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PubMedDate not supplied

[Effect of acrylates on the level and isozyme composition of cytochrome P-450 in rat liver microsomes].

Content of cytochrome P-450 was decreased in rat liver microsomes, pretreated with phenobarbital, after incubation with acrylamide, methyl methacrylate and butyl methacrylate in presence of NADPH in vitro. The phenomenon was not observed in the analogous experiments but carried out without NADPH, thus suggesting the microsomal metabolism of the acrylates. At the same time, after intraperitoneal administration of acrylamide 0.4 mmole/kg, methyl methacrylate 6.0 mmole/kg and butyl methacrylate 9.0 mmole/kg within 3 days into intact and protected with phenobarbital rats alterations in total content of cytochrome P-450 were not observed. All the acrylates studied exhibited the slight inducing effect on cytochrome P-450b but did not affect the cytochrome P-450c. Methyl- and butyl methacrylates decreased distinctly the content of cytochrome P-450 isoenzyme with molecular mass of 48,000 daltons.

Acrylates↗
PubMed1986

[Reconstruction methods of anterior chest wall resection--comparison between acrylic resins and myocutaneous flaps].

A total of 32 patients were treated by chest wall resection for primary and recurrent breast cancer or other malignant tumors of the chest wall. Reconstruction of the anterior chest wall was conducted using either acrylic resin plate or myocutaneous flap. Although acrylic resin plate proved to be satisfactory for maintaining stability of the chest wall and protecting important organs in the anterior mediastinum, some patients developed foreign body reactions including local infections, local retention of serous discharge and slight anterior chest pain during a prolonged observation. Reconstruction with myocutaneous flap achieved acceptable stability and caused no such foreign body reactions. We confirmed that myocutaneous flap was the best way to reconstruct the anterior chest wall after full thickness chest wall resection.

Acrylic Resins↗
PubMed1986

[Azoles. 17. Beta-(4-pyrazol)acrylic and propionic acids and their anti-inflammatory activity].

beta-(4-Pyrazole)acrylic acids 22-28 were prepared by the Knoevenagel reaction of malonic acid and 4-formylpyrazoles 8-14. 4-Pyrazolemethylenemalonic acids 15-21 were isolated as intermediates. The latter compounds were also synthesized by treating the 4-formylpyrazoles 8-14 with diethyl malonate followed by hydrolysis of the obtained diethyl esters 15a-21a. The effect of piperidine and pyridine on the Knoevenagel condensation was investigated. The beta-(4-pyrazole)acrylic acids 22-27, on catalytic reduction, gave the corresponding beta-(4-pyrazole)propionic acids 29-34. Compounds 23, 24, 27, 29-31 and 34 appeared to be less active than phenylbutazone in carrageenin-induced oedema test, but they were less toxic than the reference drug.

Acrylates↗
PubMed1985

The development and clinical use of acrylic strips containing anti-microbial agents in the management of chronic periodontitis.

Several methods have been used to deliver antimicrobial drugs into periodontal pockets. This study was concerned with the development of acrylic in strip form for such an application. Initially the release of chlorhexidine acetate from cold cured acrylic strips into water, was measured spectrophotometrically over a 15 day period. The release of chlorhexidine was highest on day 1, was reduced considerably by day 2 and then fell progressively to day 15. With the exception of the release on day 1 there was little difference in daily release from drug admixtures between 40 to 80 per cent. Comparison of the release of chlorhexidine, metronidazole and tetracycline demonstrated a similar release pattern for metronidazole and chlorhexidine but the daily release of tetracycline was considerably less. A bioassay indicated that all drugs were released in active form. In a clinical study chlorhexidine, tetracycline and metronidazole rods were placed in periodontal pockets for 2-3 days and the effects monitored by dark field microscopy. All drugs produced a proportional increase in cocci and marked reductions in other organisms, notably the curved and motile rods and spirochaetes. The effects of metronidazole and tetracycline were greater than those of chlorhexidine. A second clinical study compared the effects of metronidazole and tetracycline strips placed for 2 weeks. Clinically, both treatment methods had immediate effects upon pocketing, bleeding on probing and crevicular flow, which for metronidazole were maintained to the 3-month follow-up period. For tetracycline, the bleeding and crevicular flow were significantly reduced and maintained to the 3-month period but the initial pocket reduction returned to baseline levels by 3 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗
PubMed1986

Bony ankylosis of the temporomandibular joint: follow-up of 70 patients treated with arthroplasty and acrylic spacer interposition.

