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PubMedDate not supplied

Stability of the screw joints in patients with implant-supported fixed prostheses in edentulous jaws: a 1-year follow-up study.

PURPOSE: The purpose of this follow-up study was to evaluate the stability of the screw joint in edentulous patients 1 year after treatment with implant-supported fixed prostheses (Brånemark system). MATERIALS AND METHODS: A total of 20 patients were included, 10 treated in the maxilla and 10 in the mandible. The fixed prostheses were removed approximately 1 year after insertion, and the stability of the screw joints was evaluated using a rating scale based upon the CDA quality evaluation criteria of dental care. RESULTS: All implant-supported fixed prostheses were recorded as stable before the prosthetic screws (gold screws) were unscrewed. "Unacceptable loosening" was observed in 4% of the prosthetic screws and in 29% of the abutment screws. CONCLUSION: In this study, only a few of the prosthetic screws showed unacceptable loosening after 1 year of function. The clinical relevance of the observed high occurrence of loose abutment screws could be questioned, as all fixed prostheses were initially recorded as stable.

Aged↗
PubMed2004

Cantilever fixed prostheses utilizing dental implants: a 10-year retrospective analysis.

OBJECTIVE: The dental literature has been unclear about long-term success of fixed cantilever prostheses supported by dental implants. The disappointing results reported when cantilever fixed partial dentures (FPDs) are supported with natural teeth are not directly applicable to implant cantilever FPDs. This article reports on 10 years of implant-retained fixed prostheses primarily in the maxillary arch using the ITI dental implant system. METHOD AND MATERIALS: Sixty cantilever prostheses using 115 ITI dental implants on 36 patients were placed and monitored over a 10-year period. RESULTS: No implant fractures, abutment fractures, porcelain fractures, prosthesis fractures, soft tissue recession, or radiographic bone loss were recorded. All 60 cantilevered prostheses remain in satisfactory function. CONCLUSION: Positive, long-term results, using implant-retained cantilever FPDs can be achieved by: (1) using a rough surface implant of 4.1 mm or greater; (2) using an implant/abutment design that reduces stacked moving parts and reduces the implant-to-crowns ratio; and (3) using a cementable prosthesis design that eliminates the need for occlusal screw retention.

Adult↗
PubMed2004

Long-term performance of prostheses in mitral valve replacement.

The long-term performance of prostheses in mitral valve replacement (MVR) is now available with representatives of current generation prostheses to 15 years. Mechanical prostheses have been implanted for 33 years and bioprostheses for 22 years. The predominant complication of mechanical prostheses is hemorrhage from anticoagulation and reoperation for late structural valve deterioration of bioprostheses. Mitral valve (MV) reconstruction, over MVR, is recommended whenever possible, especially with the advancement of atrial fibrillation ablation techniques. The current indications for MVR are those valvular lesions that are unlikely to be repaired by most surgeons or which long-term results are suboptimal with reconstruction. Reconstruction is more common for degenerative disease, replacement for rheumatic disease and variable for advanced ischemic and infective disease. The recommendations for MVR for mitral stenosis (MS) are moderate to severe MS with advanced functional status and severe pulmonary hypertension when percutaneous balloon valvotomy or mitral reconstruction is not feasible. MVR is recommended in non-ischemic severe mitral regurgitation (MR) and for non-reparable acute symptomatic MR, advanced symptomatic status, systolic dysfunction and/or ventricular dysfunction. The recommendations for MV surgery in ischemic MR are acute post-infarction MR with cardiogenic shock, unstable angina with persistent moderate-severe and severe MR and chronic, dilated ischemic cardiomyopathy with moderate-severe and severe MR.

Adult↗
PubMed1977

Geometric comparison of aortic bifurcation prostheses to the normal and atherosclerotic human aorta, and clinical trial of a vertical seamed bifurcation prosthesis.

The 12 bifurcation prostheses generally available in the United States were compared. One was woven Teflon, two woven Dacron, and nine knitted Dacron. Ten were "seamless" in construction, and two were "seamed," but close examination revealed that all prostheses actually were seamed at the bifurication point. The grafts varied considerably in construction, porosity, and geometry. To compare the geometries, each prosthesis was preclotted in plasma, inflated to 120 mm. Hg, and quick frozen in alcohol and dry ice. Transverse and frontal bisections of the frozen specimens were photographed with a millimeter scale for sizing. For comparison, eight human aortofemoral bifurcations were distended and frozen similarly. The prostheses had far wider bifurcation shelves than did the normal aortas. The five normal human aortofemoral bifurcations had an average ratio of limb: body diameter of 0.61; the three atherosclerotic specimens averaged 0.49. The prostheses had an average limb:body diameter ratio of 0.48. or the "seamless" grafts, 0.48 for the circular transverse limb-seamed grafts, and 0.58 for the vertical-seamed grafts. Vertical-seamed aortic bifurcation grafts implanted in 102 patients between 1970 and 1976 (average follow-up, 29.5 months) have developed only a single limb closure, at 53 months.

