Current Issue : October - December Volume : 2012 Issue Number : 4 Articles : 6 Articles
Patients with bilateral and severe neurosensorial hypoacusia are candidates for cochlear implantation. Eventhough it�s a relatively modern procedure, it has a very low rate of complications (5-10%), making it a safe surgery. The Cohen classification is currently used to measure and group the complications of this surgery, classifying them according to the moment in which they appear whether it�s intraoperative or postoperative time. We present the case of a female patient who suffered the extrusion of the implant several months after the procedure. She was re-operated successfully, but she returned months later with a second extrusion of the same implant. We did not find any other report of this phenomenon in the revised literature. We present this case with pictures of the repair surgery and the patient�s current condition. We also analyze possible causes of this cochlear implant rejection, citing both magnetomechanical and immunomediated factors....
There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early\r\nfailure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after\r\nsuccessful implant integration can result in physical failure of the implant structure.Many clinicians believe that overload of dental\r\nimplants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses.\r\nIt has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching) affects the outcome of implant\r\nprostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack\r\nof evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of\r\ntooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant\r\nlongevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related\r\nto bruxism....
Neurofibromatosis type 1 (NF1), also known as von Recklinghausen�s disease, is a human genetic disorder. It is\r\nprobably the most commonly inherited disorder caused by a single gene.\r\nThis is a report of a 57-year-old man affected by NF1 who has severe atrophy of the jaws and extremely\r\nunsatisfactory anatomical conditions for conventional dental restauration. Radiographic and clinical evaluations\r\nshowed inadequate quantity of bone for immediate implant rehabilitation. Delayed implant protocol was performed to\r\nobtain the correct bone volume and implants were inserted in the anterior parts of both jaws to support a prosthetic\r\nrestoration....
Background: Modern cochlear implants have integrated recording systems for\r\nmeasuring electrically evoked compound action potentials of the auditory nerve. The\r\ncharacterization of such recording systems is important for establishing a reliable\r\nbasis for the interpretation of signals acquired in vivo. In this study we investigated\r\nthe characteristics of the recording system integrated into the MED-EL PULSARCI100\r\ncochlear implant, especially its linearity and resolution, in order to develop a\r\nmathematical model describing the recording system.\r\nMethods: In-vitro setup: The cochlear implant, including all attached electrodes, was\r\nfixed in a tank of physiologic saline solution. Sinusoidal signals of the same\r\nfrequency but with different amplitudes were delivered via a signal generator for\r\nmeasuring and recording on a single electrode.\r\nComputer simulations: A basic mathematical model including the main elements of\r\nthe recording system, i.e. amplification and digitalization stage, was developed. For\r\nthis, digital output for sinusoidal input signals of different amplitudes were calculated\r\nusing in-vitro recordings as reference.\r\nResults: Using an averaging of 100 measurements the recording system behaved\r\nlinearly down to approximately -60 dB of the input signal range. Using the same\r\nmethod, a system resolution of 10 �µV was determined for sinusoidal signals. The\r\nsimulation results were in very good agreement with the results obtained from invitro\r\nexperiments.\r\nConclusions: The recording system implemented in the MED-EL PULSARCI100\r\ncochlear implant for measuring the evoked compound action potential of the\r\nauditory nerve operates reliably. The developed mathematical model provides a\r\ngood approximation of the recording system....
Background: Dental implants have revolutionised restorative dental care but this is complex surgical and prosthodontic treatment. Excellent results have been reported in many institutional studies with a small but acceptable failure rate. It is largely unknown which of these results translate directly into a private practice setting.\r\n \r\nMethods: All patients who have dental implants placed in the maxilla by a single oral and maxillofacial surgeon in private practice in over a 3 year period were included in this study. All implants were placed in a two stage approach.\r\n \r\nAll the data was collected through retrospective review of patient files and radiographic assessment. Patient data included full demographics, referral source, type and site of implants placed, and adjunctive procedures.\r\n \r\nThe outcome including any complications in the first phase between placement and uncovering were recorded. The restorative phase was performed by a variety of general dentists and prosthodontists, with patients being followed up in surgical outpatients post final prostheses being issued.\r\n \r\nIn all cases the individual who referred the patient and performed the reconstruction had been present at the time of surgical implantation. The outcome, including any complications in the prosthodontic reconstruction phase was recorded.\r\n \r\nThis data was recorded on a standardised data sheet and maintained and analysed using SPSS (Statistical Package for the Social Sciences, version 9.05, Chicago, IL). Where two different factors were compared, the 95% confidence interval (CI) of the difference between the survival rates was calculated. A difference was considered statistically significant on a 5% level when this confidence level did not contain 0.\r\n \r\nResults: 179 mandibular implants were placed in 57 patients. On review at three years 166 (93%) were successful with 13 implant failures. Of the implants which failed, nine of them failed in the first 6 months, and none after 18 months.\r\n \r\nThere were a number of trends which did not reach statistical significance. Failures were more common in the following circumstances; in the posterior mandible (11 of 13), with older mark II & III version implants (12 of 13) and implants shorter than 8 mm. There was no correlation to medical conditions or smoking. An incidental finding was a correlation between those who smoked and had heart disease. (P<0.005)...
Partial knee replacement (PKR) results in fast recovery and good knee mechanics and is ideal to treat medial knee osteoarthritis.\r\nCementless PKR depends on bone growing into the implant surface for long-term fixation. Implant loosening may occur due to\r\nhigh tensile strain resulted from large mechanical loads during rehab exercises. The purpose of this study is to investigate whether\r\nexternal fixations such as superior screw and frontal flange could reduce the tensile strain at the implant-bone interface. Three\r\nmedial PKRs were designed. The first PKR had no external fixations. A superior screw and a frontal flange were then added\r\nto the first PKR to form the second and third PKR designs, respectively. Finite element analysis was performed to examine the\r\ntensile strain at the implant-bone interface during weight-bearing exercises. The PKR with no external fixations exhibited high\r\ntensile strain at the anterior implant-bone interface. Both the screwed and flanged PKRs effectively reduced the tensile strain at the\r\nanterior implant-bone interface. Furthermore, the flanged PKR resulted in a more uniform reduction of the tensile strain than the\r\nscrewed PKR. In conclusion, external fixations are necessary to alleviate tensile strain at the implant-bone interface during knee\r\nrehab exercises...
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