A Technique for Duplicating a Fixed Complete Denture

The fixed implant prosthesis often requires repair due to fracture and/or wear of acrylic resin teeth. Repair of such a prosthesis, although simple, requires retaining the prosthesis to be revised in the laboratory. In order to reveneer the implant prosthesis, a provisional restoration should be fabricated for the patient that provides similar function and esthetics. This article presents a technique for duplicating the existing fixed implant-supported prosthesis prior to repair/reveneer, thus providing a smooth transition from the provisional to the definitive prosthesis

Prosthetic management of mid-facial defect with magnet-retained silicone prosthesis

Background and aim: Mid-facial defect is one of the most disfiguring and impairing defects. A design of prosthesis that is aesthetic and stable can be precious to a patient who has lost part of his face due to surgical excision. Prosthesis can restore the patients' self-esteem and confidence, which affects the patients and their life style. The aim of this case report is to describe a technique of mid-facial silicone prosthesis fabrication. Technique: To provide an aesthetic and stable facial prosthesis, the extra-oral prosthesis was fabricated using silicone material, while the intra-oral defect was restored with obturator prosthesis, and then both prostheses were connected and attached to each other using magnets. Discussion: This clinical report describes the rehabilitation of a large mid-facial defect with a two-piece prosthesis. The silicone facial prosthesis was made hollow and lighter by using an acrylic framework. Two acrylic channels were included within the facial prosthesis to provide the patient with clean and patent airways. Clinical relevance A sectional mid-facial prosthesis was made and retained in place by using magnets, which resulted in a significant improvement in the aesthetical and functional outcome without the need for plastic surgery. Silicone prostheses are reliable alternatives to surgery and should be considered in selected cases.Article Link: http://poi.sagepub.com/content/38/1/6

An exploratory evaluation of psychological factors in the rejection of upper limb prostheses : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Psychology at Massey University

This study investigated the reactions of arm amputees to their prostheses and explored possible reasons for these reactions. A questionnaire was constructed to determine the use to which the recipients put their prostheses. A preliminary validation study was conducted to determine the final form of the questionnaire. Rather than selecting a sample of prosthesis recipients, a census of the recipient population was attempted with 48.57 per cent responding. Respondents were asked questions measuring their use of the prosthesis, the nature of their prosthesis, the rehabilitation services they had used, and various demographic variables including age, sex, occupation and so on. It was found that up to 55.9% of the respondents could be classified as low-users of their prosthesis. A regression analysis showed that 44 per cent of the variance in the use of the prosthesis was due to the two variables of prosthesis type and prosthesis length. No other variables explained significant amounts of the variance. A lower-user and a high-user were selected to pilot a further study examining psychological factors that may affect prosthesis use. The areas examined were those of training, perceptions of independence and stigma, and perceptions of the prosthesis. A number of modifications were made to the original questions as a result of the pilot study. The results of the pilot study indicated that the areas of training and expectations of the prosthesis' capabilities prior to receiving it would be most likely to prove useful in explaining different levels of prosthesis use. Some issues relating to possible future research, interventions, and the rehabilitation process were also discussed

The use of sensory feedback in the adaptation of perturbed /s/

The study investigates the contribution of tactile and auditory feedback in the adaptation of /s/ towards a palatal prosthesis. Five speakers were recorded via electromagnetic articulography, at first without the prosthesis, then with the prosthesis and auditory feedback masked, and finally with the prosthesis and auditory feedback available. Tongue position, jaw position and acoustic centre of gravity of productions of the sound were measured. The results show that the initial adaptation attempts without auditory feedback are dependent on the prosthesis type and directed towards reaching the original tongue palate contact pattern. Speakers with a prosthesis which retracted the alveolar ridge retracted the tongue. Speakers with a prosthesis which did not change the place of the alveolar ridge did not retract the tongue. All speakers lowered the jaw. In a second adaptation step with auditory feedback available speakers reorganised tongue and jaw movements in order to produce more subtle acoustic characteristics of the sound such as the high amplitude noise which is typical for sibilants

Performance of the resurfaced hip. Part 1: the influence of the prosthesis size and positioning on the remodelling and fracture of the femoral neck

Hip resurfacing is an established treatment for osteoarthritis in young active patients. Failure modes include femoral neck fracture and prosthesis loosening, which may be associated with medium-term bone adaptation, including femoral neck narrowing and densification around the prosthesis stem.Finite element modelling was used to indicate the effects of prosthesis sizing and positioning on the bone remodelling and fracture strength under a range of normal and traumatic loads, with the aim of understanding these failure modes better.The simulations predicted increased superior femoral neck stress shielding in young patients with small prostheses, which required shortening of the femoral neck to give an acceptable implant–bone interface. However, with a larger prosthesis, natural femoral head centre recreation in the implanted state was possible; therefore stress shielding was restricted to the prosthesis interior, and its extent was less sensitive to prosthesis orientation. With valgus orientation, the implanted neck strength was, at worst, within 3 per cent of its intact strength.The study suggests that femoral neck narrowing may be linked to a reduction in the horizontal femoral offset, occurring if the prosthesis is excessively undersized. As such, hip resurfacing should aim to reproduce the natural femoral head centre, and, for valgus prosthesis orientation, to avoid femoral neck fracture

Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

The wear equation is applied to the wear process in a hip joint prosthesis and a wear modulus is defined. The sliding distance, wear modulus, wear volume, wear area, contact angle and the maximum normal stress were calculated and the theoretical calculations applied to test results.\ud \ud During the wear process the increase of the wear modulus is about 100 Nmm−2 per mm sliding distance in the Charnley and the Charnley-Muller hip joint prosthesis. From the wear volume point of view the Charnley prosthesis is probably superior to the Charnley-Muller prosthesis if run-in before implantation

Finite element analysis of porously punched prosthetic short stem virtually designed for simulative uncemented hip arthroplasty

Background: There is no universal hip implant suitably fills all femoral types, whether prostheses of porous short-stem suitable for Hip Arthroplasty is to be measured scientifically. Methods: Ten specimens of femurs scanned by CT were input onto Mimics to rebuild 3D models; their *stl format dataset were imported into Geomagic-Studio for simulative osteotomy; the generated *.igs dataset were interacted by UG to fit solid models; the prosthesis were obtained by the same way from patients, and bored by punching bears designed by Pro-E virtually; cements between femora and prosthesis were extracted by deleting prosthesis; in HyperMesh, all compartments were assembled onto four artificial joint style as: (a) cemented long-stem prosthesis; (b) porous long-stem prosthesis; (c) cemented short-stem prosthesis; (d) porous short-stem prosthesis. Then, these numerical models of Finite Element Analysis were exported to AnSys for numerical solution. Results: Observed whatever from femur or prosthesis or combinational femora-prostheses, “Kruskal-Wallis” value p > 0.05 demonstrates that displacement of (d) ≈ (a) ≈ (b) ≈ (c) shows nothing different significantly by comparison with 600 N load. If stresses are tested upon prosthesis, (d) ≈ (a) ≈ (b) ≈ (c) is also displayed; if upon femora, (d) ≈ (a) ≈ (b) < (c) is suggested; if upon integral joint, (d) ≈ (a) < (b) < (c) is presented. Conclusions: Mechanically, these four sorts of artificial joint replacement are stabilized in quantity. Cemented short-stem prostheses present the biggest stress, while porous short-stem & cemented long-stem designs are equivalently better than porous long-stem prostheses and alternatives for femoral-head replacement. The preferred design of those two depends on clinical conditions. The cemented long-stem is favorable for inactive elders with osteoporosis, and porously punched cementless short-stem design is suitable for patients with osteoporosis, while the porously punched cementless short-stem is favorable for those with a cement allergy. Clinically, the strength of this study is to enable preoperative strategy to provide acute correction and decrease procedure time

Prosthesis coupling

A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump

Temporal development of compensation strategies for perturbed palate shape in German /S/-production

The palate shape of four speakers was changed by a prosthesis which either lowered the palate or retracted the alveoles. Subjects wore the prosthesis for two weeks and were recorded several times via EMA. Results of articulatory measurements show that speakers use different compensation methods at different stages of the adaptation. They lower the tongue immediately after the insertion of the prosthesis. Other compensation methods as for example lip protrusion are only acquired after longer practising periods. The results are interpreted as supporting the existence of different mappings between motor commands, vocal tract shape and auditory-acoustic target

The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking

Background: Robotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing of positive prosthesis push-off work in isolation and measure the effects on energetics, mechanics and muscle activity. Methods: We tested 10 able-bodied participants walking on a treadmill at 1.25 m.s(-1). Participants wore a tethered ankle-foot prosthesis emulator on one leg using a rigid boot adapter. We programmed the prosthesis to apply torque bursts that began between 46% and 56% of stride in different conditions. We iteratively adjusted torque magnitude to maintain constant net positive push-off work. Results: When push-off began at or after leading leg contact, metabolic rate was about 10% lower than in a condition with Spring-like prosthesis behavior. When push-off began before leading leg contact, metabolic rate was not different from the Spring-like condition. Early push-off led to increased prosthesis-side vastus medialis and biceps femoris activity during push-off and increased variability in step length and prosthesis loading during push-off. Prosthesis push-off timing had no influence on intact-side leg center-of-mass collision work. Conclusions: Prosthesis push-off timing, isolated from push-off work, strongly affected metabolic rate, with optimal timing at or after intact-side heel contact. Increased thigh muscle activation and increased human variability appear to have caused the lack of reduction in metabolic rate when push-off was provided too early. Optimal timing with respect to opposite heel contact was not different from normal walking, but the trends in metabolic rate and center-of-mass mechanics were not consistent with simple model predictions. Optimal push-off timing should also be characterized for individuals with amputation, since meaningful benefits might be realized with improved timing