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PubMed2005

Evaluation of biodegradable synthetic scaffold coated on arterial prostheses implanted in rat subcutaneous tissue.

Polyester arterial prostheses impregnated with various synthetic biodegradable materials and with gelatin were implanted subcutaneously in rats for 3-180 days. The inflammation was assessed by quantifying the activity of alkaline phosphatase and by histology. The degradation of the scaffold materials was determined by scanning electron microscopy (SEM), size exclusion chromatography (SEC), and differential scanning calorimetry (DSC). The alkaline phosphatase activity induced by the polymer-impregnated grafts was similar to that induced by the non-impregnated controls during most of the post-implantation periods. Histological studies revealed that the acute inflammatory response was moderate to mild and was similar for all types of specimens, except for the gelatin-impregnated grafts that induced a severe acute inflammation during the first 2 weeks post-implantation. At 4 and 6 months, significant disintegration of the scaffold was observed, accompanied by enhanced tissue infiltration and a reactivation of the acute inflammatory phase. Linear and exponential degradation rates of the synthetic polymers were described. The relative degradation rates of the biodegradable polymers were ranked as following: PLLACL > PDLLA > PLLA > PCEL. In conclusion, biodegradable polymers may provide an option as sealant/scaffolding materials for vascular prosthesis. It is suggested that the degradation rate of the polymer scaffolding materials should be higher to achieve early healing while without inducing strong inflammation.

Absorbable Implants↗
PubMed1997

Analysis of 274 Omniflow Vascular Prostheses implanted over an eight-year period.

BACKGROUND: Polytetrafluoroethylene (PTFE), dacron, and, more recently, collagen prostheses are finding increasing use for femoropopliteal reconstruction when a suitable vein is not available. The main factors to be considered when choosing a prosthesis are patency, susceptibility to infection and formation of aneurysms. METHODS: Sheep collagen prostheses were implanted on 274 occasions in the femoropopliteal or crural regions. RESULTS: The patency rate for supragenual bypass after 3 years was 61.9% with good vascular periphery and 44% with poor vascular periphery. If the prosthesis extended below the knee, the patency rate was 55.4% with good and 35.3% with unfavourable vascular periphery. Patency for the femorocrural bypass was 28.7% after 2 years. The rate of infection was 0% and an aneurysm occurred in three patients (1.1%). CONCLUSIONS: With this low infection rate and very slight danger of aneurysm, the long-term results suggest that the ovine collagen prosthesis can be recommended for use when no suitable vein is available.

Adult↗
PubMed1995

Three-dimensional distortion of gold alloy castings and welded titanium frameworks. Measurements of the precision of fit between completed implant prostheses and the master casts in routine edentulous situations.

Thirty routine patients, provided with fixed prostheses supported by osseointegrated Brånemark implants in edentulous lower jaws, were arranged into three different groups with regard to design of the metal framework. Ten patients received cast gold alloy frames and the other two groups were provided with two different designs of welded titanium frames. The fit of the completed prostheses was measured in three dimensions (3-D) in relation to the master cast, by means of a photogrammetric technique, prior to insertion. Mean 3-D distortion of the centre point of the gold cylinder was 42 (s.d. 8) microns for the cast framework. The corresponding mean distortion for the two designs of titanium frameworks was 43 (s.d. 16) and 36 (s.d. 10) microns, respectively. Least distortion was observed in vertical direction for all three designs. None of the different designs of metal frames showed a significantly better fit (P > 0.05), but the cast and oldest titanium framework design presented a much wider range of distortion. This indicated a higher risk of sectioning and resoldering during the fabrication of the prostheses as compared to the more consistently fabricated prostheses, with a new titanium framework design.

Dental Casting Technique↗
PubMedDate not supplied

[Implant prostheses].

Explore the source record for details and available documents.

Dental Implantation, Endosseous↗
PubMed2003

A longitudinal study of quality of life outcomes in older adults requesting implant prostheses and complete removable dentures.

