Prosthesis

Background: Transtibial prosthetic sockets are critical components in the complete assembly of a prosthetic, as they form the major load-bearing parts by housing the residual limb of a prosthesis user. Conventional procedures for manufacturing these sockets require repeated iterations and manual casting, baking, and drying, which often lead to longer processing and waiting times. Additive Manufacturing (AM) enables the creation of bespoke designs with meticulous control over the socket’s shape, thickness, and material composition. Method: To design and propose an optimal socket design to a lower-limb prosthetic user based on their preference of activity such as walking, running, and jumping, we investigated seven materials—Polypropylene (PP) standard material for conventional socket fabrication, Polylactic-acid-plus (PLA+), Polyamide (PA) Natural, Polyamide-6-Glass-Fiber (PA6-GF), Polyamide-copolymer (CoPA), Polyamide-6-Carbon-Fiber (PA6-CF), and Polyamide-12-Carbon-Fiber (PA12-CF)—that have AM compatibility by subjecting them to heavy external loading and evaluating their von Mises stress–strain behavior. Result: Using Finite Element Analysis (FEA), we evaluated a single-material design and a combination design with two materials—one major (low cost) and one minor (higher cost)—to optimize a composition that would bear heavy external loads without yielding. A maximum load-bearing capacity of 3650 N was achieved with the combination of PLA+ and 31.54 vol% PA6-CF (30.23 weight%, 99.13 g), costing about USD 14 for the total socket material. Similarly, a combination of PLA+ with 31.54 vol% PA6-GF (30.76 weight%, 101.67 g) exhibited a maximum load-bearing capacity of 2528.91 N. Conclusions: The presence of high-strength CF and GF in minor compositions and at critical locations within the transtibial socket are the suggested reasons for these enhanced load-bearing capacities, due to which these sockets could be used for undertaking a wider range of activities by the prosthesis users. Full article

Introduction: Mandibular complete dentures often pose challenges due to anatomical and functional limitations. Impression techniques, including functional, mucostatic, compressive, selective pressure, and neutral zone methods, play a crucial role in achieving stability and retention. In 1999, Abe introduced the Suction Effective Mandibular Complete Denture (SEMCD) technique, revolutionizing mandibular denture retention by incorporating functional extensions and achieving a peripheral seal even in the presence of mobile soft tissues. Case report: An 87-year-old male presented to a private dental clinic with the chief complaint that his current lower complete denture lacked retention and stability. Intraoral examination revealed a severely resorbed mandibular edentulous ridge with movable retromolar pads and a prominent spongy lingual area. This case report describes the integration of Abe’s concepts into a digital workflow, using a single-step intraoral scanning technique and digital design software to fabricate a mandibular denture with enhanced retention and stability. Conclusions: This approach minimizes the number of clinical steps involved, improves patient comfort, and achieves predictable outcomes, highlighting the utility of digital technologies in modern prosthodontics. Full article

Background/Objectives: The subject of this work is the reconstruction of the inner mechanics of Götz von Berlichingen’s second iron hand. The complex inner mechanics were unknown until Christian von Mechel published a detailed description in 1815. In this artificial hand, each finger can be engaged individually in its three joints and the thumb in one joint. Methods: Based on this description, the individual components were reconstructed at an enlarged scale of 2:1 using computer-aided design (CAD) software and a three-dimensional (3D) printer for the mechanisms. In addition, a finite element method (FEM) analysis was carried out for the components exposed to the greatest stress in order to identify critical areas. Results: By making some adjustments to the mechanics, it was possible to reproduce the mechanisms on a scale of 2:1 on the basis of the index finger. However, when the model was rescaled to 1:1, the internal plastic components were too fragile. This problem was caused by the properties of the 3D printing materials and could be solved by manufacturing the springs from steel. Conclusions: This work aims to make a valuable contribution to the preservation and understanding of the historical artificial second iron hand of Götz von Berlichingen. It once again demonstrates the very precise and detailed craftsmanship of goldsmiths of that time. Full article

