Replica Model Research Articles

Fracture load of three-unit full-contour fixed dental prostheses fabricated with subtractive and additive CAD/CAM technology.

The aim of this study was to test the fracture load of ceramic and composite three-unit full-contour fixed dental prostheses (FDPs) fabricated with additive and subtractive computer-aided design (CAD)/computer-aided manufacturing (CAM) technology. A newly developed alveolar socket replica model for a three-unit FDP replacing one molar was used in this study. Five CAD/CAM materials were used for fabrication of three-unit FDPs (each n = 12). The subtractive CAD/CAM fabrication method was used for groups BC (BRILLIANT Crios), TC (Telio CAD), EX (e.max CAD), and TZ (inCoris TZI C), and the additive method was used for group 3D (els 3D resin even stronger). FDPs were adhesively seated to the abutment dies (PANAVIA V5 system). Thermomechanical loading was performed prior to fracture testing with a universal testing machine. The data for maximum fracture load values was analyzed with one-way ANOVA and post hoc Scheffé test (α = 0.05). All FDPs survived the thermomechanical loading test. Statistically significant differences were found for the fracture load of three-unit FDPs fabricated from different CAD/CAM materials (p < 0.05). The highest mean fracture load was found for group TZ (2099.5 ± 382.1N). Group 3D showed the lowest mean fracture load (928.9 ± 193.8N). Group BC performed statistically significantly differently from group 3D with a mean fracture load of 1494.8 ± 214.5N (p < 0.05). Particle-filled composite resin CAD/CAM materials showed fracture load values within the range of ceramic materials with a specific indication of use for three-unit FDPs. Particle filled composite CAD/CAM materials may offer new treatment possibilities for the CAD/CAM workflow.

Experimental investigation of seismic behaviour of the ancient Protiron monument model

SummaryThroughout history, dry‐stone masonry structures have been strengthened with different types of metal connectors in order to increase their resistance which enabled their survival, especially in the seismically active area. One such example is the ancient Protiron monument placed in the Peristyle square of the Diocletian's Palace in Split, Croatia. The Protiron was built at the turn of the 3rd century as a stone masonry structure with dowels embedded between its base, columns, capitals and broad gable. The stone blocks in the broad gable were connected by metal clamps during restoration at the beginning of the 20th century. In order to study the seismic performance of the strengthened stone masonry structures, an experimental investigation of seismic behaviour of a physical model of the Protiron was performed on the shaking table. The model was designed as a true replica model in a length scale of 1:4 and exposed to representative earthquake with increasing intensities up to collapse. The tests provided a clear insight into system behaviour, damage mechanism and failure under intensive seismic load, especially into the efficiency of connecting elements, which had a special role in increasing seismic resistance and protection of the structure from collapse. Additionally, this experiment provided valuable data for verification and calibration of numerical models for strengthened stone masonry structures.

Design and analysis of ISO standard bolt and nut in FDM 3D printer using PLA and ABS materials

Abstract A process of generating 3D object from a digital file consistently by arranging many thin layers of metals in succession is named as 3D printing. It has been gaining tremendous development in present years. By the use of additive manufacturing technology, a 3D digital design is reformed into virtual product by depositing metal consecutively. 3D printing provides resourceful feasibilities for complying various parameters based on engineering arena. In Fusion Deposition Modeling 3D printer, the primary materials needed are ABS and PLA. This experimental analysis is proposed by modelling a 3D ISO standard nut and bolt. A replica model of nut and bolt is created using 3D printer, by the use of Poly Lactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) materials. By using software titled CURA the slicing has been done precisely and directed to printing. Later this model is analyzed on ANSYS software for shear stress, equivalent stress and deformation. The PLA as well as ABS bolts are correlated with each other and evaluated.

Bases para implementar una consultoría económica, financiera y de gestión para la Mipymes

This article aims to make a compilation and analysis of relevant and up-to-date information that provides input to see the feasibility and implications of the start-up of a consultancy service for small and medium-sized enterprises rendered by Centro de Servicios Financieros (CSF); this article is derived from the research project Implementation of consultancy for the economic, financial and management areas of MSMEs enterprises of Bogota and Cundinamarca of financed by SENNOVA since 2016. This bibliographical review article seeks to contextualize interested readers about the nature of consultancies (particularly as regards economic issues) and previous experiences in Colombia, as a result, interesting practices that can be a replica model to be implemented within the CSF are identified to set up a portfolio of services for MSMEs that cannot afford specialized consultancy and need a great deal of support to guarantee their profitability and sustainability in the medium and long term.

