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At least 1,117 records · Page 62Linked to original sources
PubMed2002

New organosilicon maxillofacial prosthetic materials.

OBJECTIVES: The silicone elastomer A-2186 is a widely used maxillofacial prosthetic material. It is a pourable two-component silicone rubber cured by a platinum catalyst. Used as a prosthetic material, A-2186 has short working time and because of its hydrophobic nature, poor adhesion to non-silicone based adhesives. The purpose of this study is to evaluate the physical properties of new prosthetic materials based on methacryloxypropyl-terminated polydimethylsiloxane (MPDS-MF), and to compare the properties with those of A-2186. METHODS: Hardness, tensile strength, ultimate elongation, tear strength and adhesive bonding strength of MPDS-MF and A-2186 with and without additives were determined and compared. The bonding strengths of the extrinsic colorant carrier with the prosthetic materials were also determined. Statistical analyses were done using a two-way analysis of variance (ANOVA). For significant effects, post-hoc tests were done using the Bonferroni correction. RESULTS: The hardness of MPDS-MF is similar to A-2186. However, tensile strength, tear strength, ultimate elongation, and adhesive bonding strength of MPDS-MF are higher than those of A-2186. SIGNIFICANCE: MPDS-MF is cured by free radical thermal polymerization and crosslinking. The working time of MPDS-MF, unlike A-2186, is long. The presence of methacrylate groups in MPDS-MF enhances its adhesion to non-silicone based adhesive. Based on the present study, it appears that MPDS-MF is suitable for use in fabricating of clinical prostheses.

Adhesives↗
PubMed2004

Computer-aided direct all-ceramic crowns: preliminary 1-year results of a prospective clinical study.

The objective of this study was to investigate the clinical performance of: (1) adhesively placed Cerec crowns with reduced stump preparations, and (2) Cerec endo crowns. The crowns were examined at baseline using modified USPHS criteria in 20 patients with 10 Cerec crowns with reduced stump preparations and 10 Cerec endo crowns. All crowns had been produced chairside with the Cerec 3 CAD/CAM method using the function mode. The crowns were machined from Vita Mk II feldspathic ceramic blocks, polished manually, and placed with dual-curing composite luting agent using a functional adhesive. After 1 year, a follow-up examination of the crowns was conducted; all 20 Cerec crowns were rated with a clinically acceptable A or B rating. Fractures or loss of retention were not observed. The method of producing and placing all-ceramic crowns with reduced stump preparations and endo crowns chairside in one appointment can be implemented successfully in private practice.

Adult↗
PubMed1995

Endovascular repair of an ascending aorta-to-left common femoral artery graft with aneurysmal degeneration.

PURPOSE: To report the use of endovascular grafting to repair degenerative aneurysmal changes in an extra-anatomic bypass graft. METHODS: A 14-year-old extra-anatomic ascending aorta-to-left common femoral bypass graft ("ventral aorta") had undergone aneurysmal degeneration, producing symptoms of progressive claudication and local abdominal swelling. The aneurysmal graft dilatation began within the thoracic cavity and extended through the entire extraperitoneal abdominal segment. The option for minimally invasive repair using a customized stent-graft device was offered to the patient as an alternative to standard reoperation. RESULTS: An 8-mm x 42-cm endovascular graft was constructed by polytetrafluoroethylene with 30-mm Palmaz stents sutured to each end. With balloon occlusion of antegrade and retrograde blood flow, the stent-graft was delivered retrograde through an incision in the distal end of the existing bypass graft. The device was successfully positioned and deployed with complete exclusion of the aneurysm. No complications occurred, and the patient's symptoms abated. Follow-up arteriography at 1 months showed a pseudoaneurysm at the distal graft incision site; surgical repair was necessary. At 6 months, angiography demonstrated continued patency of the extra-anatomic bypass graft. CONCLUSIONS: Intraluminal aneurysm exclusion techniques in degenerated extra-anatomic bypass grafts may evolve into a viable therapeutic alternative to complex reoperative surgery.

Aged↗
PubMed1996

Granular histiocytosis of pelvic lymph nodes following total hip arthroplasty. The presence of wear debris, cytokine production, and immunologically activated macrophages.

