Prosthesis, Volume 6, Issue 1 (February 2024) – 16 articles

(1) Background: Computer-guided surgery is now established as the main technique for implant placement, reducing intraoperative complications and helping the clinician avoid damaging sensitive anatomical structures, such as, for example, the maxillary sinus. (2) Methods: A complex case is discussed to suggest how computer-aided surgery can merge with freehand surgery, as a surgical guide can make a freehand surgical procedure less complicated and more predictable. (3) Results: A surgical procedure was executed following digital planning, except for sites 1.5 and 2.5, where a mixed approach was adopted: they were initially prepared with a milling depth of 1 mm from the base of the maxillary sinus and were then finished using osteotomes, according to the technique described by Summers. Radiography confirmed the correct positioning of the implants and the sinus lift. (4) Conclusions: A mixed digital/analogical approach used in complex cases increases the accuracy of the results and reduces complications and treatment time. The presence of a correctly digitally planned surgical guide helps in the freehand approach and not only in the digital approach. Full article

Background: A key point in assessing dental implant prosthetic joints is their mechanical strength and biological response under the masticatory loading. The aim of the present systematic review was to evaluate the marginal bone loss and prosthetic behaviour of different internal/external bi-phasic implants. Methods: Randomized Clinical Trials (RCTs) have been considered for analytic purposes. The article screening was conducted on the Pubmed/MEDLINE, EMBASE and Google Scholars databases through an electronic process. Eligibility and risk of bias assessments were conducted for an article to be included in the data process. A series of pairwise meta-regressions for continuous variables was conducted considering the mean differences and 95% CI at two different timepoints: baseline and 1-year follow-up. The meta-analysis was performed comparing the following groups: internal conical prosthetic joint with index (IC), external hexagon bone level position (EI), internal tri-channel connection bone level position (ITC), internal hexagon 1 mm below the bone level (HI), internal hexagon bone level position (HI crest), cone morse 1 mm below the bone level (CM), cone morse bone level position (CM crest) and internal octagon bone level position (IO). The following parameters were considered for descriptive data synthesis: sample size, implant manufacturer, prosthetic joint type, prosthetic complications, marginal bone loss, study outcomes. Results: A total of 247 papers were identified by the electronic screening and 241 were submitted for the full text assessment. The eligibility process excluded 209 articles, and 32 studies with a low risk of bias were considered for the qualitative synthesis and further statistical methods. At the baseline, the CM showed a more effective efficiency and reduced marginal bone loss compared to IC, EI, ITC, internal hexagon, cone morse and internal octagon (p < 0.05). CM showed the lower rate of prosthetic complications and structural device failure including abutments and joint components under the loading compared to other joint types. Conclusion: Within the limits of the present investigation, the heterogeneity, the weight of the study model considered and the inherent differences between the dental implant properties, the pure CM showed a more consistent control of marginal bone loss at short- and medium-term follow-up. Despite the low rate of cumulative complications for all joints considered, the CM abutment joints were less prone to prosthetic failure at an early and medium-term follow-up. Full article

Background: Bleeding complications are strong predictors of mortality and major morbidity in elderly patients undergoing surgical aortic valve replacement (SAVR) or transcatheter aortic valve implantation (TAVI). Despite the high prevalence of frailty in this population, little is known about its effects on bleeding risk. Methods: We conducted a retrospective observational study of 502 patients undergoing isolated SAVR or TAVI between January 2015 and February 2022. The occurrence of blood products transfusions and MACEs were the primary endpoints. In-hospital mortality was the secondary endpoint. Results: The Elderly group (age < 80 years old) included 475 subjects, whereas the Very Elderly group (age ≥ 80 years old) included 127 patients. The need for blood product transfusion was similar among the two groups, regardless of the type of procedure. MACEs occurred similarly between groups [SAVR: Elderly group: 7.9% vs. Very Elderly group: 8.6%, p = 0.864; TAVI: Elderly group: 5.5% vs. Very Elderly group: 8.7%, p = 0.378]. The was no difference in in-hospital mortality rate in patients submitted to TAVI, whereas very elderly patients had higher mortality rate compared to the elderly patients submitted to SAVR [SAVR: Elderly group: 0% vs. Very Elderly group: 2.8%, p = 0.024; TAVI: Elderly group: 4,8% vs. Very Elderly group: 8%, p = 0.389]. Conclusions: Age alone should not be considered as a predictive factor for post-operative adverse events or in-hospital mortality in elderly patients with severe symptomatic AS. Full article