Background/Objectives: Corrosion resistance of dental alloys, indicated by metal ion release, is a significant concern. The aim of this study was to investigate the impact of various sandblasting methods on the corrosion resistance of Co-Cr-W alloy samples in an artificial saliva solution. Materials and Methods: Co-Cr-W samples, obtained by additive manufacturing (selective laser melting) and subjected to different processes, were evaluated using electrochemical corrosion tests on potentiostat equipment in Carter–Brugirard artificial saliva. All measurements were conducted at a temperature of 37 °C. The morphology of the samples was analyzed using scanning electron microscopy to highlight changes in roughness and the effects of the electrolyte solution on the surface of the samples. Results: The corrosion current density values decreased as surface processing increased, dropping from an average of 38.5 μA/cm² in non-sandblasted samples (group A) to 0.74 μA/cm² in samples sandblasted with both Al₂O₃ and glass particles (group C), while the corrosion rate of group A (434.8 mm/year) was significantly higher than that of group C (8.08 mm/year). Conclusions: The results demonstrated different behaviors between sandblasted and non-sandblasted samples, which could be attributed to surface morphology differences influencing the corrosion process. Full article

Background/Objectives: Three-dimensional scanning and printing techniques have gained prominence in the fabrication of upper limb prostheses. This paper provides an overview of various studies on the current utilization of 3D scanning and 3D printing techniques in upper limb prostheses. Methods: A scoping review of the literature was performed following the PRISMA-ScR guidelines in Scopus, PubMed, Google Scholar, and Web of Science, with a total of 274 papers included. A bibliometric analysis was conducted, analyzing the field via keyword co-occurrence visualized using VOSviewer software. Results: Keyword co-occurrence analysis identified four key areas, “prosthesis design and evaluation for people”, “prosthesis control and sensing technologies”, “robotics and mechanical prostheses design”, and “accessibility for prosthesis”. Temporal analysis identified three trends: a focus on fingers, advancement of control systems, and the rise of 3D scanning. In addition, qualitative analysis was conducted to discuss the areas and trends that were shown from the bibliometric analysis, highlighting several studies. Conclusions: This review shows the utilization and notable success of 3D printing and scanning techniques when making upper limb prostheses, with the contents of this article informing healthcare professionals and the general public about the field. Full article

Objectives: CAD-CAM technology has enabled clinicians to provide accurate and predictable restorations. Chairside time has been reduced and patient’s comfort has been improved. A fully digital workflow can be now predictably adopted in implant surgery and implant restorations. Methods: A male patient, 55 years old, was referred for the restoration of his edentulous mandible. Radiographs and clinical evaluation were assembled to plan implant placement. The flapless approach is preferred to provide for a mucosa-supported surgical guide and lessen the patient’s post-operative complications. In flapless cases, the operator does not have any direct overview of the surrounding soft tissues and underlying bone. In this case, a new, minimally invasive H-shaped incision technique was performed. A fully digital protocol is presented with a two-piece stackable surgical guide to confirm accurate implant placement. Results: A high-performance polymer framework (PEEK) combined with zirconia crowns completes the digitally designed edentulous restoration. Conclusions: Adopting this technique offers the clinician benefits in both the surgical and the restorative part. Full article

Objectives: The disinfection of fabricated prostheses is crucial to prevent cross-infection between dental laboratories and clinics. However, there is a lack of information about the effects of chemical disinfection on 3D-printed denture base resins. This study aimed to evaluate the impact of different disinfectants on the flexural strength, elastic modulus, micro-hardness, surface roughness (Ra), and change in color of 3D-printed and conventional heat-polymerized (HP) denture base resins (DBRs). Methods: A total of 240 specimens (80 bar-shaped (64 × 10 × 3.3 mm) and 160 disk-shaped (10 × 2 mm)) were made from HP and 3D-printed DBRs. For each resin, the specimens were divided into four groups (n = 10) according to the disinfectant solution. One remained in water without disinfection as a control group, while the other three groups were disinfected using 1% sodium hypochlorite, 2% glutaraldehyde, or 10% Micro 10+ for 30 min. The flexural strength, elastic modulus, micro-hardness, Ra, and color change were measured. The collected data were statistically analyzed using a two-way ANOVA and Tukey’s post hoc test (α = 0.05). Results: A significant decrease in flexural strength, elastic modulus, and hardness was found with sodium hypochlorite (p < 0.05). When comparing the resins per solution, the 3D-printed resin showed a significant decrease in flexural strength, elastic modulus, and hardness compared with PMMA (p < 0.001), while no change was found in the Ra of both resins with all disinfectants (p > 0.05). Disinfecting with sodium hypochlorite resulted in a significant increase in color change for both resins (p < 0.05); however, all the changes were within clinically acceptable limits. Sodium hypochlorite showed the highest color change, while 2% glutaraldehyde and 10% Micro 10+ showed no significant changes in the tested properties (p > 0.05). Conclusions: Neither resin showed a change in surface roughness with immersion in disinfectants. Sodium hypochlorite had an adverse effect on the flexural properties, hardness, and change in color of the PMMA and 3D-printed DBRs, while the other disinfectants had no effect on the tested properties. Full article