A Novel Marker Based Method to Teeth Alignment in MRI

Abstract Magnetic resonance imaging (MRI) can precisely capture the anatomy of the vocal tract. However, the crowns of teeth are not visible in standard MRI scans. In this study, a marker-based teeth alignment method is presented and evaluated. Ten patients undergoing orthognathic surgery were enrolled. Supraglottal airways were imaged preoperatively using structural MRI. MRI visible markers were developed, and they were attached to maxillary teeth and corresponding locations on the dental casts. Repeated measurements of intermarker distances in MRI and in a replica model was compared using linear regression analysis. Dental cast MRI and corresponding caliper measurements did not differ significantly. In contrast, the marker locations in vivo differed somewhat from the dental cast measurements likely due to marker placement inaccuracies. The markers were clearly visible in MRI and allowed for dental models to be aligned to head and neck MRI scans.

A History of Israel: From the Bronze Age through the Jewish Wars

A History of Israel: From the Bronze Age through the Jewish Wars

XP-endo Shaperによる楕円根管模型形成における切削量および非接触領域のマイクロCTによる評価

XP-endo Shaperによる楕円根管模型形成における切削量および非接触領域のマイクロCTによる評価

Evaluation on the Perception of the New Portable Set for Hajj Course (P.A.H.A.M) Based on Design Characteristics

This paper is about the perceptions of the pilgrims to the innovation of the portable training set for hajj course (P.A.H.A.M). The acronym P.A.H.A.M come from the Malay word “Praktikal Haji Mudahalih” as a tool in helping the hajj and umrah pilgrims to better understand the concept while doing the hajj and umrah practical. In Malaysia, one of the managing bodies of pilgrimage for Muslims in is Pilgrims Fund Board. It provides a series of courses every year to help in boosting the understanding of the pilgrims before leaving for the Holy Land. During the practical session, they will provide the replica model to help pilgrims to familiarise themselves with the actual situation in Mecca. However, the current replica model was built using an iron structure that is relatively heavy, not portable and embarks more cost of transportation and labour. Therefore, this paper discusses the perceptions of the pilgrims on the characteristics of Portable Training Set for Hajj Course (P.A.H.A.M) compared to the existing set in order to increase the understanding of pilgrims. A total of 53 samples of hajj and umrah pilgrims participated in this study consisted of the general public. From the data analysed using Statistical Software for Social Sciences (SPSS v19), the results of the survey showed that more than 90% of respondents agreed that this portable training set meets the characteristics such as easy to handle, more safety in crowd, portable, stability, light weight, suitable in-door and out-door activity, easy to clean, and more structured with average score 4.00 (agreed) and above. In conclusion, it is expected that this Portable Training Set for Hajj Course (P.A.H.A.M) can be used by Muslim’s communities in Malaysia particularly and Muslim countries in general to better understand the hajj and umrah activities before leaving to the Holy Land.

Validation of newly developed physical laparoscopy simulator in transabdominal preperitoneal (TAPP) inguinal hernia repair.

A realistic simulator for transabdominal preperitoneal (TAPP) inguinal hernia repair would enhance surgeons' training experience before they enter the operating theater. The purpose of this study was to create a novel physical simulator for TAPP inguinal hernia repair and obtain surgeons' opinions regarding its efficacy. Our novel TAPP inguinal hernia repair simulator consists of a physical laparoscopy simulator and a handmade organ replica model. The physical laparoscopy simulator was created by three-dimensional (3D) printing technology, and it represents the trunk of the human body and the bendability of the abdominal wall under pneumoperitoneal pressure. The organ replica model was manually created by assembling materials. The TAPP inguinal hernia repair simulator allows for the performance of all procedures required in TAPP inguinal hernia repair. Fifteen general surgeons performed TAPP inguinal hernia repair using our simulator. Their opinions were scored on a 5-point Likert scale. All participants strongly agreed that the 3D-printed physical simulator and organ replica model were highly useful for TAPP inguinal hernia repair training (median, 5 points) and TAPP inguinal hernia repair education (median, 5 points). They felt that the simulator would be effective for TAPP inguinal hernia repair training before entering the operating theater. All surgeons considered that this simulator should be introduced in the residency curriculum. We successfully created a physical simulator for TAPP inguinal hernia repair training using 3D printing technology and a handmade organ replica model created with inexpensive, readily accessible materials. Preoperative TAPP inguinal hernia repair training using this simulator and organ replica model may be of benefit in the training of all surgeons. All general surgeons involved in the present study felt that this simulator and organ replica model should be used in their residency curriculum.

