Prosthesis, Volume 6, Issue 2 (April 2024) – 14 articles

(1) Background: Since new intraoral scanner (IOS) versions are introduced to the market and software continues to advance, there is an ongoing need to assess the accuracy of newer IOS models. (2) Methods: Four types of IOSs and one laboratory scanner (used as a reference) were used to scan an edentulous model with six parallel implants and their respective scan bodies, which were connected to each other. Using dedicated software, the distances between all scan bodies were calculated, generating a total of 540 measurements. Trueness (comparisons to the reference model) and precision (intragroup comparisons) were statistically compared with ANOVA and Tukey tests. (3) Results: When considering trueness values, statistically significant differences were observed between the tested scanner for all subgroups considered (p < 0.05). By contrast, no statistically significant differences were reported for precision values. (4) Conclusions: Within the limitations of the present in vitro study, it can be concluded that all tested IOSs were similar in terms of precision, while Trios and i700W yielded the worst trueness values. Nevertheless, increasing the measuring distance leads to a decrease in both trueness and precision. Full article

The use of 3D-printed highly porous titanium acetabular cups in total hip arthroplasty (THA) is increasing. The porosity and mechanical properties of such highly porous titanium structures mimic those of natural cancellous bone, possibly allowing biological implant fixation to be improved. Recently, a 3D-printed highly porous Dual Mobility (DM) monobloc construct fully manufactured using Ti6Al4V alloy, with a titanium–niobium nitride (TiNbN) ceramic coating on the articular side to allow articulation against the mobile liner by improving the titanium vs. polyethylene tribological behavior, was introduced in THA. To the best of our knowledge, this is the first highly porous titanium monobloc DM implant on the market. The reasons for using a Ti alloy highly porous DM are multifarious: to prevent any possible adverse reactions due to the corrosion of Cobalt–Chromium–Molybdenum Alloy (CoCrMo) and Stainless Steel (SS) implants and to improve implant primary and secondary stability, particularly in cases of poor bone quality. Finally, with the introduction of an inner TiNbN ceramic coating surface, it was possible to overcome the poor tribological quality of titanium. Another interesting characteristic is this material’s higher implant radiolucency, which might facilitate the radiographic assessment of cup orientation, which can, in turn, facilitate the detection of any intraprosthetic dislocation (IPD) and the measurement of polyethylene wear, which is very important in the study of the durability of THA. Full article

Dental implant utilization has emerged as a contemporary strategy for rectifying dental arch anomalies. However, the effective management of potential complications is paramount. Peri-implantitis, characterized by inflammation and bone resorption around dental implants, resembles periodontitis but specifically affects implant sites. Restoring lost peri-implant tissues poses a multifaceted challenge, with bioprinting methods showing promise as a viable solution. Three-dimensional bioprinting represents a forefront advancement in tissue engineering, traditionally focusing on scaffolds, cells, and signaling pathways. This systematic review aims to aggregate and synthesize data concerning bioprinting’s application in peri-implantitis treatment. Adhering to PRISMA guidelines, the review conducted an extensive literature search across PubMed, Scopus, Google Scholar, and ScienceDirect. Importantly, the search timeframe was not limited, reflecting the scarcity of available information on the subject. Bioprinting advancements offer auspicious avenues for refining treatment modalities, prompting clinicians to explore optimal solutions for establishing ideal anatomical conditions. In essence, this systematic review underscores 3D bioprinting’s potential in peri-implantitis management, highlighting its pivotal role in contemporary dental medicine and its capacity to reshape clinical approaches toward achieving optimal outcomes. Full article

