Prosthesis

Background/Objectives: The potential application of electromyography (EMG) as a method for precise force control in prosthetic devices is investigated, expanding on its traditional use in gesture detection. Variability in EMG signals among individuals is influenced by physiological factors such as muscle mass, body fat percentage, and subcutaneous fat, as well as demographic variables like age, gender, height, and weight. This study aims to evaluate how these factors impact EMG signal quality and force output. Methods: EMG data was normalized using the maximum voluntary contraction (MVC) method, recorded at 100%, 50%, and 25% of MVC with simultaneous grip force measurement. Physiological parameters, including fat percentage, subcutaneous fat, and muscle mass, were analyzed. An extreme gradient boosting algorithm was applied to model the relationship between EMG amplitude and grip force. Results: The findings demonstrated significant linear correlations, with r² coefficients reaching up to 0.93 and 0.83 in most cases. Muscle mass and fat levels were identified as key determinants of EMG variability, with significance coefficients ranging from 0.36592 to 0.0856 for muscle mass and 0.281918 to 0.06001 for fat levels. Conclusions: These results underscore the potential of EMG to enhance force control in prosthetic limbs, particularly in tasks such as grasping, holding, and releasing objects. Incorporating body composition factors into EMG-based prediction algorithms offers a refined approach to improving the precision and functionality of prosthetic control systems for complex motor tasks. Full article

Background/Objectives: The purpose of this in vitro study was to evaluate and compare the internal adaptation and cement film thickness of cast-gold custom post and core (CPC), three-dimensionally (3D)-printed titanium (Ti) CPC, and milled Ti CPC. Methods: Forty-eight 3D printed resin models, simulating a tooth prepared to receive a CPC, were fabricated. Models were randomly assigned to one of three groups (n = 16 per group): (A) cast-gold CPC (control group), (B) 3D-printed Ti CPC, and (C) milled Ti CPC. Following the manufacturing of CPCs, each CPC was cemented using dual-cure polymerizing resin cement. Then, each model/post-and-core assembly was sectioned at the coronal, middle, and apical thirds of the post at a specific point. Each section was photographed using a microscope in a standardized setting (25×). The pixel count for cement surface area was calculated for each image using Adobe Photoshop software. Descriptive statistics of the mean and standard deviation of the cement film thickness around posts were calculated. Kruskal–Wallis and Dwass–Steel–Critchlow–Fligner tests were used for statistical analysis, with a significance level of α = 0.05. Results: Pairwise comparisons in the coronal section revealed a statistically significant difference (p < 0.05) between groups A and B and groups B and C. In the middle section, there was a statistically significant difference (p < 0.05) between groups A and B only. In the apical section, there was a statistically significant difference (p < 0.05) between all groups. Conclusions: Within the limitation of the present study, neither 3D printed nor milled Ti CPC could achieve comparable cement film thickness to cast-gold CPC in all three sections. Cast-gold CPC cement film thickness was found to be more reduced and consistent, thus having superior internal adaptation to 3D-printed and milled Ti CPCs. Full article

Introduction: This preliminary in vitro study aims to evaluate the application of micro-CT in analyzing the microstructural coupling between dental implant fixtures and prosthetic abutments, with an emphasis on understanding the effectiveness and limitations of this technique in dental implantology. Materials and Methods: A search of PubMed, MEDLINE, and the Cochrane Library up to May 2024 identified eight relevant studies that examined different facets of dental implantology, such as osseointegration, implant stability, and the comparative accuracy of micro-CT versus other imaging techniques. A comparative micro-CT radiographic analysis was performed on five different implant fixtures with respective prosthetic and healing abutments, by using SkyScan1174 micro-CT. Results: The reviewed studies demonstrated that micro-CT is reliable for assessing bone quality, implant stability, and the microstructural integrity of dental implants. Micro-computed tomography (micro-CT) studies reveal bone–implant contact (BIC) ratios of 40–80%, bone volume per total volume (BV/TV) values of 20–60%, and detect microgaps as small as 0.3 µm, highlighting its high-resolution capability (5–10 µm) for detailed implant analysis. The comparative analysis of the implant fixtures analyzed the implant–abutment connection, highlighting the relevance of implant design for ensuring stability. Conclusions: Micro-CT analysis has proven to be a valuable tool for evaluating the intricate microstructural properties of dental implants, offering insights into implant stability, bone quality, and osseointegration. The literature reviewed highlights consistent findings that underscore micro-CT’s accuracy and reliability in capturing high-resolution data, suggesting its potential as a standard imaging modality in implant research and clinical assessment. Full article