Investigation of flow pattern in upper human airway including oral and nasal inhalation by PIV and CFD

Breathing is one of the most essential processes in the human body. The basic functions of breathing are to exchange gases (supplying oxygen from ambient air and removing carbon dioxide from the blood) and also to exchange heat and moisture through mucous surfaces of the airway. During an average lifetime, human beings experience significant exposure to indoor air and countless of contaminants/particles via inhalation. In this study, experimental and numerical results of flow fields in a realistic respiratory model were obtained. Flow patterns in a realistic replica model of the human respiratory tract were investigated with particle image velocimetry (PIV) under three constant breathing conditions; 7.5, 15 and 30 L/min. Computational fluid dynamics (CFD) analyses were conducted on turbulent models with boundary conditions corresponding to the experimental models. We used four RANS turbulence models to predict airflow in a realistic human airway model: two low Reynolds (Re) number-type k–ε turbulence models, RNG k–ε model, and the SST k–ω model. The CFD results were compared with PIV data and showed relatively good agreement in trachea region in all cases.

Letter to the Editor: “High-Fidelity Meets Athletic Training Education: An Innovative Collaborative Teaching Project”

Letter to the Editor: “High-Fidelity Meets Athletic Training Education: An Innovative Collaborative Teaching Project”

Continuing robotic surgery education in da Vinci training using virtual reality and actual simulator of 3D printing body organ replica model

手術支援ロボットda Vinciにおける手術の安全性・正確性の向上と手技習熟の効率化を目的とした, 認定資格取得後修練の現状と, 近年注目されている3Dプリンティングによる実物大臓器立体モデルおよび体腔実体モデルを用いたシミュレーションおよびトレーニングを解説した. 現在行われているda Vinciのcertificate認定後の継続的トレーニングは, おもにOJTやデュアルコンソールトレーニング, 基礎手技用トレーニングキットやドライボックス, バーチャルリアリティシミュレータ, 動物臓器などのwet tissue, 生体動物などのlive animal labo, cadaverトレーニング, 臓器や体腔などの実体モデルによるトレーニングなどが行われている. 筆者らが開発した臓器体腔実体モデルは, 患者のCT画像に基づき, 実際の手術の状態を再現するために, 体位変換や気腹状態を計算して, 臓器と体腔を実物大実体モデルに再現した. 各種臓器の解剖学的構造と立体的位置関係, 体腔内のワーキングスペースの制限を再現することで, 実際の手術手技を正確に再現し患者個別化に対応できるトレーニングとなった. 臓器モデルは生体の質感まで再現し, 出血や縫合などの手技が実際の手術同様に再現できるため, 手術シミュレーションとしても有用であり, 他のトレーニングに変わる新たな手法として期待できる.

Lower limb kinematics and physiological responses to prolonged load carriage in untrained individuals

The aim of this study was to simultaneously assess the changes in physiology, and kinematic and spatiotemporal features of gait, during prolonged load carriage in individuals without load carriage experience. Eleven males, representative of new military recruits, walked for 120 min at 5.5 km h− 1, 0% grade, on a motorised treadmill while carrying a 22 kg load. The load ( ≤ 30% body mass) was distributed over a weighted vest, combat webbing and replica model firearm, to reflect a patrol order load. Oxygen consumption and heart rate increased throughout the trial; however, apart from a minor increase in step length, there were no changes in the kinematic or spatiotemporal parameters, despite an increase in perceived exertion and discomfort. These data suggest that individuals with no experience in load carriage are able to maintain normal gait during 2 h of fixed speed walking, while carrying a patrol order load ≤ 30% body mass.

