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PubMed2006

[Ultrasound biomicroscopy in deep sclerectomy with a new acrylic implant].

OBJECTIVE: To describe the ultrasound biomicroscopic (UBM) characteristics seen in patients who have undergone deep phaco-sclerectomy with a new acrylic implant (Esnoper). SUBJECTS, MATERIAL AND METHODS: UBM exploration was performed 12 months after deep phaco-sclerectomy in three patients with chronic open angle glaucoma. RESULTS: One year after surgery, all three patients had intraocular pressure levels under 15 mmHg and were on no treatment. All of them had an intrascleral space in UBM, in which the hyperechogenic implant was visible. CONCLUSIONS: The new non-absorbable implant has proven to be effective in these cases. Information provided by UBM is useful and assists in understanding the mechanism of action of deep sclerectomy.

Acrylic Resins↗
PubMed2004

[Interaction between a ceiling pendent-type lead acrylic protective board for use in IVR and scattered radiation].

Scattered radiation was measured following the application of a ceiling pendent-type lead acrylic protective board (protective board) for use in IVR, and the dose-reduction rate was obtained. As a result of the interaction between the protective board and the scattered radiation, the dose reduction rate in the space between the protective board and floor surface became negative, resulting in an increase in scattered radiation. It was demonstrated that the increase in scattered radiation could be prevented by installing an added filter. This report presents a method to evaluate the effect of a protective board on scattered radiation by converting its property to that of a material with a similar effective density, and explains the experimental results. This report also shows that a conventional method, which calculates scattered radiation on the basis of lead equivalent, carries the risk of underestimating the effect on scattered radiation. The necessity of training operators based on the above findings is also emphasized.

Acrylates↗
PubMed1997

Glass fiber reinforcement in repaired acrylic resin removable dentures: preliminary results of a clinical study.

The clinical usefulness of continuous E-glass partial fiber reinforcement of acrylic resin removable dentures was evaluated an average 13 months after the insertion of the fibers. Twelve removable complete dentures and ten removable partial dentures with a history of recurrent fracture were selected for this study. The partial fiber reinforcement was incorporated into the denture at the time of repair. One complete denture and one removable partial denture fractured in the region of reinforcement during the examination period. These fractures were most likely caused by faulty placement of the fiber reinforcement in the denture in the dental laboratory. In six dentures, new fractures occurred in regions without partial fiber reinforcement. The results revealed the importance of both the correct positioning of the partial fiber reinforcement in the denture and the use of accurate laboratory techniques.

Acrylic Resins↗
PubMed1999

[Percutaneous vertebroplasty complicated by pulmonary embolus of acrylic cement].

Although venous escape of cement has been frequently noted during percutaneous vertebroplasty, no case of pulmonary embolus directly linked to this manoeuvre has been described in the literature. We report a case of pulmonary embolus of acrylic cement occurring immediately after the procedure. Outcome was favorable following anticoagulant therapy despite the persistence of some vascular obstruction suggesting the association of residual fibrinous matter in the pulmonary artery.

Acrylic Resins↗
PubMedDate not supplied

Monitoring the polymerization process of acrylic resins.

Four groups of autopolymerizing acrylic resins used for various purposes in current dental practice were investigated by monitoring their temperature changes during the polymerization process. Resins were compared in terms of characteristic parameters (such as the time interval needed to reach mechanical stability and the maximum temperature generated during the polymerization process) and interpretations were made of such temporal temperature profiles.

Acrylic Resins↗
PubMed1999

Glutathione-dependent metabolism of cis-3-(9H-purin-6-ylthio)acrylic acid to yield the chemotherapeutic drug 6-mercaptopurine: evidence for two distinct mechanisms in rats.

cis-3-(9H-Purin-6-ylthio)acrylic acid (PTA) is a structural analog of azathioprine, a prodrug of the antitumor and immunosuppressive drug 6-mercaptopurine (6-MP). In this study, we examined the in vitro and in vivo metabolism of PTA in rats. Two metabolites of PTA, 6-MP and the major metabolite, S-(9H-purin-6-yl)glutathione (PG), were formed in a time- and GSH-dependent manner in vitro. Formation of 6-MP and PG occurred nonenzymatically, but 6-MP formation was enhanced 2- and 7-fold by the addition of liver and kidney homogenates, respectively. Purified rat liver glutathione S-transferases enhanced 6-MP formation from PTA by 1.8-fold, whereas human recombinant alpha, mu, and pi isozymes enhanced 6-MP formation by 1.7-, 1.3-, and 1.3-fold, respectively. In kidney homogenate incubations, PG accumulation was only observed during the first 15 min because of further metabolism by gamma-glutamyltranspeptidase, dipeptidase, and beta-lyase to yield 6-MP, as indicated by the use of the inhibitors acivicin and aminooxyacetic acid. Based on these results and other lines of evidence, two different GSH-dependent pathways are proposed for 6-MP formation: an indirect pathway involving PG formation and further metabolism to 6-MP, and a direct pathway in which PTA acts as a Michael acceptor. HPLC analyses of urine of rats treated i.p. with PTA (100 mg/kg) showed that 6-MP was formed in vivo and excreted in urine without apparent liver or kidney toxicity. Collectively, these studies show that PTA is metabolized to 6-MP both in vitro and in vivo and may therefore be a useful prodrug of 6-MP.

