Three-dimensional Replica Research Articles

Digital Simulation and Designing of a Novel Osteotomy Guide for Autotransplantation in the Anterior Region.

Autotransplantation of teeth (ATT) is a viable treatment option for replacing teeth lost due to various reasons. Periodontal ligament (PDL) on the donor tooth is one of the most crucial factors determining the success of ATT. To preserve the PDL during surgery and improve the success rate of ATT, digital dentistry has been applied to ATT. In this article, a digital workflow including surgical simulation, a three-dimensional (3D) replica fabrication, and a novel osteotomy guide design is introduced. Digital simulation of ATT on a patient's integrated model enables visualization of anatomical structures and the 3D position of the donor tooth prior to the actual surgery. The 3D-printed osteotomy guide allows the transfer of the direction and depth of the planned osteotomy into the intraoral environment. The 3D replica helps prepare the recipient site before the actual transplantation, which minimizes the extra-alveolar time of the donor tooth and decreases trauma during the try-in process. The proposed virtual planning and the use of the guide and the 3D replica can facilitate the surgical procedures while minimizing complications.

Three-dimensional replica of the temporal bone in the teaching of human anatomy.

The current study proposes the comparison of the visualization and identification of anatomical details between natural human temporal bone, its respective copy from three-dimensional printing, and the virtual model obtained from CBCT. The sample consisted of undergraduate students in Dentistry (Group UE, n = 22), Postgraduate students in Radiology and Imaging (Group P-RI, n = 20), and Postgraduate students in Forensic Odontology (Group P-FO, n = 24). All participants attended a theoretical class on specialized anatomy of the temporal bone and subsequently performed the markings of 10 determined structures. The number of correct identifications was similar in natural bone and printed three-dimensional models in all groups (p > 0.05). The virtual model showed a significantly lower number of correct structures (p < 0.05) in the 3 groups. In general, there were significantly higher percentages of accurate answers among postgraduate students compared to undergraduate students. Most graduate students believed that the printed three-dimensional model could be used to teach anatomy in place of natural bone, while undergraduate students disagreed or were unsure (p < 0.05). Regarding the virtual tomographic image, in all groups, students disagreed or were not sure that its use would be beneficial in replacing natural bone. Three-dimensional and virtual models can be used as auxiliary tools in teaching anatomy, complementing practical learning with natural bones.

Development of a soft three-dimensional replica of the mitral valve for procedural planning.

Mitral valve (MV) disease is the most common and the most heterogeneous valvular pathological condition in the general population [1]. Repair is superior to replacement in most cases and offers the patient a normal life expectancy and normal quality of life. However, due to individual anatomical variations, the lack of standardization, the steep learning curves, the variety of repair techniques and the lack of available expertise everywhere, the quality of care is extremely operator dependent. Ideally, a surgeon needs to perform >25-MV operations per year to sustain predictable and durable results, whereas a surgeon performs a median number of 5-MV operations per year in the USA [2–4]. Moreover, the learning curve for minimally invasive MV surgical procedures requires >75–125 cases due to their complexity [5]. In addition, there are >70 new transcatheter devices in development for the treatment of MV disease, though few are actually being used in clinical practice [6]. These new transcatheter devices are image-guided and target a specific lesion for which patient selection, procedural planning and image guidance are crucial. All of the above necessitate the application of new technologies, such as three-dimensional (3D) reconstruction, 3D printing and simulation, in selecting patients, planning the procedure and executing MV surgical techniques.

Quality Evaluation of Epoxy Pore Casts Using Silicon Micromodels: Application to Confocal Imaging of Carbonate Samples

