Application effect of computer-aided design combined with three-dimensional printing technology in autologous tooth transplantation: a retrospective cohort study

Background The activity of donor periodontal membrane is the key factor of autologous tooth healing. The application of digital aided design, 3D printing model and guide plate in autotransplantation of tooth (ATT) is expected to reduce the damage of periodontal membrane and preserve the activity of periodontal membrane, so as to improve the success rate of ATT. This study tried to prove the role of digital technology in improving the success rate of ATT, although there are differences in model accuracy in practice. Methods We included 41 tooth autotransplantation cases which assisted by 3D-printed donor models and surgical guides and divided them into two groups in accordance with whether the donor tooth could be placed successfully after the preparation of alveolar socket guided by the model tooth. Then, we compared and analyzed the preparation time of alveolar socket, extra-alveolar time, and number of positioning trials of the donor tooth between the two groups. We also included a comparison of the in vitro time of the donor tooth with that of 15 min. The incidence of complications was included in the prognostic evaluation. Results The mean preparation time of the alveolar socket, mean extra-alveolar time of donor tooth, and mean number of positioning trials with donor tooth of 41 cases were 12.73 ± 6.18 min, 5.56 ± 3.11 min, and 2.61 ± 1.00, respectively. The group wherein the donor tooth cannot be placed successfully (15.57 ± 6.14 min, 7.29 ± 2.57 min) spent more preparation time of alveolar socket and extra-alveolar time than the group wherein the donor tooth can be placed successfully (9.75 ± 4.73 min, 3.75 ± 2.57 min). The number of positioning trials with the donor tooth of the group wherein the donor tooth cannot be placed successfully (3.19 ± 0.75) was higher than that of the other group (2.00 ± 0.86). There was no significant difference in survival rates between the two groups. Conclusions Compared with the traditional tooth autotransplantation, the introduction of computer-aided design combined with 3D printing of the model tooth and surgical guides evidently shortens the preparation time of the alveolar socket and the extra-alveolar time of the donor tooth and reduces the number of positioning trials with the donor tooth regardless of the shape deviation between the model and actual teeth.

Warm sheet metal forming of energy-absorbing elements made 7075 aluminum alloy in the hardened state T6

The article covers experimental research on the forming of products made of 7075 aluminum alloy. This aluminum alloy grade is characterized by high strength, but due to its low formability in T6 temper, its use in the stamping processes of complex structural elements is limited. The authors have manufactured a U-shaped element at an elevated temperature and determined the optimal parameters of the process. Conventional heating of the sheet and shaping it at the temperature of 100 and 150 °C allowed to obtain a product of high strength similar to the T6 state, above 540 MPa. Due to the excessive springback of the sheet during forming, these products were characterized by a large deviation of the shape geometry, exceeding the allowable values of + / − 1 mm. Only the use of an alternative method of heating the sheet to temperatures of 200 and 240 °C (between plates at 350 °C, heating time 2 min, heating rate 1.8 °C/s) allowed to obtain a product that meets both the strength and geometric requirements. The determined optimal process’ parameters were later transferred to the stamping process of elements of a more complex shape (lower part of the B-pillar). The sheet was heated up and formed in the previously pre-heated tools. In the subsequent series of tests, the heating method and the blank’s temperature were being analyzed. In the case of the foot of the B-pillar, it was necessary to lower the initial blank temperature to 200 °C (heating in a furnace with a temperature of 340 °C, heating speed 0.5 °C/s). The appropriate combination of the process parameters resulted in the satisfactory shape deviation and reaching the product’s strength comparable to the strength of the material in as-delivered T6 temper. Using electron microscopy, it was verified that the structure of the finished product contained particles MgZn2 that strongly strengthen the alloy. The obtained results complement the data on the possibility of using 7075 aluminum alloy to produce energy-absorbing elements of motor vehicles.

Mathematical Modeling and Optimization of Fused Filament Fabrication (FFF) Process Parameters for Shape Deviation Control of Polyamide 6 Using Taguchi Method

Fused filament fabrication (FFF) is a layer-by-layer additive manufacturing (AM) process for producing parts. For industries to gain a competitive advantage, reducing product development cycle time is a basic goal. As a result, industries’ attention has turned away from traditional product development processes toward rapid prototyping techniques. Because different process parameters employed in this method significantly impact the quality of FFF manufactured parts, it is essential to optimize FFF process parameters to enhance component quality. The paper presents optimization of fused filament fabrication process parameters to improve the shape deviation such as cylindricity and circularity of 3D printed parts with the Taguchi optimization method. The effect of thickness, infill pattern, number of walls, and layer height was investigated as variable parameters for experiments on cylindricity and circularity. The MarkForged® used Nylon White (PA6) to create the parts. ANOVA and the S/N ratio are also used to evaluate and optimize the influence of chosen factors. As a result, it was concluded that the hexagonal infill pattern, the thickness of 5 mm, wall layer of 2, and a layer height of 1.125 mm were known to be the optimal process parameters for circularity and cylindricity in experiments. Then a linear regression model was created to observe the relationship between the control variables with cylindricity and circularity. The results were confirmed by a confirmation test.