Aorta↗
PubMed1991

[Effect of hemodynamic conditions and prosthesis structure on endothelialization of clinical and experimental small lumen vascular prostheses].

Seeding of small-diameter vascular prostheses (ID less than or equal to 6 mm) with autologous microvascular cells (AMVC) results in a complete endothelial cell layer on the luminal surface. The purpose of this study was to examine the influence of the blood flow velocity (due to 4 or 6 mm ID) and the structure of inner graft surface (crimped, uncrimped) on the endothelialization. AMVC were harvested from omental adipose tissue (mean: 0.56 X 10(6) cells/g tissue) from 10 mongrel dogs (mean: 27.9 kg). During preclotting, the 4 mm uncrimped and the 6 mm crimped double velour Dacron prostheses (Meadox Medicals, Inc.) were seeded with 1.0 X 10(6) cells/cm2 graft surface. Grafts were implanted into the carotid arteries (N = 5 in each group). The animals received antiplatelet therapy. After five weeks, all seeded prostheses were patent. The thrombus free surface (TFS) of seeded prostheses was 99.9% (4 mm) and 90.5% (6 mm). Scanning electron microscopy revealed an athrombogenic layer of endothelial cells on a smooth surface. -It is concluded that in canine experiments endothelialization of 4 and 6 mm grafts after seeding with AMVC is not affected by blood flow velocity or graft structure.

Animals↗
PubMed1991

[The course after amputation of upper extremities with special reference to the use of prostheses and social conditions].

Sixty-six patients with upper limb amputations were followed-up in their homes. The object of this article was to assess the course as regards the prosthesis, the extent to which this was employed, and to investigate the factors which influence the type of prosthesis and the social conditions of the patient. The amputees were divided into four groups. Twenty-six employed an active prosthesis for more than eight hours daily, six for less than eight hours daily, 16 employed passive prostheses and 18 did not employ prostheses. 65% of the amputations were performed on account of accidents. A group of six were submitted to amputation as part of the treatment of irreversible brachial plexus lesion. The investigation demonstrated the significant importance of the year of amputation. This is explained by late development of the prosthesis supply and the possibilities for rehabilitation and the legislative conditions. Great differences were observed between the prosthetic conditions at the primary equipment and at follow-up investigation. The type of prosthesis employed depended on loss of the dominant arm, prostheses available and the general condition of the individual patient. There were differences in the mental reactions for patients with planned and traumatic amputations. It is recommended that this patient group should be ensured rapid fitting with prostheses by an experienced prosthesis and adequate rehabilitation within a geographically manageable district. This patient group requires team therapy and this functions best when the relevant staff are experienced with this type of patient.

Adolescent↗
PubMed1991

A comparative analysis of Giliberty, Bateman, and Universal femoral head prostheses. A long-term follow-up evaluation.

This study compares four different types of bipolar hip prostheses used from 1977 to 1984. The devices studied were the Giliberty I and II hip prostheses, the Bateman I prosthesis, and the Universal Hip Replacement (UHR) prosthesis. The surgical indications for prosthetic hip replacement in all cases were displaced subcapital hip fractures (Garden Types 3 and 4). Postoperative evaluation included D'Aubigńe's hip rating system and roentgenograms to assess prosthetic placement, dislocation, disassembly of the components, and the presence of inner and outer bearing motion of the prostheses. Results of the study revealed intact inner bearing motion in all of the devices investigated in the immediate postoperative period. The UHR prosthesis demonstrated a statistically significant lower incidence of dislocation and no incidence of prosthesis disassembly. This study demonstrates the superiority of the bipolar prosthesis when compared to published results of the so-called unipolar prosthesis and also suggests superiority of the design and function of the UHR prosthesis when compared to the Bateman I and Giliberty prostheses. Longer follow-up evaluation is needed to assess the effects of a functioning bipolar prosthesis on acetabular wear.