UNLABELLED: Infiltration of regional lymph nodes by macrophages has been demonstrated after total joint arthroplasty. Although lymph nodes regulate the immune response, neither cytokine production nor the degree of immunological activation of cells within these nodes after total joint arthroplasty has been investigated. Pelvic lymph nodes were obtained from five patients who had had a total of eleven arthroplasties in seven hips three to twenty years before a pelvic staging procedure for adenocarcinoma (of the prostate in four patients and of the endometrium in one). All lymph nodes had polyethylene or metal debris as well as effacement of the normal nodal architecture by a histiocytic infiltrate. These changes were bilateral in the patients who had had an arthroplasty of one hip. Analysis of specimens from pelvic lymph nodes on the side of the involved hip demonstrated intense immunohistochemical staining of histiocytes for the major histocompatibility complex class-II antigen HLA-DR, a marker of histiocyte immune activation. In contrast, staining was absent in specimens from the contralateral lymph nodes as well as in those from seven patients who had had a prostatectomy but not a hip arthroplasty. Immunohistochemical staining for interleukin-1beta, tumor necrosis factor-alpha, and interleukin-6 demonstrated a much greater expression of these cytokines in the involved lymph nodes. CLINICAL RELEVANCE: Additions improvements in total joint replacement will be facilitated by a more thorough understanding of the biological response to the components and materials of implants. While local biological factors leading to failure of prostheses are currently under intense investigation, the mechanisms and importance of regional and systemic immune responses to wear debris require further study.

Adenocarcinoma↗
PubMed1999

The stentless quadrileaflet bovine pericardial mitral valve: early clinical results.

BACKGROUND AND AIMS OF THE STUDY: Although bioprosthetic valves currently in use have low thrombogenicity, durability remains very unsatisfactory. Valve failure occurs early from calcification, and later from tissue wear. Stentless design lessens the latter, and anticalcification treatments the former. Recently, a stentless chordally supported quadrileaflet mitral valve (QMV) bioprosthesis made of selected tanned bovine pericardium, treated to minimize calcification, has become available for clinical study. The aim of this study was to report the early results relating to valve performance, and patient outcome. METHODS: Since December 1996, the QMV has been implanted in 23 patients (mean age 38 +/- 12 years) requiring isolated mitral valve replacement for valve lesions not suited for repair. All patients were symptomatic (three in NYHA functional class II, 16 in class III, four in class IV). Preoperatively, all underwent full clinical and echocardiographic assessment, and intraoperative transesophageal evaluation immediately after valve implantation. Blood tests for hemolysis were performed preoperatively and at 3 months after surgery. RESULTS: After a mean follow up of 8.3 months (range: 1 to 18 months), 22 patients were alive and symptomatically improved (NYHA class I or II). One patient died of sternal sepsis soon after surgery. There have been no reoperations, nor cases of infective endocarditis or thromboembolism. Subclinical hemolysis was shown pre- and postoperatively in 35% and 32% of cases, respectively. Intraoperative transesophageal echocardiography post valve implantation demonstrated mitral regurgitation which was trivial in 15 patients (78%) and mild in five (22%). CONCLUSIONS: The QMV can be implanted safely, and the early clinical results relating to patient outcome and valve performance are encouraging.

Adult↗
PubMed2002

Direct restoration of anterior teeth: review of the clinical technique and case presentation.

Direct composite resin bonding procedures are growing in popularity as conservative and predictable restorative treatment alternatives. An understanding of the fundamental layering, contouring, and polishing principles is paramount to the success of any direct composite restoration; this awareness can be subsequently applied to indirect restorations and significantly enhance laboratory/clinician communication. This article presents a clinical technique that describes the incremental placement of direct resin veneers on a typodont and demonstrates the application of these procedures on an actual clinical case.

Adult↗
PubMed2005

Clinical evaluation of a polyacid-modified resin composite in class V carious lesions: 3-year results.

This study evaluated the three-year clinical performance of Class V restorations made of a polyacid-modified resin composite, Dyract. Ninety-two Class V carious lesions in 28 patients were restored with Dyract. Restorations were clinically evaluated at baseline, first, second, and third year recall visits, according to the modified Ryge criteria by two experienced, calibrated examiners. Retention rate after three years in Class V carious restorations was 92.4%, with only seven failed restorations. Color change and marginal discoloration in restorations were found to be statistically significant (p = 0.013 and p < 0.001, respectively) at the end of third year, but none of the affected restorations required replacement. The results of this study revealed that at the end of three years, Dyract exhibited good clinical success rate but significant color change and marginal discoloration in Class V carious lesions.

