Prosthesis Prototype Research Articles

A technique to enhance the gingival esthetics of a prototype complete arch fixed implant-supported prototype prosthesis using a 3D printed gingival veneer.

An important step in the workflow for a complete arch fixed implant-supported prosthesis is the fabrication of a prototype resin prosthesis to allow the patient to visualize the definitive treatment outcome and also to use as an interim prosthesis. Producing a prototype prosthesis with the natural appearance of the gingival color and contour has been challenging. Current methods include painted stains, manually applied pink composite resin or autopolymerizing acrylic resin, and multicolored resin blocks, but these are all relatively expensive, have less than optimal esthetics, and are labor-intensive and time-consuming. This technique article describes a digital workflow to design and fabricate a complete arch 3D printed gingival veneer that can be directly bonded onto a white prototype resin prosthesis to enhance gingival esthetics. Additional technical details related to the design and fabrication of the separate pink and white components and bonding and sealing them together are also provided.

Design of a Customized Thumb Prosthesis: Focus on Functionality and Comfort

This research focuses on addressing the scarcity of personalized and affordable prostheses in Honduras by designing and developing a functional prosthesis for a thumb. The general objective was to design a model suitable for 3D printing adapted to the specific needs of a patient who had her index and thumb fingers amputated. To achieve this, an integral methodology was employed, ranging from an exhaustive literature review of current solutions to detailed material evaluations, including interviews with patients and medical experts, SolidWorks modeling, and simulations. The result was the successful design of a functional prosthesis prototype, with the selection of intentionally 3D printable materials to ensure comfort and functionality. In conclusion, this research demonstrates the viability of addressing the scarcity of personalized prostheses through innovative approaches and comprehensive design methodologies, with a focus on effectiveness and streamlining the process.

Reverse scan body: Complete digital workflow for double full-arch zirconia prostheses.

During intraoral complete-arch digital implant scanning, one of the most technique-sensitive steps is the implant data acquisition and merging of different surface geometry data sets for prototype prosthesis fabrication due to the absence of fixed landmarks. Recently developed extraoral techniques have allowed for an alternative approach for the digital acquisition of implant position in completely edentulous patients. Specifically, extraoral digital scanning of the conversion prosthesis after connecting reverse scan bodies has been proposed as an efficient approach. The reverse scan body protocol digitally simulates the traditional back-pouring technique long utilized in analog workflows. The present article describes a technique for simplifying the digital workflow for the fabrication of passive-fitting definitive prostheses using the reverse scan body concept.

A New Temporary Training Prosthesis for People With Transtibial Amputation: a Technical Note.

While waiting to receive a prosthesis, individuals with amputations could benefit from using a temporary training prosthesis to expedite the rehabilitation process and prepare them for subsequent walking with their prosthesis. To design and build a temporary training prosthesis for people with a transtibial amputation. Various temporary training prostheses were designed and simulated using SolidWorks software, followed by fabricating and testing multiple prototypes. Initial tests were conducted on five able bodied subjects without amputation to evaluate comfort, ensure the prototype functioned as intended, and to refine the design. The final prototype design had no weight-bearing on the residual limb end and required the person to wear a shrinker or silicone liner. SolidWorks simulations showed that the device could tolerate up to 200 kg load. Subjective feedback indicated that body weight is primarily supported by the thigh section, while partially utilizing the patellar tendon and tibial flares. The thigh section can be shifted 5 cm up or down and 2.5 cm to the front or back from the knee joint center (to enhance knee stability or function). Additionally, the thigh angle can be adjusted to 0, 5, 10, or 15 degrees to accommodate hip flexion contracture. The shank section width is adjustable and can be shifted up or down based on the residual limb shape. All five able-bodied participants successfully walked with the non-amputee version of the temporary prosthesis prototype and the device withstood walking, sitting, and standing loads. An adjustable temporary training prosthesis was successfully designed, and pilot tested by five able-bodied individuals. Future testing will involve five experienced prosthetic users before conducting trials with individuals with a new transtibial amputation.

Computational Analysis of Polymeric Biodegradable and Customizable Airway Stent Designs.