Achieving a comfortable socket residual limb interface is crucial for effective prosthetic rehabilitation, depending on the precise characterisation and fluctuations in the shape and volume of residual limbs. Clinicians rely on subjective and iterative methods for shaping sockets, often involving a trial-and-error approach. This study introduces a framework for measuring, analysing, and comparing residual limb shape and volume using scanned data to facilitate more informed clinical decision-making. Surface scans of 44 transtibial residual limb casts of various sizes and lengths were examined. All scans were spatially aligned to a mid-patella and subjected to analysis using a shape analysis toolbox. Geometric measurements were extracted, with particular attention to significant rectified regions during the cast rectification process. Following PTB guidelines, our analysis revealed substantial alterations, primarily in the mid-patella region, followed by the patellar tendon area. Notably, there was a significant volume change of 6.02% in the region spanning from mid-patella to 25% of the cast length. Beyond this point, linear cast modifications were observed for most amputees up to 60% of the cast length, followed by individual-specific deviations beyond this region. Regardless of residual limb size and length, the modifications applied to positive casts suggested categorising patients into five major groups. This study employs the AmpScan shape analysis tool, to comprehend the cast rectification process used for capturing and assessing the extent of rectification on patients’ residual limb casts. The clinical implications of our research are threefold: (a) the comparison data can serve as training resources for junior prosthetists; (b) this will aid prosthetists in identifying specific regions for rectification and assessing socket fit; (c) it will help in determining optimal timing for prosthetic fitting or replacement. Full article

The purpose of this study was to evaluate the inter-limb asymmetry in the kinematic parameters of the approach run in elite-level female Class T63/T64 long jumpers and its relationship to performance. Three Class T63 and nine Class T64 female long jumpers were examined during a competition. The temporal and kinematic parameters of their approach steps (step length: SL; step frequency: SF; average step velocity: SV) were measured using a panning video method and speed radar. The symmetry angle was the measure of inter-limb asymmetry. The results revealed that SF and SV were significantly (p < 0.05) larger in the intact lower limb. Significant (p < 0.05) asymmetry was revealed for SL, SF, and SV in 2/12, 3/12, and 1/12 jumpers, respectively. The direction of asymmetry for SF was towards the leg wearing the prosthesis for all examined jumpers. The official jump distance was significantly (p < 0.05) positively correlated with the maximum velocity attained during the approach and negatively correlated with the symmetry angle for SF. It is concluded that the observed asymmetry in SF was compensated for by the modifications observed in the SL that consequently resulted in no asymmetry in SV, leading the participants to effectively utilize their approach speed optimally in terms of long jump performance. Full article

Background: The present case report serves as a proof of concept for the fabrication and effective clinical administration of a 3D-printed chin cup tailored to the patient’s anatomical characteristics. Methods: An 11-year-old male with a Class III malocclusion was treated using a chin cup appliance to intercept and control a Class III mandibular skeletal growing pattern early. Two tailored chin cup devices were designed using 3D face scanning and CBCT scanning and were produced with additive manufacturing techniques. The chin pads were digitally designed based on a 3D scan of the patient’s face. The 3D modeling of chin cup components was performed using 3Shape Appliance Designer and 3D printed with biocompatible resin. An analogic chin pad was also produced for the same patient. The treatment plan involved the patient wearing the chin cup for 13 h per day. The patient was instructed to use all three chin pads produced at intervals of 4 months. The patient’s experience was assessed by reporting the comfort experience via a VAS scale. The treatment strategy was effective in improving the skeletal Class III malocclusion. Additionally, the integration of 3D face scanning (or CBCT scanning), modeling, and printing enables the production of customized chin cups with superior fit and comfort, contributing to enhanced patient compliance and treatment efficacy. Full article

Due to their lack of periodontal ligaments (PLs) and the differences between dental implants and natural teeth, it is necessary to improve and generate a new occlusal scheme to prolong the life of implants and prostheses. The age and the sex of patients must be considered because of their effects on the stomatognathic system’s physiology. Operators must manage all the changes to obtain good sensations during mastication and a better occlusal scheme for implanting fixed partial prostheses. Dentists should try to protect this type of prosthesis using adjacent teeth and the PL. This is why new digital systems were created. The combination of T-Scan^® (digital software for occlusal analysis) and electromyography (EMG) could allow doctors to find areas where it is necessary to act and to find suitable solutions for the problems generated by using conventional methods of occlusal analysis (such as articulating paper). In this study, a new method for establishing occlusion on fixed partial implant prostheses has been created, combining digital systems with conventional articulating paper. This method consists of asking the patient to bite down with different forces and situations in an attempt to achieve Implant-Protected Occlusion (IPO). The use of digital systems has been shown to be more effective than using only conventional systems. This new method allows a safer mode of occlusion which protects implants and prostheses, saving all the differences between them and natural teeth, and increasing the satisfaction of patients. This method also helps to overcome the changes in the stomatognathic system as age increases, adjusting the occlusion to changes in PLs with age. Full article