Adolescent↗
PubMed1988

[Color vision in cataract, aphakia and pseudophakia].

Color vision examinations were performed using a clinical test battery and two spectral laboratory methods. With aphakia and iris-clip lenses (ICL) there were slight acquired blue-yellow defects six months to three years after surgery, especially when the more sensitive laboratory methods were used. They were possibly caused by photochemical damage to the retina or by a barrier deprivation syndrome. Color vision with posterior chamber lenses (PCL) was superior to that with ICL, and in aphakic subjects it was quite normal. In the clinical tests no differences could be found between PCLs of clear PMMA material and those with UV absorbing properties. Slight acquired blue-yellow defects in the immediate postoperative phase after implantation of PCLs can be attributed to postoperative irritation and are reversible. Lasting and severe blue-yellow defects indicate inflammation or macular edema.

Adult↗
PubMed1998

Atherosclerotic aneurysm of the proximal subclavian artery: a case report.

Aneurysms of the upper extremities, and particularly the intrathoracic segment of the subclavian artery, are unusual. Surgical approach and timing of repair remain controversial. We successfully treated a case of a large proximal subclavian artery aneurysm, atherosclerotic in origin. In spite of the size, the symptoms were vague. The patient underwent partial resection of the lesion located in the proximal third of the right subclavian artery, and repair using 8 mm dacron interposition graft. She did well postoperatively and remains symptom free at 1 year. A discussion of this disorder with the relevant literature review is herein included.

Aneurysm↗
PubMed1998

Pathologic findings in explanted clinical bioprosthetic valves fabricated from photooxidized bovine pericardium.

BACKGROUND AND AIMS OF THE STUDY: The study aim was to assess tissue quality and host-biomaterial interactions in clinical bioprostheses fabricated from bovine pericardium preserved by dye-mediated photooxidation, but not glutaraldehyde-pretreated. METHODS: Ten aortic valves explanted for regurgitation after 8-23 months' function from 10 patients aged 67-83 years were analyzed by gross and dissecting microscope examination, radiography and light microscopy. RESULTS: Each valve had one to several commissural-basal tears (5 mm) to complete leaflet detachment (four valves). The pattern of tearing was consistent among valves and suggested that a mechanism of design-related proximal inflow surface cuspal abrasion against Dacron cloth was contributory. Mild cuspal sagging/stretching was noted in five valves, pannus overgrowth was mild, and there was no evidence of infection or macroscopic thrombus. Microscopically, tissue distant from tears in all valves had an essentially intact but acellular collagenous matrix, was devoid of residual connective tissue cells and host inflammatory cells, with mild fragmentation of the inflow collagen bundles, and showed no evidence of endothelialization. Despite radiographs uniformly negative for mineralization, focal intrinsic cuspal microcalcification was noted histologically in four valves. CONCLUSIONS: Design-related and largely abrasion-induced tearing caused failures of this cohort of photooxidized pericardial valves. Nevertheless, this nonglutaraldehyde-preserved photofixed pericardial tissue from valves suffering design-related cuspal tears to two years postoperatively remained without significant degradation, inflammation, infection, thrombus, pannus or calcification.

Aged↗
PubMed1998

Clinical utility of cardiac valve Gram stain and culture in patients undergoing native valve replacement.

OBJECTIVES: To determine if routine cardiac valve culture is useful in diagnosing clinically unsuspected infective endocarditis in patients undergoing native valve replacement, to see if false-positive culture results have a deleterious effect on patient care, and to determine if microbiology and histopathology can be used to differentiate partially treated and untreated infective endocarditis from valve contamination. DESIGN: Case series. SETTING: Tertiary-care teaching hospital with 1125 beds. PATIENTS: Forty-eight patients with culture-positive cardiac valves after native valve replacement. RESULTS: A single unsuspected case of endocarditis was disclosed by microbiology over a 5-year period. Histopathology in this case was also positive, however, and the diagnosis should have been suspected clinically. Eighty-three percent of positive cultures were the result of contamination over an 18-month period; results were disregarded appropriately by clinicians. Clinical context or histopathology was required to categorize microorganisms correctly as pathogens or contaminants; only the presence of organisms on Gram stain had a good predictive value for endocarditis. CONCLUSION: Routine valve cultures in patients undergoing native valve replacement are not warranted. Although false-positive culture results had no deleterious effects on patient care in this study, misinterpretation of such results could lead to overtreatment. Microbiology results alone are not sufficient to distinguish endocarditis from contamination.

