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At least 343 records · Page 19Linked to original sources
PubMed1986

A prospective evaluation of the Björk-Shiley, Hancock, and Carpentier-Edwards heart valve prostheses.

From 1975 to 1979, 540 patients undergoing valve replacement were entered into a randomized trial and received either a Björk-Shiley (273 patients) or a porcine heterograft prosthesis (initially a Hancock valve [107 patients] and later a Carpentier-Edwards prosthesis [160 patients]). Two hundred and sixty-two patients required mitral valve replacement, 210 required aortic valve replacement, 60 required mitral and aortic valve replacement, and eight also required associated tricuspid valve replacement (six mitral valve replacement; two mitral plus aortic valve replacement). Analysis of 34 preoperative and operative variables showed the treatment groups to be well randomized. In-hospital mortality was not significantly different among patients receiving the three prostheses for aortic valve replacement (7.6% overall) and mitral plus aortic valve replacement (10% overall), but there was a higher in-hospital mortality for patients undergoing mitral valve replacement with the Carpentier-Edwards prosthesis (15.5% compared with 8.8% overall; p = .03). This difference could not be explained on the basis of any preoperative or operative variable. Median follow-up was 5.6 (range 2.8 to 8.3) years. Actuarial survival after mitral valve replacement was 56.7 +/- 7.0% at 7 years, that after aortic valve replacement was 69.6 +/- 9.6% at 7 years, and that after mitral plus aortic valve replacement was 62.5 +/- 20.0% at 7 years. There was no significant difference in actuarial survival of patients receiving the three prostheses within the mitral, aortic, and mitral plus aortic valve replacement groups, nor was there a difference when these groups were amalgamated. Thirty-seven patients required reoperation for valve failure (15 with Björk-Shiley, 12 with Hancock, and 10 with Carpentier-Edwards valves; p = NS) and 11 died at reoperation (four with Björk-Shiley, four with Hancock, and three with Carpentier-Edwards valves; overall operative mortality 29.7%). Up to 7 years after surgery, there was no significant difference in the incidence of thromboembolism in patients with different prostheses undergoing mitral or aortic valve replacement. There were too few patients undergoing mitral plus aortic valve replacement for meaningful comparison. There was no significant beneficial effect of anticoagulants in patients undergoing mitral or aortic valve replacement with porcine prostheses, but patients were not randomly allocated to anticoagulant treatment. All patients with Björk-Shiley prostheses received anticoagulants.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1998

Assessment of small-diameter aortic mechanical prostheses: physiological relevance of the Doppler gradient, utility of flow augmentation, and limitations of orifice area estimation.

BACKGROUND: Noninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo. METHODS AND RESULTS: Relations between the orifice transprosthetic gradient (equivalent to Doppler), the downstream gradient in the zone of recovered pressure (equivalent to catheter), and fluid mechanical energy losses were examined in vitro. Pressure-flow relations across the 2 prostheses were evaluated by Doppler echocardiography in vivo. For both types of prosthesis in vitro, the orifice was higher than the downstream gradient (P<0.001), and fluid mechanical energy losses were as strongly correlated with orifice as with downstream pressure gradients (r2=0.99 for both). Orifice and downstream gradients were higher and fluid mechanical energy losses were larger for the St Jude than the Medtronic Hall valve (all P<0.001). Whereas estimated effective orifice areas for the 2 valves in vivo were not significantly different, model-independent dynamic analysis of pressure-flow relations revealed higher gradients for the St Jude than the Medtronic Hall valve at a given flow rate (P<0.05). CONCLUSIONS: Even in the presence of significant pressure recovery, the Doppler-derived gradient across small-diameter aortic mechanical prostheses does have hemodynamic relevance insofar as it reflects myocardial energy expenditure. Small differences in function between stenotic aortic mechanical prostheses, undetectable by conventional orifice area estimations, can be identified by dynamic Doppler echocardiographic analysis of pressure-flow relations.

Aortic Valve Stenosis↗
PubMed1994

Within-subject comparisons of implant-supported mandibular prostheses: evaluation of masticatory function.