The placement of endotracheal prostheses is a procedure used to treat tracheal lesions when no other surgical options are available. Unfortunately, this technique remains controversial. Both silicon and metallic stents are used with unpredictable success rates, as they have advantages but also disadvantages. Typical side effects include restenosis due to epithelial hyperplasia, obstruction and granuloma formation. Repeat interventions are often required. Biodegradable stents are promising in the field of cardiovascular biomechanics but are not yet approved for use in the respiratory system. The aim of the present study is to summarize important information and to evaluate the role of different geometrical features for the fabrication of a new tracheo-bronchial prosthesis prototype, which should be biodegradable, adaptable to the patient's lesion and producible by 3D printing. A parametric design and subsequent computational analysis using the finite element method is carried out. Two different stent designs are parameterized and analyzed. The biodegradable material chosen for simulations is polylactic acid. Experimental tests are conducted for assessing its mechanical properties. The role of the key design parameters on the radial force of the biodegradable prosthesis is investigated. The computational results allow us to elucidate the role of the pitch angle, the wire thickness and the number of cells or units, among other parameters, on the radial force. This work may be useful for the design of ad hoc airway stents according to the patient and type of lesion.

Oculopalpebral prosthesis prototype design using the additive manufacturing technique: A case study

Three-dimensional (3D) printing technology has advanced for applications in the field of reconstructive surgery. This study reports the application of a comprehensive methodology to obtain an anatomical model, using computed tomography and 3D printing, to treat a patient with cancer who designed a prototype oculopalpebral prosthesis for the reconstruction of the affected area of the face (left eye). A personalized prototype was obtained, which adapted to the face of the person, and improved the aesthetics and quality of life. The applied techniques helped to make definitive prostheses using materials that could be permanent. The training and tests carried out in this study favored the understanding and assimilation of the technology and the possibility of applying it to patients in need of facial prosthetic rehabilitation.

Design and Manufacturing of a Low-Cost Prosthetic Foot

Below-knee prosthetics are used to restore the functional activity and appearance of persons with lower limb amputation. This work attempted to design and manufacture a low-cost, novel, comfortable, lightweight, durable, and flexible smart below-knee foot prosthesis prototype. This prosthesis foot was designed according to the natural leg measurement of an adult male patient. The foot is composed of rigid PVC layers interspersed with elastic strips of PTFE, and the axis of the ankle joint is flexible and consists of metal layers and a composite of polymeric damping strips with different mechanical properties, making it flexible and allowing it to absorb shocks and store and release energy. The design, modeling, and simulation of the manufactured prosthetic foot were performed via the ANSYS 18.0 software and the finite element method (FEM), where a large number of parallel and oblique planes and sketches were created. This work included four adult patients weighing 50, 75, 90, and 120 kg with different walking cycles. The results show that the highest equivalent von Mises stress and total deformations for the prosthetic limb occur at the beginning of the walking step, while the highest equivalent elastic strains and strain energy release rates are observed at the end of the walking step, regardless of the weight. This prototype can satisfactorily perform the biomechanical functions of a natural human foot, and it can be produced in attractive sizes, models, and shapes to suit different levels of below-knee amputations for different ages and weights, especially for patients with limited income.

Reverse scan body: The scan pattern affects the fit of complete-arch prototype prostheses.

To assess the effect of different scan patterns on the fit of implant-supported complete-arch prototype prostheses fabricated via a complete digital extraoral protocol with a reverse scan body. A mandibular cast with four multi-unit abutment (MUA) implant analogs with adequate antero-posterior spread served as the reference cast, simulating a common clinical patient situation, and a polymethylmethacrylate interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis on the intaglio of the MUA abutments and extraoral scanning was performed with a white light intraoral scanner (TRIOS 4; 3 shape) and three different scan patterns: starting from the occlusal surface of the interim prosthesis (O-group), starting from the intaglio (I-group), and helix pattern (H-group). The resulting STL files from the three groups were then imported to computer-aided design (CAD) software and after the digital design, the STL files were exported to a computer-aided manufacturing (CAM) milling machine which generated a total of 15 CAD-CAM milled prototype prostheses per group. Two clinicians assessed the fit of each digitally fabricated prototype prosthesis on the reference cast, utilizing the screw-resistance test and radiographic evaluation. Fisher's exact test was used to test the difference between the three groups, and Cohen's k-score was used to assess the inter-examiner agreement. Out of the three different groups, the O-group scan pattern led to 100% prosthesis fit, while the prototype prostheses generated from I- and H-groups had 80% and 53% fit, respectively. The results were statistically significant (p = 0.008). Occlusal scan pattern leads to fitting milled prototype prostheses after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Hand prosthesis prototype construction with the implementation of phalanges through 3D printing technology