Background: This case report addresses the challenges of integrating orthodontic and prosthodontic treatment, particularly in clear aligner cases. The study introduces a novel milled-provisional crown with attachment (M-PCA) technique designed to enhance treatment efficacy and reduce orthodontic attachment debonding, a common issue in clear aligner therapy. Case Report: This is a case report that presents a 49-year-old female patient seeking orthodontic treatment for Class III malocclusion along with periodontal and prosthodontic challenges. The treatment plan involved a multidisciplinary approach, including using M-PCA for temporization during clear aligner therapy. Conclusions: The M-PCA approach demonstrated promising results, with no reported complications such as orthodontic attachment debonding throughout the treatment period. This innovation offers a significant advantage in managing orthodontic cases requiring provisional crowns, ensuring retention, and facilitating orthodontic treatment. Full article

Introduction: Generally, after an oral oncological therapeutic process in which, unfortunately, surgery plays a fundamental role, a reconstructive and rehabilitative procedure should be initiated, seeking as far as possible to recover the patient’s vital functions (mastication, aesthetics, and phonetics). Case report: We present the case of a patient who successfully underwent treatment for mandibular sarcoma. After a disease-free period of one year, following oncological treatment, an intervention was performed for the insertion of dental implants into the fibula to subsequently rehabilitate the patient prosthetically. There were several challenges, including free-end edentulous space in the lower jaw with a depth of 18 mm on peri-implant tissues consisting of osteoseptocutaneous skin graft, hypotonic perioral musculature, and high aesthetic expectations of the patient. An overdenture with a titanium milled bar substructure with retentive prosthetic components was chosen for treatment. This implant-supported removable prosthesis was selected to facilitate cleaning, since the patient did not maintain oral hygiene habits. The patient was educated on using and handling the prosthesis, and the treatment objectives were achieved (to restore aesthetics and masticatory function). Conclusions: Removable prostheses are a valid alternative for oncologic patients and patients with unfavorable conditions for more complex implant-supported rehabilitation. Full article

Background/Objectives: The increasing demand for total hip arthroplasty (THA), due to aging populations and active lifestyles, necessitates advancements in implant materials and design. This review evaluates the role of surface coatings in enhancing the performance, biocompatibility, and longevity of hip implants. It addresses challenges like wear, corrosion, and infection, focusing on innovative surface engineering solutions. Methods: The review analyzes various surface modification techniques, including physical vapor deposition (PVD), chemical vapor deposition (CVD), electrophoretic deposition (EPD), plasma spraying, and ion implantation. It also examines their effectiveness in improving tribological properties, biocompatibility, and resistance to infection. Computational methods such as finite element analysis (FEA) are discussed for predicting potential coating failures. Results: The findings underscore the challenges posed by wear debris and corrosion in common configurations, like metal-on-metal (MoM) and metal-on-polyethylene (MoP). Innovative coatings, such as diamond-like carbon (DLC) films and hydroxyapatite (HA) layers, demonstrate enhanced performance by reducing friction, wear, and bacterial adhesion, while promoting osteogenic cell attachment. Surface textures and optimized tribological properties further improve implant functionality. Multifunctional coatings exhibit potential in balancing biocompatibility and infection resistance. Conclusions: Surface engineering plays a critical role in advancing next-generation hip implants. The integration of advanced coatings and surface modifications enhances implant durability, reduces complications, and improves patient outcomes. Future research should focus on combining innovative materials and computational modeling to refine coating strategies for long-term success in THA. Full article