Background: With the growing use of dental implants, there is an urgent need to determine a prosthetic placement protocol by assessing implant stability and monitoring healing. Implant Stability Quotient (ISQ) values are produced using dental non-invasive devices through resonance frequency analysis, considered as indicators for measuring primary stability (i.e., at implant placement), monitoring biological stability (osseointegration), and prosthetic loading. A systematic and detailed comparison of ISQ measurement devices, for a given patient population, is lacking in the literature. This aspect is the subject of the present work, with the devices being two that are widely used in clinical practice (Osstell^® and Osseo^®100). The aim of this study was to evaluate the reliability of ISQ measurement using two standard devices most commonly used in clinical practice and to highlight any differences when comparing measurements at undefined time intervals. Methods: We enrolled 50 patients (16 males and 34 females) with a mean age of 55.4 years, who indicated dental implant placement and met the inclusion criteria. The sample was divided into two equal groups based on bone density: A (D1–D2 bone density) and B (D3–D4 bone density); each had 25 patients with 40 implants. ISQ was measured using two devices: Osstell^® and Osseo 100^®, at different time points (A: three and B: four follow-ups). Results: All enrolled patients completed the study without adverse events; all implants placed were successful, with no implant failure. In each of the study groups, ISQ values increased gradually with increasing follow-up time, and there was no significant difference between Osstell and Osseo 100 values at follow-up times except for the T1 follow-up in group A. Temporal comparisons for the two devices revealed significant differences in T0 vs. T2 in group A, whereas significant differences existed in T0 vs. T1, T2, and T3 in group B. Our findings indicated that the overall effect significantly depended on bone density rather than on the device used to measure ISQ. Conclusion: Regardless of the devices used, the ISQ measurement effectively monitors healing after implant insertion and allows prosthetic load to be modulated according to the ISQ value, especially when prosthetizing implants placed in fine trabecular bone (D4 or regenerated bone). Full article

The number of people with diabetes is rising day-by-day, which also raises the incidence of diabetic ulcers, sensation loss in the foot’s plantar area, and in extreme instances, amputations. Using customized shoes, unloading orthoses, insoles, and other strategies may help control these issues to some degree. In this work, a novel modular diabetic insole was designed and fabricated to effectively offload the abnormal or peak plantar pressures in diabetic patients. The pressure values in the plantar region were quantified using an in-house-developed plantar pressure-measuring insole consisting of force sensitive resistor (FSR) sensors. The effectiveness of the modular diabetic insole was tested qualitatively and quantitatively. The qualitative performance of the insole was reported using Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0) in terms of subjective parameters like comfort, ease of use, effectiveness, etc. and calculated as 4.7 ± 0.18. Thereafter, the wearable pressure-measuring insole was used to investigate the feasibility of modular insole for the plantar pressure offloading during standing and walking conditions. It was observed that the maximum average zonal pressure (AZP) was reduced by up to 99% from 121.30 ± 3.72 kPa to 0.22 ± 0.18 kPa for the standing condition whereas it was reduced to 6.76 ± 2.03 kPa from 197.71 ± 3.21 kPa with a percentage value of 96% for the walking condition. In conclusion, the findings of this work validate the effectiveness of the modular diabetic insole as an intervention tool for diabetic foot ulcer prevention. Full article

Pressed lithium disilicate is largely used for veneer manufacturing, but a new block formulation has recently been released on the market. This study evaluated the clinical performance of milled lithium disilicate veneers (LiSi Block, GC Co., Tokyo, Japan) realized with a fully digital or hybrid workflow using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 24 months of clinical service together with the patient’s satisfaction using the Visual Analog Scale (VAS). A total of 105 veneers on natural anterior teeth were made on twenty-nine patients with LiSi Block (GC, Tokyo, Japan). Patients were randomly divided into three groups: Group 1, 35 veneers realized with a completely digital workflow using Trios 3 (3Shape A/S, Copenhagen, Denmark); Group 2, 35 veneers realized with a completely digital workflow using Experimental IOS (GC, Tokyo, Japan); and Group 3, 35 veneers realized with a hybrid workflow. The restorations were followed up for 24 months, and the modified USPHS evaluation was performed at baseline, 12 months, and 24 months together with periodontal evaluation. Repeated measures two-way ANOVA and the Tukey test were applied to compare the modified USPHS method values (α = 0.05). STATISTICA 10.0 software and SIGMAPLOT 12.0 software were used to perform statistical analysis. There were no statistically significant differences between the three groups and with the interaction of group vs. time periods. The satisfaction scores of 7.35 ± 1.8 and 9.4 ± 0.37 were recorded before and after treatment, respectively. Milled lithium disilicate veneers showed a good clinical outcome after 2 years of clinical service. No difference was found between fully digital or hybrid workflow. Full article