Background: Grapefruit seed skin particles (GSSPs) have antifungal properties due to the presence of flavonoids. Therefore, it has the potential to display antifungal characteristics when added to acrylic resin, but it could affect the mechanical properties of the resin. This study investigated the effects of adding GSSPs on the mechanical characteristics of 3D-printed denture base resins. Purpose: The aim of the present study was to determine the effects of the addition of GSSPs to 3D-printed acrylic at different concentrations on the degree of conversion (DC), surface hardness, flexural strength, and tensile strength. Methods: In this study, 90 samples were printed with acrylic resin via a Digital Light Processing (DLP) printer. Thirty square samples were used for the surface hardness test. Thirty rectangular samples were used for the flexural strength test, and thirty dumbbell-shaped samples were used for the tensile strength test. These materials were prepared by adding different concentrations of GSSPs (0.0 wt.%, 5.0 wt.%, and 7.0 wt.%), which were determined by a pilot study to be the most effective in 3D denture base resins. The Durometer Shore Hardness Scale (DSHS) was used to measure the surface hardness, and a universal testing machine was employed to gauge the flexural strength and tensile strength. Field emission scanning electron microscopy (FE-SEM) was employed for particle size analysis and fracture behavior determination. Results: Compared with those of the control group, the degree of conversion (DC), surface hardness, flexural strength, and tensile strength of the treated groups significantly improved after the addition of 5.0 wt.% and 7.0 wt.% GSSPs. The FE‒SEM images revealed a decrease in porosity as the concentration of GSSPs increased with a brittle fracture behavior. Conclusions: The addition of GSSPs to 3D-printed acrylic is recommended because of their significant positive impacts on the mechanical properties of 3D-printed denture base resin. Full article

Background: Denture stomatitis is an inflammatory condition involving swelling and redness of the oral mucosa beneath a denture. Among various available treatments, zinc oxide nanoparticles (ZnONPs) and nano-wire nanostructures have been suggested as potential future therapies. However, there is a lack of information in the literature about the effectiveness of ZnONPs regarding microbial adhesion to different denture base resins. Here, we review studies on the effect of ZnONP use on microbial adhesion to denture base resins to answer the following study question: “Does incorporating ZnONPs into denture base resins reduce microbial adhesion?” Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, an electronic and manual search ranging from Jan 2000 to May 2024 was performed using PubMed, Web of Science, and Scopus databases to answer the study question. All full-length English-language articles investigating the effects of ZnO nanostructures on Candida albicans adhesion to polymethyl methacrylate (PMMA) denture base resins were included. The extracted data were tabulated for qualitative and quantitative analysis of the included studies. Results: Of the 479 studies reviewed, 7 studies successfully met the eligibility criteria. All included studies utilized PMMA as the denture base material with different polymerization methods. C. albicans was the most extensively studied microbial species, with various count methods used. Six studies concluded a statistically significant impact of ZnONPs on decreasing C. albicans adhesion to the denture base. However, one study reported the opposite. Conclusions: Incorporating ZnONPs into PMMA denture base resin has a positive impact on reducing C. albicans adherence and could be recommended for denture stomatitis treatment. However, further studies are needed to cover the notable gap in data regarding the safety and effectiveness of ZnO nanostructures. Full article