Adult↗
PubMed1994

Color duplex Doppler ultrasound scanning for detection of deep venous thrombosis in total knee and hip arthroplasty patients. Incidence, location, and diagnostic accuracy compared with ascending venography.

Ninety-nine patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) were prospectively studied for deep venous thrombosis (DVT) of the lower extremity. Eighty-three hips in 42 THA patients and 107 knees in 57 TKA patients were studied with noninvasive color duplex Doppler ultrasound flow scanning and ascending venography 3-9 days after surgery. In all patients, surveillance studies were performed within 24 hours. The ultrasonographer and radiologist were blinded to the study. The incidence of DVT was significantly greater following TKA (61%) than THA (17%) (P < .001). After TKA, significantly more DVT was found in the ipsilateral (32 of 57 patients) versus contralateral knees (3 of 50 patients), and more thrombi were located below the knee (34 of 107 knees) than above the knee (1 of 107 knees) (P < .001). More thrombi were found in the contralateral limb after THA (5 of 41 patients vs 3 of 42 patients), but this was not significant. Two patients developed nonfatal pulmonary emboli. The sensitivity of color flow scanning was relatively poor initially (67% of above-knee patients and 57% of below-knee patients), but improved in the last 50 patients (100% of above-knee patients and 79% of below-knee patients). Negative predictive values exceeded 90% in the THA group and 87% in the TKA group. Positive predictive values ranged from 89 to 100%. Specificity was always above 96%. Longitudinal ultrasound scanning with the newer Quantum 2000 angiodynograph (Issaquah, WA) provided the best image quality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Pitfalls in the diagnosis of periprosthetic valvular regurgitation by pulsed Doppler echocardiography.

Pulsed Doppler echocardiographic diagnosis of periprosthetic valvular insufficiency may be difficult. This report details the pulsed Doppler echocardiographic findings in two patients who developed severe periprosthetic mitral regurgitation after porcine mitral valve replacement. In both patients, mitral regurgitation was difficult to diagnose and left atrial turbulence, when detected, appeared localized, suggesting only mild mitral regurgitation. However, the combination of abnormally high peak transmitral diastolic flow velocity, with a normal pressure half-time, and increased flow velocity in the tricuspid regurgitant jet compatible with severe pulmonary hypertension, in the absence of other apparent left heart disease, suggested the correct diagnosis of severe mitral regurgitation in both cases. Techniques for optimal pulsed Doppler assessment of the mitral anulus region are emphasized, as are the theoretic advantages of continuous wave and color-coded pulsed Doppler echocardiography for detection of periprosthetic regurgitation.

Adult↗
PubMed2003

Interobserver variation in duplex scanning of infrainguinal arterial bypass grafts.

OBJECTIVE: to determine the degree of interobserver variation of color-flow duplex scanning of infrainguinal arterial bypass grafts. METHODS: two experienced vascular technologists randomly assessed bypass grafts in 32 consecutive patients, using a color-flow duplex scan. In pre-defined segments the highest peak systolic velocity (PSV(max)) and end-diastolic velocity (EDV) were measured and a peak systolic velocity ratio (PSV ratio) was calculated. Results were analyzed as continuous variables (Bland and Altman plots and Intraclass Correlation Coefficient=ICC) and also as categorical data (weighted Kappa coefficient) for the PSV ratio 1-2.5, > or =2.5-4, > or =4.0. RESULTS: the ICC for the PSV(max), PSV ratio and EDV indicated "almost perfect" agreement for all three parameters. However, the Bland and Altman plots showed impressive interobserver variation for the higher values of all three parameters. For the PSV ratio categories a weighted kappa of 0.31 was calculated, indicating only fair agreement. Substantial variation was found for the categories with PSV ratios > or =2.5-4.0 and > or =4.0. CONCLUSION: though performing accurately for the lower values of the assessed parameters, duplex scanning shows considerable interobserver variation for the clinically significant higher values. Particularly in the PSV ratio interval > or =2.5-4.0, most relevant for clinical decision-making, the interobserver variability is unacceptable.

Aged↗