Pore casting refers to filling the void spaces of porous materials with an extraneous fluid, usually epoxy resin, to obtain a high-strength composite material, stabilize a fragile porous structure, produce a three-dimensional replica of the pore space, or provide imaging contrast. Epoxy pore casting may be accompanied by additional procedures, such as etching, in which the material matrix is dissolved, leaving a clean cast. Moreover, an epoxy resin may be mixed with fluorophore substances to allow fluorescence imaging. Our work aims to investigate and optimize the epoxy pore casting procedure parameters, for example, impregnation pressure. We use silicon micromodels as a reference to validate the key parameters of high-pressure resin impregnation. We demonstrate possible artifacts and defects that might develop during impregnation with resin, e.g., resin shrinkage and gas trapping. In the end, we developed an optimized protocol to produce high-quality resin pore casts for high-resolution 3D imaging and the description of microporosity in micritic carbonates. In our applications, the high-quality pore casts were acid-etched to remove the non-transparent carbonate material, making the pore casts suitable for imaging with Confocal Laser Scanning Microscopy (CLSM). In addition, we evaluate the quality of our etching procedure using micro-computed tomography (micro-CT) scans of the pre- and post-etched samples and demonstrate that the etched epoxy pore casts represent the pore space of microporous carbonate rock samples with high fidelity.

Image-based method for evaluation of effective thermal conductivity of metal foam with hollow ligaments

A feature preserving image-based method was used to estimate the effective thermal conductivity of copper metal foam having hollow ligaments. Hollow portions of the ligament and node were identified from X-ray computed microtomography images, through image processing. The effective thermal conductivity was estimated for foams with hollow ligaments filled with water, air, or vacuum. The fluid filling the pore was considered as water or air. Estimations were also conducted for the case where the metal foam is kept in a vacuum condition, where the heat transfer happens only through the ligaments and nodes. The effective thermal conductivity of metal foam with hollow ligaments was compared with that of metal foams with solid ligaments, maintaining the same ligament cross-sectional area. Two metal foams, having total porosity of 90.8% and 90% and hollowness of 4.45% and 1.65% respectively, were selected for the study. The effective thermal conductivity values obtained were compared with the analytical and empirical models available in the literature. Microtomography-based computational fluid dynamics study was also conducted based on the three-dimensional replica of the metal foam, generated from the two-dimensional tomography images. The thermal conductivity obtained from the computational microtomography based study and the image-based method was found to be in good agreement.

Transplant surgical templates for dental autotransplantation: a technical note

Introduction: This technical note presents the autotransplantation of an impacted third molar to replace a severely damaged homolateral molar using a surgical template of the tooth to be transplanted to prepare the recipient site based on an original protocol. Technique: Mandibular molar extraction is first performed, and autotransplantation is done after 7 days. Alveolar adjustment of the receiving socket is done using a resin replica of the tooth to be transplanted; the replica is obtained using DICOM diagnosis data. The three-dimensional (3D) replica is produced using 3D printing techniques with photopolymerizable methacrylate resin. Once the recipient site is ready, the transplant is avulsed. Immediate positioning of the tooth in the new socket will save a tremendous amount of extra-alveolar time. Cross-stitch sutures are done to obtain complete restraint, and endodontic treatment is administered after 15 days. Postoperative clinical and radiographic examination showed periodontal healing after postoperative 6 months. Comments: The use of the surgical template resulted in an extra-alveolar time of below 5 s and preservation of healthy periodontal ligament cells of the donor tooth as much as possible. Conclusion: The 3D technology, from imaging to printing, can drive the improvement of prognosis in a tooth autotransplantation protocol.

MRI versus CT as Image Data Source for 3D Printing Bone

In orthopedics, 3D printing is a novel way of visualizing dense human tissue and structures, for example bones and ligaments, but also the respective relations between them, thus providing the surgical team with taking the preoperative planning of an intervention one step further from 3D computer reconstructions. In order for a medical 3D print reconstruction to be possible, bidimensional imaging is necessary, in the form of DICOM files. These are then used by specific software in order to create an STL file, that can then be inputted into a 3D printer and a three-dimensional replica of the desired structure, usually on a 1:1 scale, can be generated. We aim to compare two methods of acquiring and processing of 2D images � MRI and CT scans � as sources of DICOM files, with the end purpose of 3D printing the image of human bone.