심장 혈관계 시스템의 교육 모형 고안

심장의 모양 및 혈관에 관한 의료학적 지식습득은 의료인 및 의료기사들과 같은 의료전문인들에게는 필수적 요구사항이다. 심장의 모형을 통한 의료지식의 습득은 환자의 생명과도 직결되는 중요한 사항이기 때문에 보다 정확한 의료지식이 필요하다. 따라서 심장모양 및 심장혈관질환에 대한 다양한 의료교구재의 연구 및 개발이 필요하다. 이번 연구에서 만들어진 심장 및 심장혈관의 투시 모형장비를 사용하여 심장 혈류의 투시조영시의 볼 수 있는 방사선학적 사진 영상을 미리 습득할 수 있으며, 또한 투시 조영 중 환자의 자세의 따른 심장의 위치와 모형을 미리 예측해 볼 수도 있다. 결론적으로 우리가 고안한 심장혈관 투시 장비를 사용하여 심장혈관의 해부학적 지식을 미리 습득함으로서 면허 취득 후에 임상생활에 있어서의 심장혈류에 관한 정확한 이해에 도움을 줄 수 있을 것으로 사료된다. The understanding of medical knowledge regarding cardiac shape and cardiovascular system is essentially required for a medical personnel as well as a medical technician. Correct acquisition of medical knowledge through cardiac miniature model is very critical because it is directly related to a patient life. therefore replica model is necessary for the education regarding cardiac and cardiovascular system. In this study anatomical cardiovascular system on fluoroscopy can be shown by cardiac and cardiovascular fluoroscopy replica model. Also, it helps to understand a cardiovascular radiograph. Consequentially medical personnel and medical technician are able to take advantage of this equipment to understand cardiovascular fluoroscopy system.

Keldysh approach to the renormalization group analysis of the disordered electron liquid

We present a Keldysh nonlinear sigma-model approach to the renormalization group analysis of the disordered electron liquid. We include both the Coulomb interaction and Fermi-liquid type interactions in the singlet and triplet channels into the formalism. Based on this model, we reproduce the coupled renormalization group equations for the diffusion coefficient, the frequency, and interaction constants previously derived with the replica model in the imaginary time technique. With the help of source fields coupling to the particle-number and spin densities, we study the density-density and spin density-spin density correlation functions in the diffusive regime. This allows us to obtain results for the electric conductivity and the spin susceptibility and thereby to re-derive the main results of the one-loop renormalization group analysis of the disordered electron liquid in the Keldysh formalism.

Fabrication of Hip and Pelvis Part for Designing Acetabular Implant by Using Fused Deposition Modeling (FDM) Machine

The purpose of this research is to fabricate the hip and pelvis part for designing the acetabular implant by using Fused Deposition Modeling (FDM) technique. The methodology of this research is begin by converting the 2D image of CT into 3D image through Invesalius 3.0 software. Then the 3D image is converted to .stl format and exported to FDM machine for fabrication purpose. The finish prototype of 3D biomodel replica is evaluated in order to define the problem face by the patient. Also, the dimensional accuracy is measured between 3D replica model and 3D virtual model. Based on the result of 3D biomodel, the ball joint of the femur on the right side is dislocating from its original position because of the fracture occur on acetabular socket. The implant for acetabular fracture is design by using CATIA software and the design must ensure to be fit with the fracture area. Therefore, this study has contributed to medical area especially in Malaysia in improving patient specific preoperative planning and giving better visualization information of the fracture.

Effect of surface treatment on stress distribution in immediately loaded dental implants—A 3D finite element analysis

ObjectiveTo investigate, by means of FE analysis, the effect of surface roughness treatments on the distribution of stresses at the bone–implant interface in immediately loaded mandibular implants. Materials and methodsAn accurate, high resolution, digital replica model of bone structure (cortical and trabecular components) supporting an implant was created using CT scan data and image processing software (Mimics 13.1; Materialize, Leuven, Belgium). An anatomically accurate 3D model of a mandibular-implant complex was created using a professional 3D-CAD modeller (SolidWorks, DassaultSystèmes Solid Works Corp; 2011). Finite element models were created with one of the four roughness treatments on the implant fixture surface. Of these, three were surface treated to create a uniform coating determined by the coefficient of friction (μ); these were either (1) plasma sprayed or porous-beaded (μ=1.0), (2) sandblasted (μ=0.68) or (3) polished (μ=0.4). The fourth implant had a novel two-part surface roughness consisting of a coronal polished component (μ=0.4) interfacing with the cortical bone, and a body plasma treated surface component (μ=1) interfacing with the trabecular bone. Finite element stress analysis was carried out under vertical and lateral forces. ResultsThis investigation showed that the type of surface treatment on the implant fixture affects the stress at the bone–implant interface of an immediately loaded implant complex. Von Mises stress data showed that the two-part surface treatment created the better stress distribution at the implant–bone interface. SignificanceThe results from this FE computational analysis suggest that the proposed two-part surface treatment for IL implants creates lower stresses than single uniform treatments at the bone–implant interface, which might decrease peri-implant bone loss. Future investigations should focus on mechanical and clinical validation of these FE results.