Restorative dentistry is the repairing of damaged teeth and restoring oral health and function. Dental implants are typically placed within the cortical bone of the jaw to provide stability and support for prosthetic restorations. The successful restoration of complex anatomical features of the maxillary anterior is difficult for prosthodontists. Using a 3D slicer, CT scan images were used to create a detailed three-dimensional model of the maxilla bone. This study utilizes ANSYS Workbench, a finite element software program, to analyze the abutment angles, ranging from 0° to 25°, and the impact stress distribution within peri-implant bone. The outcomes of our studies align with and substantiate certain evidence in the literature documenting bone resorption, specifically at the level of the implant neck and near the cortical bone. The study aims to provide a comprehensive understanding of angled abutment stress patterns in the bone surrounding dental implants, offering valuable insights for clinical applications in critical areas of the mouth. Full article

In dental implant insertion, an artificial foundation is prepared for the prosthetic device, which involves the surgical positioning of the implant in the jaw bone. The success of dental implants relies on the osseointegration process. The biomechanical factors, such as stress and strain, developed during the insertion affect the jawbone and its surroundings. In this current study, the stresses during the implant insertion in the mandibular jawbone bone are analyzed using three-dimensional explicit dynamic analysis, and the Cowper–Symonds model is implemented with the damage model. The implant’s design has a substantial impact on stress distribution within the cancellous bone during the insertion procedure. The stress variation takes place as the implant moves into the pre-drilled hole. This is because of the contact between the bone and the fixture on the implant. The upper edge of the predrilled site shows that the stresses are more at the crestal region of the implant due to surface area. There is a gradual increase in the stress level as the implant reaches the lower edge from the top edge. This is because of the concept of mechanical interlocking. Clinicians can use this information to anticipate and address potential stress-related challenges during implant placement. Full article

This review article aims to provide an updated and comprehensive overview of the latest trends in adult upper limb prostheses, specifically targeting various amputation levels such as transradial, transmetacarpal, transcarpal, and transhumeral. A systematic search was conducted across multiple databases, including IEEE Xplore, MDPI, Scopus, Frontiers, and Espacenet, covering from 2018 to 2023. After applying exclusion criteria, 49 scientific articles (33 patents and 16 commercial prostheses) were meticulously selected for review. The article offers an in-depth analysis of several critical aspects of upper limb prostheses. It discusses the evolution and current state of input control mechanisms, the number of degrees of freedom, and the variety of grips available in prostheses, all tailored according to the level of amputation. Additionally, the review delves into the selection of materials used in developing these prostheses and examines the progression of technology readiness levels. A significant focus is also placed on the evolution of prosthesis weight over the years for different amputation levels. Moreover, the review identifies and explores critical technological challenges and prospects in upper limb prostheses. Finally, the article culminates with a conclusion that encapsulates the key findings and insights on the advancements and ongoing developments in this field. Full article

The literature shows evidence of the mechanical investigation of numerous polymeric dental biomaterials using a static approach. A more representative mechanical analysis of such materials must take into account the dynamic masticatory load of the oral cavity. The aim of this work is to study the dynamic mechanical proprieties and provide an in vitro characterization of 11 3D-printed new dental biomaterials to understand their clinical applications under physiological conditions. The analysis included Dynamical Mechanical Analysis (DMA) and an MTT cytotoxicity assay. The mechanical results at low frequencies (1–11 Hz) show high uncertainty, less fragility, and less strength. The biological results show a significant reduction in cell viability (p < 0.01) at both the 3 and 24 h timepoints, with a degree of recovery observed at 24 h. To assess the clinical potential of dental biomaterials, it is necessary to determine whether there are good dynamic mechanical properties and reduced adverse biological effects on oral cells. This may allow for the facile fabrication via 3D printing of prosthetic devices that can support masticatory loads over long periods of time. Further investigations of the presented polymeric materials are needed, exploring biological assessments for longer than 24 h. Full article