Casting Materials and their Application in Research and Teaching

From a biological point of view, casting refers to filling of anatomical and/or pathological spaces with extraneous material that reproduces a three-dimensional replica of the space. Casting may be accompanied by additional procedures such as corrosion, in which the soft tissue is digested out, leaving a clean cast, or the material may be mixed with radiopaque substances to allow x-ray photography or micro computed topography (µCT) scanning. Alternatively, clearing of the surrounding soft tissue increases transparency and allows visualization of the casted cavities. Combination of casting with tissue fixation allows anatomical dissection and didactic surgical procedures on the tissue. Casting materials fall into three categories namely, aqueous substances (India ink, Prussian blue ink), pliable materials (gelatins, latex, and silicone rubber), or hard materials (methyl methacrylates, polyurethanes, polyesters, and epoxy resins). Casting has proved invaluable in both teaching and research and many phenomenal biological processes have been discovered through casting. The choice of a particular material depends inter alia on the targeted use and the intended subsequent investigative procedures, such as dissection, microscopy, or µCT. The casting material needs to be pliable where anatomical and surgical manipulations are intended, and capillary-passable for ultrastructural investigations.

Evaluation of the marginal and internal gap of metal-ceramic crown fabricated with a selective laser sintering technology: two- and three-dimensional replica techniques

PURPOSEOne of the most important factors in evaluating the quality of fixed dental prostheses (FDPs) is their gap. The purpose of this study was to compare the marginal and internal gap of two different metal-ceramic crowns, casting and selective laser sintering (SLS), before and after porcelain firing. Furthermore, this study evaluated whether metal-ceramic crowns made using the SLS have the same clinical acceptability as crowns made by the traditional casting.MATERIALS AND METHODSThe 10 study models were produced using stone. The 20 specimens were produced using the casting and the SLS methods; 10 samples were made in each group. After the core gap measurements, 10 metal-ceramic crowns in each group were finished using the conventional technique of firing porcelain. The gap of the metal-ceramic crowns was measured. The marginal and internal gaps were measured by two-dimensional and three-dimensional replica techniques, respectively. The Wilcoxon signed-rank test, the Wilcoxon rank-sum test and nonparametric ANCOVA were used for statistical analysis (α=.05).RESULTSIn both groups, the gap increased after completion of the metal-ceramic crown compared to the core. In all measured areas, the gap of the metal cores and metal-ceramic crowns produced by the SLS was greater than that of the metal cores and metal-ceramic crowns produced using the casting. Statistically significant differences were found between cast and SLS (metal cores and metal-ceramic crown).CONCLUSIONAlthough the gap of the FDPs produced by the SLS was greater than that of the FDPs produced by the conventional casting in all measured areas, none exceeded the clinically acceptable range.

Three-Dimensional Replica of a Life-Sized Model of Aortic Arch Aneurysm for Preoperative Assessments

In the treatment of extended distal aortic arch aneurysms with open stent grafting, detailed preoperative minute evaluation is essential to determine the optimal operative strategy and reduce the incidence of complications. We describe a three-dimensional replica of a life-sized aortic arch aneurysm model for aiding preoperative assessments. Life-sized replicas of an aortic arch aneurysm were made for 4 patients who underwent total aortic arch replacement with open stent-grafting. These replicas were used to determine the curve of the CLATE, a newly developed open stent delivery system (Senko Medical Instrument Mfg, Co, Ltd, Tokyo, Japan), and the depth of the open stent grafting. The replica and the CLATE system were also used to obtain informed consent from the patients. Surgeons could simulate the operative procedure precisely. Insertion of the graft was smooth in all patients. Use of the replica made it easier for the patients to understand the form and site of the aneurysm, as well as the operative procedure. The combination of the three-dimensional replica and the CLATE system may be useful for both surgeons and patients in the treatment of extended distal aortic arch aneurysms.

Three-dimensional fit of CAD/CAM-made zirconia copings

Objectives CAD/CAM-technologies aim for a standardized, accurate production of dental restorations out of high strength materials (zirconia). The three-dimensional internal fit of CAD/CAM-manufactured zirconia copings was evaluated in vitro to verify the realizability of this aim. Methods The analysis was based on ceramic master dies of prepared teeth and corresponding virtual CAD surfaces. Five copings per die were manufactured with two different CAD/CAM-technologies: milling and grinding. The internal fit was determined by a three-dimensional replica technique by optical digitization and computer-assisted analysis. Results Mean internal gaps were 134/84 μm (SD 78/28) for molar and 93/69 μm (SD 56/35) for premolar copings (milling/grinding) using a digitizable silicone for the replicas representing the cement space; they were statistically significant regarding tooth and CAD/CAM-system ( p < 0.001). Significance All zirconia copings showed an internal accuracy of fit where the gap widths ranged within the current clinical recommendations. However, there still is room for improvement and further standardization of CAD/CAM-technologies.

