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PubMed2005

Intralenticular opacification of hydrophilic acrylic intraocular lenses.

PURPOSE: To find out the incidence of intraocular lens (IOL) optic opacification in a suspect IOL. METHODS: Retrospective review of patients' notes 3-4 years postimplant. RESULTS: In all, 56 IOLs showed signs of opacification, resulting in reduced vision out of 181 lenses traced. CONCLUSION: Certain hydrophilic acrylic IOLs like the model in question (SC60B-0UV) show opacification of the IOL, which may impair the vision of pseudophakic patients. However, not all lenses of this variety exhibit this cloudiness. Factors affecting this phenomenon are not yet completely clear but may include changes in the UV absorbant material incorporated in the lens substance itself. We report a series of patients who had received this lens and experienced loss of vision due to opacification of the IOL. In a follow-up ranging from 1 to 4 years postoperatively, a higher incidence of postoperative opacification of this lens emerges, after comparison with existing literature. IOL exchange in such patients is the only option. However, this mode of treatment should not be offered lightly as results may be guarded at best even in the face of a technically satisfactory procedure.

Acrylates↗
PubMed2005

Intraoperative explantation of two single-piece hydrophobic acrylic intraocular lenses due to surface deposits.

PURPOSE: To report clinical, pathological, and laboratory analyses of two cases of single-piece hydrophobic acrylic intraocular lenses (IOLs), which presented with significant surface deposits during implantation. METHODS: The lenses were implanted with the manufacturer's recommended injector (loaded with Viscoat and Healon GV, respectively). Immediately after injection into the anterior chamber, areas on the lenses' surfaces were covered by deposits, which could not be entirely removed by irrigation/aspiration. The lenses were explanted and replaced with lenses of the same design. They underwent gross analyses, light microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy for analysis of the elemental composition of the deposits. Liquid chromatography/mass spectroscopy was also performed to identify the presence of proteins. RESULTS: The deposits on the first lens had a granular appearance, forming a homogeneous layer mostly on the posterior lens surface. Larger crystal-like deposits were present mostly on the anterior surface of the second lens. Elemental analyses of the deposits in both cases revealed the presence of peaks of sodium, chloride, phosphate, and potassium, in addition to the peaks of carbon and oxygen (normal constituents of the lens material). Only protein components normally found in the anterior chamber during surgery, such as haemoglobin and albumin, were identified. CONCLUSIONS: The results obtained suggest that the deposits in both cases may have resulted from crystallization of the ophthalmic viscosurgical device normally used during the loading of the IOLs into the cartridges.

Acrylic Resins↗
PubMed2006

Comparison of posterior capsule opacification between fellow eyes with two types of acrylic intraocular lens.

PURPOSE: To compare the degree of posterior capsule opacification (PCO) and visual function between fellow eyes that received two different types of hydrophobic acrylic intraocular lenses (IOLs). METHODS: Forty-five patients underwent bilateral phacoemulsification and implantation of an Alcon AcrySof IOL (MA60AC) in one eye and an AMO Sensar IOL (AR40e) in the fellow eye. The PCO density value was measured using the Scheimpflug videophotography system at 1, 6, 12, and 24 months after surgery. The incidence of eyes that required a neodymium:YAG (Nd:YAG) laser capsulotomy, visual acuity, and contrast sensitivity with and without a glare source were also examined. RESULTS: The mean PCO value did not show a significant increase in either the AcrySof MA60AC or Sensar AR40e IOL groups, and was similar between the two groups throughout the 24-month follow-up period. The incidence of Nd:YAG laser capsulotomy was also the same between the groups. No significant difference was found in mean visual acuity between the two IOL groups during the follow-up, and there was no significant difference in photopic or mesopic contrast visual acuity with and without a glare source at 1 and 24 months after surgery. CONCLUSION: The degree of PCO in eyes with an AcrySof IOL are almost the same as that in eyes with a Sensar IOL, with the results that visual acuity and contrast sensitivity with and without glare are similar.

Acrylic Resins↗
PubMed2005

Rapid synthesis of quinoline-4-carboxylic acid derivatives from arylimines and 2-substituted acrylates or acrylamides under indium(III) chloride and microwave activations. Scope and limitations of the reaction.