In the past, fixed prostheses were believed to be more efficient implant-supported devices than removable types for edentulous patients. However, this hypothesis was never properly tested. Therefore, a within-subject crossover clinical trial was designed in which 145 completely edentulous subjects were tested wearing implant-supported mandibular fixed prostheses and long-bar overdentures. Eight subjects received the fixed appliance first and seven the removable type. The patients' perceptions of various characteristics of the implant-supported prostheses were measured after a minimum of two months' adaptation. Mandibular movements and jaw muscle electromyographic activity were recorded while the patients chewed five standard-sized test foods: bread, apple, hard cheese, sausage, and raw carrot. The prostheses were then changed, worn for the same period of adaptation, and the procedures repeated. There were three test sessions per prosthesis, and each included five trials per food. The measurements were repeated three times at one-week intervals. Mastication time was found to be shorter for three foods (bread, cheese, and sausage) when subjects wore the long-bar overdenture. The vertical amplitude of the masticatory strokes was significantly less with the overdenture for all foods except carrot. Cycle duration was significantly longer with the overdenture for sausage and carrot. Contrary to what might be expected, the long-bar overdenture appears to be no less efficient than the fixed prosthesis. Furthermore, these data suggest that patients are capable of adapting their masticatory movements to the characteristics of the two prostheses.

Adult↗
PubMed1997

A within-subject comparison of mandibular long-bar and hybrid implant-supported prostheses: psychometric evaluation and patient preference.

Although it has been shown that patients are more satisfied with prostheses supported by implants than with conventional dentures, there have been few direct comparisons of the various designs of implant-supported prostheses. This within-subject crossover clinical trial was designed to compare two forms of removable prostheses which are frequently prescribed for the edentulous mandible: a long-bar overdenture supported by 4 implants and a two-implant hybrid overdenture. Sixteen completely edentulous subjects were given a new maxillary conventional denture: Ten of them received the mandibular long-bar prosthesis first and six the hybrid. After a two-month adaptation period, psychometric measures of various aspects of the prostheses and physiological tests of masticatory efficiency were carried out over three weeks. The mandibular prostheses were then changed and the procedures repeated. At the end of the study, subjects were asked to choose the mandibular prosthesis that they wished to keep, and final psychometric measures were taken. In this paper, the results of the psychometric assessment and patient preference are presented. Subjects assessed factors such as general satisfaction, quality of life, stability, retention, comfort, esthetics, ease of cleaning, speaking, and chewing, and how well-chewed foods were before being swallowed. Most of the factors except ease of cleaning and speaking were rated significantly better with long-bar overdentures than with hybrid ones. These results are consistent with the fact that all subjects chose long-bar overdentures, reporting stability, ease of chewing, and comfort as the most important factors influencing their choice. These results suggest that, although subjects assign high ratings for most factors to hybrid overdentures, they find long-bar overdentures to be significantly more stable, comfortable, and easier for chewing.

Adult↗
PubMed2004

Speech with maxillary implant prostheses: ratings of articulation.

Speech is often perturbed after placement of maxillary implant-retained prostheses. We tested the hypothesis that the rate of speech errors varies with prosthetic design. Thirty edentulous subjects with mandibular implant prostheses entered two within-subject crossover trials. Subjects wore maxillary fixed prostheses and removable long-bar overdentures (Trial 1), or overdentures with and without palates (Trial 2). Test words from a French language speech battery were recorded after each prosthesis had been worn for two months. The percentages of stops, fricatives, and vowels correctly perceived by lay judges were calculated. Subjects produced a significantly higher percentage of sounds correctly with overdentures than with fixed prostheses. Between-treatment differences were significant for stops and fricatives (p < 0.01), but not for vowels. There were no significant differences in error rates between the two overdentures. In conclusion, maxillary implant overdentures with and without palates enable patients to produce more intelligible speech than fixed prostheses.

Adult↗
PubMed2002

A comparison of the user-friendliness of hydroxyapatite and titanium ossicular prostheses.

Both hydroxyapatite (Ha) and titanium (Ti) are well-accepted alloplastic materials for ossicular prostheses. Many different designs of Ha and Ti prostheses are presently available. Fourteen surgeons of different seniority and surgical experience were asked to 'test-drive' four different types of ossicular prostheses in cadaveric temporal bones to investigate the user-friendliness of these protheses. The Goldenberg design Ha incus prosthesis and the Dusseldorf design Bell Ti prosthesis were used as partial ossicular replacement prostheses (PORP). The Richards design Ha incus-stapes prosthesis and the Dusseldorf design Aerial Ti prosthesis were used as a total ossicular replacement prostheses (TORP). Nine out of 14 surgeons found the Ha PORP to be more user-friendly because of the notch design in the head. The Ti prosthesis was found to be more difficult to manipulate because it was too light. Half of the surgeons preferred the Ti TORP because of the open design of the top-plate. The Ha TORP was thought to be too top-heavy and to have a tendency to fall over.