This paper presents the author's experience with interpositional arthroplasty using an acrylic cylinder in 70 cases of bony ankylosis of the temporomandibular joint. Ankylosis followed trauma in all but one patient. The diagnosis was established when restriction of mouth opening was associated with roentgenologic evidence of deformation of the condyle, obliteration of the joint space, and abnormal bone formation in and around the joint. The pathologic changes were classified into four types depending on severity, and each type influenced the treatment. Surgical treatment included creation of a transversely elliptical gap between the two bony components of the joint using a neurosurgical burr and perforator and a chisel through a preauricular approach and interposition of an acrylic cylinder. This maintained the gap, facilitated movement, and encouraged nonunion. The results following a long follow-up of 2 to 10 years showed uniformly good results with a range of mouth opening varying from 2 to 5 cm. Only three bilateral cases recurred and two others had a limited range of mouth opening, with interincisor distance varying from 2 to 2.5 cm.

Acrylic Resins↗
PubMed1979

The influence of 5-nitro-2-furyl acrylic acid on human fibroblasts cultivated in vitro.

The authors studied the in vitro effects of 5-nitro-2-furyl acrylic acid on growth activity of EUE human fibroblasts. They investigated the course and intensity of macromolecular syntheses, mainly DNA synthesis in these cells. Going by the results obtained it can be concluded that the cytotoxic effects of 5-nitro-2-furyl acrylic acid are also connected with its genotoxic effects, since that substance will induce damage to DNA in human cells.

Acrylates↗
PubMed1984

[Experimental study of acrylic resin coated gentamicin tablets for local antibiotic therapy].

Gentamicin tablets were prepared and evaluated for local antibiotic therapy. Two types of tablet were used. One, a slow release tablet, was coated with acrylic resin (Eudragit R.S.) and another was non-coated. The release of gentamicin from the coated tablets can be controlled by changing the thickness of the film coating. The thickness of the film coating was adjusted to release gentamicin within three weeks when placed in Ringer's solution. Coated tablets were inserted into the bone marrow of rabbits. Thereafter, daily excretion of gentamicin was measured in the urine for three weeks. Constant excretion of gentamicin was seen for ten to fourteen days, which suggests the release of gentamicin from the bone marrow. Plasma concentrations were very low, thus precluding side effects. Non-coated tablets were inserted to the bone marrow by the same method as above. Plasma concentrations of gentamicin peaked in one hour and then rapidly decreased. This pattern is similar to that seen with intramuscular administration. As acrylic resin was non-absorbable material in vivo, the tissue reactions around coated tablets were examined. Histological findings at three weeks, six weeks and six months after insertion, respectively, did not show any severe tissue reactions. The possible use of local therapy by coated antibiotic tablets for bone infections is discussed.

Acrylic Resins↗
PubMed1980

[Muscle relaxants / 3rd communication: Development of acrylic acid derivatives of potential muscle relaxing activity (author's transl)].

With reference to the occurrence of C=C partial structures and alkyl carboxylate groupings in muscle relaxants, the synthesis of acrylic acid derivatives by the aminomethinylation procedure has been followed up. From the reaction of s-triazine (1) with methyl acetoacetate (2a) and piperidine (5a), methyl 2-acetyl-3-piperidino acrylate (6a) arises. Analogously, 3-pyrrolidinoacrylophenone (6b) and 3-morpholinoacrylophenone (6c) are formed. In the same manner, the three-component reaction comprising the interaction of 1 with malononitrile (7) and a secondary amine (5) gives rise to the formation of the aminomethylenemalononitrile structure 8.

Acrylates↗
PubMed1978

Experimental scleral buckling with a soft xerogel implant. I. Properties of poly(hydroxyethyl acrylate) compared with gelatin and other swelling implants.

Scleral buckling can be obtained with insoluble hydrophilic polymers that are implanted in the dry state (xerogels, which then expand to a predetermined size by imbibing tissue fluids. Absorbable gelatin, nonabsorbable poly(hydroxyethyl methacrylate) (PHEMA), and poly(glyceryl methacrylate) (PGMA), have been implanted as xerogels in scleral buckling procedures. Gelatin, PHEMA, and PGMA are soft when hydrated, but are hard and brittle in the dehydrated state. However, poly(hydroxyethyl acrylate) (PHEA) is soft not only in the dehydrated state. However, poly(hydroxyethyl acrylate) (PHEA) is soft only when hydrated but also when dehydrated. Dry PHEA can be carved easily to shape and size, and because it is soft it could be very useful for operations on thin, weakened sclera. We have implanted PHEA intrasclerally and suprasclerally in rabbit eyes. Tolerance of PHEA appears to be as good as that of other materials in clinical use. We have impregnated PHEA and gelatin implants with antibiotics to achieve prolonged antibiotic delivery to the surgical site. When dried impregnated gels were assayed for antibiotic activity in agar plates with Sarcina lutea, both gels displayed high but rapidly decreasing activity.