Aged↗
PubMed1990

Clinical and roentgenographic evaluation of bipolar prostheses with noncemented anatomic medullary locking femoral stems.

Fifty-six DePuy anatomic medullary locking femoral bipolar prostheses were reviewed clinically and roentgenographically in 50 patients at an average follow-up period of 30 months (range, 24-71 months). Forty-four of the implantations were in 40 male and 12 were in ten female patients. Forty-five devices were placed in primary operations, while 11 were used in revisions. The overall average age was 53.5 years. The average Harris hip scores for the primary bipolars were 29.8 preoperative and 77.3 postoperative, while the revision bipolars had Harris hip scores of 35.9 preoperative and 75.1 postoperative. Nearly one-half (47%) of all primary and 54% of the revision patients experienced pain to some degree on ambulation. Roentgenographically, all femoral components appeared to be well fixed biologically. Roentgenographic changes occurred with time in both primary and revision prostheses. On roentgenographic zonal analysis of primary prostheses, radiolucencies greater than 1 mm were present most frequently in the most proximal lateral zone and at the distal tip of the prosthesis. Although the use of noncemented bipolar prostheses generally shows acceptable clinical results, noncemented fixed acetabular components with noncemented femoral components produce a more satisfactory clinical result.

Adult↗
PubMed1986

A comparison of isobutyl 2-cyanoacrylate glue, fibrin adhesive, and oxidized regenerated cellulose for control of needle hole bleeding from polytetrafluoroethylene vascular prostheses.

Prolonged anastomotic and needle hole bleeding from synthetic vascular prostheses is a common surgical problem in heparinized patients and in the patient with a coagulopathy. The relative effectiveness of various hemostatic agents has not previously been determined by controlled comparisons. In this study 6 mm polytetrafluoroethylene (PTFE) vascular prostheses were used to perform carotid-carotid and femorofemoral bypasses in eight heparinized dogs. The relative effectiveness of isobutyl 2-cyanoacrylate, fibrin adhesive, and oxidized regenerated cellulose was determined by application of these hemostatic agents to three sources of bleeding: arterial-PTFE anastomoses, PTFE-PTFE anastomoses, and 18-gauge needle holes in PTFE vascular prostheses. The mean time to hemostasis (MTH) was determined for each hemostatic agent. Although application of isobutyl 2-cyanoacrylate resulted in the shortest MTH in each experimental group, the reported inflammatory response that it induces and its possible carcinogenicity limits its availability for clinical use. Application of fibrin adhesive prepared from single-donor hepatitis-screened plasma resulted in a significantly shorter MTH in each experimental group when compared with oxidized regenerated cellulose. We recommend clinical use of fibrin adhesive to control needle hole and anastomotic bleeding from PTFE vascular prostheses.

Animals↗
PubMed1989

Incus replacement prostheses of hydroxylapatite in middle ear reconstruction.

Hydroxylapatite is a calcium bioceramic that has the same chemical composition as living bone, Ca10 (PO4) 6 (OH) 2. Since 1970 it has been used as a material in reconstructive prostheses and augmentation of lost tissues in various surgical specialties including maxillofacial surgery, plastic surgery, otolaryngology, and orthopedics. For over 20 years the author has used autograft and homograft ossicles in tympanoplasty. These incudi have been modified into prostheses that were utilized in ossicular reconstruction. During this time two principle prostheses have evolved, the notched incus with short and long processes. The short process prosthesis is used with an intact stapes, whereas the notched incus with long process carries the sound pressure directly to the stapedial footplate. These prostheses have been successful in improving and maintaining hearing following tympanoplasty. Unfortunately, however, the use of human tissue has certain limitations: it is not readily accessible and has a limited shelf life. Furthermore, clinicians are wary of using homograft tissue as concern over the AIDS virus spreads. Therefore it was felt prudent to develop a manmade prosthesis that would as nearly as possible match the advantages of living bone. Hydroxylapetite most nearly met those qualifications.

Adult↗
PubMedDate not supplied

[Comparative hemodynamic characteristics of Soviet-made mechanical heart valve prostheses in the mitral position].

The article deals with hemodynamic evaluation of Soviet-made, and heart valve prostheses in late-term periods after operation for mitral valve replacement. Fourty-six patients were examined: a ball prosthesis was implanted in 21 patients (1st group), as disk prosthesis--in 15 patients (2nd group) and a prosthesis--in 10 patients (3rd group). A good clinical result of the operation was achieved in all patients, they were referred to functional class I and II. Catheterization of the left and right parts of the heart, left ventriculography, and test with dosed physical exertion were carried out. Loading was continued till cardiac output increased approximately by 60 per cent in 6 patients of the 1st group, 12 patients of the second group, and in all 10 patients of the 3rd group. The study showed that the prostheses do not yield to foreign models of heart valves in hemodynamic characteristics and cause a lower stenosing effect than the prostheses do. No essential differences were detected between the prostheses.