Hand prosthesis prototype construction with the implementation of phalanges through 3D printing technology

Design and manufacture of a forelimb prosthesis prototype for a dog

The objective of this writing is to develop a methodology for the design and selection of materials that allows for the manufacturing of a canine prosthesis prototype based on anthropometric measurements, element simulation, and finite analysis. The canine prosthesis aims to restore mobility to a missing limb of a dog due to amputation and/or congenital malformation. The methodological approach for this study has been determined based on the analysis of a series of parameters, such as the dimensions of the animal leg, as well as its weight and the location of the amputation, to mention just a few points. As a contribution, a prototype of an exoprosthesis is proposed for a missing front limb, where it should fit within the range of the leg length, from 35 cm to 45 cm, and its weight should range between 30 kg and 40 kg. Additionally, the amputation should be located starting from the elbow region, and the optimal design should be able to adapt to different anthropometric measurements and the needs of the dogs.

Patient-specific testicular prosthesis prototype produced with polylactic acid and coated with cyanoacrylate or polymethylmethacrylate

In order to reduce the psychological and aesthetic consequences caused by elective or therapeutic orchiectomy, we developed two types of testicular prostheses, which were produced using a 3D printer, with polylactic acid filament, and coated with cyanoacrylate or polymethylmethacrylate (PMMA). They were tested in Wistar rats, with orchiectomy performed on the left testicle and the prosthesis implanted inside the tunica vaginalis, in group 1 we implanted the prosthesis coated with cyanoacrylate and in group 2 with PMMA. The implants showed interesting features such as low cost, reduced production time, and ease of customization for the patient. Two rats in group 1 had monocular vaginalitis in the region of the tunica vaginalis implant and 3 (3/10, 30%) had fibrous dermatitis. In group 2, 5 rats (50%) had fibrous dermatitis, and none had alterations in the tunica vaginalis. We performed a logistic regression model, the results showed no significant association between the type of prosthesis and the presence of inflammation in the tunica vaginalis (p=0.08) or fibrous dermatitis (p=0.22). However, we suggest further studies with cyanoacrylate. PMMA proved to be an excellent option as a biomaterial for prosthesis. Fibrous dermatitis occurred due to the dermal healing process caused by the surgical incision.

Maxillary and mandibular complete-arch implant rehabilitation using a complete digital workflow: A case report.

This paper summarizes the clinical steps involved in maxillary and mandibular complete-arch implant rehabilitation using a complete digital workflow. The maxillary arch was recorded was using the double digital scan technique, and the mandibular arch using the triple digital scan technique. The digital protocol used in this case report allowed the recording of implant positions via scan bodies, soft tissues, and, most importantly, interocclusal relationship in the same visit. A new technique for mandibular digital scan was described that uses soft tissue landmarks by creating windows in the patient's provisional prostheses to superimpose the three digital scans and consequently fabricate and verify the maxillary and mandibular prototype prostheses and definitive complete-arch zirconia prostheses. This article is protected by copyright. All rights reserved.

Custom Prosthetic Finger Device Using 3D Printable PA11 CF Powder

This article presents a study on how to prototype a finger joint exoprosthesis using different CAD software and 3D printing techniques. The article describes the measurement of morpho-anatomical parameters, the creation of a 3D model based on these parameters, and the integration of an articulation mechanism into the patient's finger. This study also outlines the process of producing the custom prosthesis prototype by using PA11 CF material, which has applications in various fields including medicine. The prosthesis was then introduced to Sinterit Studio where a G-code was generated and the layers that would be printed were visualized. This method provides insight into the process of creating a prototype using 3D printing technology and specific software applications.

Reverse scan body: A complete digital workflow for prosthesis prototype fabrication.

