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At least 127 records · Page 7Linked to original sources
PubMed2004

An evaluation of impression techniques for multiple internal connection implant prostheses.

STATEMENT OF PROBLEM: Movement of impression copings inside the impression material using an open-tray impression technique during clinical and laboratory phases may cause inaccuracy in transferring the 3-dimensional spatial orientation of implants intraorally to the definitive cast. Consequently the restoration may require corrective procedures. PURPOSE: This in vitro study evaluated the accuracy of 3 different impression techniques using polyether impression material to obtain a precise definitive cast for a multi-unit implant restoration with multiple internal connection implants. MATERIAL AND METHODS: A reference acrylic resin model with 4 internal connection implants (3i Implant Innovations) was fabricated. Forty-five medium-consistency polyether impressions (Impregum Penta) of this model were made with square impression copings using an open-tray technique. Three groups of 15 specimens each were made with different impression techniques: in the first group, nonmodified square impression copings were used (NM group); in the second group, square impression copings were used and joined together with autopolymerizing acrylic resin before the impression procedure (R [resin] group); and in the third group, square impression copings previously airborne-particle abraded and coated with the manufacturer-recommended impression adhesive were used (M [modified] group). Matching implant replicas were screwed into the square impression copings in the impressions. Impressions were poured with ADA type IV stone (New Fujirock). A single calibrated examiner blinded to the nature of the impression technique used examined all definitive casts to evaluate the positional accuracy (mum) of the implant replica heads using a profile projector (at original magnification x10). These measurements were compared to the measurements calculated on the reference resin model which served as control. Data were analyzed with a 1-way analysis of variance at alpha=.05, followed by the Student Newman-Keuls test (alpha=.05). RESULTS: The data obtained with the profile projector revealed significant differences within the 3 impression techniques ( P <.001). The Student Newman-Keuls procedure disclosed significant differences between the groups, with group R casts being significantly more accurate than group NM and group M casts ( P =.05). The mean distance (+/-SD) between the posterior implants compared to the reference acrylic resin model was 18.17 mum (+/- 6.4) greater for group R casts, 41.27 mum (+/- 8.4) greater for group M casts, and 46.21 mum (+/- 8.9) greater for group NM casts. Distances between the anterior implants were also greater than those recorded on the reference model. The distance was 15.23 mum (+/- 5.9) greater on group R casts, 38.17 mum (+/- 8.3) greater on group M casts, and 43.23 mum (+/- 8.7) greater on group NM casts. CONCLUSION: Within the limitations of this study, improved accuracy of the definitive cast was achieved when the square impression copings joined together with autopolymerizing acrylic resin were used to make an impression of multiple internal connection implants.

Acrylic Resins↗
PubMed1992

Mandibular restoration in the cancer patient: microvascular surgery and implant prostheses.

This article deals with state of the art reconstruction and rehabilitation of the head and neck cancer patient who requires mandibular resection. The mandible can be reconstructed by microvascular free tissue transfer of bone and soft tissue from distant body sites. The dental units and missing soft tissue contours can be supported by osseointegrated implants placed in the grafted bone. This article discusses the rationale for patient selection and sequencing of this complex and rewarding rehabilitation.

Dental Implants↗
PubMed1984

Speech processing for cochlear implant prostheses.

The transformation of speech into electrical signals which can stimulate the auditory nerve in order to create hearing sensations that carry speech information depends on many factors. These include the limitations imposed by the current state-of-the-art in otological surgery, microelectronic and micromechanical technology, and knowledge of the functioning of the auditory system under both acoustic and electrical stimulation. Sufficient advances have been made in all these areas to enable several research centers to develop cochlear prostheses which give some hearing to certain totally deaf persons. The work of these centers towards the goal of full unaided speech perception via the prosthesis is examined and evaluated.

Adolescent↗
PubMed2002

Osteoporosis: the effect on mandibular bone resorption and therapeutic possibilities by means of implant prostheses.

In recent years, considerable attention has been given to the interrelationship between the outbreak of a systemic process of reduction in the bone mass and the possibility of a significant resorption of the alveolar bone. The degree of alveolar bone loss increases with age, and this may be related, at least in part, to the systemic conditions that also encourage the development of osteoporosis. Although numerous studies have documented the possible role of osteoporosis as a deteriorating factor in both tooth loss and mandibular bone resorption, this article underlines how the morphostructural evolution of the edentulous mandible is primarily correlated to mechanical factors as a result of modifications to its function. We will also take into consideration the therapeutic advantages provided by prosthetic rehabilitation on osseointegrated implants, in terms of reinstatement of the loading conditions through patterns of propagation of mechanical forces that are similar to physiologic ones.