Objectives: The study’s objective was to evaluate the accuracy of dynamic computer-assisted surgical implant placement systems during practical training on fresh defrozen cephali. Methods: Three defrozen cephali with terminal dentition received a total of 26 implants (15 4.3 × 13 mm and 11 4.3 × 13 mm, Nobel Biocare Service AG (Zrich-Flughafen Switzerland)) following a standardized protocol: a digital scanning and planning protocol followed by dynamic navigation surgery (X-Guide, X-Nav Technologies, LLC, Lansdale, PA, USA). All surgical interventions were performed by two surgeons: a senior oral surgeon (OE) with more than 5 years of implant dentistry experience and a non-experienced surgeon (NE). Results: Different linear and angular measurements (i.e., deviation shoulder point; deviation tip point; depth deviation shoulder point; depth deviation tip point; B/L and M/D angular deviations) were calculated in duplicate to estimate the discrepancy of the virtual digital planning with respect to the real clinical scenario. The differences between the two operators were also explored. The results of the bivariate analysis detected clinical negligible differences between the operators, without any statistically significant differences for all investigated parameters (p > 0.05). Conclusions: The preliminary positive findings of this pilot study suggest that the investigated dynamic navigation system could be a viable and safe technique for implant surgery and may offer additional safety benefits to non-experienced operators, despite the required learning. Full article

Objectives: This study evaluates the effectiveness of laser surface texturing (LST) using a Surface Transition Machine (STM) on pre-sintered zirconia, comparing its impact on surface characteristics and shear bond strength (SBS) with resin cement to conventional sandblasting techniques. Methods: Zirconia specimens were treated with either STM or sandblasting, followed by surface analysis through scanning electron microscopy (SEM) and White Light Interferometry (WLI), wettability assessment via contact angle measurements, and SBS testing with resin cement and a 10-MDP-containing primer. Results: SEM and WLI revealed significant surface alterations in STM-treated zirconia, producing microscale textures. STM-treated surfaces exhibited significantly lower contact angles (28.4 ± 10.0°) compared to untreated (78.2 ± 8.0°) and sandblasted (79.2 ± 5.7°) surfaces, indicating enhanced wettability (p < 0.05). SBS was highest in the STM with primer group (46.3 ± 8.3 MPa) and STM without primer (43.4 ± 4.3 MPa), both of which significantly outperformed sandblasting with primer (30.06 ± 3.09 MPa) and sandblasting alone (9.8 ± 3.7 MPa) (p < 0.05). Conclusions: These findings suggest that STM-based LST is a more effective method for improving zirconia surface characteristics and adhesion in dental restorations, simplifying bonding procedures, and potentially offering better clinical outcomes than conventional sandblasting. Full article

Background: The optimum bond strength of glass fiber posts can be compromised; it has not yet been established which final irrigant, when used in combination with luting cement, can improve this bond strength. Objectives: This study assessed the effectiveness of 2% chitosan as a final irrigant in combination with different types of luting cement used to improve the bond strength of glass fiber posts bonded to root canal-treated teeth. Methods: Thirty single-rooted anterior teeth were collected and sectioned 2 mm above the most incisal point of the cementoenamel junction. After root canal filling, post spaces were prepared and irrigated in Group I using 17% EDTA for 3 min and in Group II using 2% chitosan for 3 min. Each group was divided into three subgroups: Fiber posts were cemented in subgroup A with Fuji II Cement (resin-reinforced glass ionomer cement), in subgroup B with RelyX Unicem (self-adhesive resin cement), and in subgroup C with Metacem Refill (total-etch resin cement). Push-out bond strength (N) for each sample was measured using a universal testing machine, and the failure mode was assessed with a stereomicroscope at 30× magnification. The fiber post’s morphological structure was analyzed through scanning electron microscopy. Statistical analysis included one-way ANOVA followed by Tukey’s post hoc test in the case of significant differences between the groups. p-Values less than 0.05 were considered statistically significant. Results: This study found no statistically significant difference between using 17% EDTA and 2% chitosan as the final irrigant before post placement (p > 0.05). RelyX Unicem cement showed significant bonding strength when used with 2% chitosan in the coronal, middle, and apical thirds (p = 0.009, p = 0.02, p = 0.01, respectively). Conclusions: Chitosan at 2% can be considered a good alternative to 17% EDTA when used as a final irrigant for the post space. Full article