Rapid synthesis of quinoline-4-carboxylic acid derivatives has been achieved by reaction of 2-methoxy acrylates or acrylamides with N-arylbenzaldimines in acetonitrile under InCl3 catalysis and microwave irradiation. Isolated yields up to 57% within 3 min have been obtained. The Lewis acid and the microwave activation appeared as crucial parameters for the reaction. The role of indium chloride and ytterbium triflate was specified using 13C NMR data and model theoretical studies.

Acrylates↗
PubMed1970

Identification of the acrylate porphyrin S-411 from meconium.

A new porphyrin isolated from calf and foal meconium has been characterized as a tris-(2-carboxyethyl)-mono-(2-carboxyvinyl)-tetramethyl porphin, that is as an analogue of coproporphyrin in which one propionate group has been replaced by an acrylate group. The porphyrin is mainly a type III isomer and its possible significance in haem biosynthesis is discussed.

Acrylates↗
PubMed1984

The concentration of the mitochondrial pyruvate carrier in rat liver and heart mitochondria determined with alpha-cyano-beta-(1-phenylindol-3-yl)acrylate.

alpha-Cyano-beta-(1-phenylindol-3-yl)acrylate inhibited pyruvate transport into both liver and heart mitochondria approximately linearly with respect to its concentration until 65% inhibition was achieved. The extent of inhibition was dependent on the mitochondrial protein concentration. By extrapolation of plots of inhibition versus inhibitor concentration to total inhibition, or by mathematical analysis of the plots, the concentration of pyruvate transporter molecules per mg of protein was calculated to be approximately 100 pmol/mg for both heart and liver mitochondria, and the Ki about 7 nM. The data also suggest that pyruvate transport is rate-limiting for pyruvate oxidation by heart mitochondria in State 3, but not by liver mitochondria.

Acrylates↗
PubMed2002

Effects of a modified acrylic bonded rapid maxillary expansion appliance and vertical chin cap on dentofacial structures.

The aim of this study was to determine the sagittal, transverse, and vertical effects of a modified acrylic bonded rapid maxillary expansion (RME) device used with a vertical chin cap on dentofacial structures. The study group consisted of 34 patients (25 girls and 9 boys) who were selected without regard to their skeletal class and gender. All subjects had permanent dentition (mean age, 12.7 years) and needed maxillary expansion. Study Group I (RME only) was composed of 17 subjects, and study Group II (RME with vertical chin cap) was composed of 17 subjects. Twenty-nine measurements were made on the patients' cephalometric films and plaster models. The means and standard deviations for linear and angular cephalometric measurements were analyzed statistically, and intra-group and inter group changes were evaluated by paired and Student's t-tests using SPSS 10.1 for windows. We found that the maxilla moved anteriorly relative to the anterior cranial base. The nasal width, maxillary width, intercanine width, mandibular intermolar width, maxillary intermolar width, and overjet all increased, while the upper molars tipped buccally in both groups. In Group I, the mandible rotated posteriorly, the lower anterior facial height increased, and the overbite decreased. These effects were reduced in Group II. We conclude that the vertical chin cap is an effective appliance for preventing the adverse vertical effects of RME in patients with a crossbite and a vertical growth pattern.

Acrylic Resins↗
PubMed1997

Effect of 4-META adhesive on the bond strength of different metal framework designs and acrylic resins.

The effect of relining the 4-META adhesive resin onto metal alloy of a partial denture framework was tested. Seventy-two metal frameworks with three different retentive patterns were designed. Half of the specimens were treated with 4-META, the other group was left untreated. Thirty-six specimens were first divided into three groups in which 12 samples had different designs of retention, i.e. mesh, ring-shaped and flat plane. Then, each different retentive design was divided into two groups and in one group Lucitone 199 and the other QC acrylic resin were processed. Finally they were subjected to shear test. While samples with adhesive exhibited greater bond strength than the others, samples without adhesive may be ranked in the order mesh, ring-shaped and flat planes with regard to shear bond strength. In samples with adhesive, the flat plane ones displayed better results. Statistically significant differences were observed in the relationships between the groups.

Acrylic Resins↗
PubMed2003

Effects of chemical disinfectants on the transverse strength of denture base acrylic resins.