Adolescent↗
PubMed1989

[The evaluation of pressure gradients of various aortic valve prostheses by Doppler ultrasound and influence of pressure gradients to left ventricular function].

Although the pressure gradients of heart valve prostheses has been discussed over the years, currently available valve prostheses are still not sufficient and may leave pressure gradients following aortic valve replacement. The selection of valve prosthesis and its size is still controversial. This study is aimed to measure the pressure gradients of 64 aortic valve prostheses noninvasively by means of doppler ultrasound and determine which size and what kind of valve prosthesis is suitable for aortic valve replacement. 1. Pressure gradients and LV function were serially assessed pre- and post operatively. Left ventricular mass index regressed to a normal range and the response to exercise test is quite satisfactory in the patients whose pressure gradients were less than 25 mmHg. In the cases that showed pressure gradients more than 25 mmHg, however, left ventricular hypertrophy significantly remained even 5 years after aortic valve replacement and the response to exercise was not good enough. From these results, it is concluded that the upper limit of acceptable pressure gradients is 25 mmHg in aortic valve prosthesis. 2. The pressure gradients of St. Jude Medical (SJM) valve (11 cases), Björk-Shiley (B-S) valve (7 cases), Lillehei-Kaster (L-K) valve (13 cases) and Omniscience (O-S) valve (33 cases) was evaluated to compare the hemodynamic characteristics in the long term follow-up periods. In SJM and B-S, a correlation between valve area index (geometrical valve orifice area/body surface area) and pressure gradients was significant. The valve area index more than 1.4 cm2/m2 in SJM or more than 1.7 cm2/m2 in B-S should be selected. Whereas for L-K and O-S, a correlation between valve area index and pressure gradients was not significant and it is suggested that his is due to suboptimal disc opening angle (L-K; 54 degree on the average, O-S; 46 degree on the average). For this reason, the use of these prostheses is not recommended for choice in the aortic position.

Adult↗
PubMed1989

The surface composition of commercial polyester arterial prostheses--an XPS study.

The importance of identifying and quantifying the level of contaminants on the surface of biomaterials has long been recognized as a significant step towards predicting the biocompatibility and rate of healing of implantable devices. Yet suitable techniques for characterizing the surface chemistry of soft and flexible biomaterials with an uneven surface contour such as those used in vascular prostheses have only recently been made available. As a first step towards determining the effect of surface contaminants on the healing behaviour of vascular prostheses, this study used X-ray photoelectron spectroscopy (XPS) to characterize the surface chemistry of 14 virgin polyester arterial prostheses from a wide variety of sources. Generally speaking, all surfaces appeared relatively clean. However, the results indicate that certain prostheses were not manufactured with Dacron-like fibres, and that some exhibit significantly carbon-rich surfaces. This suggests that the surface of these devices has been modified either by a hydrocarbon lubricant or by vapour phase hydrocarbons during fabrication.

Biocompatible Materials↗
PubMed1989

Rest and exercise evaluation of St. Jude Medical and Medtronic Hall prostheses. Influence of primary lesion, valvular type, valvular size, and left ventricular function.

To compare St. Jude Medical and Medtronic Hall mechanical prosthetic heart valves, we prospectively randomized 90 consecutive patients requiring mechanical valve replacement and studied their rest and exercise hemodynamics by Doppler echocardiography. Fifty-six aortic and 42 mitral valves were implanted. All patients were examined preoperatively and postoperatively, and follow-up studies were obtained at rest and immediately after upright, treadmill exercise at 6 months (n = 68). Clinical parameters (mortality, morbidity, and congestive heart failure classification), as well as rest and exercise hemodynamics (valvular area, gradients, and left ventricular ejection fraction), were examined, and their relation to exercise duration was defined. Mortality (perioperative, 8.8% and late, 2.4%) was similar between patients in the two valve groups (five in each group). There was one late thromboembolic episode with each valve. Improvement in New York Heart Association congestive heart failure class was seen in 85% of patients at 6 months. There were no significant differences in calculated aortic valve areas (2.2 vs. 2.0 cm2), resting (24 vs. 21 mm Hg) and exercise (41 vs. 35 mm Hg) peak aortic gradients, and exercise duration between patients with the St. Jude Medical and Medtronic Hall aortic prostheses. In patients with aortic prostheses, valvular size was correlated with exercise duration (r = 0.41, p less than 0.05). In patients with mitral prostheses, we observed no significant differences between St. Jude Medical and Medtronic Hall prostheses in calculated mitral valve areas (3.4 cm2 vs. 3.4 cm2) and rest (2.5 vs. 3.0 mm Hg) and exercise (5.1 vs. 7.0 mm Hg) mean gradients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Biotolerant and haemodynamic effects of copolymerization with acrylic acid on Dacron arterial prostheses.