Attitude of Health Personnel↗
PubMed2004

AICRG, Part IV: Patient satisfaction reported for Ankylos implant prostheses.

PROBLEM: Although many maxillary dentures exhibit sufficient retention and stability for patients to adapt well to them, mandibular dentures present a major challenge. The introduction of the endosseous dental implant provided the opportunity for the patient to have esthetic replacements (implant prostheses) that were retentive and stable for all missing natural teeth. METHOD: This paper reports on the satisfaction of over 470 patients with implant prostheses fabricated using a new and innovative implant design (Ankylos, Dentsply-Friadent, Mannheim, Germany). RESULTS: A total of 1500 Ankylos implants were placed, restored, and followed for 3 to 5 years. Patients were asked to respond to a series of questions related to their satisfaction with their new replacements for missing natural teeth. A total of 95.6% of the patients rated chewing ability with Ankylos prosthesis as excellent to good; 92.2% indicated a significant improvement in their ability to chew; 92.6% reported overall clinical function much better than conventional dentures; 99.1% indicated that speech had improved or was not changed; 96.3% indicated hot and cold foods tasted better; 98.8% indicated no pain or discomfort during clinical function; 99.4% liked their new implant prosthesis; 98.0% would seek implant-prostheses treatment again, if necessary; 99.1% would recommend implant prostheses to friends and relatives; and 98.8% indicated the advantages of Ankylos prostheses far exceeded any disadvantages that may exist. CONCLUSIONS: Patients indicated that they (1) were highly satisfied with the final results of the replacements for their natural teeth that were retained or supported by this new implant design, (2) would not hesitate to recommend this form of treatment to their friends and relatives, and (3) would not hesitate to seek the same treatment again if necessary in the future.

Bone Screws↗
PubMedDate not supplied

Colorimetric analysis of silicone cosmetic prostheses for upper-limb amputees.

Every year the Italian National Insurance Institute of Accidents on Work (INAIL) Prosthesis Centre manufactures more than 300 silicone cosmetic upper-limb prostheses that are aesthetically similar to patients' missing limbs; however, the prostheses have the following drawbacks: subjectivity in color choice, high production costs, and long time frames for patient tests and prosthesis production. In an attempt to minimize these factors, we performed a study to test various systems that automatically detect the color of human skin. Such a system would allow us to reproduce a patient's exact skin color for silicone cosmetic prostheses. We analyzed the color identification systems available on the market and assessed the possibility of introducing such a system into the production cycle of the prostheses. We found that because of intrinsic factors of the materials, automatic color detection for prosthesis production is complex. Therefore, any of the systems we tested will require further development for full satisfaction of the needs of prostheses manufacturers.

Amputees↗
PubMed1994

Appearance of septic hip prostheses on plain radiographs.

OBJECTIVE: The purpose of this study was to evaluate the spectrum of plain radiographic findings in patients with septic hip prostheses. MATERIALS AND METHODS: Radiographs of 20 confirmed infected hip prostheses were examined for the presence or absence of lucency, type of lucency (focal or nonfocal), rapidity of radiographic change, periostitis, subsidence, and cement fracture. RESULTS: Findings were normal in 10 prostheses, but nonfocal lucencies mimicking mechanical loosening were seen in four cases. Two cases showed focal bone loss, indistinguishable from aggressive granulomatosis. A variety of findings, including subsidence and periostitis, were seen in the remaining four prostheses. CONCLUSION: Plain radiographs of septic hip prostheses often show normal findings but can show focal bone loss that mimics aggressive granulomatosis.

Hip↗
PubMed1993

Association of polyacrylamide beads to polyethylene terephthalate prostheses.

A method for the coupling of polyacrylamide beads to polyethylene terephthalate (PET) vascular prostheses is described. The reactional procedure used is performed along several steps; acrylic acid grafting on PET textile fibres, in order to introduce reactive carboxylic groups, introduction of terminal primary amine groups onto the beads, and then, attachment method which consists in coupling carboxylic groups of prostheses with amine groups of modified beads. The relative weight increase of the samples before and after the coupling reaction and, microscopic observations of beads distribution onto the prostheses surface demonstrate the binding feasibility of polyacrylamide matrices to PET prostheses. In the near future, authors expect to replace these beads by microcapsules with polyacrylamide wall and containing active compounds to improve the vascular prostheses biocompatibility.

Acrylic Resins↗
PubMed1992

[Magnified tomography for identification of ceramic prostheses].

