Microstructure and dry wear properties of Ti-Nb alloys for dental prostheses

The microstructure and properties of a series of binary Ti-Nb alloys for dental prostheses with niobium contents ranging from 5% to 20% were investigated. The experimental results indicate that the crystal structure and morphology of Ti-Nb alloys are sensitive to their niobium contents. When Nb content is 5%, the acicular α crystal grain is observed. When Nb content is 10%, the coarse equiaxed crystal grain and the fine, acicular α crystal grain are observed. When Nb content is 15%, only the α equiaxed crystal grain is observed. When the alloy contains 20%Nb, the equiaxed and dendritic α crystal grain are observed. For Ti-Nb alloys, the increase of Nb content modifies the microstructure of Ti-Nb alloys significantly and decreases their compression elastic modulus, in which Ti-20Nb alloy shows the largest compression strength and Ti-5Nb alloy shows the best plasticity. The dry wear resistance of Ti-Nb alloys against Gr15 ball was investigated on CJS111A ball-disk wear instrument. For Ti-Nb alloys, Ti-10Nb alloy shows a smallest steady friction coefficient, Ti-5Nb alloy shows the smallest wear depth and best wear resistance, and Ti-15Nb alloy shows the largest wear depth and worst wear resistance. The phenomenon of furrow cut happens and furrows form during wear tests.

Neural prostheses for restoring functions lost after spinal cord injury

Spinal cord injury（SCI）is a debilitating condition that affects more than 2.5 million individuals worldwide（Thuret et al.,2006）.In addition to its devastating effects on the individual,this disease is a heavy burden to the society in terms of health care costs, which are estimated in billions of dollars annually in most developed countries （Cadotte and Fehlings, 2011）.

Visual prostheses, optogenetics, stem cell and gene therapies: splitting the cake

The size of the blind population in 2015 was estimated to be approximately 36 million（Bourne et al.,2017）.According to the predictions by Bourne and co-workers,the number of the visually impaired is expected to reach nearly 100 million by 2050.

Preparation and Mechanical Performance of Blended Polyester/Silk Small Diameter Arterial Prostheses

Small diameter arterial prostheses were required to treat coronary and cerebrovascular arterial diseases. The diameters of the artificial blood vessels should match the diameters of the host arteries. Besides,the mechanical properties of the arterial prostheses should be strong enough to endure the forces in the body after implantation. In this study,silk and polyester were woven into small diameter arterial prostheses and the dimensional and mechanical properties,as well as the water permeability,were investigated. The woven samples had an inner diameter ranging from 3. 65 to 3. 94mm. The wall thickness of the samples ranged from 0. 26 to 0. 28mm. Compared with polytetrafiuoroethylene( ePTFE) commercial devices,whose probe bursting strength was measured to be 15. 64 N /mm2,the woven samples had superior strength values ranging from20. 53 to 28. 97 N /mm2. In addition,the radial compliance of the woven samples was found to lie between the ePTFE sample and the pig's carotid artery,and the water permeability of all the woven samples was less than 300 mL /( cm2·min) which indicated that these woven samples could be implanted without preclotting.

New Design of Textile Vascular Prostheses for the Reconstruction of Small Diameter Vascular Blood Vessels

The general object of research is to design new idea of the semi-biodegradable,multilayered vascular prosthesis used for the reconstruction of significantly small diameter vascular vessels( microreconstruction). The paper studies the selection of appropriate sterilization technique for resorbable tubular structures made of poly( L-lactide-co-glicolide)( PLAGA) and nonbiodegradable tubular structures made of polypropylene( PP). The designed grafts are characterized by the physical properties as well as mechanical properties according to ISO 7198 ∶ 1998 Standard.Moreover,the process of the grafts fabrication will be explained considering the stages affected the critical properties of the elaborated textile implants. The increase of PLAGA melt-electrospun tubular structures mechanical properties was observed due to the thermal stabilization use. The ethylene oxide( EO) and steam sterilization had a destructive effect on the designed PLAGA meltelectrospun tubular, fibrous structures, whereas the irradiation yielded in the changes in mechanical and physical properties on the acceptable level,taking into account the future clinical applications.

Binding mechanism of interface of porous coated titanium alloy prostheses

ＢｉｎｄｉｎｇｍｅｃｈａｎｉｓｍｏｆｉｎｔｅｒｆａｃｅｏｆｐｏｒｏｕｓｃｏａｔｅｄｔｉｔａｎｉｕｍａｌｌｏｙｐｒｏｓｔｈｅｓｅｓＺｏｕＨｏｎｇｅｎ（邹宏思）；ＹｅＪｕｎ（叶军）；ＴａｎｇＮｏｎｇｘｕａｎ（唐农轩）；ＹｕａｎＣｕｎｈｕａ（袁存华）（Ｄｅ...