The removable partial denture, despite new technologies and new materials, continues to play a significant role in clinical dental practice. The purpose of the following study was to evaluate the design of new retention devices in Kennedy class II scenarios. For the study of “lamellar” retentive devices, four prosthetists were chosen. According to inclusion and exclusion criteria, prosthetists selected 16 patients (8 women and 8 men) whose upper arches had to be rehabilitated using a removable partial prosthesis. The results showed that the parameters taken into consideration, such as satisfaction, stability, aesthetics, and retention, had an average score that was higher than 3.30 (range 1–4), with an average standard deviation of 0.6225 in the four parameters, indicative that the data were relatively homogeneous and coherent. In conclusion, we can state that the skeletonized prosthesis with lamellar retentions, designed for Kennedy class II scenarios, has shown high acceptance in selected patients. Full article

Limb disability is a frequent healthcare problem, especially for patients in primary care. Orthotic treatment has become the most common practice for either rehabilitation or permanent assistance, due to the emergence of 3D scanning and 3D printing technologies. A CAD model rebuilt from captured data is a key step in the rapid prototyping process of customized orthoses. An accurate and robust surface reconstruction technique remains a research challenge, aiming for a well-fitting design and the patient’s comfort. Thus, this paper presents of a new 3D curve-based reconstruction algorithm to obtain a precise 3D surface of an orthotic device from a scanned body part. Numerical experiments of two orthosis design case studies are shown to evaluate the reliability and accuracy of the proposed approach compared to other reconstruction methods. Full article

This study aims to assess and compare the impact of Monolithic Zirconia (MZ) and In-Ceram Zirconia (ZP) superstructures on stress distribution within implants and D2/D4 bone densities under 200 N vertical and oblique occlusal loads using three-dimensional finite element analysis via ANSYS WORKBENCH R2. The analysis employed maximum and minimum von Mises stress values. Modeling an implant (4.2 mm diameter, 10 mm length) and abutment (0.47 mm diameter), with an 8 mm diameter and 6 mm length single crown, the research identified lower von Mises stresses in D2 cancellous bone with the MZ model under vertical loading. Conversely, under oblique loading, the ZP model exhibited maximum von Mises stresses in D4 bone around the implant. This underscores the critical need to consider physical and mechanical properties, beyond mere aesthetics, for sustained implant success. The findings highlight the effect of material composition and stress distribution, emphasizing the necessity of durable and effective implant treatments. Full article

The aim of the present systematic review was to assess the antinociceptive efficacy of 15-deoxy-Δ12,14-prostaglandin J₂ (15d-PGJ₂) therapy in rats with experimentally induced temporomandibular joint (TMJ) arthritis. The focused question was “Is 15d-PGJ₂ therapy effective in the management of TMJ nociception?” Indexed databases were searched without time and language restrictions up to and including September 2023 using different key words. Original studies were included. Risk of Bias (RoB) was assessed using the SYRCLE tool. Six studies performed in male Wistar rats with experimentally induced TMJ arthritis were included. The observation or follow-up period ranged between 45 min and 14 days. Four studies reported that 15d-PGJ2 therapy retards the production of proinflammatory cytokines in TMJ tissues. Four studies reported that 15d-PGJ₂ therapy inhibits leukocyte migration and plasma extravasation in TMJ tissues. In one study, the expression of decay-accelerating factor in TMJ tissues increased after 15d-PGJ₂ therapy. One study showed that 15d-PGJ₂ inhibits nociception in a dose-dependent manner via the activation of peripheral kappa/delta opioid receptors. Prior sample-size-estimation (SSE) was performed in none of the studies and all studies had a high RoB. Due to a high RoB, methodological variations, and the absence of prior SSE within the included studies, it is demanding to derive an absolute verdict regarding the antinociceptive efficacy of 15d-PGJ₂ therapy in response to experimentally induced TMJ arthritis. Full article

