Manufacturing Engineering Department, Faculty of Industrial Engineering and Robotics, University Politehnica of Bucharest, Splaiul Independenței 313, 060042 București, Romania
Dr. Cristian Tarba
Manufacturing Engineering Department, Faculty of Industrial Engineering and Robotics, University Politehnica of Bucharest, Splaiul Independenței 313, 060042 București, Romania
Purpose: This paper aims to propose a new solution for producing customized three-dimensional (3D)-printed flat-shaped splints, which are then thermoformed to fit the patient’s hand. The splint design process is automated and is available to clinicians through an online application. Design/methodology/approach: Patient anthropometric data measured by clinicians are associated with variables of parametric 3D splint models. Once these variables are input by clinicians in the online app, customized stereo lithography (STL) files for both splint and half mold, in the case of the bi-material splint, are automatically generated and become available for download. Bi-materials splints are produced by a hybrid manufacturing process involving 3D printing and overmolding. Findings: This approach eliminates the need for 3D CAD-proficient clinicians, allows fast generation of customized splints, generates two-dimensional (2D) drawings of splints for verifying shape and dimensions before 3D printing and generates the STL files. Automation reduces splint design time and cost, while manufacturing time is diminished by 3D printing the splint in a flat position. Practical implications: The app could be used in clinical practice. It meets the demands of mass customization using 3D printing in a field where individualization is mandatory. The solution is scalable – it can be extended to other splint designs or to other limbs. 3D-printed tailored splints can offer improved wearing comfort and aesthetic appearance, while maintaining hand immobilization, allowing visually controlled follow-up for edema and rapidly observing the need for revision if necessary. Originality/value: An online application was developed for uploading patient measurements and downloading 2D drawings and STL files of customized splints. Different models of splints can be designed and included in the database as alternative variants. A method for producing bi-materials flat splints combining soft and rigid polymers represents another novelty of the research.
This article proposes the integration of two novel aspects into the production of 3D-printed customized wrist-hand orthoses. One aspect involves the material, particularly Colorfabb varioShore thermoplastic polyurethane (TPU) filament with an active foaming agent, which allows adjusting the 3D-printed orthoses’ mechanical properties via process parameters such as printing temperature. Consequently, within the same printing process, by using a single extrusion nozzle, orthoses with varying stiffness levels can be produced, aiming at both immobilization rigidity and skin-comfortable softness. This capability is harnessed by 3D-printing the orthosis in a flat shape via material extrusion-based additive manufacturing, which represents the other novel aspect. Subsequently, the orthosis conforms to the user’s upper limb shape after secure attachment, or by thermoforming in the case of a bi-material solution. A dedicated design web app, which relies on key patient hand measurement input, is also proposed, differing from the 3D scanning and modeling approach that requires engineering expertise and 3D scan data processing. The evaluation of varioShore TPU orthoses with diverse designs was conducted considering printing time, cost, maximum flexion angle, comfort, and perceived wrist stability as criteria. As some of the produced TPU orthoses lacked the necessary stiffness around the wrist or did not properly fit the palm shape, bi-material orthoses including polylactic acid (PLA) inserts of varying sizes were 3D-printed and assessed, showing an improved stiffness around the wrist and a better hand shape conformity. The findings demonstrated the potential of this innovative approach in creating bi-material upper limb orthoses, capitalizing on various characteristics such as varioShore properties, PLA thermoforming capabilities, and the design flexibility provided by additive manufacturing technology.
Mandibular reconstruction is essential for restoring both function and aesthetics after segmental resection due to tumoral pathology. This study aimed to conduct a comparative analysis of three reconstruction strategies for defects resulting from segmental mandibular resection, utilizing finite element analysis (FEA). Methods: A digital model of the mandible was created from CBCT data and optimized for FEA. Three reconstruction scenarios were simulated: fixation with a titanium plate, reconstruction with an autogenous fibular graft stabilized with the same titanium plate, and fixation with a customized PEEK plate. Various plate thicknesses were analyzed to determine the stress and deformation patterns under masticatory loads. Results: Titanium plates provided superior mechanical stability but showed stress concentrations near screw fixation points. The addition of autogenous bone grafts reduced stress on the plate and improved structural integrity. PEEK plates exhibited reduced stress shielding and better load distribution, but thinner designs were prone to deformation. Minimum recommended thicknesses of 1.2 mm for titanium plates and 1.8 mm for PEEK plates were identified by FEA. Conclusions: This study highlights the importance of material selection and patient-specific design in mandibular reconstruction. Autogenous bone grafts combined with titanium plates demonstrated the best biomechanical outcomes, while PEEK plates offer a promising alternative, particularly for patients where grafting is contraindicated.
The treatment of maxillofacial defects presents significant challenges due to the complexity of facial anatomy and the diversity of affected tissues. Traditional workflows are labor-intensive, costly, and limited in customization. Recent advancements in fully digital workflows and direct 3D printing technologies offer new possibilities for improving the fit, aesthetics, and efficiency of prosthetic manufacturing. This scoping review aims to evaluate the current state of direct 3D printing for maxillofacial soft prostheses, assess material properties and biocompatibility, and identify challenges and future directions in this field. Methods: A comprehensive search of PubMed and Scopus databases, along with a manual search of relevant journals, was conducted to identify studies published up to December 2024. Articles focusing on direct 3D printing of maxillofacial soft prostheses were included, while studies involving traditional or mold-based workflows, ocular prostheses, and literature reviews were excluded. Data on materials, manufacturing techniques, and clinical outcomes were extracted and analyzed. Results: Out of 898 articles screened, 11 were included, 5 of which were in vivo studies (case reports). The additive manufacturing methods used in these case reports were Drop-on-Demand (DoD) silicone printing and PolyJet technology. Conclusions: Fully digital workflows and direct 3D printing technologies show promise for advancing maxillofacial prosthesis manufacturing. However, the absence of dedicated software, biocompatible materials, and medium- to long-term clinical evaluations highlight significant research gaps. Future research should focus on material development, workflow optimization, and clinical validation to enable widespread clinical adoption.
18 September 2018 in IOP Conference Series: Materials Science and Engineering
Due to their good biocompatibility, mechanical properties and corrosion resistance, the Co-Cr alloys are one of the metallic materials used for manufacturing medical implants. When talking about manufacturing, it is well known that a significant constraint for this type of products is their surface quality. For this reason, various researches focus on the way the required surface quality of a part can be achieved with the minimum cost and resources. The aim of the research presented in this paper is to analyse the cutting regime parameters influence upon part surface quality when dry turning a CoCrMo alloy by using TiAlN PVD coated cutting inserts. The research results consist of the interdependence between the surface Ra and Rz roughness parameters of the machined CoCrMo samples and the cutting data variation and of a prediction mathematical model of the Ra roughness parameter in terms of cutting regime parameters.
18 September 2018 in IOP Conference Series: Materials Science and Engineering