OBJECTIVES: To describe our experience with a new high-density porous polyethylene orbital implant post-enucleation and evisceration and comment on their performance and safety. METHODS: Patients with an indication of enucleation or evisceration with orbital implantation were included in a prospective study. All patients were implanted with OCULFIT orbital implants (AJL Ophthalmic S.A.) and followed up over 12 months. Anatomical and functional parameters, motility, and aesthetic appearance were evaluated. Patient satisfaction on a scale of 0 (very bad) to 5 (excellent), complications and success rates were reported. RESULTS: Overall, 16 enucleated and 17 eviscerated eyes were analyzed. Orbital implant motility was good for 93.8% and 100% of enucleated and eviscerated patients, respectively. No shortened fornixes were found after external prosthesis placement, and palpebral fissure, orbital volume, and lower eyelid laxity were symmetric with the contralateral eye for the vast majority. The aesthetic appearance was good for 87.5% and 100% of enucleated and eviscerated patients at the last visit with no differences between groups. Excellent satisfaction was reported for 100% and 94.1% of enucleated and eviscerated patients. Anatomical and functional success rates were 78.8% and 81.8%, respectively. No exposure, infection or complications related to surgery were reported during the follow-up. CONCLUSIONS: After 1 year of follow-up, OCULFIT orbital implants provide excellent patient satisfaction and performance in terms of motility and symmetry with the contralateral eye after external prosthesis placement with no complications related to the surgical procedure. No differences between enucleated and eviscerated eyes were found, and aesthetic results were remarkable for both groups. Conclusions should be interpreted with caution due to the small sample size. Full article

Background: Shade selection is a critical procedure of any esthetic prosthodontic treatment process. Despite its importance, there is a concern regarding the awareness and knowledge of shade selection among dental students and practitioners. Purpose: To evaluate the knowledge of dental students and practitioners regarding shade selection principles and investigate the differences in aesthetic prioritization between fixed and removable prostheses. Additionally, to investigate the emphasis placed on aesthetics in removable prosthetic cases compared to fixed prostheses, and to examine how this emphasis differs between dental students and experienced practitioners. Methods: A cross-sectional questionnaire-based study was conducted involving students and dental practitioners. The questionnaire consisted of multiple-choice questions designed to evaluate participants’ knowledge of shade selection principles and methods used in contemporary dental clinical practice and the perceived impact on treatment outcomes in Saudi Arabia. This study involved 554 participants, divided into three groups: 117 who treated fixed cases, 51 who treated removable cases, and 398 who treated both fixed and removable cases. The collected data was tabulated for data analysis using the Mann–Whitney U test and the Kruskal–Wallis test to generate the significance per category. Results: The study revealed no significant differences in knowledge and practice scores across the demographic factors for participants who exclusively treated either fixed or removable cases, suggesting a uniformity in expertise and application. However, among participants who managed both fixed and removable cases, significant variations emerged based on gender, age, and educational or professional level. Notably, a statistically significant disparity (p < 0.05) was observed in the comprehension of digital shade-matching technology, with practicing dentists exhibiting a higher level of awareness compared to dental students. Conclusions: The study concluded that age, gender, and education level significantly impact the knowledge and practice of shade selection. The findings highlighted a concerning gap in the awareness and knowledge regarding shade selection by dental students compared to practitioners, which emphasizes the need for enhanced educational training programs focusing on shade selection techniques and their implications for prosthodontic outcomes. Full article