Recently, ceramic prostheses for ossicular replacement have become very popular in middle ear surgery. These prostheses have a good affinity with the surrounding tissue. But, it is difficult to identify the position of these prostheses postoperatively. We used magnified tomography in order to identify the implanted ceramic prostheses, and to determine whether these prostheses were in the appropriate position. In the case of patients without stapes, we usually use Apaceram type T, which restores ossicular continuity to the inner ear. When the shaft of the ceramic prosthesis is placed on the oval window niche, the overhanging Fallopian canal obstructs the tip of the prosthetic shaft to obtain the appropriate place in the oval window. The angle of the shaft should be slightly tilted inferiorly against the medial wall of the middle ear cavity.

Adult↗
PubMed1993

Intra- and extraoral prostheses using osseointegrated implants after maxillofacial surgery.

Maxillary and orbital defects due to the resection of maxillary tumors in six cases were treated utilizing maxillofacial prostheses employing pure titanium osseointegrated implants (Brãnemark system). A total of 17 fixtures were installed in the maxillary region, and 16 achieved osseointegration. For the orbital region, nine fixtures were installed, and all fixtures integrated well. Using these fixtures as anchors, four maxillary prostheses and three orbital prostheses were set. The stability of the prostheses were improved by anchors, and the prostheses were highly satisfactory to the patients.

Adult↗
PubMedDate not supplied

Outcome of treatment with implant-retained dental prostheses in patients with Sjögren syndrome.

The purpose of this investigation was to evaluate the outcome of treatment with implant-retained prostheses in patients suffering from Sjögren syndrome. Eight women were included in the study; all had suffered oral symptoms of Sjögren syndrome for many years. Seven patients were edentulous in both arches, and 1 patient was edentulous in the maxilla only. All patients reported poor or very poor comfort levels with their conventional dentures. It was the intention to treat each arch that showed subjective and objective denture problems with a complete fixed prosthesis after placement of 6 implants. In all, 54 Brånemark dental implants were placed in these patients. No implants were lost, but 7 implants in 4 patients were clinically not osseointegrated at the time of the abutment connection procedure. Because of nonosseointegrated implants and lack of jawbone, 3 arches were treated with an implant-retained overdenture. Fixed prostheses were made with a titanium framework of premachined components welded together (Procera) and acrylic resin teeth and flanges. Patients answered a questionnaire regarding their oral function before the onset of treatment and 1 month and 2 years after treatment. An average radiographic bone loss of 0.7 mm from the time of implant placement to 1 year after treatment was observed; additional bone loss of less than 0.6 mm was recorded 4 years after treatment. During the first year of function 2 implants lost osseointegration. No prostheses were lost or remade. Treatment with implant-retained prostheses considerably increased the prosthetic comfort and function of the patients. Two years after prosthetic treatment, only 1 patient indicated poor comfort of the prostheses, while the remaining patients reported good or very good comfort levels.

Acrylic Resins↗
PubMed1999

Surgical treatment of tracheal collapse using pliable total ring prostheses: results in one experimental and 4 clinical cases.

Pliable total ring prostheses were created from the polyvinyl chloride drip chambers of intravenous administration sets. The total ring prostheses were placed in one clinically normal research dog and in 4 client-owned dogs diagnosed with tracheal collapse. The research dog was euthanized one month after placement of the prostheses. Histopathological analysis of the trachea adjacent to the prostheses revealed a mild inflammatory response. The follow-up period for the clinical cases was from 4 months to 11 years. Radiographs taken and fluoroscopy performed 1 day to 5 months after surgery revealed improvement or resolution of the tracheal collapse. One dog was asymptomatic 28 weeks following surgery. Two dogs died 7 and 9 years after surgery, with one requiring intermittent medical management for coughing. They were euthanized for nonrespiratory illness. One dog had a persistent nonproductive cough, due to collapse of the mainstem bronchi, when last evaluated 4 months postoperatively. Pliable total ring prostheses provided adequate stability to the trachea and had the advantage of conforming to the trachea and being easy to create, place, and suture.

Animals↗
PubMedDate not supplied

Within-subject comparison between connected and nonconnected tooth-to-implant fixed partial prostheses: up to 14-year follow-up study.