To assess the accuracy of fit of prosthesis prototypes fabricated via a complete digital workflow protocol with a reverse scan body skipping intraoral scanning for implant data acquisition. A maxillary stone cast with four multiunit abutment implant analogs (Screw-Retained Abutments, Institut Straumann AG, Basel, Switzerland) with adequate anteroposterior spread simulated a common clinical patient situation. This stone cast served as the master cast and an interim screw-retained prosthesis was fabricated on it. Novel reverse scan bodies were connected to the interim prosthesis, and extraoral scanning was performed with a white light intraoral scanner. The produced standard tessellation language (STL) files were then imported to computer-assisted design software and after the digital design, the STL file was exported to a computer-assisted machining milling machine and a three-dimensional (3D) printer to produce a total of 50 milled and 50 printed fixed complete denture prototypes, respectively. Two clinicians assessed the accuracy of fit of each digitally fabricated prosthesis prototype on the master cast, utilizing the screw-resistance test and radiographic evaluation. Out of the 100 prototypes, 94% (94/100) were fitting accurately. Fisher's exact test was used to test the difference among the groups. The test revealed statistically significant results (p=0.027). Out of the 50 digitally fabricated milled prosthesis prototypes, 50 (100%) presented with accurate fit under in vitro assessment. Out of the 50 digitally fabricated 3D printed prototypes, 44 (88%) presented with accurate fit under in vitro assessment. Accurately fitting digitally fabricated prosthesis prototypes can be milled after extraoral scanning with reverse scan bodies without intraoral implant data acquisition.

Development and testing of a virtual simulator for a myoelectric prosthesis prototype – the PRISMA Hand II – to improve its usability and acceptability

Artificial limbs can help people missing body parts to restore some of their daily-life activities. However, the user should spend up to a few months to intuitively control the new device. During this period, she/he may suffer pain due to wearing or using the prosthesis inappropriately. This research presents a virtual simulator that allows the user to carry out training sessions for controlling the prosthesis. A set of Surface Electromyographic (sEMG) sensors are used to acquire the signals from user’s muscles and send them to a recognition algorithm that interprets the patient’s intentions. Simultaneously, the patient observes the response of her/his device on the simulator. Two studies are presented: the first study evaluate the performance of three different recognition algorithms i.e., Linear Discriminant Analysis (LDA), Support Vector Machine (SVM), and Multi-Layer Perceptron (MLP), based on the successful recognition of the patient’s intentions. The second study investigates the least number of sEMG sensors to be used, as having less components improves the patient’s wearability and decreases the processing time. The developed simulator represents a real prosthetic device, PRISMA hand II.The results showed the superiority of the MLP with 80% of successful recognition when 6-sEMG sensors are used. If a reduced set of gestures is considered (frequently needed by the patient), 90% of successful recognition could be achieved. Less sEMG sensors significantly degraded the performance of the recognition algorithm as only 53.8% of successful recognition could be achieved. All experiments were conducted with the help of a patient with below-elbow amputation.

Complete digital workflow for prosthesis prototype fabrication with double digital scanning: A retrospective study with 45 edentulous jaws.

To assess the accuracy of fit of complete-arch printed prosthesis prototypes generated with a digital workflow protocol for completely edentulous jaws. Forty-five edentulous jaws (35 patients) underwent intraoral complete-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software. After STL merging, each master STL file was used for printing a prosthesis prototype. The primary outcome was the accuracy of fit assessment of the printed prototypes on verified master stone casts. Two experienced clinicians tested the accuracy of fit with radiographs and screw-resistance tests. Secondary outcomes were the effect of the scan body shape and implant number on the accuracy of fit. Out of the 45 DDS-generated prosthesis prototypes, 39 presented with accurate fit on verified master stone casts, yielding an 86.70% accuracy of fit. Cylindrical scan bodies led to 100% accuracy of fit (25/25), whereas polygonal scan bodies presented with 70% accuracy of fit (14/20). Four implant-supported prostheses yielded 100% accuracy of fit (12/12), compared with 25/29 (86.30%) accuracy of fit for the six-implant-supported ones. Fisher's exact test was used to assess the effect of different scan body shapes (p=0.005) and implant number on accuracy of fit. Chi-squared test was used to assess the association between the number of implants per arch and the accuracy of fit (p=0.039). Thirty-nine out of 45 complete-arch prosthesis prototypes generated with a completely digital workflow presented with clinically acceptable fit. The effect of the scan body design and implant number was statistically significant, favoring cylindrical scan bodies and four-implant-supported prostheses.