A longitudinal clinical trial involving 103 subjects was undertaken to assess the impact of oral implant therapy on the psychosocial well-being of subjects with complete denture wearing problems. There were four experimental groups: (1) an implant group, where subjects were edentulous/edentate in one jaw and requested and received implants to retain an oral prosthesis (IG); (2) subjects edentulous/edentate in one jaw requesting implants but who received conventional dentures (CDG1); (3) edentulous subjects requesting replacement of their dentures by conventional means (CDG2); (4) dentate subjects requiring routine treatment, who were included for comparison. Data were collected in each group pre- and post-treatment using validated oral specific [the Oral Health Impact Profile (OHIP)], and generic (the SF36) health status measures. Subjects in IG, CDG1 and CDG2 also completed a denture satisfaction scale. IG and CDG1 subjects reported that tooth loss and denture wearing problems had a much greater impact on their quality of life than subjects seeking conventional dentures. Dentate subjects had a much better oral health status compared with denture-wearing subjects. Following treatment, subjects who received implant-retained prostheses (IG) reported a significant improvement in satisfaction and health-related quality of life, as did subjects who requested and received conventional dentures (CDG2). Subjects who requested implants, but received conventional dentures (CDG1), reported little improvement in denture satisfaction and only modest improvement in their quality of life. None of the denture-wearing subjects reported health-related quality of life that was as good as that of dentate subjects. The findings have significant implications in the assessment of outcomes in future clinical trials.

Adult↗
PubMed1975

Use of implantable prostheses for the treatment of urinary incontinence and impotence.

Silicone-Silastic implants to restore continence and potency have been used in one hundred twenty and twenty-five patients, respectively, and in eight patients a combined anti-impotence and anti-incontinence operation has been performed. The results have been gratifying, the complication rate has been minimal with fewer than five patients in our series having infection and a draining perineal sinus after the incontinence implant, and in no patient have delayed problems with the penile implants developed. Because of the design of the penile implants, fracture is extremely unlikely to occur, and the rods can be replaced if necessary because of inadequate length or asymmetry.

Erectile Dysfunction↗
PubMed2005

Stress distribution in bone: single-unit implant prostheses veneered with porcelain or a new composite material.

The purpose of this study was to simulate dynamic and static occlusal loading on one unit fixed, implant-supported prostheses veneered with porcelain and with GRADIA in a 3-dimensional finite element model of the human mandible to analyze and compare the resultant stresses in the superstructures and in the supporting bone. Calculation and visualization of stress, deformation, and displacement of complex structures under simulated forces were evaluated by finite element analysis (FEA) using ANSYS. The device employed was from the OSTEOFIX Dental Implant System (Oulu, Finland), and the veneering materials used were standard dental porcelain and GC GRADIA (Tokyo, Japan), a new composite material. Two different loading conditions were considered: static and transitional or impact, each delivered in three different directions: horizontal (Fh) at 0 degrees , vertical (Fv) at 90 degrees , and oblique (Fo) at 120 degrees . The proportion of the force: magnitude was fh:fv:fo = 1:3.5:7. A vertical load of 500 N, a horizontal load of 143 N, and an oblique load of 1000 N were applied. The results showed that the highest stresses in the bone-implant interface occurred in the region of cortical bone adjacent to the first thread of implants in all models and varied within 6.5%. Maximum stresses and displacements were higher (7%) in those models with statically loaded implants as compared with those that had been dynamically loading. The direction of loading played a major role in determining stress levels and they varied at up to 85%. It was shown that with dynamic loads, the peak of 1.568 mm was registered in the model with the GRADIA veneering material. This displacement was 6.5% higher than that found with the Vita VMK 68 veneers. These results suggest that the implant superstructure-fixed single crown veneering materials-porcelain and GRADIA played minor influences to the displacements and stresses in the implant supported bone with a 1% variance. One of the reasons for this element resulting in so minor a contribution to stress relief was the relatively small volume of the veneers as compared with the far greater volume and stiffness of the superstructures and implants. One of the advantages of GC GRADIA is that it reduces impact force under dynamic load up to a 6.5%.

Bite Force↗
PubMed1990

Patency and healing of polymeric microvenous prostheses implanted into the rat femoral vein by means of the sleeve anastomotic technique.

The sleeve anastomotic technique was used to enhance the longer term patency and healing of polyurethane-based (PU) microvenous prostheses (ID: 1 mm, length: 5 mm, wall thickness: 0.2 mm; n = 34) in the rat femoral vein. In the control group, PU prostheses (n = 12) were implanted by means of the conventional end-to-end technique, and all were found to be occluded after one day (n = 6) and three weeks (n = 6). In the other experimental groups, the prostheses were evaluated after one day (n = 6), three weeks (n = 10), and six weeks (n = 18) of implantation by means of routine light- and scanning-electron microscopy. The occluded prostheses in the control group demonstrated a firmly attached mural thrombus at the anastomoses at one day and a completely organized thrombus at three weeks after implantation. Thirty-one of the 34 PU prostheses implanted by means of the sleeve technique were patent. At one day, all patent PU prostheses (five out of six) demonstrated minimal thrombus accumulation and a smooth transition at the anastomotic sites. At three and six weeks, all patent PU prostheses (16 out of 18) were covered by a complete endothelial layer. Underneath the endothelial layer, a subendothelial layer, composed of two to four layers of smooth muscle cells, could be observed. The wall of the prostheses were penetrated by fibrohistiocytic tissue. Stenosis was not observed. These results demonstrate that the sleeve anastomotic technique not only improves the short-term patency of PU microvenous conduits, but also the longer-term patency rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1993

Progressive loading of bone with implant prostheses.

