mandibular second premolar with aberrant pulp canal morphology detected by CBCT and confirmed by 3D modeling. An accessory canal was suspected during endodontic treatment of the mandibular left second premolar in a 21 year-old woman with a chief complaint of pulsating pain. Axial cross-sectional CBCT scans revealed that the pulp canal divided into mesiobuccal, lingual, and buccal canals in the middle third and ended as four separate foramina. 3D modeling confirmed the anomalous configuration of the fused root with a deep lingual groove. Endodontic treatment of the tooth was completed in two appointments. The root canals were obturated using lateral compaction of gutta-percha and root canal sealer. The tooth remained asymptomatic and did not develop periapical pathology until 12 months postoperatively. CBCT and 3D modeling enable preoperative evaluation of aberrant root canal systems and facilitate endodontic treatment.
Subject(s)
Female , Humans , Appointments and Schedules , Bicuspid , Cone-Beam Computed Tomography , Dental Pulp Cavity , Gutta-Percha , Pathology , ToothABSTRACT
Objective To make biomechanical evaluation on three prosthesis retention schemes for unilateral maxillary defects-clasp retention, one or two zygomatic implants and zygomatic implant and clasp united retention. Methods A three-dimensional (3D) finite element model of normal human skull was constructed based on CT scan data. The maxillary complex stress distributions on three reconstructed models were calculated and analyzed by 3D finite element method to make comprehensive comparison on stress level of the prosthesis, abutment, clasp, implants and zygoma. Results For single clasp retention, peak stress of the abutment was 130.7 MPa, and displacement of the prosthesis was 4.439 mm, while peak stress of the clap was 452.4 MPa, and stress of the contralateral orbital rim was 23.32 MPa. After one zygoma was implanted, the stress of the clap was reduced to 118.1 MPa, while peak stress of the abutment was 31.12 MPa, and stress of the contralateral orbital rim was only 5.387 MPa. For two zygomatic implant retention, zygomatic stress was decreased from 66.11 MPa to 48.12 MPa, and the maximum stress on the zygomatic implants was reduced from 500.2 MPa to 313.8 MPa. Conclusions For zygomatic implant and clasp united retention, the maxillofacial skeleton stress distributions were more consistent with the rules of bite force transduction. The research findings will provide important references for design and optimization of human unilateral maxillary defect reconstruction program.