Synthesis of a periodic SiC/C nanostructure

Highly porous periodic structures consisting of a three-dimensional replica of pores in the initial opal lattice have been synthesized by high-temperature thermochemical treatment of opal matrices filled with carbon compounds, followed by dissolution of silicon dioxide. It has been shown that the main phases of the composite are carbon and silicon carbide. Based on the X-ray diffraction, Raman, and IR spectroscopy data, it has been assumed that the composite contains fragments of hexagonal diamond. The photoluminescence and optical reflection spectra of the composites have been measured.

Validation of a new method for building a three-dimensional physical model of the skull and dentition

We present a new method for replicating the skull and occlusal surface with an accurate physical model that could be used for planning orthognathic surgery. The investigation was made on 6 human skulls, and a polyvinyl splint was fabricated on the dental cast of the maxillary dentition in each case. A cone beam computed tomogram (CBCT) was taken of each skull and a three-dimensional replica produced. The distorted dentition (as a result of magnification errors and streak artefacts) was removed from the three-dimensional model and replaced by new plaster dentition that was fabricated using the polyvinyl splint and a transfer jig replication technique. To verify the accuracy of the method the human skulls and the three dimensional replica model, with the new plaster dentition in situ, were scanned using a laser scanner. The three-dimensional images produced were superimposed to identify the errors associated with the replacement of the distorted occlusal surface with the new plaster dentition. The overall mean error was 0.72 and SD was (0.26) mm. The accuracy of the method encouraged us to use it clinically in a case of pronounced facial asymmetry.

SiC/C nanocomposites with inverse opal structure

The synthesis, morphology, structural and optical characteristics of SiC/C nanocompositeswith an inverse opal lattice have been investigated. The samples were preparedby thermochemical treatment of opal matrices filled with carbon compoundswhich was followed by silicon dioxide dissolution. The samples were studied byelectron microscopy, x-ray diffraction, photoluminescence, IR and Raman scatteringspectroscopy. The electron microscopy data revealed a highly porous periodicstructure which was a three-dimensional replica of the voids of the initial opallattice. The hexagonal silicon carbide was found to be non-uniformly distributedthroughout the volume, its greater part located in the surface layer up to50 µm deep. The data of x-ray diffraction, IR and Raman scattering spectroscopy enabled us toassume that the composite had hexagonal diamond fragments. The photoluminescence andoptical reflection spectra of the composites have been measured.

Finite-element-assisted modelling of a thermoplastic pultrusion process for powder-impregnated yarn

The pultrusion of thermoplastics represents an efficient production process, which promises to deliver superior product quality in an economic way. In order to develop a fundamental understanding, endeavours are undertaken to elucidate the mechanisms inside the pultrusion die. Therefore, efforts are directed towards an analytical investigation of the various process parameters while considering the usage of thermoplastic prepreg such as powder-impregnated sheathed yarn. The presented approach focuses on the finite-element simulation of the conditions occurring in a heated pultrusion die. Essential for the accuracy of such a model is the close approximation of the die geometry, boundary conditions, and material properties. The advanced three-dimensional replica of the cavity also distinguishes between the thermoplastic matrix and the enclosed fibre bundles. Hence, the model accounts for anisotropic fluid and thermal properties within the die region. For symmetry reasons the model resembles a quarter of the heated section into which a total of 17 fibre bundles is introduced. A material model is incorporated, which considers non-Newtonian and temperature-dependent matrix behaviour and accounts for the transition from a solid to a molten state. Here the effect of the melting enthalpy on the temperature distribution is considered as well as the underlying drastic changes in viscosity. The intricately coupled equations of motion and of energy are solved in their three-dimensional form to obtain various process parameters such as flow velocity, pressure, temperature and shear rate. In particular the influence of the shear-thinning behaviour is discussed and its impact on the matrix flow profile is shown. The numerical simulations evaluate the effect of pulling velocity, die- and preheater settings and viscous energy dissipation. In order to verify the computations all the results are compared with experimental data including the internal pressure and temperature of the die. The simulation reproduces actual observations, such as the backflow of matrix. The correlation between the experiments and the analytical solutions were found to be very satisfactory.