PURPOSE: This long-term follow-up study aimed to compare the outcome of fixed prostheses supported by teeth and implants and by freestanding implants only. MATERIALS AND METHODS: From prosthesis insertion up to 14 years (mean 6.5 y), 18 patients were followed. Implant-supported prostheses with and without tooth connection were compared within the same jaw. The tooth-implant prostheses were supported by 30 implants and 30 teeth, and the freestanding prostheses were supported by 48 implants. Implant outcome, marginal bone stability, and mechanical complications were recorded. RESULTS: Neither implant mobility nor fractures of any component of the implants were observed. No prosthesis complications were observed, and the same applied for crown cement failure and intrusion of teeth. Only one periapical lesion was detected at the first follow up. The annual change of the marginal bone level around connected and freestanding implants did not differ significantly. The mean marginal bone loss (over the 2 groups) for the first 6 months amounted to 1.08 mm. After the first 6 months, an annual marginal bone loss of 0.015 mm was observed. There was no difference between the 3 connection types (single implant connected to single tooth, multiple implants and/or multiple teeth connected with single connector, and multiple connectors) for the first 6 months or thereafter. The marginal bone loss (over the 3 groups) for the first 6 months was 1.15 mm. After the first 6 months, the annual bone loss (over the 3 groups) amounted to 0.015 mm. CONCLUSION: Based on the results of this study, splinting teeth with implants for implant-supported fixed prostheses did not affect the long-term outcome in comparison to freestanding implants.

Adult↗
PubMed2000

A new prosthodontic technique for fabricating cement-retained implant-supported prostheses.

This article describes a new technique for fabricating cement-retained implant-supported prostheses. The technique involves cementation of the prostheses over customized gold cylinders. Access channels are incorporated in the prostheses to allow future access of the gold screws. This technique can be used in various clinical situations to achieve total passive fit of the framework without compromising retrievability. The technique overcomes the problems encountered with other previously advocated methods for constructing such prostheses. In addition, maintenance of the resulting prostheses is uncomplicated.

Cementation↗
PubMed2001

[A scanning electron microscopy study of the surface of porous-textured breast implants and their capsules. Description of the "velcro" effect of porous-textured breast prostheses].

The efficacy of breast prosthesis texturing in the prevention of capsular contracture has been established for about 20 years. This successful procedure has led to the development and marketing of a number of different models. In the present study, four porous-textured breast prostheses have been examined: the Arion monoblock implant, the CUI (McGahn), the Biocell (Mcgahn), and the Sebbin LS21. Scanning electron microscopic (SEM) investigation of the implant surfaces of the different prostheses was carried out on new samples received from the manufacturers. During a prospective study on eight patients, capsule samples corresponding to the four above-mentioned prostheses were taken to determine whether a secondary intervention was necessary for correction of asymmetry or malpositioning. These samples were analyzed by SEM to investigate whether there could be a correlation between prosthesis texturing and the aspect of the corresponding capsules. Significant ultrastructural differences were found between the various prostheses examined: the results showed that only the CUI and Biocell prostheses presented a mirror image of the capsule texturing, with a correspondence between the depressions on the prosthesis and the contacts on the capsule. This finding seems to be linked to the existence of a critical size for the pores that constitute the implant surface. This observation led to the hypothesis of an adhesive "velcro" effect between the prosthesis and its capsule. Although the latter may not be directly linked to the prevention of capsular contracture it can, however, have a major effect on implant stabilization in cases of primary breast reconstruction and in possible secondary adjustments of asymmetry and malpositioning.

Adult↗
PubMed2001

Quantitative analysis of wear and wear debris from metal-on-metal hip prostheses tested in a physiological hip joint simulator.

Osteolysis and loosening of artificial joints caused by UHMWPE wear debris has prompted renewed interest in metal-on-metal (MOM) hip prostheses. This study investigated the wear and wear debris morphology generated by MOM prostheses in a physiological anatomical hip simulator for different carbon content cobalt chrome alloys. The low carbon pairings demonstrated significantly higher "bedding in" and steady state wear rates than the mixed and high carbon pairings. The in vitro wear rates reported here were up to one or two orders of magnitude lower than the clinical wear rates for first-generation MOM hip prostheses. Two methods for characterising the metal wear debris were developed, involving digestion, scanning electron microscopy and transmission electron microscopy. The metal wear particles characterised by the two methods were similar in size, 25-36 nm, and comparable to particles isolated from periprosthetic tissues from first and second-generation MOM hip prostheses. Due to the small size of the metal particles, the number of particles generated per year for MOM prostheses in vitro was estimated to be up to 100 times higher than the number of polyethylene particles generated per year in vivo. The volumetric wear rates were affected by the carbon content of the cobalt chrome alloy and the material combinations used. However, particle size and morphology was not affected by method of particle characterisation, the carbon content of the alloy or material combination.

Biomechanical Phenomena↗