The disinfection of dental prostheses by immersion in a chemical solution should be capable of rapid inactivation of pathogenic microorganisms, without causing any adverse effect on the denture base resins. This study evaluated the effect of disinfection immersion on the transverse strength of two heat-cured resins. The denture base resins (Lucitone 550 and QC 20) were polymerized according to the manufacturers' instructions. After polymerization, the specimens were polished, and then stored in water at 37 degrees C for 50 +/- 2 h prior immersion in one of the following solutions for 10 min: 4% chlorhexidine, 1% sodium hypochlorite and 3.78% sodium perborate. The specimens were submitted to disinfection twice, simulating when dentures come from the patient and before being returned to the patient. Ten specimens were made for each group. The transverse strength was evaluated by a 3-point bend test. The flexural strength of the two denture base acrylic resins evaluated remained unaffected after immersion in the three solutions evaluated. In general, the QC 20 resin specimens exhibited lower transverse strength than the Lucitone 550 resin specimens, regardless of immersion solutions.

Acrylic Resins↗
PubMed1999

A new, semi-automated technique for quantification of Candida adherence to denture acrylic surfaces.

Adherence of Candida species to various host surfaces is an important prerequisite for colonization and pathogenesis. Researchers have problems in quantifying candidal adherence to plastic surfaces (used for fabrication of prostheses) due to coaggregation of adherent yeasts and to the laborious, time-consuming method of microscopic quantification. We describe here, a semi-automated image analysis system which is superior to conventional visual light microscopic techniques of quantifying yeasts attached to solid substrates such as acrylic. The results demonstrated a significant positive correlation between the number of cells quantified by traditional light microscopy and the corresponding area obtained by the semi-automated image analysis system (r = 0.83, P < 0.02). The new system is simple, less laborious and is particularly useful when the adherent attributes of a large battery of yeasts are characterized.

Acrylic Resins↗
PubMed2002

The in vitro elution characteristics of vancomycin combined with imipenem-cilastatin in acrylic bone-cements: a pharmacokinetic study.

The aim of this in vitro study was to compare the elution characteristics of vancomycin alone and in combination with imipenem-cilastatin from 3 acrylic bone-cements (CMW1 [DePuy International, Blackpool, UK], Palacos R [Schering-Plough, Wehrheim, Germany], and Simplex P [Howmedica International, London, UK]). Six groups of 3 antibiotic-loaded cement disks were prepared, incorporating 2 g of vancomycin (3 groups) and 2 g of vancomycin plus 2 g of imipenem-cilastatin (3 groups). The disks were placed in saline baths for 5 weeks, with the baths being sampled periodically and the elution rates calculated. The total amount of vancomycin released by the cements treated with vancomycin alone was 7.98 mg for CMW1, 7.74 mg for Palacos R, and 6.76 mg for Simplex P; with the addition of imipenem-cilastatin, the total amount of vancomycin released by the 3 cements increased by 30.58%, 50.52%, and 50.15%. CMW1 had better elution characteristics than the other cements when treated with vancomycin alone; the elution of Palacos R and Simplex P was better than that of CMW1 when vancomycin was combined with imipenem-cilastatin.

Acrylic Resins↗
PubMed1976

[Evaluation of experimental arterial occlusion, with special reference to its complications (micro-spheres, Histo-Acryl, Paladur, alternating and direct currents (author's transl)].

Permanent arterial occlusion can be obtained experimentally by using plastic micro-spheres, polymerising materials (Histo-Acryl, Paladur) and direct current thrombosis. Certain limitations in their use arise from the properties of the substances. In our experience, plastic microspheres are not suitable for blocking entire organs or large vascular territories. They are more appropriate for occlusion of individual, small vessels by super-selective injections. Sole use of polymerising materials is not possible; they are best used in combination with other techniques (magnets, balloon catheters). Induction of thrombosis by small direct currents (50 volt, 10 mA). produces permanent and complete occlusion. The method can be used selectively or super-selectively. Unwanted thrombosis can be avoided by using catheters with the smallest possible external diameters.

Acrylic Resins↗
PubMed2003

[Evaluation of posterior capsule opacification after implantation of the Akreos Disc and Akreos Fit acrylic intraocular lenses - pilot studies].

In the course of the past few years the incidence of secondary cataract has reduced continually due to advanced surgical technique and better lens material and design. To evaluate the progression of posterior capsule opacification (PCO) and IOL-decentration after implantation of two hydrophilic acrylic intraocular lenses (IOL) we set up two pilot studies at two different ophthalmological surgical centres. After extracapsular cataract extraction 15 patients got the Akreos Disc-IOL (Bausch and Lomb) and 12 patients the Akreos Fit-IOL (Bausch and Lomb) implanted. Examinations were done over a period of 12 months. The protocol included the determination of visual acuity, an examination of the anterior segment, evaluation of IOL-decentration and the scoring of PCO with EPCO 2000 by digital photography of the posterior capsule. All patients showed a well centred IOL and stable visual acuity over 12 months. None had to undergo Nd:YAG-capsulotomy. PCO was low and only slightly progressive over the time period.

