Development and improvement of 3D digitizing systems provide for the ability to digitize a growing number of materials and geometrical forms of greater complexity. This paper presents the application of 3D digitizing system using close range photogrammetry on the upper jaw cast in plaster in order to obtain its 3D model. Because of the low visual characteristics of gypsum, such as color and texture, many questions arise about the possibility of applying this particular method to this type of physical models. In order to overcome bad visual properties of gypsum, this paper analyzes the possibility of the photogrammetry method application supported by the projected light texture which is based on patterns in the form of noise-obtained mathematically modeled functions. In order to determine the selected image for light texture which gives the better results, an experiment was designed and carried out. Only two images were tested. One image is selected based on previous research and the other one was generated by the Matlab function for uniformly distributed random numbers. For validation and a comparative analysis of the results, an object of 3D digitization was generated with and without projected light texture. CAD inspection was applied for the analysis of the obtained 3D digitizing results. 3D model obtained by approved professional optical 3D scanner as a reference was used. The results in this paper confirm better accuracy of 3D models obtained with the use of light textures, but this approach requires additional hardware and setup adjustment for images acquisition.
The purpose of the study was to test new method for in vitro evaluation of dental material wear with 3D digitization procedure. Thirty dental crowns, made of polyetheretherketone and veneered with composite material, were subjected to wear test. The crown surface was digitized using coordinate measuring machine before and after the performed wear test. Mesh 3D models were reconstructed and average and maximum depth of lost material and volume loss was calculated (GOM Inspect 2016 software). Mean average depth value amounted 12±7 µm, maximum depth value was 42 µm, while mean volume loss was 0.0024 mm 3. The smallest measured values were 4 µm for depth value and 0.0003 mm 3 for volume loss. Coefficient of variation was very high for all tested parameters (>50%) as a result of data inconsistency. Within the limitations of applied methodology, the possibility of using coordinate measuring machine in measurement of dental material wear was confirmed.
Application of 3D CBCT images, computer-aided systems and software in manufacturing custom bone grafts represents the most recent method of guided bone regeneration. This method substantially reduces time of recovery and carries minimum risk of postoperative complications, yet the results fully satisfy the requirements of both the patient and the therapist.
Small and start-up companies that need product quality control can usually only afford low-cost systems. The main goal of this investigation was to estimate the influence of high dynamic range images as input for the low-cost photogrammetric structure from motion 3D digitization. Various industrial products made of metal or polymer suffer from poor visual texture. To overcome the lack of visual texture and ensure appropriate 3D reconstruction, stochastic image in the form of the light pattern was projected on the product surface. During stochastic pattern projection, a set of low dynamic range and sets of high dynamic range images were captured and processed. In this investigation digital single lens reflex camera that supports five different tonemapping operators to create high dynamic range images were used. Also, high precision measurements on a coordinate measuring machine are performed in order to verify real product geometry. The obtained results showed that reconstructed polygonal 3D models generated from high dynamic range images in this case study don't have a dominant influence on the accuracy when compared to the polygonal 3D model generated from low dynamic range images. In order to estimate 3D models dimensional accuracy, they were compared using computer-aided inspection analysis. The best achieved standard deviation distance was +0.025 mm for 3D model generated based on high dynamic range images compared to the nominal CAD model.
Purpose
Computer-aided design and additive manufacture (CAD/AM) technologies are sufficiently refined and meet the necessary regulatory requirements for routine incorporation into the medical field, with long-standing application in surgeries of the maxillofacial and craniofacial regions. They have resulted in better medical care for patients and faster, more accurate procedures. Despite ever-growing evidence about the advantages of computer-aided planning, CAD and AM in surgery, detailed reporting on critical design decisions that enable methodological replication and the development and establishment of guidelines to ensure safety are limited. This paper aims to present a novel application of CAD and AM to a single-stage resection and reconstruction of fibrous dysplasia in the zygoma and orbit.
Design/methodology/approach
It is reported in sufficient fidelity to permit methods replication and design guideline developments in future cases, wherever they occur in the world. The collaborative approach included engineers, designers, surgeons and prosthetists to design patient-specific cutting guides and a custom implant. An iterative design process was used, until the desired shape and function were achieved, for both of the devices. The surgery followed the CAD plan precisely and without problems. Immediate post-operative subjective clinical judgements were of an excellent result.
Findings
At 19 months post-op, a CT scan was undertaken to verify the clinical and technical outcomes. Dimensional analysis showed maximum deviation of 4.73 mm from the plan to the result, while CAD-Inspection showed that the deviations ranged between −0.1 and −0.8 mm and that the majority of deviations were located around −0.3 mm.
Originality/value
Improvements are suggested and conclusions drawn regarding the design decisions considered critical to a successful outcome for this type of procedure in the future.
Personalized bone grafts are one of the best examples of the latest achievements in the biomedical engineering. In the area of maxillofacial bone tissue reconstruction or jaw bone augmentation, their application has for some time been on the rise, and its ever increasing significance is driven by the growing technical support. One of the key segments is the bone graft modelling customized to suit patient's specific needs, since it greatly determines not only the future anatomic functionality but also the acceptance probability of the graft by the bone tissue. With the graft geometry importance in mind, presented in this paper is an approach to personalized bone graft modelling. The approach is based on application of modern computer-aided systems and methods, and enables efficient geometric design while minimizing the risk of errors during modelling and placement stages. Verification is based on a case study of a personalized bone graft designed for a patient requiring mandible augmentation.
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