Alveolar Bone Loss↗
PubMed2003

Osteoporosis: the effect on maxillary bone resorption and therapeutic possibilities by means of implant prostheses--a literature review and clinical considerations.

Osteoporosis is a systemic disease in which the skeletal condition is characterized by a decreased mass of normally mineralized bone. It is considered the most common metabolic bone disease, and it constitutes a major public health problem. Given the evidence that alveolar processes provide the bony framework for tooth support, the decline of skeletal mass has to be correlated with an increased risk of oral bone loss and has a negative consequence on tooth stability. Data from past research confirm that aging and estrogen depletion have a negative influence on both tooth retention and residual alveolar crest preservation. The goal of the present article is, however, to underline how the morphostructural evolution of the edentulous maxilla is mainly due to mechanical factors as the result of alterations in maxillary function. The advantages of prosthetic rehabilitation supported by osseointegrated implants are also considered, focusing the therapeutic role of this procedure on preserving the residual alveolar ridge from atrophy.

Alveolar Bone Loss↗
PubMed1995

Postoperative alteration in the size of Dacron vascular prostheses implanted in the infrarenal abdominal aorta.

The degree and significance of postoperative alteration in the size of Dacron grafts in the infrarenal abdominal aorta was assessed by computed tomography. We studied a total of 41 knitted Dacron fabric grafts, comprising 28 Gelseal triaxial grafts and 13 Hemashield Microvel grafts, and 29 woven Dacron fabric (Veri-Soft Woven) grafts which were used to replace the infrarenal abdominal aneurysms. These three types of Dacron fabric dilated immediately after replacement to 1.4-1.5 times the manufactured size, but did not dilate further after the surgery.

Aortic Aneurysm, Abdominal↗
PubMed2000

[Thromboembolic and bleeding complications in patients treated with oral anticoagulant therapy after mechanical heart valve prostheses implantation].

Thromboembolic and bleeding events are major cause of morbidity and mortality in patients with mechanical heart valves. Ninety-three patients had been received anticoagulant (warfarin with bucolome 300 mg) for mechanical prosthetic valves, and the regulation of anticoagulation was performed within a prothrombin time international normalized ratio (PT-INR) about 2.0 of normal. The mean duration of follow-up was 64.1 months, and the total duration of follow-up was 496.8 patient-years (py). The valve related complications occurred in 10 cases (2.0 per 100 py). Anticoagulant related hemorrhagic events occurred in 7 cases, and valve thrombosis in 3 cases. All three cases of valve thrombosis were in cases with Björk-Shiley valve at the mitral position. An artificial valve in mitral position increased the valve related risk compared with the aortic position (3.1%/py vs 0.0%/py). Bileaflet valve showed a lower incidence of thromboembolism than tilting disc valve (2.3%/py vs 0.0%/py). The risk of valve related complication varied with the type and the position of the prosthesis, it is desirable that the intensity of anticoagulation would be changed according to the prosthetic valve type and its position. These results suggest that the intensity of anticoagulation is optimal when the PT-INR is 1.8-2.0 for patients with bileaflet valve in the mitral position, and is 1.6-1.8 in the aortic position. Tilting disc valve needs more intensity of anticoagulation, and needs additional antiplatelet agent in the mitral position.

Anticoagulants↗
PubMed1991

[Kinetics of cellular elements in the neointima of synthetic prostheses implanted into the rabbit aorta during development of experimental atherosclerosis].

Experimental atherosclerosis in 30 rabbits was combined with the implantation into the abdominal aorta of the synthetic prosthesis MPL-79. Formation of neointima and transformation of mesenchymal cells into the endothelial ones are studied using scanning and translucent electron microscopy and autoradiography. Neointimal hyperplasia is shown to result in significant narrowing of the prosthesis lumen up to its complete occlusion. It is important that neointima fibroplasia is particularly intense against the background of progressing atherosclerosis.

Animals↗
PubMed1977

Local activation of blood coagulation by polyester prostheses implanted into defects of the abdominal aorta of dogs.

An 8 cm long Dallon prosthesis was implanted into defects of the abdominal aorta of dogs, and the following changes were found: the blood flow through the vascular prosthesis induced a shortening of the blood clotting time and the heparin-thrombin time and a slight increase in the prothrombin consumption. It has a favourable effect of the sealing of pores in the prosthesis and covering its internal surface with a fibrin membrane.

Animals↗