The biotolerant and haemodynamic effects of three types of woven polyethylene terephthalate (Dacron) arterial prostheses were compared. Two of these were unmodified, one low, one high porosity; and the third was the latter type radiation graft copolymerized with 5% acrylic acid. The prostheses were implanted as aorto-aortic bypass grafts, in dogs, for periods ranging from three to seventeen months. The copolymerized prosthesis exhibited the smallest rise in circumferential elastance from the 'as supplied' state, as well as a significantly slower pulse wave velocity, a significantly thinner internal lining, and a markedly lower longitudinal impedance. Of the unmodified prostheses, the low porosity graft had a significantly greater circumferential elastance, the poorest handling characteristics, and a tendency for pseudo intimal detachment. It was concluded that, although there was little difference between the two unmodified prostheses, the low porosity one had little to recommend it for use in small calibre bypass grafting. Copolymerization with acrylic acid produced better haemotolerant and haemodynamic results as well as surface properties which appeared to discourage fibrin and platelet adherence, and promote a more complete and organised pseudointima.

Acrylates↗
PubMed1988

[Doppler evaluation of the Sorin and Medtronic-Hall prostheses in the aortic position].

Doppler characteristics of normally functioning tilting disk prostheses in aortic position were studied in 55 patients (30 Medtronic-Hall and 25 Sorin) whose valvular function was considered normal using clinical and echocardiographic evaluation. Peak gradients, mean gradients and effective orifice area were estimated for different sizes of prostheses. The peak gradient calculated from maximal aortic velocity was 27.3 +/- 11.1 mmHg in Sorin and 21.1 +/- 9.7 mmHg in Medtronic-Hall valves; the mean gradients were 12.9 +/- 6.2 mmHg and 10.8 +/- 5.7 mmHg in Sorin and Medtronic-Hall valves respectively. The effective orifice area calculated by the continuity equation was 1.4 +/- 0.5 cm2 in Sorin and 1.5 +/- 0.57 cm2 in Medtronic-Hall prostheses; the performance index calculated as the ratio between functional area and manufactured area was 0.4-0.6 for Medtronic-Hall and 0.45-0.52 for Sorin prostheses. Prosthetic regurgitation was found in 64% of Sorin valves and 80% of Medtronic-Hall valves; prosthetic regurgitation was mild in 81% and moderate in 19% of cases. Doppler echocardiography is a reliable method for the characterization of the normal function of prosthetic aortic valves and provides information similar to cardiac catheterization.

Adult↗
PubMed1988

Biological performance of TiNi shape memory alloy vascular ring prostheses: a two year study.

A method was developed for the noninvasive insertion of a vascular ring prostheses aimed at preserving arterial patency and preventing restenosis following angioplasty. Using a specially designed 7F catheter 22 nitinol (TiNi) wire prostheses (I.D. 5 mm; 0.25 mm thickness) were torsion reduced in diameter and inserted under fluoroscopy into both carotid (n = 2) and iliac-femoral arteries (n = 20) of dogs. Aspirin (650 mg BID) and Persantin (200 mg BID) were given for only 30 days postoperatively. Angiography of all rings at 1, 6, 12 months exhibited excellent biocompatibility and long term patency 91% (20/22) as reported in Trans ASAIO 32:30, 1986. Four rings inserted in the right and left common iliac arteries and femoral artery were followed for up to 2 years and exhibited 100% patency. Angiography demonstrated that the anchorage of the prostheses was stable and the lumen was uniformly covered by a thin neointimal layer of endothelial like cells. The prostheses were patent with no evidence of thrombosis or inflammation. In view of the problem of recurrent stenosis occurring during the healing period after balloon angioplasty (PTA or PTCA), this approach may lead to a new means of clinical intervention in atherosclerosis.

Alloys↗