DESIGN AND CONSTRUCTION OF A PROTOTYPE OF A LOW-COST HAND PROSTHESIS IN A 3D PRINTER

This study aims to present the design and implementation of a low-cost prosthesis prototype that covers the basic movement needs, built using 3D printing. The development of this prototype, in particular, focuses on low-income people, especially children with some amputation or malformation in their upper extremities. First, an electromyograph was developed to capture the electrical signals produced by the muscles of the body as they move and to amplify them for further processing by an Arduino development board that works as the central system of the prosthesis. With the electromyograph designed and built, we proceeded to design the mechanical part of the prosthesis in SolidWorks software and prototype it in a 3D printer. The first tests conducted with the finished prototype yielded various data regarding the treatment of the signals used to make modifications and reach the necessary performance. With this work, it is possible to develop a basic prosthesis prototype that helps low-income children who are victims of amputations or malformations to meet their basic motor needs and demonstrate once again that the implementation of engineering provides solutions to local and global problems. Keywords: Electromyograph, Signals, 3D Printer, Hand Prosthesis, Electrodes DOI： https://doi.org/10.35741/issn.0258-2724.58.3.20

Clinical effectiveness of fixed polymer prototype prostheses: a randomized controlled trial

Relevance. An analogous recording of occlusal relationships (articulating paper, foil, etc.) is not sufficiently informative for precise determination of occlusal forces and sequence, which is related to the large inaccuracy, labour intensity and lower predictability of prosthetic treatment results. Aim. The study aimed to evaluate the effectiveness of fixed polymer prototype dental bridges in patients with tooth-bounded edentulous spaces and occlusal defects.Material and Methods. The randomized controlled study comprised two study groups: control (n = 21) and main (n = 21), which included the patients with tooth-bounded posterior missing teeth (second premolar and first molar). Prosthetic treatment corresponded to the conventional protocol in the control group. The main group had the missing teeth replaced with prototype prostheses and analogous-digital analysis of occlusal relationships. Intergroup effectiveness comparison rested on the integral occlusal score (IOS) data that considered scores received with T-scan 3 system (TekScan, USA). We also performed an intragroup comparative analysis of the periodontium condition around the abutment teeth using the Doppler ultrasound integral score (DUIS) at the stages before and after the treatment.Results. The study did not reveal statistically significant differences between the values of IOS in the control and main study groups before the treatment (p > 0.05). At the followed treatment stages, control group IOS values significantly differed from those of the main group, namely, by 65.35 % (p < 0.05) just before the replacement of the provisional bridge by the final prosthesis; by 76.19 % (p < 0.05) immediately after the final prosthesis delivery; and by 65.94 % (p < 0.05) one week after the delivery of the final prosthesis. The Doppler ultrasound integral score values reflected the statistically significant positive changes in the study groups (p < 0.05).Conclusion. Fixed polymer prototype prosthesis placement in patients with posterior tooth-bounded edentulous spaces and occlusal defects allowed us to increase prosthetic treatment effectiveness, improve microcirculation around abutment teeth, and harmonize the occlusion, decreasing the risk of possible damage to a ceramic bridge.

Control of a 2 DOF Elbow Prosthesis prototype

This paper presents a 2 DOF elbow prosthesis design and its control, which includes developing the mechanism, adapting a torsional spring for the flexo-extension movement, and a crown pinion transmission with two torsional springs pronosupination movement. In addition, this prototype has planned an elbow joint control method. The control has been obtained using the kinematic of a pendulum with a torsional spring, where the model comes with a set of dynamic simulations to determine how feasible the proposed mechanism is, and the torque needed for daily activities performance. The results show the physical and kinematic characteristics of the designed system.

Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae.

To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow. Sixteen patients received intraoral full-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer-aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw-resistance test and direct observation. Out of the 16 digitally fabricated prototypes from intraoral full-arch digital scans, all 16 presented with an accurate fit on verified master stone casts. Digitally fabricated full-arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.