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PubMed1982

The development and in vitro evaluation of acrylic strips and dialysis tubing for local drug delivery.

This study reports on the development of drug containing acrylic strips for delivering antimicrobial agents and compares the in vitro release pattern with dialysis tubing. Polyethylmethacrylic strips of suitable dimensions containing 10 to 50% chlorhexidine acetate, 40% metronidazole and 40% tetracycline were prepared. Daily release of the incorporated drugs into 1 ml aliquots was measured spectrophotometrically over a 14 day period. Similarly the release of chlorhexidine gluconate from various lengths of patent and heat sealed dialysis tubing was recorded for 4 days. At 30%, 40% and 50% admixtures the acrylic strips released chlorhexidine up to the 14 day period and a parallel bioassay confirmed the maintenance of antibacterial activity to this time. At the same admixture the release of metronidazole was greater than chlorhexidine and tetracycline. All drugs were released at high levels on day 1 followed by a marked fall in release by day 2 and progressive fall thereafter. The release from tubing was almost total within 24 hours and was independent of sealing the ends. The strips appear to have potential for prolonged drug delivery to periodontal pockets. Preliminary clinical use revealed no patient acceptability problems and alterations in subgingival flora were produced.

Chlorhexidine↗
PubMed2002

Characterization of oligomeric polypropyleneglycol acrylate by GC, SFC and MALDI-TOF-MS.

Polypropyleneglycol acrylate (PGA), one of the typical acrylic oligomers manufactured industrially, was comprehensively characterized by gas chromatography (GC), supercritical fluid chromatography (SFC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The homologous series of polypropyleneglycol diacrylate (DA), polypropyleneglycol monoacrylate (MA), and unreacted polypropyleneglycol (PG) were observed as Na adducts in the MALDI-MS spectra of the PGA samples. The relative intensities of these peaks reflect the distributions of the homologues, although their accurate quantification was generally difficult because of change in the ionization efficiency depending on the chemical structure and the molecular weight of the species. On the other hand, the DA and the MA homologues were observed in the chromatograms obtained by SFC in a temperature-programming mode, while the PG homologues were not detected under the given SFC conditions using UV detection. Here, the determination of the degree of polymerization of each component in the chromatograms was accomplished through SFC fractionation for the corresponding peaks, followed again by MALDI-TOF-MS measurement. Furthermore, most of the components in the PGA samples were almost completely separated in the resulting gas chromatograms, and their unequivocal assignments were made also using the retention data on the gas chromatograms of the SFC fractions. As for the quantitative analysis, the relative abundances among DA, MA and PG for lower degrees of polymerization can be easily calculated based on the observed gas chromatograms, whereas the distribution of DA and MA can be estimated from the observed SFC data even for the relatively higher molecular weight fractions, which are generally difficult to determine accurately by GC because of their lower volatility. These results demonstrated that even the complex PGA samples were able to be characterized in detail by using GC, SFC and MALDI-TOF-MS complementarily.

Journal Article↗
PubMedDate not supplied

Thermal effects of acrylic cementation at bone tumour sites.

The use of acrylic bone cement as an adjunct to surgical excision of giant cell tumour of bone appears to reduce the incidence of tumour recurrence. Possible mechanisms for this apparent tumour inhibition include cytotoxic effects from the methylmethacrylate monomer and tissue hyperthermia from the heat of polymerization of the cement. This work presents a method for the prediction of temperature fields and resulting tissue necrosis arising from the implantation of polymethylmethacrylate (PMMA) at the site of a curretted giant cell tumour of bone. This is accomplished using a two-dimensional model based on geometry obtained from digitized MRI images of the distal femur. A general-coordinate, non-orthogonal grid generation technique is used and solutions are obtained with an alternating-direction implicit (ADI) finite-difference scheme. The nodal temperature histories are then used to evaluate the effect of variable defect size on the zone of thermally induced cell necrosis. The results suggest the depth of the necrotic region is quite sensitive to the size of the implant. In at least some cases, the heating effect is sufficient to cause significant necrosis of tumorigenic cells. Implanting a large mass of acrylic may risk overkill, damaging substantial amounts of healthy tissue.