Aims: this study aims to investigate the impact of simulated skin color and the use of fiducial markers on the accuracy of 3D facial scans, comparing two types of structured light scanners under constant ambient lighting conditions. Materials and Methods: Three mannequins with different skin colors—black, white, and pink—were scanned using two light based hand-held scanners (infrared light and blue-light). Each mannequin was scanned with and without fiducial markers placed on defined anatomical landmarks. A total of one hundred thirty-two scans were performed and converted into standard tessellation language (STL) files. STL files from each scanner were compared to their respective control scans using point cloud comparison software. Accuracy was evaluated based on root mean square (RMS) values. Descriptive statistics summarized the data, and a t-test was performed to assess differences in RMS values between scans with and without fiducial markers for each scanner type. Results: The infrared light scanner showed the highest accuracy for the white mannequin, as evidenced by lower RMS values compared to the pink and black mannequins. Adding fiducial markers significantly enhanced scan accuracy for the pink and black mannequins. The blue-light scanner achieved accuracy for the white and pink mannequins comparable to that of the infrared scanner. However, it was unable to scan the black mannequin, even with the use of markers. Conclusions: Within the limitations of this study, simulated skin color significantly affects the accuracy of facial 3D scans. Scans of lighter (white) tones demonstrate higher accuracy compared to darker tones. Fiducial markers enhance the accuracy for an infrared scanner; however, a blue-light scanner is unable to capture dark simulated skin, even with the addition of fiducial markers. Full article

Objectives: The purpose of this clinical study is to compare implant full-arch intraoral scans taken immediately after implant placement with those obtained after tissue healing in patients rehabilitated with implant-supported fixed prostheses. Methods: Between September 2023 and March 2024, a total of 19 patients with compromised residual dentition (6 women; 13 men) were rehabilitated using 4-to-6 immediately loaded post-extraction implants. These implants supported fixed full-arch screw-retained prostheses either in the lower jaw (9 patients) or upper jaw (10 patients). Intraoral scans were taken immediately after implant placement (termed “immediate scan”). After a healing period of four months, the provisional prosthesis was removed, and a second intraoral scan was performed using the same scan bodies and scan pattern as the initial scan (termed “delayed scan”). The two scans were overlaid, and the discrepancies between them were measured. Results: The average discrepancy between the immediate and delayed scans was 0.1905 mm. Our statistical analysis revealed larger discrepancies for implants placed in the posterior areas, with the implant in site 1.6 (Implant 1) showing a discrepancy of 0.2326 mm, and the implant in site 2.6 (Implant 4) showing a discrepancy of 0.2124 mm (p = 0.05). No statistically significant difference was observed when comparing patients treated in the upper and lower jaws. Conclusions: Within the limitations of the study and based on this result, clinicians should be aware that an immediate post-surgical intraoral digital scan for implant-supported full-arch rehabilitations may result in a higher risk of imprecision. Furthermore, according to the results of the study, the accuracy of the digital impression on implant full-arch rehabilitations seems to be influenced by the clinician’s skills. Further studies with larger sample sizes are required to confirm our results. Full article

Emulating very soft tissues with synthetic materials is important for clinical prosthetists who want to improve compliance in maxillofacial and breast prosthesis. It is equally important for theatrical prosthetists wanting to model bariatric conditions and soft organs for surgical or palpation training. Polydimethylsiloxane (PDMS) gels, which are often used in medical model construction, are stiff and highly elastic compared to the friable soft tissues found in the body. Silicone oil is known to soften PDMS gels, but it is not known precisely how oil dispersal affects these gels and what proportion of oil is needed to simulate very soft tissue membranes like adipose tissue. In this work, internationally agreed test standards were used to mechanically characterize a range of PDMS gel membranes saturated with different amounts of silicone oil to determine whether materials with behavioral similarities to adipose tissue could be created. Mechanical properties like hardness, elasticity, strength, viscoelastic behavior and cure-time are presented in this study, which are all key factors required by the creators of such membranes. Results were compared to identical tests on porcine fat and data in the literature for porcine and human fat. The data revealed a strong correlation between increases in oil content and decreases in membrane hardness, strength and elastic modulus. It was also found that increases in oil content caused proportional increases in cure time, while membranes with equal amounts of oil and gel were best at mimicking characteristics of human and porcine fat, like hardness and elasticity. Full article