Background: Prosthetic hip replacement is a widely practiced surgical procedure with excellent results. Hip stems based on the Zweymüller design have a long history and their philosophy focuses on achieving long-term stability promoting physiological load transfer. The aim of this study is to evaluate outcomes, survivorship, and complication rates in a cohort of patients treated with this stem. Methods: A retrospective review was conducted to identify patients who underwent primary THA with Zweymüller stems. A total of 86 hips (43%) were implanted in men, and 114 hips (57%) in women. The mean follow-up time was 5.4 years. Patient charts were reviewed for adverse events occurring after primary THA as well as for revision and indication for revision. Patients still implanted with the hip stem were asked to complete the HOOS JR survey. Results: Ten hips (5.0%) were lost to follow up. The mean HOOS JR score at final evaluation was 96.3 points (range, 60.0–100.0). Two revisions were performed during the study for femoral stem loosening due to a periprosthetic Vancouver B2 fracture and for multiple hip dislocations. Conclusions: The Zweymüller design hip stem showed excellent survivorship and favorable clinical outcomes at a mean follow-up of 5.4 years. Full article

Background: The present study analyzes the clinical aspects of the use of small-diameter implants for the fixation of total overdenture-type prostheses on both totally edentulous dental arches. Materials and methods: This is a review of all randomized controlled trials of at least ten patients with a control group in which at least two narrow implants were placed, published between January 2010 and July 2023. Most databases were analyzed, and clinical studies involving the insertion of at least two narrow implants (<3.5 mm in diameter) were analyzed. Results: Studies showed that the survival rate of narrow implants varied from 78% to 100%. Conclusions: The results indicated that narrow-type implants have satisfactory and predictable clinical performance for the long-term stability of overdenture-type prostheses. Full article

The field of additive manufacturing, particularly 3D printing, has ushered in a significant transformation in the realm of joint arthritis treatment through prosthetic surgery. This innovative technology allows for the creation of bespoke prosthetic devices that are tailored to meet the specific needs of individual patients. These devices are constructed using high-performance materials, including titanium and cobalt-chrome alloys. Nevertheless, the routine physical activities of patients, such as walking, sitting, and running, can induce wear and tear on the materials comprising these prosthetic devices, subsequently diminishing their functionality and durability. In response to this challenge, this research has endeavored to leverage novel techniques. The primary focus of this study lies in the development of an algorithm designed to optimize hip replacement procedures via the mechanical design of the prosthesis. This optimization process exploits the capabilities of machine learning algorithms, multi-body dynamics, and finite element method (FEM) simulations. The paramount innovation in this methodology is the capacity to design a prosthetic system that intricately adapts to the distinctive characteristics of each patient (weight, height, gait cycle). The primary objective of this research is to enhance the performance and longevity of prosthetic devices by improving their fatigue strength. The evaluation of load distribution on the prosthetic device, facilitated by FEM simulations, anticipates a substantial augmentation in the useful life of the prosthetic system. This research holds promise as a notable advancement in prosthetic technology, offering a more efficacious treatment option for patients suffering from joint arthritis. The aim of this research is to make meaningful contributions to the enhancement of patient quality of life and the long-term performance of prosthetic devices. Full article

Designs of active prostheses attempt to compensate for various functional losses following amputation. Integration of sensory feedback with the functional control re-enables sensory interaction with the environment through the prosthetic. Besides the functional and sensory loss, amputation induces anatomical and physiological changes of the sensory neural pathways, both peripherally and centrally, which can lead to phantom limb pain (PLP). Additionally, referred sensation areas (RSAs) likely originating from peripheral nerve sprouting, regeneration, and sensory reinnervation may develop. RSAs might provide a non-invasive access point to sensory neural pathways that project to the lost limb. This paper aims to report on the sensory input features, elicited using non-invasive electrical stimulation of RSAs that over time alleviated PLP in two upper-limb amputees. The distinct features of RSAs and sensation evoked using mechanical and electrical stimuli were characterized for the two participants over a period of 7 and 9 weeks, respectively. Both participants received transradial and transhumeral amputation following traumatic injuries. In one participant, a relatively low but stable number of RSAs provided a large variety of types of evoked phantom hand (PH) sensations. These included non-painful touch, vibration, tingling, stabbing, pressure, warmth/cold as well as the perception of various positions and movements of the phantom hand upon stimulation. Discomforting and painful sensations were induced with both mechanical and electrical stimuli. The other participant had a relatively large number of RSAs which varied over time. Stimulation of the RSAs provided mostly non-painful sensations of touch in the phantom hand. Temporary PLP alleviation and a change in the perception of the phantom hand from a tight to a more open fist were reported by both participants. The specificity of RSAs, dynamics in perception of the sensory input, and the associated alleviation of PLP could be effectively exploited by designs of future active prostheses. As such, techniques for the modulation of the sensory input associated with paradigms from interaction with the environment may add another dimension of protheses towards integrating personalized therapy for PLP. Full article