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At least 19 recordsLinked to original sources
PubMed1992

[Silicone molding compounds and latex gloves. The effect of latex gloves on addition and condensation silicones].

Inhibited setting of addition silicones has been observed using latex gloves in the dental office. Therefore four addition silicones as well as four condensation silicones were mixed with seven latex gloves with different properties (sterility, powder, accelerator, inner layer). The masses were mixed with bare hands as a control and--additionally--with powdered hands. Condensation silicones stayed unaffected when put together in exact amounts, while some addition silicones showed nearly complete inhibition. Mixing the condensation silicones under the conditions of daily practice--one spoon of body plus a distinct amount of catalyst-resulted in hardness differences compared to using the exact dose. Nevertheless the resulting impressions were of satisfying quality. The powder-component (Bio-sorb, Surgikos) leads to an accelerated setting. The general dental practitioner/dental hygienist have to consider these aspects while choosing gloves and silicone putties for taking impressions.

Dental Impression Materials↗
PubMed1992

Vitrectomy with silicone oil or sulfur hexafluoride gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial. Silicone Study Report 1.

Between September 1985 and September 1987, 101 eyes with rhegmatogenous retinal detachment and severe (with a classification of at least C-3) proliferative vitreoretinopathy but without prior vitrectomy were treated with vitrectomy and randomized to either a mixture of 20% sulfur hexafluoride gas and air or to 1000 centistokes of silicone oil. Between 50% and 60% of eyes that received silicone oil had visual acuity better than or equal to 5/200 compared with 30% to 40% of the eyes that received sulfur hexafluoride gas (P less than .05). Macula attachment was more frequent in eyes that received silicone oil than in those that received sulfur hexafluoride gas (80% vs 60%, P less than .05). Hypotony was more prevalent in eyes with a detached macula (40% to 50% for sulfur hexafluoride gas vs 25% to 30% for silicone oil) when compared with those with attached maculas (less than 5% for either modality). Keratopathy was more prevalent in eyes with detached maculas (about 55% to 60% for either modality) compared with eyes with attached maculas (25% to 30% for sulfur hexafluoride gas vs 10% to 15% for silicone oil). In a companion article, we show that these differences between a gas tamponade and silicone oil are not found for perfluoropropane gas.

Adult↗
PubMed1991

Early failure of silicone radial head implants in the rheumatoid elbow. A complication of silicone radial head implant arthroplasty.

Three cases of early recurrent synovitis of the rheumatoid elbow following silicone radial head implant arthroplasty are presented. All three patients underwent synovectomy with silicone radial head implant for pain and loss of function due to rheumatoid synovitis. All three implants failed within 4-9 months after surgery. This failure was associated with radiographic medial joint space widening. At reexploration, recurrent synovitis with hemosiderin pigmentation was noted. Patterns of prosthetic failure included fracture, fraying, and compressive deformation or rotary wear ("motar and pestle") of the silicone radial head; a prosthetic stem fracture was also present. Histologic examination of the synovium revealed evidence of silicone-induced synovitis; particulate, refractile silicone debris was associated with inflammatory and foreign body giant cells. The presence of rheumatoid destruction of the joint surface may have accelerated this process and may be a relative contraindication to silicone radial head implant arthroplasty.

Adult↗
PubMed1992

Silicon metabolism. The interrelations of inorganic silicon (Si) with systemic iron (Fe), Zinc (Zn), and copper (Cu) pools in the rat.

The influence of silicon treatment on the levels of trace elements zinc (Zn), copper (Cu), and iron (Fe) in serum and tissues was studied in rats. The concentrations of silicon, iron, and zinc were estimated in samples of sera and tissues of rats receiving per os a soluble, inorganic silicon compound--sodium metasilicate nonahydrate (Na2SiO3.9H2O), dissolved in the drinking water. An increase of copper concentrations in liver and aortic walls in the experimental group was observed, with simultaneous reduction of zinc amounts in serum and all the tissue samples in the course of the experiment. The iron concentrations in the analyzed samples did not show any significant changes between both groups. The silicon levels in serum and in all the examined tissues were significantly higher in the tested group. The results provide evidence for the silicon interaction with copper and zinc, which could result in a number of metabolic process modifications, antiatheromatous activity among them.

Animals↗
PubMed1990

Histologic changes and silicone concentrations in human breast tissue surrounding silicone breast prostheses.

Using a previously developed method for quantitative measurements of silicone concentrations in breast tissue, material from 86 biopsies from 67 breasts in 55 patients who had silicone implants was examined. In the 49 breast with unruptured prostheses, there was a positive relation between the concentrations and inflammatory reactions, the only exception being the amount of plasma cells, which showed a negative relation. It is concluded that silicone prostheses provoke an inflammatory response not only because they act as foreign bodies, but also because of silicone seepage through intact membranes.