The rationale and protocol to gradually load the implant after the initial bone interface have been established and discussed. Bone density is the most critical factor in determining the amount of healing time between first and second-stage surgeries and also between the five appointments for prostheses which are cement-retained.

Alveolar Process↗
PubMed1988

Patency rate of small caliber fibrous polyurethane vascular prostheses implanted in the dog carotid and femoral artery improved by use of acetylsalicylic acid and dipyridamol.

Segments of 3 mm diameter fibrous polyurethane vascular prosthesis of length 3-4 cm were prepared. They were bilaterally implanted in the carotid and femoral arteries of male and female beagles. Four groups consisting of animals receiving either no medication or thrombocyte aggregation drugs were studied: Group A (8 dogs), no medication: group B (19 dogs), 500 mg acetylsalicylic acid (ASA) once daily and 25 mg dipyridamol (DIP) three times daily orally for 6 weeks after the implantation operation; group C (14 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 6 weeks after the implantation operation; group D (12 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 25 weeks after the implantation operation. Medication was started one week prior to the implantation operation. In group A, all prostheses were occluded at week 6. There was a significant difference in patency rates between groups B-D and C-D. No significant differences in patency rates could be found between groups B and C. The best patency rates were obtained 25 weeks after implantation in group D for both the right and left carotid and right and left femoral implantation sites. Highest patency rates were observed when ASA and DIP were given for 25 weeks.

Animals↗
PubMedDate not supplied

Relationship between prosthodontic evaluation and patient ratings of mandibular conventional and implant prostheses.

PURPOSE: The purpose of this study was to compare clinicians' ratings of the state of oral tissues and their satisfaction with treatment to edentulous patients' ratings of treatment success after provision of mandibular implant overdentures or conventional dentures. MATERIALS AND METHODS: Sixty subjects randomly received either mandibular overdentures retained by two implants (n = 30) or new conventional mandibular complete dentures (n = 30). All were given new conventional maxillary dentures. Baseline measures included clinical evaluation of the oral soft and hard tissues. Patients rated their general satisfaction before and after treatment, as well as their satisfaction with stability, speech, and esthetics on visual analogue scales. The treating prosthodontist rated the dentures for the same categories. Patient and clinician ratings were compared using correlations, t tests, and linear regression. RESULTS: None of the clinical variables were significantly correlated with patient satisfaction before or after treatment. The prosthodontist rated mandibular implant overdentures significantly better than conventional dentures regarding general satisfaction, stability, speech, and esthetics. Implant overdentures were also easier to fabricate (P < .0001). The prosthodontists' scores were not significantly correlated with patient scores for any question. CONCLUSION: Clinicians' assessments of the quality of denture-supporting tissues are poor predictors of patient satisfaction with mandibular implant or conventional prostheses. Prosthodontists and patients both rate mandibular implant overdentures as significantly superior to conventional dentures, but patients and clinicians do not usually agree when evaluating individual prostheses.

Aged↗
PubMedDate not supplied

Endothelialization of polyurethane vascular prostheses implanted in the dog carotid and femoral artery.

A new type of vascular prosthesis made of polyurethane with a fibrous structure of the wall was implanted in the carotid and/or femoral artery of dogs. The healing process and neo-intima formation after implantation of this type of prosthesis was followed with light- and scanning electron microscopy. A total of 18 prostheses, which had been implanted for 1, 3, 6, 9 or 20 weeks were studied. Endothelial like cells invaded the prosthesis over the anastomoses, starting the first week after implantation. The growth zones advanced steadily, and prostheses measuring 3 cm in length were completely endothelialized by 20 weeks after implantation, a mean growth rate of the endothelial like cells of 0.09 mm/day. Subsequently, fibroblasts and smooth muscle cells grew between the neoendothelial layer and the prosthetic inner surface, forming a new multi-layered neo-intima. Cellular elements of the neo-intima were firmly anchored onto the inner wall of the prosthesis by cells with extending cytoplasmic protrusions between the fibers of the prosthetic wall. Since in this type of fibrous polyurethane prosthesis, endothelial like cells continually grew until a new lining was formed, apparently facilitated by the fibrous structure of the wall, further investigations are indicated for progression toward clinical implantation of this type of prosthesis.

Animals↗