Bone Cements↗
PubMed1975

The influence of acrylic cement on the femur of the dog. A histological study.

Using dogs as experimental animals, polymerizing methylmethacrylate was inserted into the marrow cavity of the femur. The influence on bone over a period of 21 months was studied by means of histological techniques and microradiography. To distinguish the effect of the methacrylate proper from the circulatory disturbance resulting from the operation, control experiments were performed in which the marrow cavity was emptied, but no acrylic cement was inserted. Polymerization of the methacrylate in vivo resulted in a local rise in temperature to about 58 degrees C. In the femurs containing the acrylic cement a consistent picture developed, consisting of: a) necrosis and removal of the central part of the cortex and b) apposition of a thick layer of bone on the outer surface of the cortex, c) deposition of a cylindrical bone sleeve in contact with the methacrylate. In the control experiments only a minimal resorption at the inside surface of the cortex and the deposition of a thin layer of bone at the outside of the cortex were observed. It is concluded inter al. that circulatory distrubance contributes only slightly to the total reaction of bone to the insertion of methacrylate.

Animals↗
PubMed1992

Hyperthermia during occipito-cervical fusion with acrylic cement. Epidural thermometry in 23 cases.

In 22 patients, 23 posterior occipito-cervical fusions using acrylic cement were studied; 18 had seropositive rheumatoid arthritis and 4 traumatic atlanto-axial instability. The mean age was 60 (39-75) years. During the curing of the cement, epidural temperature measurements were performed over the cerebellum and between the foramen magnum and C1. Temperatures up to 69 degrees C were recorded. Cooling with profuse surface irrigation using normal saline solution or precooled 8 degrees C fluid did not influence the maximal temperatures recorded under the cement. Even though no gross neurological damage was noted, the epidural temperatures in occipito-cervical fusion with acrylic cement can be of sufficient degree to be hazardous; surface irrigation does not seem to be an effective way to reduce this risk.

Adult↗
PubMed2006

Optical quality measurements of hydrophobic acrylic intraocular lenses.

PURPOSE: To compare the optical quality of several models of hydrophobic acrylic intraocular lenses (IOLs). METHODS: Modulation transfer function (MTF) measurements were performed using a model eye system on four models of hydrophobic acrylic IOLs. Models tested were the AcrySof SA60AT, MA60AC, and MA60BM (Alcon, Ft Worth, Tex), as well as the model VA-60BB (Hoya, Tokyo, Japan). For benchmarking, the Alcon model MZ60BD polymethylmethacrylate (PMMA) lens was also measured. Three lenses of each model were tested at frequencies of 50 and 100 line pairs (lp)/mm (corresponding to 20/40 and 20/20, respectively). RESULTS: With a 3-mm aperture, the Alcon AcrySof models had mean MTF values ranging from 58.5% to 60.3% at 100 lp/mm and 78.0% to 79.7% at 50 lp/mm. The Hoya model VA-60BB provided statistically significantly lower (P<.05) MTF values than the Alcon AcrySof models at both frequencies (47.3 +/- 1.2% at 100 lp/mm and 71.8 +/- 1.9% at 50 lp/mm). With a 5-mm aperture, the Alcon AcrySof models had MTF values ranging from 32.9% to 34.3% at 100 lp/mm and 45.2% to 46.7% at 50 lp/mm. Under these larger aperture conditions, the Hoya model VA-60BB also had statistically significantly lower MTF values (20.9 +/- 0.8% at 100 lp/mm and 27.2 +/- 1.1% at 50 lp/mm). Under both apertures and frequencies, the Alcon PMMA lens had statistically significantly higher MTF values than the Hoya lens and statistically significant lower MTF values than all AcrySof models. CONCLUSIONS: Using both 3- and 5-mm aperture settings as well as frequencies corresponding to 20/20 and 20/40 vision, statistically significantly higher MTF values were obtained for AcrySof lenses, which were greater than the PMMA lens, which were greater than the Hoya model VA-60BB. The differences in MTF values between lens models are more exaggerated with a 5-mm aperture and may highlight differences in lens manufacturing processes.

Humans↗
PubMed2006

Phacoemulsification and acryl foldable intraocular lens implantation in dogs: 32 cases.