Acrylates↗
PubMed2000

Clear acrylic resin device for orientation and placement of a small facial prosthesis.

A small-sized facial prosthesis can be difficult to orient accurately in correct relationship to a defect. This problem may be reduced by embedding a magnet in the prosthesis and constructing a magnetic holding device from clear acrylic resin. This device can be used as a stand during adhesive application to reduce adhesive contamination and acts as orientation guide during prosthesis placement.

Acrylic Resins↗
PubMed2000

Relative influence of composition and viscosity of acrylic bone cement on its apparent fracture toughness.

The composition and viscosity of an acrylic bone cement have both been identified in the literature as being parameters that affect the mechanical properties of the material and, by extension, the in vivo longevity of cemented arthroplasties. The objective of the present study was to determine the relative influence of these parameters on a key cement mechanical property; namely, its fracture toughness. Two sets of cements were selected purposefully to allow the study objective to be achieved. Thus, one set comprised two cements with very similar compositions but very different viscosities (Cemex RX, a medium-viscosity brand, and Cemex Isoplastic, a high-viscosity brand) while the other set comprised two cements with similar viscosities but with many differences in composition (Cemex Isoplastic and CMW 1). Values of the fracture toughness (as determined using chevron-notched short rod specimens) [K(ISR)] obtained for Cemex RX and Cemex Isoplastic were 1.83 +/- 0.12 and 1.85 +/- 0.12 MPa square root(m), respectively, with the difference not being statistically significant. The K(ISR) values obtained for Cemex Isoplastic and CMW 1 were 1.85 +/- 0.12 and 1.64 +/- 0.18 MPa square root(m), respectively, with the difference being statistically significant. Thus, the influence of cement composition on its K(ISR) is more marked relative to the influence of cement viscosity. Explanations of this finding are offered, together with comments on the implications of the results for the in vivo longevity of cemented arthroplasties.

Acrylic Resins↗
PubMedDate not supplied

Simplified technique for acrylic intraocular lens explantation.

A simplified technique to explant an acrylic (AcrySof) intraocular lens through the original scleral frown incision is presented. After the haptics have been separately removed from the optic, the optic is grasped by a lens holder forcep and wiggled through the incision site. No wound enlargement is necessary. The limited intracameral manipulations minimize any potential damage to the posterior capsule or corneal endothelium.

Acrylates↗
PubMed2000

Workers' dermal exposure to UV-curable acrylates in the furniture and Parquet industry.

The use of ultraviolet radiation-curable coatings (UV-coatings) has increased rapidly in the parquet and furniture industry. Work with UV-coatings involves risk from skin exposure to chemically reactive, concentrated acrylates that are known skin contact irritants and sensitizers. Yet, the methods and tools for measuring and quantifying dermal exposure from hazardous chemicals directly on the skin are limited and methods to measure skin exposure to UV-coatings in occupational or environmental settings have been lacking. Skin exposure to UV-coatings was measured employing a quantitative tape stripping method that we have developed for this purpose. A pilot study was performed at three workplaces. In the main study, workers' skin exposure to uncured UV-coatings was measured at seven workplaces and on two separate workdays (rounds 1 and 2) within a six-month period to determine exposure variation. Skin exposure was measured at four standardized sites on the hand, 3-4 times per work shift. The forehead was sampled once. A questionnaire was carried out with the workers in both rounds to find out factors that can affect skin exposure to UV-coatings. The pilot study indicated that both skin and surface contamination to TPGDA-containing UV-coatings were common and varied up to 2110 microgram on the sampling area of 10cm(2). In the main study skin contamination due to TPGDA was found on 16 of 23 workers, at 6 out of the 7 workplaces, and from 36 (5. 4%) of the 664 samples. In round one 8.6% (n=383) of the samples contained TPGDA and in round two 1.1 % (n=281). The average TPGDA mass on all the positive samples (n=36) was 30.4+/-77.0 microgram for the first and second rounds alone this mass was 30.6+/-80 (n=33) and 28.3+/-16.5 microgram (n=3), respectively. Despite the limited sampling area and sampling sites, we could find residues of TPGDA at all sampling times, even at the beginning of the work shift. This may be due to transfer of UV-coatings through contaminated equipment, shoes and surfaces. Our study indicates that there is a risk of harmful skin exposure to UV-coatings in the furniture and parquet industry.

Acrylates↗
PubMed2000

Laboratory-fabricated, acrylic resin cylinders for fixed, provisional implant restorations.

Commercially produced provisional cylinders are commonly used during fabrication of fixed, provisional implant restorations. A procedure is presented for the fabrication of fixed, provisional implant restorations using laboratory-fabricated, autopolymerizing acrylic resin cylinders. These cylinders offer a number of advantages over commercially produced cylinders and may reduce the treatment cost of implant prosthodontics.

