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PubMedDate not supplied

Prosthetically formulated natural aesthetics in implant prostheses.

The discrepancy in the anatomic dimensions between an endosteal root-form dental implant and the root of a natural tooth can compromise the aesthetic appearance of the final restoration. For the past five years the authors have used an abutment system, the components of which are designed to enable the clinician to achieve a predictable aesthetic result. This article describes and illustrates the anatomic abutment system (AAS). Until recently, the restoration usually began at the gingival line where a cylindrical implant emerged to be restored with a noncylindrical prosthesis. The new system uses components which compensate for the difference between the diameter of the natural tooth root and the endosteal implant. The importance of teamwork is emphasized, and a step-by-step procedure is presented, indicating which steps are performed by the combined team and which are the responsibility of the laboratory or the restorative dentist. The learning objective of this article is to introduce this system to the reader.

Dental Abutments↗
PubMed1993

Are total hip prostheses implanted with the use of methylmethacrylate biocompatible?

OBJECTIVES: The biocompatibility of total hip replacement prostheses and methylmethacrylate cement which is used for fixation of the prosthetic components has been subject to debate for three decades. METHODS: We have studied the host response to total hip replacement prostheses in a number of clinical and experimental investigations. RESULTS: Methylmethacrylate cement is immunologically relatively inert while it causes, in in vitro experiments and in vivo, a foreign body type of reaction. In cementless prostheses, the wear of polyethylene which is used for lining of the acetabular component causes a similar foreign body type of reaction. CONCLUSION: Ultimately, the total hip prosthesis cannot be made invisible to the host system. The host response can be controlled and reduced, but not eliminated by technical improvement and development of more biocompatible materials.

Biocompatible Materials↗
PubMedDate not supplied

Evaluation of small caliber vascular prostheses implanted in small children: activated angiogenesis and accelerated calcification.

Healing characteristics of small-caliber vascular prostheses used in small children have rarely been observed because removing specimens are troublesome. Modified Blalock Taussig shunt procedures were performed using small caliber expanded polytetrafluoroethylene (ePTFE) vascular grafts and fabric grafts in 13 patients with congenital heart disease. At the time of total corrective procedures, a piece of 10 ePTFE grafts in 10 patients and six fabric grafts in four patients were removed from the distal pulmonary anastomosis, and evaluated. The implantation duration was from 11 months to 5 years and 7 months (mean, 2 years and 6 months). At removal, average patient age was 4 years and all grafts were patent. Microscopically, the wall of three ePTFE grafts were calcified, and macrophages were immunohistologically observed in the graft wall. Thrombus formation, intimal hyperplasia, and pannus detachment was common. In the fabric grafts, many capillaries infiltrated the interstices and often reached the lumen from the perigraft side. These results suggested that in cyanotic small children, angiogenesis in and around fabric grafts was active and calcification was accelerated in ePTFE grafts. Complete endothelialization throughout the length, caused by angiogenesis, might be possible in small children when highly porous fabric vascular prostheses are used.

Blood Vessel Prosthesis↗
PubMed1990

Soldering technique for osseointegrated implant prostheses.

This article describes a method for making changes in the alignment of superstructures for osseointegrated implants. After a cast is made from a transfer impression, the teeth and plastic are removed from the framework. The framework is sectioned into as many pieces as necessary to realign it on the analogs in the cast. The pieces are held in soldering investment with guide pins and abutment screws for soldering in the new position. The prosthesis is completed, finished, and replaced in the mouth.

Dental Implantation, Endosseous↗
PubMedDate not supplied

[Unicompartmental femorotibial arthroplasty and lateral gonarthrosis. Outcome of 52 prostheses implanted for more than 5 years].

The results of 52 Lotus unicompartmental knee implants with a follow up time exceeding 5 years are analysed. Forty-one prostheses with a mean follow-up of 6.5 years have given very good or good relief of pain. In almost all cases, flexion range exceeds 90 degrees and the preoperative motion has been most often clearly improved. Except for those due to prosthesis infection, all the poor and fair results in terms of pain, are explained by mechanical causes i.e. persistence of a frontal instability, loosening of the tibial component (2 cases) or narrowing of the nonprosthetic femorotibial space (11 cases). The latter is not related to the presence of any radiological chondrocalcinosis. These poor anatomical and clinical results appear to be preventable by a correct operative technique. In particular, the complete correction, by the prosthesis, or the angular deformity which has caused the lateral knee OA must be avoided. This is in contrast to what must be done in osteotomies. Unicompartmental prostheses thus have to stay in stress so that their long term future is uncertain. In the surgical management of lateral knee OA, these prostheses are not to be preferred to correction of frontal angular deformity by osteotomy, except in the elderly, when deformity cannot be completely corrected. Unicompartmental prostheses are particularly indicated in unstable knees in which osteotomies are known to be difficult to perform correctly.

Aged↗
PubMed1991

Systemic effects of implanted prostheses made of cobalt-chromium alloys.

Systemic effects of Co-Cr alloy/polyethylene hip joint prostheses were investigated using instrumental neutron activation to determine the concentrations of up to 16 elements. First, in a prospective study whole blood and serum taken from 10 patients from 1 day before to 90 days after implantation were analyzed. Secondly, in a retrospective study whole blood and serum from 23 patients who had had prostheses in place for up to 18 years were analyzed. For comparison, normal trace element levels in humans were determined by analyzing whole blood and serum from 21 patients. Finally, various tissues and organs from two decreased implant patients were analyzed and compared with normal concentrations obtained from the analysis of five "normal" patients without implants. In agreement with other recent investigations, our analyses of normal serum, whole blood, tissues, and organs show that most previously defined "normal" trace element concentrations were too high, chiefly owing to contamination and insufficient blanks. A detailed discussion shows that for many elements the ranges of normal concentrations have to be revised. This conclusion is of particular importance with respect to the sometimes conflicting earlier reports of systemic effects of metal prostheses. In the work reported here, both the prospective and the retrospective investigations of serum and whole blood showed massive Co enrichments as a consequence of implant corrosion. The data show a wide range of individual burdening, ranging from practically no effect to the most extreme values. The analyses of tissues from the vicinity of the implants in the two deceased implant patients showed strong local effects of Co, Cr, Zr, and Hf, the latter two elements originating from the X-ray contrast media in the bone cement. The analyses of organs revealed significant Co and Cr enrichment in several tissues and organs. Consequently, it can be seen that implant corrosion is not an occurrence of merely local significance, but one that affects the trace element status of the entire organism.

Bioprosthesis↗
PubMed1994

Silicone breast prostheses implantation and explanation.

Breast implants have been used for augmentation and reconstruction for a 30-year period. Standard techniques have been used for the successful placement of mammary prostheses to enhance or replace breast tissue. All breast implants are surrounded by a capsule. The most common complication of breast implant surgery is hardening and contracture of the capsule. Explanation of implants is indicated for implant rupture, infection, extrusion, siliconoma, breast pain, painful capsular contracture, malposition, significant patient fear, and systemic symptoms thought secondary to implants. A number of alternatives are available for postexplant reconstruction, including myocutaneous flaps and free tissue transfers.

Breast Implants↗