Anticoagulation in Pregnant Women with Mechanical Heart Valve Prostheses: 25-Year Experience at a Tertiary Care Hospital in a Developing Country

The aim of this retrospective study was to compare the different anticoagulation regimens used in pregnant women with prosthetic heart valves. We reviewed 86 pregnancies in 57 women from 1987 to 2011. The patients were divided into two groups: group A (39 pregnancies) had oral acenocoumarol throughout pregnancy;and in group B (47 pregnancies), acenocoumarol was replaced by subcutaneous heparin during the first trimester. Both groups received heparin at the time of delivery. The valves replaced were mitral (59.65%), aortic (12.28%), or both (28.07%). 74 pregnancies (86.04%) resulted in live births, 9 (10.46%) had stillbirths, 1 (1.16%) had spontaneous abortion and 2 (2.32%) underwent therapeutic abortions. The live birth rate was higher in women on heparin (87.23%) compared with those on acenocoumarol (84.61%). No malformations appeared in the 74 newborns, except for one case of hydrocephalus. There was one maternal death due to acute mitral valvular thrombosis while on heparin in the first trimester. Hemorrhagic complications occurred in 13 patients in the postpartum period, 4 of whom required transfusion. No anticoagulant regimen can be said to be entirely safe for use during pregnancy as there is a degree of risk with each regimen. Heparin does not offer a clear advantage over oral anticoagulation in the pregnancy outcome.

Anatomical and Functional Preliminary Results of Total Non-Cemented Hip Prostheses

The aim of this work was to assess the preliminary anatomical and functional results of patients to establish prospects. Materials and method: We report here the preliminary results of a retrospective mono-centric, homogeneous and continuous series, of 21 non-cemented total hip implants, implanted from January 2011 to December 2014. The mean follow-up time was 24 months. The patients were evaluated by Harris’s hip at the last follow-up. Results: The mean age of the intervention was 30 years. In our series, we observed a male predominance (60% of cases). Clinically, the Harris score varied significantly from 52.6 ± 11.4 pre-operatively to 85.1 ± 5.1 during the last follow-up visit. Among the items in the score, pain was the parameter that showed the greatest improvement. Thigh pain was observed in only one patient operated on the two sides. At the level of radiology, the femoral implant showed great stability. Bone resorption was suspected in 14 cases (66.66%), and confirmed in 4 cases (19.04%) with excellent bone remodeling, illustrated by the Engh and Massin scores. A loosening and a prosthetic dislocation was observed in a patient (4.76%). Any heterotopic ossification was observed. Conclusion: Our study confirmed good clinical and radiological results of the non-cemented hip prosthesis series in young patients. The rates of aseptic loosening, acetabular edges or osteolysis are low and stable over time.

Iatrogenic Oesophageal Perforations in Neoplastic Lesions: Management with Covered Self-Expanding Prostheses

Background:Perforation of the oesophagus is a serious condition. Most of them are iatrogenic and are associated with significant morbidity and mortality, especially with late diagnosis. Aim: To prospectively analyse the results of the endoscopic management of iatrogenic perforations in oesophageal neoplasia, through the immediate insertion of a covered self-expanding prosthesis (CSES). Materials and Methods: Between 01.01.2006 and 12.30.2016, a series of 19 consecutive patients attended the Teaching Unit of Endoscopic Surgery of the Regional de Concepción Hospital, Chile, with the diagnosis of oesophageal neoplasia confirmed by biopsy were prospectively studied. All were subjected to a prior evaluation by the oncology team and subsequently referred for endoscopic palliative management of dysphagia. The average age was 77 ± 9.3 years, 8 (42.1%) were female and 11 (57.9%) were male. In 17 patients (89.5%) the stenosis compromised the oesophagus, in 2 (10.5%) the gastro-oesophageal junction, 16 had a squamous carcinoma (84.2%) and 3 an adenocarcinoma (15.8%). Results: Perforation was diagnosed during the procedure in 18 patients (94.7%) and in 1 (5.3%) 22 hours later. Follow-up was done for a minimum of 90 days or until death. The prostheses were inserted successfully in all cases. The immediate evolution was satisfactory in 12 patients (63.2%). In the rest (36.8%), 18 complications appeared. The most frequent were retrosternal pain, subcutaneous emphysema and fever. The early evolution was satisfactory in 12/19 cases (63.2%). Complication was evidenced in 7 (36.8%), the most frequent was retrosternal pain (36.8%). Fever occurred in 3 (15.8%), pleural effusion in 3 (15.8%) and mediastinitis in 2 of these. The prosthesis was kept in situ as a definitive palliation method for neoplastic dysphagia. In 10 of the 18 cases that survived more than a month, there were late complications (55.6%), none of them associated with the perforation itself. The only death (5.3%) was due to an oesophagus-pleural fistula, associated with an early prosthetic migration. Recovery of the oral intake occurred, on average, at 3.7 days. The hospital stay averaged 9.6 days. Conclusion: The use of CSES for the treatment of iatrogenic oesophageal perforations in the context of neoplasia, is a safe and effective method, with low morbidity, adequate recovery of the oral intake and prompt discharge from hospital.