Introduction: Upper limb deficiencies pose a series of challenges, and current traditional prosthetic solutions often come with limitations and high costs. This is particularly true for sports applications, leading to a high percentage of people with congenital or acquired limb amputations abandoning their preferred physical activities and, consequently, missing out on numerous health benefits. Design and 3D Printing: this paper outlines the design and 3D printing process for upper limb sports devices, emphasizing a user-centered approach and harnessing the customization potential of additive manufacturing technology to create affordable and fully personalized functional devices. Results: The five case studies presented in this paper—a swimming aid, binding bicycle aid, non-binding bicycle aid, handlebar extender bicycle aid, and tennis serve aid—demonstrate the iterative design process, the incorporation of user feedback, and the 3D printing and assembly process of the devices. User Feedback: The questionnaires sent to the end users and the continued communication resulted in a 100% satisfaction rate and the request for new devices. Full article

This scoping review aims to provide comprehensive evidence on methods used to assess the accuracy and acceptance of three-dimensional (3D)-printed removable partial dentures (RPDs). An electronic search of English language literature from January 2014 to 2024 was performed on five databases, PubMed, Scopus, Web of Science, EMBASE, and Google Scholar, using MesH terms. The parameter of interest was extracted and presented in tabular form. Of 1025 retrieved studies, 35 studies were included in the final analysis. Most studies were laboratory-based, and clinical trials were conducted between 2018 and 2022 without a control group. The studies included the use of the stone model or duplication model as a reference, as well as the direct 3D printing method and polished frame for detecting the accuracy of fit. The assessment method was divided into two categories: (1) qualitative (visual and tactile method) and (2) quantitative assessment, which includes optical and computerized methods for assessing the accuracy of fit. Dentist perception and patient-related outcomes were evaluated to measure the acceptance of 3D-printed RPDs. In conclusion, patients’ satisfaction and dentists’ acceptance of digitally printed RPDs were greater than those of conventional ones. The quantitative method (mainly computerized) provides a more accurate and precise assessment to evaluate the accuracy of fit. It allows clinicians to detect minute changes that cannot be inspected with visual and optical methods. Full article

The present study describes the case of a severe surgical complication in a 42-year-old female patient undergoing bimaxillary orthognathic surgery for the correction of skeletal class III, where a detachment of the surgical plates and fibrous healing of the palatal suture occurred. The aim of this study was to enlighten two important concepts: (I) how occlusal and mandible position changes can be well tolerated by the temporomandibular joint even in the case of a failed orthognathic surgery; (II) how a prosthodontic approach based on the search for occlusal stabilization made it possible to manage a complicated clinical case. Clinical Presentation: Clinically, the patient presented an occlusal instability and a split and mobile maxillary bone with respect to the cranial base. The case was resolved using full-mouth prosthodontic rehabilitation to fix the occlusal instability and guide maxillofacial surgeons, establishing the new occlusal position during an orthognathic reintervention. Clinical Relevance: The function was reestablished independently on any treatment planning centered on the temporomandibular joint repositioning concepts. However, although neuromuscular plasticity and the patient’s adaptation skills can explain the clinical success in such complex rehabilitations, these findings must be interpreted with caution due to the limited generalizability inherent to the study’s design. Full article