Background: Patients with edentulism often have an impaired functional, phonetic, and esthetic status, resulting in poor quality of life; hence, the mandibular overdenture has been considered the standard implant treatment for such patients. Therefore, this study aimed to assess the effectiveness of mandibular overdentures retained using mini-implants on patient-reported satisfaction and their long-term survival. Methods: We searched patients’ medical records for eligible subjects, screening and inviting patients who received a mandibular overdenture anchored on mini-implants over ten years ago. We used a numerical rating scale from 0 (the worst) to 10 (the best) to assess four aspects: comfort, retention, chewing ability, and speaking ability before and after having mini-implants. We carried out Kaplan–Meier analysis to assess their survival. Results: Forty-eight elderly patients who were medically compromised and had a mandibular overdenture anchored on four permucosal mini-implants were included. All patient-reported satisfaction (comfort, retention, chewing ability, and speaking ability) was significantly improved after supporting mandibular overdentures with mini-implants (p-values < 0.05), with retention and chewing ability being the most substantially improved. The 10- and 15-year mini-implant survival rates were both 97.9%. Conclusions: Mandibular overdentures with mini-implants can be considered a valid and practical alternative to conventional implant-supported overdentures in patients with atrophic ridges, medically compromised, and the elderly. Full article

Objective: To train a machine-learning (ML) algorithm to classify stumbling in transfemoral amputee gait. Methods: Three subjects completed gait trials in which they were induced to stumble via three different means. Several iterations of ML algorithms were developed to ultimately classify whether individual steps were stumbles or normal gait using leave-one-out methodology. Data cleaning and hyperparameter tuning were applied. Results: One hundred thirty individual stumbles were marked and collected during the trials. Single-layer networks including Long-Short Term Memory (LSTM), Simple Recurrent Neural Network (SimpleRNN), and Gradient Recurrent Unit (GRU) were evaluated at 76% accuracy (LSTM and GRU). A four-layer LSTM achieved an 88.7% classic accuracy, with 66.9% step-specific accuracy. Conclusion: This initial trial demonstrated the ML capabilities of the gathered dataset. Though further data collection and exploration would likely improve results, the initial findings demonstrate that three forms of induced stumble can be learned with some accuracy. Significance: Other datasets and studies, such as that of Chereshnev et al. with HuGaDB, demonstrate the cataloging of human gait activities and classifying them for activity prediction. This study suggests that the integration of stumble data with such datasets would allow a knee prosthesis to detect stumbles and adapt to gait activities with some accuracy without depending on state-based recognition. Full article

The arrangement of a stress breaker in the pier abutment of a fixed-mobile bridge affects the deformations that may occur in its supports. This article aims to study the most appropriate position and arrangement of a stress breaker. To verify the established objectives, an experimental “in vitro” study was carried out with five different bridge designs: one with rigid connectors and four with non-rigid connectors (interlocks), placed on the distal and mesial surface of the intermediate abutment, and combining the retention stop at cervical and occlusal positions. The strain level at the support ground of each bridge was measured with strain gauges. The statistical analysis was performed with the help of the Kruskal–Wallis test and a linear regression model. Initial results show that the model with the highest average value of maximum strain is the non-rigid bridge with the interlock on the distal surface of the pier abutment and the occlusal retention stop. In any case, the presence of an intermediate abutment, with or without interlock, influences the maximum tension supported by the abutment, especially in relation to the intermediate abutment. Full article