This study evaluated the surgical outcome and complications of phacoemulsification and the implantation of an acryl foldable intraocular lens (IOL) with a squared edge in dogs with cataracts. Thirty-two eyes from 26 dogs were examined. The mean follow up period was 75.9 days ranging from 23 to 226 days. The complications after phacoemulsification were posterior capsular opacity (PCO) around the IOL (n = 11), ocular hypertension (n = 4), focal posterior synechia (n = 4), hyphema (n = 3) and corneal ulcer (n = 2). The complications associated with the IOL were decenteration of the optic (n = 2) and ventral haptic displacement (n = 1). Most cases of PCO were found only around the margin of the IOL, and all eyes had vision during the observation period. In conclusion, the implantation of an acryl-foldable lens with a squared edge at the time of phacoemulsification is an effective method for preserving the central visual field of dogs with cataract.

Animals↗
PubMed2000

Stereospecific polymerization of alpha-(menthoxymethyl)acrylate

Novel alpha-(alkoxymethyl)acrylates bearing a chiral substituent, racemic and optically active benzyl alpha-(menthoxymethyl)acrylates ((+)- and (-)-BMnMA), were synthesized and polymerized by radical and anionic methods. The effects of the chiral substituent on the stereoregularity and chiroptical property of the obtained polymers were investigated. 13CNMR spectra of the polymers obtained by anionic polymerization of the racemic monomer showed sharper peaks than that of the radically obtained polymers, indicating that the former polymers possessed higher stereoregularity than the radically obtained polymers. The polymers prepared from optically pure (-)-monomer with anionic initiators had low solubility in common organic solvents. However, the THF-soluble parts were highly isotactic, and exhibited lower specific rotation ([alpha]25(365) = -92 degrees) than those of the monomer ([alpha]25(365) = -226 degrees) and the radically obtained polymer ([alpha]25(365) = -201 degrees). The circular dichroism (CD) spectra of the copolymers prepared from a (+)- and (-)-monomer mixture with various optical purity suggested that the highly isotactic (-)-polymer may possess a chiral helical conformation.

Journal Article↗
PubMed2000

[Assessment of nitric oxide level in aqueous humor under physiological conditions and after lens extraction and artificial foldable acrylic lens implantation during experimental work in rabbits].

PURPOSE: To evaluate the presence of nitric oxide (NO) and its level in the aqueous humor of rabbit's eye physiological conditions and after phacoemulsification and acrylic foldable artificial lens implantation. We also investigated nitric oxide maintenance during early postoperative period (between 1-5 days after surgery). MATERIAL AND METHODS: We examined 30 rabbits (weighing 3.0-3.5 kg) Just before surgery samples of aqueous humor were aspirated. Lens was extracted with phacoemulsification technique. In 15 eyes acrylic foldable IOL (group III) was implanted and 15 eyes were left aphakic (group IV). The aqueous samples were collected on 1, 3, 5 days after surgery. Nitric oxide in each sample was determined with fluorometric assay. RESULTS: The level of NO in aqueous humor in physiological conditions was estimated to 26.52 nM/dl. After phacoemulsification in both groups the level of nitric oxide was higher than in control group. The day and value of the highest NO level was different among examined groups. The highest level of NO was released during 1st day in group III and on the 3rd day in the group IV. CONCLUSION: We came to conclusion that the level of nitric oxide in aqueous humor after phacoemulsification in both groups is higher than in control group but significantly lower than in previously examined groups in which the surgery was made with extracapsular technique.

Animals↗
PubMed2001

[Comparison of preoperative target ametropia and postoperative refraction for three types of lenses and intra-ocular differences (one pliable acrylic, one pliable PMMA-copolymer and one non-pliable PMMA) ].