Breast↗
PubMedDate not supplied

Enamel silicon and fluoride relationships demonstrating a surface silicon effect that facilitates fluoride uptake.

This study indicated that a clear relationship exists between silicon and fluoride. We have also demonstrated a probable surface enamel silicon effect that increases fluoride uptake. The complex set of relationships described in the surface chemistry of calcium, tin, and zirconium with fluoride, hydroxide, phosphate, and other surface-occurring ions need not be considered to confuse the specific silicon-fluoride relationship presented here because in this computation we are relating the changes in the silicon and fluoride ion values only. We have, however, considered the thermodynamics of such reactions and intend to elaborate on it in a later publication. We are aware of the small depth of fluoride penetration into enamel after topical treatment Health Foundation, Research Unit at the National Bureau of Standards, Washington, DC 20034, USA.

Composite Resins↗
PubMed1977

Silicone lymphadenopathy and synovitis. Complications of silicone elastomer finger joint prostheses.

We report two complications of silicone elastomer finger joint prostheses. In one patient, the prostheses broke, with silicone particles present in synovium ("detritic synovitis"). In another patient, silicone particles were found in an axillary lymph node five years after insertion of prostheses in the ipsilateral hand (prostheses were intact at the time). Microscopically, silicone particles in synovium and lymph node were identical to particles abraded from a new prosthesis.

Arthritis, Rheumatoid↗
PubMed1992

Vitrectomy with silicone oil or perfluoropropane gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial. Silicone Study Report 2.

Between September 1987 and October 1990, 265 eyes with rhegmatogenous retinal detachment and severe (with a classification of at least C-3) proliferative vitreoretinopathy were treated with vitrectomy and randomized to treatment with perfluoropropane gas or silicone oil; 131 eyes had undergone no prior vitrectomy (group 1) while 134 eyes had undergone vitrectomy with intraocular gas tamponade (group 2). At the last examination, there were no differences between perfluoropropane gas and silicone oil in achieving visual acuity greater than or equal to 5/200 (43% vs 45% for group 1, 38% vs 33% for group 2) and complete posterior retinal reattachment (73% vs 64% for group 1, 73% vs 61% for group 2). For group 1 eyes followed up for at least 18 months, there was an advantage favoring perfluoropropane gas in achieving complete posterior retinal reattachment (83% vs 60% at 36 months, P = .045). The rates of reoperation and keratopathy were similar, while hypotony was more prevalent in eyes randomized to perfluoropropane gas (group 2). Regardless of tamponade, groups 1 and 2 had similar anatomic and visual success. However, hypotony was twice as prevalent in group 2 (perfluoropropane), and the prevalence of keratopathy increased with follow-up in group 2 (either tamponade). Either tamponade produced better results than those seen with sulfur hexafluoride gas (Silicone Study Report 1).

Adult↗
PubMed1990

Silicone rubber-hydrogel composites as polymeric biomaterials. I. Biological properties of the silicone rubber-p(HEMA) composite.

A composite material was prepared consisting of silicone rubber matrix and particulate lightly cross-linked poly(2-hydroxyethyl methacrylate) (p(HEMA] hydrogel. The material resembling common silicone rubber is hydrophilic and swells in water like hydrogels. The effects of the implanted composite on tissues of the living organism were tested in rats by methods assessing local acute and chronic inflammatory reactions and calcification by means of radioactive indicators and by histological examination. Results of a 6 month implant study indicated no difference in reactions of the animal body on the silicone rubber-p(HEMA) composite and a non-toxic, non-irritant pure solid p(HEMA) control.

Animals↗
PubMed1990

Reactions at silicone-injected sites on the face associated with silicone breast implant "inflammation" or "rejection".

Although complications in various parts of the body have been suggested as being produced when silicone mammary implants are "rejected" or produce inflammation, there have apparently been no reports describing "flares" at previous sites of facial silicone injections as complications of mammary silicone implants. Such reactions appear to be comparable to so-called "systemic contact dermatitis." However, in the absence of results of skin testing, the mechanism of such "ectopic" flares remains in doubt.

Breast↗
PubMed1989

Classification of proliferative vitreoretinopathy used in the silicone study. The Silicone Study Group.

The Silicone Study is a multicenter randomized clinical trial that compares a long-acting gas with silicone oil for the surgical treatment of proliferative vitreoretinopathy (PVR). As part of the study, a topographic classification of PVR has been developed that is based on the characteristic patterns of retinal distortion produced by the contraction of proliferative membranes on the retina or within the vitreous base. This classification is used to document the extent and anatomic distribution of PVR present preoperatively and to help standardize the surgical treatment. Experience has shown that this classification facilitates the identification of these membranes and their systematic dissection, and the authors therefore suggest that it be used to augment the Retina Society classification of PVR.

Humans↗