Influence of Ni and Cr Content on Corrosion Resistance of Ni-Cr-Mo Alloys for Fixed Dental Prostheses in 0.05% NaF Aqueous Solution

The Ni-Cr-Mo alloys have been used as dental prostheses because they own a good mechanical strength, high corrosion resistance and even to be economically viable. These alloys corrosion protection against in salt solutions typical of physiological media is due to passivation phenomenon with an oxide surface layer formation, mainly chromium oxides. This protective film, subjected to a mechanical stress in a corrosive environment, can partially dissolve by releasing ions, which have deleterious effects in a human body. Fluoride ions, existing in hygiene products, change the buccal environment and their presence may enable a localized corrosion process initiation. The aim of this work has been to investigate the chemical composition influence of three alloys in corrosion resistance to: A (Ni-73% Cr-14% Mo-8.5% Be-1.8% Al-1.8%), B (Ni-61% Cr-25% Mo-10.5% Si-1.5%) and C (Ni-65% Cr-22.5% Mo-9.5%) in media containing fluorides that simulate mouthwashes solution. The study has been done in a 0.05% NaF solution, pH 6, at 37°C using electrochemical techniques. The alloy with the highest nickel and the lowest chromium content is not passive in the middle studied, showing a continuous increase in current density with the potential increasing, while the other alloys show passivation range of 600 mV and passive current density of about 10-6 A/cm2.

Implant-Supported Full Fixed Prostheses with a Removable Oro-Nasal Obturator for the Edentulous Maxilla with Palatal Fistula due to Surgical Procedures for Oral Cancer

Open oro-nasal defects resulting after oral tumor resection need structural and functional rehabilitation using dental prostheses. Conventional removable prostheses have usually been indicated and performed for prosthodontics. When the patient has an edentulous maxilla, the unfavorable stability of the prosthesis will cause dysfunction of mastication and pronunciation. To achieve improvement of the impaired functional situation, implant-supported full fixed prostheses (IPSPs) for the edentulous maxilla with a removable obturator offer a reasonable solution. We present herein the case of a 70-year-old Japanese man who has presented with oro-nasal defect due to surgical procedures for oral cancer. He was treated with implant-supported full fixed prostheses in a conventional two-step procedure. After prosthesis treatment, a palatal obturator was set. The patient has shown no clinical or radiological evidence of failure as of 24 months after the end of treatment. Functional evaluation of mastication and pronunciation showed dramatic improvements. For a patient with an edentulous maxilla and palatal fistula, full-arch fixed prostheses supported by a combination of axially and non-axially positioned implants and a removable oro-nasal obturator, using the anterior alveolar bone, without bone transplantation or maxillary sinus elevation, could offer an effective, minimally invasive treatment alternative.