In this retrospective study we compared the preoperative target ametropia, calculated with the SRK-T formula, with the postoperative refraction after extracapsular extraction by phacoemulsification and implantation of different posterior chamber lenses. The results show, for all 3 types of lenses, a postoperative refraction stability after the first month. According to our criteria, after 6 month, we have respectively for the non foldable PMMA lens, the PMMA-copolymere foldable and the acrylic foldable lens: 78%, 72% and 78% of good results; 13%, 28% and 9% of mild results and 9%, 0% and 13% of bad results. According to our criteria, the acrylic foldable lens has a tendency to move slightly backwards and the foldable PMMA-copolymere lens to move slightly frontwards. The non foldable lens gives pretty good results, however it is difficult to compare this lens with the 2 other lenses because of the large size of the incision.

Cataract↗
PubMedDate not supplied

Neuropsychological symptoms associated with low-level exposure to solvents and (meth)acrylates among nail technicians.

OBJECTIVE: To evaluate reports of neuropsychological symptoms among women occupationally exposed to products commonly used in nail studios. BACKGROUND: Typical preparations found in nail studios contain a variety of organic solvents (e.g., toluene, acetone, formaldehyde) and (meth)acrylates with known neurotoxic properties. Little research has focused on the neuropsychological sequelae of exposure to these substances occurring in the cosmetics industry. METHOD: Participants included nail salon technicians (n = 150) and controls (n = 148). Nail technicians were compared with demographically similar controls using the Neuropsychological Impairment Scale, a self-reported measure of neuropsychological and psychological symptoms. Aspects of the workplace environment (e.g., square footage of the salon, adequacy of ventilation, hours worked) also were assessed. RESULTS: A MANOVA revealed small but significant differences in the overall level of symptoms as well as in individual scales measuring neurologic complaints, cognitive efficiency, memory, verbal learning, and academic skills (p < 0.001). Moreover, nail technicians were significantly more likely to score above the clinical cutoffs than were controls on four of the seven clinical scales and two of the three summary indices. Multiple regression analysis indicated that the severity of symptoms was associated with level of occupational exposure (p < 0.01). The cumulative impact of workplace size and ventilation were most strongly associated with symptom severity. CONCLUSIONS: Exposure to low-level neurotoxins common to nail studios results in the self-reported experience of cognitive and neurologic symptoms similar to other types of solvent and (meth)acrylate exposure. The profile of reported symptoms is consistent with deficits typically observed in this type of neurotoxic exposure: neurologic complaints as well as perceived problems with cognitive efficiency, memory, and learning. Additionally, the nail technicians reported a higher overall level of complaints and greater severity of symptoms than did the controls.

Adolescent↗
PubMedDate not supplied

In vivo registration of force development with ceramic and acrylic resin occlusal materials on implant-supported prostheses.

PURPOSE: It has been hypothesized that the shock generation on implant-supported prostheses during chewing should generate higher implant loads if the veneering material is porcelain rather than acrylic resin. MATERIALS AND METHODS: The present study uses strain-gauged abutments to measure the force transferred to the implant after a shock has been applied. This was measured in vitro and in vivo in 5 patients. RESULTS: The different occlusal materials did not lead to different forces generated to the implants of the patients. DISCUSSION: From a practical point of view, the choice of occlusal material has no bearing per se on force generation to the implants. CONCLUSIONS: The present study demonstrated that there: (a) is a difference in resilience between acrylic resin and ceramic veneering materials, but (b) this difference is only measurable in in vitro where the force is generated by a shock only and the implant is rigidly anchored.

Adult↗
PubMed2002

Thoracoplasty with acrylic plate-marlex mesh combination following near total resection of sternum: a case of chondrosarcoma of sternum.

Removal of the whole sternum for malignant tumours results in a large defect, causing severe deformity and possible paradoxical movements of the chest wall. The reconstruction of the resultant large defect of the chest wall is often complex and difficult. Commonly used materials include rib autograft, steel strus acrylic plate and various synthetic meshes such as Goretex or Marlex mesh, with a myocutaneous flap for coverage. A case of a 48-year-old man with sternal chondrosarcoma successfully treated with thoracoplasty using acrylic plate-marlex mesh combination following near total resection of sternum is reported.

Bone Cements↗
PubMed1999

Temporomandibular Joint Arthroplasty Using Metal-on-Metal and Acrylic-on-Metal Configurations : Wear In Laboratory Tests and In Retrievals.