LANDAU CONFINING REPLICA MODEL FROM AN EXPLICITLY BREAKING OF A SU(3) GROUP WITHOUT AUXILIARY FIELDS

We propose a mechanism displaying gluon confinement, as defined by the behavior of the propagators, in a model of SU(2) gauge fields. The model originates from an explicitly broken SU(3) gauge theory giving rise to a replica model composed of three mixed SU(2) groups. The mechanism consists in the usual SU(3) Yang–Mills theory in the Landau gauge, with a soft breaking term in such a way as to change the field propagation and group content at low energies. The relation of this soft mass term with the Gribov problem is presented and the link between soft terms and the scaling and decoupling solutions is discussed.

Effect of the crown design and interface lute parameters on the stress-state of a machined crown–tooth system: A finite element analysis

The effect of preparation design and the physical properties of the interface lute on the restored machined ceramic crown–tooth complex are poorly understood. The aim of this work was to determine, by means of three-dimensional finite element analysis (3D FEA) the effect of the tooth preparation design and the elastic modulus of the cement on the stress state of the cemented machined ceramic crown–tooth complex.The three-dimensional structure of human premolar teeth, restored with adhesively cemented machined ceramic crowns, was digitized with a micro-CT scanner. An accurate, high resolution, digital replica model of a restored tooth was created. Two preparation designs, with different occlusal morphologies, were modeled with cements of 3 different elastic moduli. Interactive medical image processing software (mimics and professional CAD modeling software) was used to create sophisticated digital models that included the supporting structures; periodontal ligament and alveolar bone. The generated models were imported into an FEA software program (hypermesh version 10.0, Altair Engineering Inc.) with all degrees of freedom constrained at the outer surface of the supporting cortical bone of the crown–tooth complex. Five different elastic moduli values were given to the adhesive cement interface 1.8GPa, 4GPa, 8GPa, 18.3GPa and 40GPa; the four lower values are representative of currently used cementing lutes and 40GPa is set as an extreme high value. The stress distribution under simulated applied loads was determined. The preparation design demonstrated an effect on the stress state of the restored tooth system. The cement elastic modulus affected the stress state in the cement and dentin structures but not in the crown, the pulp, the periodontal ligament or the cancellous and cortical bone. The results of this study suggest that both the choice of the preparation design and the cement elastic modulus can affect the stress state within the restored crown–tooth complex.

Comparison of the Accuracy of Biomet 3i Encode Robocast Technology and Conventional Implant Impression Techniques

To compare the accuracy of implant master casts fabricated using Robocast Technology (Biomet 3i) with that of master casts fabricated using traditional transfer (closed-tray) and pick-up (open-tray) techniques. A stereolithographic replica of a Kennedy Class I human mandible was fabricated for use as the master model. Implants were placed into both posterior quadrants (both second premolars and second molars) and set parallel (P) on one side and divergent (nonparallel, NP) on the opposite side. Impressions were made of the master model (patient replica model) with Encode Healing Abutments, open-tray, and closed-tray impression copings. Identical metallic spheres were placed onto each implant analog in the stone master casts, and the casts/spheres were scanned using a digital scanner. Measurements were made between the center points of the spheres and compared to the master model. Data were divided into P, NP, and individual sites, and the differences were analyzed statistically (α = .05). Encode master casts were less accurate than the open-tray casts in NP sites. Encode master casts were less accurate than the open-tray and closed-tray casts in P sites. NP sites demonstrated less accuracy than P sites within the Encode group. Encode master casts were less accurate than the open- and closed-tray casts at the mandibular right second premolar site. The mandibular left second premolar was less accurate than the mandibular right second molar in the Encode group. Within the limitations of this lab-based study and analysis, the Encode technique resulted in master casts that were less accurate than master casts made from traditional open- and closed-tray impression techniques. Further research is necessary before specific clinical judgments can be made.