The influence of multi-point roller-dies on the shape deviation differences of profile in flexible stretch-bending forming

In the process of flexible 3D stretch bending, the shape deviation difference between the contact zone and non-contact zone is studied. It is obvious that in the contact zone, the die regulates the deformation of the profile to make it conform to the target shape with small shape deviation; in the non-contact zone, the profile has no die restriction and deviates from the target shape with large shape deviation. When the dies are placed equidistantly along the x-axis, the shape deviation of the non-contact zone near the clamp side is greater than that near the middle of the profile. Arrange the distance between adjacent dies in equal ratio along the x-axis, so that the spacing near the clamp side is a little smaller, and the spacing near the middle of the profile is a bit larger. The difference between the shape deviation of the non-contact zone profile near the clamp side and the middle of the profile decreases, and the maximum shape deviation is reduced, which greatly improves the processing accuracy and quality. However, with the increase of the distance difference between adjacent dies, the shape deviation difference of the non-contact zone near the middle of the profile also increases greatly. Although the clamp side decreases, the maximum shape deviation has become the shape deviation of the profile in the non-contact zone near the middle of the profile.

Application Effect of Computer-Aided Design Combined with Three-Dimensional Printing Technology in Autologous Tooth Transplantation：A Retrospective Cohort Study

Background:To examine the effectiveness of computer-aided design combined with the 3D printing technology in autotransplantation of teeth by using retrospective analysis.Methods: We divided 41 tooth autotransplantation cases which assisted by 3D-printed donor models and surgical guides into two groups in accordance with whether the donor tooth could be placed successfully after the preparation of alveolar socket guided by the model tooth. Then, we compared and analyzed the preparation time of alveolar socket, extra-alveolar time, and number of positioning trials of the donor tooth between the two groups. We also included a comparison of the in vitro time of the donor tooth with that of 15 min. The incidence of complications was included in the prognostic evaluation.Results: The mean preparation time of the alveolar socket, mean extra-alveolar time of donor tooth, and mean number of positioning trials with donor tooth of 41 cases were 12.73 ± 6.18 min, 5.56 ± 3.11 min, and 2.61 ± 1.00, respectively. The group wherein the donor tooth cannot be placed successfully (15.57 ± 6.14 min, 7.29 ± 2.57 min) spent more preparation time of alveolar socket and extra-alveolar time than the group wherein the donor tooth can be placed successfully (9.75 ± 4.73 min, 3.75 ± 2.57 min). The number of positioning trials with the donor tooth of the group wherein the donor tooth cannot be placed successfully (3.19±0.75) was higher than that of the other group (2.00 ± 0.86). Conclusions: Compared with the traditional tooth autotransplantation, the introduction of computer-aided design combined with 3D printing of the model tooth and surgical guides evidently shortens the preparation time of the alveolar socket and the extra-alveolar time of the donor tooth and reduces the number of positioning trials with the donor tooth regardless of the shape deviation between the model and actual teeth.

Scalable robust graph and feature extraction for arbitrary vessel networks in large volumetric datasets

Background Recent advances in 3D imaging technologies provide novel insights to researchers and reveal finer and more detail of examined specimen, especially in the biomedical domain, but also impose huge challenges regarding scalability for automated analysis algorithms due to rapidly increasing dataset sizes. In particular, existing research towards automated vessel network analysis does not always consider memory requirements of proposed algorithms and often generates a large number of spurious branches for structures consisting of many voxels. Additionally, very often these algorithms have further restrictions such as the limitation to tree topologies or relying on the properties of specific image modalities. Results We propose a scalable iterative pipeline (in terms of computational cost, required main memory and robustness) that extracts an annotated abstract graph representation from the foreground segmentation of vessel networks of arbitrary topology and vessel shape. The novel iterative refinement process is controlled by a single, dimensionless, a-priori determinable parameter. Conclusions We are able to, for the first time, analyze the topology of volumes of roughly 1 TB on commodity hardware, using the proposed pipeline. We demonstrate improved robustness in terms of surface noise, vessel shape deviation and anisotropic resolution compared to the state of the art. An implementation of the presented pipeline is publicly available in version 5.1 of the volume rendering and processing engine Voreen.

Scheme optimization for a turbine blade under multiple working conditions based on the entropy weight vague set

The deformation of blades under complex loads of multiple working conditions will reduce the energy conversion efficiency. To reduce the deviation of the blade shape in practical working conditions, a combination and optimization method of blade design schemes under multiple working conditions, based on the entropy weight vague sets, is proposed. The sensitivity of each working condition index is analyzed based on the information entropy, and the satisfaction degree of the design scheme based on the design requirements and experiences is described with the vague set. The matching degree of different design schemes for multiple working conditions is quantified according to the scoring function. The combination and optimization of the design scheme are verified by numerical simulation analysis. The results show that the proposed design scheme has a smaller blade shape deviation than the traditional design scheme under multiple working conditions.

A 3D Printed Physical Human–Robot Interface Based on a Sizing System to Facilitate Customization: Wearable Robots for Paraplegia

Wearable robots that assist paraplegia patients should be manufactured according to the shape of the individual wearer. With the development of advanced three-dimensional (3D) printing technologies, such customizations are becoming available. However, conventional 3D printing customization requires extensive template remodeling, which is non-productive and inefficient. This study proposes a 3D-printed (3DP) physical human–robot interface (pHRI) based on a sizing system that facilitates customization to body shapes. The proposed system is a pre-developed pHRI in various sizes and shapes using a human body shape database. Conformity of shapes and dimensions were evaluated visually via shape deviation analysis for 10 persons having paraplegia. With the proposed 3DP-pHRI, the trunk comprised 18 sections and the shank comprised nine. A biased trend of coverage rates in the shank 3DP-pHRI size system was identified. The trunk and shank subsystems were found to be adequate in terms of shapes and dimensions, with values within the mean deviation range of ±10 mm. A novel 3DP-pHRI size system facilitating customization tool for fabricating wearable robots for paraplegia patients according to body shape was developed, and its effectiveness was assured. The new system can be used for various wearable robot pHRIs, and the database is expected to supply a comprehensive pHRI template library.