Introduction: The use of cementation in total hip arthroplasty (THA) has evolved over the years, with a notable shift toward cementless and hybrid techniques. The aim of this study is to evaluate data from an Italian registry on the type of fixation used in THA implants and their corresponding survival rates in a large patient cohort with long-term follow-up, and to compare these data with the most recent literature. Methods: From January 2000 to December 2020, a total of 137,256 primary THA procedures were performed, of which 10.4% were fixed with stem cementation. There were 4857 revision implants, of which 11.4% were implanted with stem cementation. Results: The trend showing a significant shift toward cementless fixation methods is particularly pronounced in younger patients, with cementless implants comprising 99.5% of procedures in patients under 40 years of age. As patient age increases, the use of cemented or hybrid fixation methods becomes more common. This trend aligns with existing literature, in which cementation is often preferred for elderly patients due to concerns about bone quality and the potential for better immediate fixation provided by cemented stems. At 10 years, the implant that showed the highest survival rate was the fully cemented implant, with a rate of 94.8%. This study also reports the causes of failure based on the different fixation techniques. Conclusions: The development of standardized guidelines that consider patient-specific factors such as age, bone quality, and comorbidities in the choice of fixation type could help reduce variability in practice and improve overall outcomes in hip arthroplasty. Full article

Stress shielding and aseptic loosening have been identified as adverse effects of short-stem total hip arthroplasty resulting in hardware failure. However, there is a gap in research regarding the impact of stress shielding in customized porous coatings. The purpose of this study was to optimize the distribution of the coefficients of friction in the porous coating of a metaphyseal femoral stem to minimize stress shielding. Static structural analysis of an implanted short, tapered-wedge stem with a titanium porous coating was performed with the use of Analysis System Mechanical Software under axial loading. To limit computational time, we randomly sampled only 500 of the possible combinations of coefficients of friction. Results indicate that the coefficient of friction in the distal lateral porous coating significantly affected the mid-distal medial femoral surface and lateral femoral surface. The resultant increased proximal strains resulted from an increased coefficient of friction in lateral porous coating and a reduction in the coefficient of friction in medial mid-distal coating. These findings suggest that a customized porous coating distribution may produce strain patterns that are biomechanically closer to intact bone, thereby reducing stress shielding in short femoral stems. Full article

This clinical report details the prosthetic rehabilitation of a patient following maxillary ablation to remove a peripheral giant cell granuloma. After a hemimaxillectomy, the defect was reconstructed with a fasciocutaneous radial free flap. Implant placement was digitally planned using the dual scanning technique, and implants were inserted with the aid of an acrylic surgical guide. After implant osseointegration, a removable implant-supported overdenture with an electroplated secondary structure retained on a titanium bar was fabricated. At the 3-year follow-up, peri-implant tissues remained healthy, showing only mild gingival hyperplasia around the bar, while no prosthesis retention loss or significant technical complications were observed. In conclusion, the reconstruction of the moderate maxillary defect using a soft-tissue flap provided satisfactory functional and esthetic outcomes, significantly enhancing patient satisfaction. However, the limited bone availability necessitated precise implant planning to ensure adequate biomechanical support for the overdenture. Full article

As the discipline of prosthodontics evolves, it encounters a dynamic landscape characterized by innovation and improvement. This comprehensive analysis underscores future developments and transformative solutions across its various subspecialties: fixed, removable, implant, and maxillofacial prosthodontics. The narrative review examines the latest advancements in prosthetic technology, focusing on several critical areas. The integration of artificial intelligence and machine learning into prosthetic design and fitting processes is revolutionizing the field, serving as a common thread that links these innovative technologies across all subspecialties. This includes advancements in automated diagnostics, predictive analysis, and treatment planning. Furthermore, the review offers a forward-looking perspective on how these innovations are influencing each prosthetic dentistry domain, patient outcomes, and current clinical practices. By thoroughly analyzing contemporary research and emerging technologies, the study illustrates how these advancements represent a growing focal point of interest in developing countries, such as Romania, with the potential to redefine the trajectory of prosthetic rehabilitation and enhance patient care not only within this country but also beyond. Full article