Acrylates↗
PubMed1987

Early posterior acrylic fixation of traumatic odontoid fractures.

Nine cases of traumatic odontoid fractures had, as a primary treatment, a posterior surgical fixation (C1 + C2 + C3) by means of acrylate, without waiting for the unpredictable results of external systems of immobilisation. No immediate or late (follow-up: six months to seven yrs) neurological complications occurred. Solid union took place in all the cases but one. Two cases of wound infection were recorded. All the patients were actively mobilised on the second postoperative day without external immobilisation.

Acrylates↗
PubMed2000

Prefabricated acrylic resin bars for splinting implant transfer copings.

Splinting of implant transfer copings with acrylic resin during impression procedures is performed to accurately transfer the spatial relationships of implants to the master cast. However, distortion may occur during the splinting procedure because of resin polymerization shrinkage. This article describes a simple technique for minimizing this effect by fabrication of resin bars.

Acrylic Resins↗
PubMed2002

Effect of a new tension system, used in acrylic resin flasking, on the dimensional stability of denture bases.

STATEMENT OF PROBLEM: The pressure of final closure may be released when the flask is removed from the mechanical or pneumatic press and placed in the spring clamp. This release in pressure may result in dimensional changes that distort the denture base. PURPOSE: The purpose of this study was to investigate differences between the dimensional stability of standardized simulated denture bases processed by traditional moist heat-polymerization and those processed by use of a new tension system. MATERIAL AND METHODS: A metal master die was fabricated to simulate an edentulous maxillary arch without irregularities in the alveolar ridge walls. A silicone mold of this metallic die was prepared, and 40 stone casts were formed from the mold with type III dental stone. The casts were randomly assigned to 4 test groups (A-D) of 10 specimens each. A uniform denture base pattern was made on each stone cast with a 1.5-mm thickness of base-plate wax, measured with a caliper. The patterns were invested for traditional hot water processing. A polymethyl methacrylate dough was prepared and packed for processing. The flasks in groups A and B were closed with the traditional pressure technique and placed in spring clamps after final closure. The flasks in groups C and D were pressed between the metallic plates of the new tension system after the final closure. The group A and C flasks were immediately immersed in the water processing unit at room temperature (25 degrees +/- 2 degrees C). The unit was programmed to raise the temperature to 74 degrees C over 1 hour, and then maintained the temperature at 74 degrees C for 8 hours. The group B and D flasks were bench stored at room temperature (25 degrees +/- 2 degrees C) for 6 hours and were then subjected to the same moist heat polymerization conditions as groups A and C. All processed dentures were bench cooled for 3 hours. After recovery from the flasks, the base-cast sets were transversally sectioned into 3 parts (corresponding to 3 zones): (1) distal of the canines, (2) mesial of the first molars, and (3) mesial of the posterior palate). These areas had been previously established and standardized by use of a pattern denture in the sawing device to determine the sections in each base-cast set. Base-cast gaps were measured at 5 predetermined points on each section with an optical micrometer that had a tolerance of 0.001 mm. Collected data were analyzed with analysis of variance and Tukey's test. RESULTS: Denture bases processed with the new tension system exhibited significantly better base adaptation than those processed with traditional acrylic resin packing. Immediately after polymerization (Groups A and C), mean dimensional change values were 0.213 +/- 0.055 mm for the traditional packing technique and 0.173 +/- 0.050 mm for new tension system. After delayed polymerization (Groups B and D), the values were 0.216 +/- 0.074 mm for the traditional packing technique and 0.164 +/- 0.032 mm for new tension system. With both techniques, dimensional changes in the posterior palatal zone were greater (conventional = 0.286 +/- 0.038 mm; new system = 0.214 +/- 0.024 mm) than those elsewhere on the base-cast set. CONCLUSION: Within the limitations of this study, the new tension packing system was associated with decreased dimensional changes in the simulated maxillary denture bases processed with heat-polymerization.

Acrylic Resins↗