Effect of a photonic band gap in the optical range on solid-state SiO2 cluster lattices — opals

It is shown that synthetic opals — cubic face-centered lattices of SiO2 clusters — are systems which exhibit a number of properties of photonic crystals in the visible-light range. By filling the voids (pores) in such lattices with different materials it is possible to vary the optical contrast of the medium and to obtain crystals of both the lattice of spheres type and its three-dimensional replica. It is shown that under conditions of identical optical contrast and in the presence of an additional optical inhomogeneity of the spheres, the transparency of the lattice of spheres is lower than that of its replica based on homogeneous media. A refractive index modulation of 1.266 was achieved in the lattice of spheres.

Volumetric multiplexed transmission holography of the heart with echocardiographic data

Three-dimensional imaging enhances delineation of cardiac anatomy and function. Currently, three-dimensional echocardiography involves complex rendering techniques to imply depth in a given image. Also, display of the final images on a video monitor neutralizes the volume information of the object. A hologram is a true, three-dimensional replica of the original object and does not entail complex data processing. Holography has not been used previously in cardiovascular imaging. In this experiment, 11 excised mammalian whole hearts and five isolated left ventricles were imaged in a water bath. Parallel, tomographic, echocardiographic images comprised the data source from which holograms were obtained by the technique of multiplexed holography. Holograms were mounted on a holographic film and viewed in a special viewing box. High-quality holograms were obtained from every data set. Excellent gray-scale discrimination allowed crisp visualization of cardiac structures and simulated diseases. Electronic sectioning and various projections optimized viewing of the three-dimensional anatomy in surgical orientations. Thus holograms can be produced from tomographic cardiac ultrasound data and could open a new avenue in three-dimensional echocardiography.

Integration of dental models in a three-dimensional replica

Integration of dental models in a three-dimensional replica

Chapter 3 Freeze-Fracture Deep-Etch Methods

Publisher Summary Freeze-fracture deep-etch methods avoids the use of both chemical fixatives and cryoprotectants and results in the production of a three-dimensional replica of the etched surface of the specimen. Samples are ultra-rapidly frozen and fractured, the ice is sublimed under vacuum from the fracture surface, and the specimen is replicated. Using this technique, great advances have been made in the understanding of the structure and molecular make up of animal cell cytoplasm. The one main advantage of the rapid-freeze deep-etch technique is that little prior preparation of material is needed other than that required by the experiments that are being carried out. Therefore, most of the material requirements are in the instrumentation, and accessability to the necessary freezing and fracturing equipment is often the major limitation in the application of this technique. The procedure can be split into two separate events: freezing, followed by the fracturing, etching, and replication of the frozen material. Specimens can be frozen and stored under liquid nitrogen for any length of time prior to the fracturing procedure.

Use of a laser-hardened three-dimensional replica for simulated surgery

The main established approaches to preoperative surgical planning for mandibular reconstruction and correction of jaw deformities have been paper simulations using radiographic images and profile photographs of the head, and plaster model simulations of the teeth and jaws. However, these do not always provide sufficient information, especially in patients with an asymmetry. Three-dimensional images generated from computerized tomographic (CT) scans have the advantage of providing the ability to simulate the operation as well as repositioning of bones on the computer screen. Accumulated experience in cases with complicated features however, has shown that the images on the monitor often do not show the preoperative structure sufficiently accurately. The inability to perform simulated surgery exactly as in the actual operation has also proven to be a 1imitation.“5 Recently a new system for performing simulated surgery using solid replicas generated from the threedimensional computer images has been deve10ped.6-s We have been participating in this work, and have produced numerous replicas of the maxillofacial bones, which have been investigated extensively. In this article, we describe the method of simulating surgery using three-dimensional replicas and demonstrate the procedure in two patients; one with a jaw deformity treated by simultaneous maxillary advancement and mandibular retrusion, and one who required mandibular reconstruction after resection of a tumor.