Percutaneous Osseointegrated Implants (POI) affix artificial limbs to the body after amputation. Several adverse events challenge mainstream uptake of this technology. This study aims to achieve a consensus regarding “the challenges and adverse events to POI integration and long-term fixation in limb amputation”. We sought a panel of clinical experts divided by profession into surgical, clinical, or clinical academic categories. We used a real time eDelphi method to develop consensus on both the challenges and adverse event items, enabling anonymity, iteration, controlled feedback, and statistical aggregation of group responses. The full panel agreed that the most impactful items are amongst 10 key challenges and eight adverse events. Panellists were in consensus regarding the five most impactful challenges, which were, in decreasing order: patient selection, absence of a multidisciplinary team, design of the implant, soft tissue stability and an experienced surgical team. Panellists considered the five most impactful adverse events, in decreasing order, to be the following: no biological fixation, deep infection, aseptic loosening, no mechanical fixation, and implant breakage. Consensus was obtained on implant breakage and deep infection items. The proportion of consensus from the whole panel across all items was in line with the literature, and we observed an improvement in consensus once the panel was stratified based on job, expertise and implant system. Full article

Background/Objectives: Periprosthetic joint infection (PJI) is one of the most common complications after joint replacement. Two-stage revision remains the standard of care in chronic infections. The aim of this systematic review was to investigate the outcomes, complications, and eradication rates of two-stage revision surgery to treat PJI of the shoulder, elbow, hip, and knee. Methods: A total of 36 studies were included. Patient demographics, follow-up, the visual analog scale (VAS) for pain, the Constant–Murley score (CMS) for shoulder, the Harris Hip Score (HHS) for hip, the Knee Society Score (KSS) for knee, the range of motion (ROM), number and types of complications, and eradication rate were recorded. Results: A total of 2484 patients were identified, of whom 145, 29, 1269, and 1041 underwent two-stage revision surgery for shoulder, elbow, hip, and knee infections, respectively. The overall mean follow-up was 5.7 ± 4.5 years. The overall mean time of re-implantation was 20.8 ± 21.3 weeks. The most common causative bacteria were Cutibacterium acnes (32.7%) for shoulder, Methicillin-Sensitive Staphylococcus aureus (44.4%) for elbow, and Staphylococcus coagulase negative (CNS) (31.3% and 23%) for hip and knee infection, respectively. The mean overall preoperative VAS score was 6.7 ± 2.3, while, postoperatively, the mean score was 4.5 ± 2.7 (p < 0.001). A total of 2059 out of 2484 patients (82.9%) experienced eradication. Conclusions: Two-stage revision is an effective procedure to treat PJI with an overall eradication rate of 83%. A significant recovery of functionality and a decrease in residual pain can be achieved after surgery. Aseptic loosening and re-infection were the most common complications in shoulder and hip infections. Death rate was high in knee infections. Full article

This study evaluated the effectiveness of atmospheric pressure plasma jet (APPJ) treatment on the surface characteristics and bond strength of zirconia and lithium disilicate ceramics for CAD-on restorations. A total of 70 cylindrical-shaped specimens of lithium disilicate and 70 disc-shaped specimens of Y-TZP zirconia were machined, thermally processed, surface-treated, and then resin-bonded. The specimens were grouped according to the following surface treatments: no surface treatment, sandblasting, plasma, sandblasting followed by plasma, sandblasting followed by universal adhesive, plasma followed by universal adhesive, and sandblasting and plasma treatment followed by universal adhesive. The treated surfaces were subjected to a wettability assessment via contact angle measurement and a topography assessment using scanning electron microscopy (SEM). The cemented assembly was subjected to shear bond strength testing with a universal testing machine, and the results were imported to SPSS 23.0 for statistical analysis. The results show that APPJ treatment induced a significantly low contact angle for both ceramics with no surface alteration upon scanning. Moreover, APPJ treatment produced a bonded assembly with a shear bond strength comparable to sandblasting. In conclusion, APPJ treatment should be considered an efficient surface treatment with a non-destructive nature that surpasses sandblasting with the provision of a high shear bond strength between CAD-on ceramics. Full article