Acrylic Resins↗
PubMedDate not supplied

An investigation of self-reinforced poly(methyl methacrylate) denture base acrylic resin using scanning electron and atomic force microscopy.

PURPOSE: The aim of this study was to examine the interfacial region of poly(methyl methacrylate) (PMMA) reinforced with untreated and surface-treated PMMA fibers in both chopped and continuous form using scanning electron and atomic force microscopy. MATERIALS AND METHODS: Acrylic resin specimens incorporating untreated and surface-treated (with butadiene styrene latex emulsion) PMMA fibers were examined using a scanning electron microscope and an atomic force microscope. RESULTS: There was evidence of random arrangement of untreated and surface-treated chopped fibers throughout specimens with areas of dense fiber aggregation and other areas containing few or no fibers. For the untreated and surface-treated fibers in continuous forms (a single and 2 unidirectional layers), there was evidence of fiber displacement and buckling, together with variation in interfiber spacing. For the specimens containing surface-treated continuous fibers in a cross-ply arrangement that had demonstrated a substantial improvement in the modulus of rupture, there was no evidence of fiber buckling, and the layer of butadiene styrene was consistently thin and even in comparison to weaker specimens. CONCLUSION: The thickness of the rubber layer and the fiber arrangement (in terms of fiber displacement and interfiber spacing) may be important factors in the success of the reinforcement.

Acrylic Resins↗
PubMed2000

Patient preference between visible light-cured and heat-cured acrylic splints.

PURPOSE: To compare the advantages/disadvantages concerning patient subjective preferences of splints made with heat-cured acrylic (Splint Resin Polymer) or visible light-cured material. MATERIAL AND METHODS: A questionnaire was developed assessing: comfort, stability, fit, taste, occlusal contacts, lip seal, smoothness, hygiene, color stability, stain resistance, salivation level, gingival irritation, bulkiness and odor. 10 patients already treatment planned to receive splints, were chosen at random from the dental school. Splints made from the two types of materials were delivered to each patient to be used for 3 wks. The material to initially be used was chosen at random and the questionnaire was answered after each 3-wk period. RESULTS: The MacNemar's Chi-square test revealed that there was no statistical difference in patient preference between the two splint materials.

Acrylic Resins↗
PubMed2002

Neurocognitive sequelae of exposure to organic solvents and (meth)acrylates among nail-studio technicians.

OBJECTIVE: To evaluate neuropsychologic performance among women occupationally exposed to products commonly used in nail studios. BACKGROUND: Organic solvents and (meth)acrylates commonly used in nail studios have known neurotoxic properties. Few studies have examined the potential for cognitive and neurosensory effects of occupational exposure to these substances, and none has addressed exposure occurring in the cosmetics industry. METHODS: Participants in this study included nail-salon technicians (n = 33) and demographically similar controls who had no known history of exposure to toxic chemicals (n = 35). The groups were administered psychologic, neuropsychologic, and neurosensory tests. Aspects of the workplace environment (e.g., square footage of the salon, adequacy of ventilation, and hours worked) also were assessed. RESULTS: Multivariate analysis of variance (MANOVA) revealed that the nail technicians performed more poorly than did controls on tests of attention and processing speed (p = 0.015; eta(2) = 0.20). Olfaction among the nail technicians was below expected performance based on normative data (p < 0.001). A trend toward poorer performance by the nail technicians was observed on the MANOVA investigating executive functioning; individual tests within that domain may be worthy of future investigation (ps = 0.03-0.10). No significant group differences were observed in the domains of learning and memory, visuospatial ability, or fine motor coordination, or on measures of depression and anxiety. Multiple regression indicated that level of occupational exposure as measured by time worked in the industry, adequacy of ventilation, and workplace size predicted 29% of the variance of performance on attentional tasks (p = 0.04). CONCLUSION: Exposure to low-level neurotoxicants common to nail studios may result in mild cognitive and neurosensory changes similar to those observed among solvent-exposed workers in other settings.

Acrylates↗
PubMed2002

The functional and esthetic deficit replaced with an acrylic resin gingival veneer.

Periodontal attachment loss in the maxillary anterior region can often lead to esthetic and functional clinical problems including disproportional and elongated clinical crowns, visible interdental embrasures, and altered linguoalveolar-labiodental consonant production. Assuming fixed prosthetic reconstructions will be chosen to treat these areas, it becomes a hygienic compromise to fill these areas in with porcelain. In the presence of these problems, an acrylic resin gingival veneer is an easily constructed, inexpensive, and practical device to optimize the esthetic and functional outcome in these special situations while permitting cleansibility of the prosthesis and supporting tissues. This article presents a step-by-step technique for the fabrication of a gingival veneer.

Acrylic Resins↗
PubMed2001

[Total anterior opacification on the anterior surface of hydrophilic acrylic implanted lens].

We report a case of cloudiness occurring on the anterior surface of a hydrophilic acrylic foldable intraocular lens 1 year following implantation. This was not a case of phimosis of the capsulorhexis; the dondiness seemed secondary to fibroepithelial proliferation. Successful reopening was obtained with YAG laser. No recurrence was observed during the six months of follow-up.

Acrylic Resins↗