Testicular prostheses-impact on quality of life and sexual function

Orchiectomy is the recommended treatment for many testicular conditions.However,testicular prosthesis placement is not always performed for different reasons.In this study,we aimed to evaluate patients'opinions and the impact on sexual function and quality of life.This retrospective observational single-center study included patients who underwent orchiectomy between January 2014 and December 2020 at the Department of Urology,Braga's Hospital(Braga,Portugal),where testicular implants were always available and the decision to undergo the procedure was made fully independent of cost.Patients completed four questionnaires that assessed demographic data,satisfaction,self-esteem,and sexual function.Of the 96 patients who underwent orchidectomy,59 replied to the questionnaires,and of these patients,86.4%decided to undergo silicone-based testicular prostheses implantation.The remaining 13.6%refused the implant based on concerns about complications(37.5%),because they felt that it was unnecessary(37.5%),or because it was not offered by the doctor(25.0%).Overall,96.1%of these patients were satisfied with the implant;however,25.5%classified it as"too firm".No statistically significant differences were found in sexual function(all P>0.05).However,it can be observed that there are more patients with prostheses presenting normal sexual activity compared to patients without prostheses(74.0%vs 50.0%),and none of them reported severe erectile dysfunction(0 vs 16.7%).Regarding self-esteem,both patients with and without prostheses present very similar average scores with no statistically significant differences.The present study highlights the highest level of satisfaction among patients who received testicular prostheses.Testicular prostheses implantation is a safe procedure that does not hamper sexual function after orchiectomy.

Three-dimensional-printed titanium prostheses with bone trabeculae enable mechanical-biological reconstruction after resection of bone tumours

Reconstruction after resection has always been an urgent problem in the treatment of bone tumours.There are many methods that can be used to reconstruct bone defects;however,there are also many complications,and it is difficult to develop a safe and effective reconstruction plan for the treatment of bone tumours.With the rapid development of digital orthopaedics,three-dimensional printing technology can solve this problem.The three-dimensional printing of personalised prostheses has many advantages.It can be used to print complex structures that are difficult to fabricate using traditional processes and overcome the problems of stress shielding and low biological activity of conventional prostheses.In this study,12 patients with bone tumours were selected as research subjects,and based on individualised reverse-engineering design technology,a three-dimensional model of each prosthesis was designed and installed using medical image data.Ti6Al4V was used as the raw material to prepare the prostheses,which were used to repair bone defects after surgical resection.The operation time was 266.43±21.08 minutes(range 180-390 minutes),and intraoperative blood loss was 857.26±84.28 mL(range 800-2500 mL).One patient had delayed wound healing after surgery,but all patients survived without local tumour recurrence,and no tumour metastasis was found.No aseptic loosening or structural fracture of the prosthesis,and no non-mechanical prosthesis failure caused by infection,tumour recurrence,or progression was observed.The Musculo-Skeletal Tumour Society(MSTS)score of limb function was 22.53±2.09(range 16-26),and ten of the 12 patients scored≥20 and were able to function normally.The results showed that three-dimensional printed prostheses with an individualised design can achieve satisfactory short-term clinical efficacy in the reconstruction of large bone defects after bone tumour resection.

Comparison of Maxillary Implant-Supported Prostpesis in Irradiated and Non-Irradiated Patients

In order to investigate the influence of radiation therapy after the treatment of maxillary implant-supported prostheses, 27 patients received a total of 131 implants in maxilla after oral cancer treatment and/or reconstructive surgery. Among them, 25 received maxillary implant-supported prostheses. The cumulative survival rates of implants and prostheses were evaluated by the product-limit-estimates method according to Kaplan-Meier. The cumulative survival rate of implants and prostheses in irradiated patients was compared with that in non-irradiated patients by statistical Log-rank test. The results showed that 112 implants were observed after implant loading. The implants cumulative survival rate was approximately 65 % for overall patients. The cumulative prosthesis successful rate was approximately 88 % for all 25 patients. Log-rank test analysis revealed that there was a significant difference in cumulative implants survival rates between non-irradiated and irradiated maxillary bone (P<0. 01). It was concluded that the implants and prostheses in irradiated patients have significantly lower survival rates than in non-irradiated patients.

Prosthetic reconstruction of the trachea:A historical perspective

This review discusses the history of tracheal reconstruction; from early work to future challenges. The focus is primarily on prosthetic tracheal reconstruction in the form of intraluminal stents, patch repairs, circumferential repairs and replacement of the trachea. A historical perspective of materials used such as foreign materials, autografts, allografts, xenografts and techniques, along with their advantages and disadvantages, is provided.

A Review of the Application of Additive Manufacturing in Prosthetic and Orthotic Clinics from a Biomechanical Perspective

Prostheses and orthoses are common assistive devices to meet the biomechanical needs of people with physical disabilities.The traditional fabrication approach for prostheses or orthoses is a materialwasting,time-consuming,and labor-intensive process.Additive manufacturing(AM)technology has advantages that can solve these problems.Many trials have been conducted in fabricating prostheses and orthoses.However,there is still a gap between the hype and the expected realities of AM in prosthetic and orthotic clinics.One of the key challenges is the lack of a systematic framework of integrated technologies with the AM procedure;another challenge is the need to design a prosthetic or orthotic product that can meet the requirements of both comfort and function.This study reviews the current state of application of AM technologies in prosthesis and orthosis fabrication,and discusses optimal design using computational methods and biomechanical evaluations of product performance.A systematic framework of the AM procedure is proposed,which covers the scanning of affected body parts through to the final designed adaptable product.A cycle of optimal design and biomechanical evaluation of products using finite-element analysis is included in the framework.A mature framework of the AM procedure and sufficient evidence that the resulting products show satisfactory biomechanical performance will promote the application of AM in prosthetic and orthotic clinics.