Background/Objectives: A cam-driven hydraulic prosthetic ankle was designed to overcome the weaknesses of commercial prostheses and research prototypes, which largely fail to mimic the energy-recycling behaviour of an intact ankle, resulting in poor walking performance for lower-limb prosthesis users. Methods: This novel device exploits miniature hydraulics to capture the negative work performed during stance, prior to push-off, in a hydraulic accumulator, and return positive work during push-off for forward body propulsion. Two cams are used to replicate intact ankle torque profiles based on experimental data. The design process for the new prosthesis used a design programme, implemented in MATLAB, based on a simulation of the main components of the prosthetic ankle. Results: In this paper, we present the design programme and explain how it is used to determine the cam profiles required to replicate intact ankle torque, as well as to size the cam follower return springs. Moreover, a constraint-based preliminary design investigation is described, which was conducted to size other key components affecting the device’s size, performance, and energy efficiency. Finally, the feasible design alternatives are compared in terms of their energy losses to determine the best design with regard to minimising both energy losses and device size. Conclusions: Such a design approach not only documents the design of a particular novel prosthetic ankle, but can also provide a systematic framework for decomposing complex design challenges into a series of sub-problems, providing a more effective alternative to heuristic approaches in prosthetic design. Full article

Background/Objectives: International guidelines recommend the use of orthoses in subjects with cerebral palsy (CP), even though there is limited evidence of their effectiveness. Little is known about their effectiveness in children and adolescents with other types of neuromotor disability. Methods: The review protocol was recorded on the PROSPERO register (CRD42024509165) and conformed to the PRISMA guidelines. The inclusion criteria were any type of ankle–foot orthoses (AFOs); pediatric subjects with any non-acquired neuromotor disease; any type of outcome measure regarding gait performance; controlled studies; and those in the English language. Screening, selection, risk of bias assessment, and data extraction were performed by a group of independent researchers. Results: Fifty-seven reports were included, with most regarding CP; three involved subjects with Charcot–Marie–Tooth disease or Duchenne dystrophy. Nine were RCTs. A meta-analysis was performed for studies including subjects with CP. The meta-analysis demonstrated the effectiveness of AFOs in increasing stride length (MD −10.21 [−13.92, −6.51]), ankle dorsiflexion at IC (MD 9.66 [7.05, 12.27]), and peak ankle DF in stance (MD 5.72 [2.34, 9.09]) while reducing cadence (MD 0.13 [0.06, 0.17]) and the energy cost of walking (MD −0.02 [−0.03, −0.00]). The peak ankle power generated at push-off was significantly increased with flexible AFOs compared to rigid AFOs (MD 0.38 [0.30, 0.46]), but it decreased with both compared to walking barefoot or with shoes (MD −0.35 [−0.49, −0.22]). Evidence regarding DMD and CMT was limited but suggested opting for individualized flexible AFOs, which preserved peak ankle power generation. Conclusions: AFOs improve gait performance in CP. Flexible AFOs are preferable because they preserve the peak ankle power generated at push-off compared to rigid AFOs. Full article

Background/Objectives: “Hermes” is an ankle–foot orthosis (AFO) with negative stiffness designed to mechanically compensate the symptomatic increase in plantarflexion (PF) torque (i.e., ankle joint torque resistance to dorsiflexion, DF) in patients with spastic paresis. Methods: The effectiveness of “Hermes” was evaluated in twelve patients with chronic unilateral spastic paresis after stroke. Using a robotic ankle manipulator, stiffness at the ankle joint was assessed across three conditions: ankle without Hermes ($A$), ankle with Hermes applying no torque compensation ($A+H_{0\mathrm{\%}}$), and ankle with Hermes tuned to compensate 100% of the patients’ ankle joint stiffness ($A+H_{100\mathrm{\%}}$). Results: A significant reduction in PF torque was found with Hermes applying compensation ($A+H_{100\mathrm{\%}}$) compared to the conditions without Hermes ($A$) and with Hermes applying no compensation ($A+H_{0\mathrm{\%}}$). Furthermore, a significant reduction in positive dorsiflexion work was found with Hermes applying compensation ($A+H_{100\mathrm{\%}}$) compared to the condition with Hermes applying no compensation ($A+H_{0\mathrm{\%}}$). Hermes did not significantly contribute to additional PF torque or positive work when applying no compensation ($A+H_{0\mathrm{\%}}$). Conclusions: The reductions in PF torque achieved with Hermes are comparable to those seen with repeated ankle stretching programs and ankle robot training. Thus, Hermes is expected to assist voluntary dorsiflexion and improve walking in patients with spastic paresis. Full article