In the long-term performance ofthe temporomaridibular joint (TMJ) implant, wear must be considered. Thus retrieved and laboratory test implants were examined both optically and in a scanning electron microscope (SEM). In laboratory testing, the volumetric wear of metal-on-metal was about an order of magnitude less than that of acrylic-on-metal TMJ implants. This metal-on-metal wear was also about half of that reported in the literature for a laboratory test of polyethylene-on-metal TMJ implants, The retrieved TMJ implants showed some abrasive wear occurred during multi-directional articulation with smaller wear zones for the metal-on-metal compared to the acrylic-on-metal configuration. Further efforts to characterize and minimize wear were recommended as prudent in the continuing development of TMJ arthroplasty.

Journal Article↗
PubMed1992

[UV cured acrylates--potent contact allergens in the occupational environment].

Allergic contact dermatitis is still an important disease in occupational medicine. Acrylic compounds are known to be potent contact sensitizers causing allergic eczema after occupational exposure. To illustrate the problem and the need for preventive arrangements the authors present an unusual clustering of allergic contact dermatitis in three technicians who produced hearing aids using ultraviolet cured akrylate compounds. All three technicians developed eczema on their fingers few months after introduction of the new acrylate compounds in the production. Skin patch testing with the products confirmed that sensitization.

Adult↗
PubMed2003

Mechanism for degradation of poly(sodium acrylate) by bacterial consortium no. L7-98.

Poly(sodium acrylate) (PSA) can be degraded by consortia of several bacterial species. We investigated the degradation mechanism for PSA (average molecular weight, 2100) by consortium no. L7-98. PSA was used as the sole carbon source in a mineral salt medium. After cultivation, the PSA had a range of molecular weights, including low-molecular-weight compounds, which were purified by gel-permeation and reversed-phase column chromatography. One purified compound, B1, with the molecular weight of 200, had a carbonyl group next to the terminus, according to 1H and 13C nuclear magnetic resonance spectrometry and X-ray analysis of the crystal structure. Two categories of metabolites of PSA were detected in the culture by electrospray ionization mass spectrometry. Results of high-resolution mass spectrometry (HR-MS) suggested that one kind of compounds had a carbonyl group and that the other kind of compounds had an aldehyde group and a double bond. Compounds having the molecular weights of 200 and 272 were rapidly produced from an acrylic acid oligomer with the molecular weight of 258 by resting cells of the consortium. HR-MS showed that a methylene group at the terminal unit was oxidized to a carbonyl group and that the compound with the molecular weight of 200 was compound B1. From these results, we propose that the degradation pathway of PSA involves (i) oxidation of a methylene group to a carbonyl group next to the terminus, (ii) decarboxylation to form an aldehyde group and dehydrogenation to form a double bond between the terminal unit and the next unit, and (iii) oxidation of the aldehyde group to a carboxyl group followed by elimination of an acetic acid.

Journal Article↗
PubMed1999

Swelling behaviour of pH-sensitive crosslinked poly(vinyl acetate co-acrylic acid) hydrogels for site specific drug delivery.

The present work was undertaken to combine nonionic vinyl acetate (VAC) with anionic acrylic acid (AA) or methacrylic acid (MAA) monomers in the presence of ethylen glycol dimethacrylate (EGDMA) as cross-linking agent through radical polymerization. Poly(vinyl acetate-co-acrylic acid) VAC/AA 50:50 to 100:0 six samples and poly(vinyl acetate-co-methacrylic acid) VAC/MAA one sample were prepared. All the samples were used for swelling studies. High swelling occurred at above pH 5.5 through chain relaxation. It was observed that swelling in VAC/MAA was lower than VAC/AA copolymers. The lower swelling in VAC/MAA copolymer is due to the presence of hydrophobic methyl group and higher pKa value of this copolymer.

Journal Article↗
PubMedDate not supplied

Acrylic artificial fingernail embedded in the palate of an 11-month-old: a case report.

Foreign bodies found embedded in the oral cavity have been reported in the literature. The purpose of this case report was to document embedding of an acrylic artificial fingernail in the palate of an 11-month-old. As the use of artificial acrylic nails increases, this case report is also meant to alert oral health professionals as to what may become a more common occurrence.

Female↗