Endovascular Stents in Arterial Injury after Radiotherapy

We evaluated preliminary success and patency of stenting for the treatment of radiation - induced arterial diseases. Thirteen stents were placed in 8 patients to treat occlusion (n = 3), aneurysm (n = 1), residual stenosis (n = 2), multiple stenoses (n = l), and delayed restenosis after previous balloon angioplas-ty (n=l). Interventional procedure was successfully performed in 8 patients for their arterial lesions after radiotherapy. Six patients underwent interventional procedure once or twice. Two patients underwent PTA 4 times. Five of these patients demonstrated primary patency with relief of clinical symptoms with a mean follow-up of 2 years (range: 8 - 60 months). Clinical improvement was noted in the other patients. Our results suggest that stent placement by single or multiple techniques may have immediate effect on arterial lesions caused by radiation and can be considered as a therapeutic option of choice in these cases.

Influence of Structures on the Mechanical Properties of PET Biotextiles

Occurrence of vascular diseases is increasing and leads to rising demand for the STENT-GRAFT( SG). To ensure the SG function properly,the materials should have low blood permeability and good mechanical properties. So far, there have been few systematic studies on the relationship between textile structures and mechanical properties of the bio-textiles used in the SG. In this study, six types of biomedical PET fabrics with different yarn structures and fabric structures were designed and fabricated. All the SG materials could meet the requirement of thickness,except the sample of 30 d × 20 d with 2 /2 twill construction,which was thicker than 0. 12 mm. Bursting strength and water permeability( WP) of the six samples were also tested. Through the comparison of comprehensive performance,the PET fabric 30 d × 20 d /12 f with2 /2 twill construction with both good resistances to permeability and bursting strength, might have good prospect in applications of vascular engineering.

Total hip replacement using MINIMA^(■)short stem:A short-term follow-up study

BACKGROUND Total hip replacement has become one of the most successful orthopaedic procedures.The length of the femoral stem constitutes one of the most important geometrical and mechanical features of the prosthesis.Several different implants are currently available but data are limited concerning the clinical results for some of these implants.AIM To report the short-term clinical and radiological results of a novel squared section,tapered design–with four conicity-short stem in total hip replacement.METHODS This is a retrospective study of a prospectively collected data using of MINIMA?short stem in 61 consecutive patients with at least 1 year follow-up.The collected data included patients’demographics,type of arthritis,bone morphology,perioperative data,clinical results using Harris Hip Score,EuroQol(EQ-5D),pain score and satisfaction rate,complications and radiological results.RESULTS Total 61 patients were included in our study with a mean age of 56 years of age(range 25-73 years).The majority of them(68.6%)were women,thirty seven patients(56.9%)were less than 60 years of age and almost half of patients(45.1%)suffered from secondary osteoarthritis(hip dysplasia,osteonecrosis,etc.).The mean time of follow-up examination was 33.4 mo(2.8 years)with a range of 12-57 months(1-4.8 years).In 35 patients(56.9%)the follow-up examination was more than 3 years.No major complications such as revision,periprosthetic fracture,dislocation or infection were presented.Re-admission 90 d postoperatively or laterwas deemed unnecessary for any reason regarding the operation.Respectively,the mean pain score,mean Harris hip score,and mean EQ-5D were improved from 6.3,58.7 and 77.3 preoperatively to 0.1,95.1,and 79.8 postoperatively.The Satisfaction rate at the final follow-up was 9.9(SD 0.3,range 8.0-10.0).All stems were classified as stable bone ingrowth and no radiolucent lineswere revealed in any of the modified Gruens’zone at the postoperative Xrays.Stem subsidence was within acceptable limits and the incidence of distal cortical hypertrophy was relatively low.CONCLUSION The clinical and radiological results concerning the MINIMA?short stem are excellent according to this first report of this specific design of the short femoral stems.Because of the small number of cases and short-term follow-up of this study,a longer follow up time and more patients’enrollment is required.