Acrylic Resins↗
PubMed1995

[The evaluation of acrylic resins for the study of nondecalcified human teeth with the light and electronic microscopes].

Resin embedding of human teeth for light and transmission electron microscopic studies becomes difficult without previous decalcification. The limited and slow infiltration of the resin into hard tissues may cause problems during preparation and observation of the samples. Moreover the type of resin that is used may affect the morphologic preservation of both tissues and cellular elements. Recently there has been an increasing number of studies on the application of acrylic resins in light and electron microscopy, in order to overcome problems encountered with the use of epoxy resins still utilized in morphologic studies. We compared different acrylic resins (Technovit 7200 VLC, LR White, LR Gold, Bioacryl) in order to understand which one was more suitable for undecalcified human dental tissues under light and transmission electron microscope. Evaluation of such resins was performed using the following criteria: ease of cutting with ultramicrotome, soft and hard tissues infiltration, uptake of tissue stains for both light and electron microscopy, morphologic preservation and stability under electron beam. This study, carried out on the pulp area comprising predentin and dentin, showed excellent quality of Bioacryl and LR Gold, the two resins presenting, by far, the best results among all the different types tested. The optimal morphologic preservation obtained with such resins is indicated for light and electron microscopic studies, allowing their application in different fields of dental research.

Acrylic Resins↗
PubMedDate not supplied

The effects of various disinfectant solutions on the surface hardness of an acrylic resin denture base material.

There is an increasing awareness of the importance of cross-infection control in dental clinics and laboratories. This study evaluates the effects of various disinfecting solutions on the surface hardness of an acrylic resin denture base material. Hardness was measured as resistance to indentation following the method specified by the British Standards Institute. The results demonstrated that immersion of denture base acrylic resin in disinfecting solution for up to 24 hours resulted in no significant effect on hardness values.

Acrylic Resins↗
PubMed1995

The effect of variation in powder particle size on the doughing and manipulation times and some mechanical properties of acrylic resin.

In this study, the hypothesis examined is that differences in polymer particle size affect the doughing and manipulation times and the mechanical properties of the cured product. Six batches of polymers were used varying in particle size from <38 micrometers diameter to > 75 micrometers diameter. A penetration test was undertaken to investigate the influence of polymer particle size on the doughing and manipulation times of acrylic resin. It was demonstrated that the particle size in the range examined influenced the doughing and manipulation times, the smaller particle sizes having shorter times. No significant difference was demonstrated in the impact resistance of surface hardness of acrylic resin specimens constructed from polymers of varying particle size and although there were some significant differences in the transverse (flexural) strength these were small in real terms. Further, the molecular weight of the polymerised product was found to be consistently higher than that of the original powder component.

Acrylic Resins↗
PubMed1997

Gas chromatographic and mass spectrometric purity analysis of acrylates and methacrylates used as patch test substances.

BACKGROUND: To make a correct diagnosis of allergic contact dermatitis, patch testing needs to be performed, and the patch test substances need to be pure. OBJECTIVE: We wanted to study how pure commercial (meth)acrylic patch test substances are. METHODS: The purity of (meth)acrylic patch test substances (diacrylates, dimethacrylates, and triacrylates) dissolved in acetone was determined by gas chromatography. The impurities were identified by mass spectrometry in both electron impact and chemical ionization mode. RESULTS: The analyzed dimethacrylates were very pure (97% to 99%). The purity of the three studied diacrylates were 81% to 91%, but tripropyleneglycol diacrylate (81% pure) contained as much as 13% of tripropyleneglycol monoacrylate. The purities of the triacrylates were 82% to 86%. All diacrylates and triacrylates contained 1% to 13% of the corresponding hydroxyacrylates. CONCLUSION: The impurities may result in false interpretation of the patch test results, and accordingly in wrong diagnosis. If the patch test substance is impure, at least, the chemical impurities that can be detected by gas chromatography should be measured and reported in a certificate of analysis, preferably from each batch.

Acrylates↗
PubMed1994

Improving interproximal access in direct provisional acrylic resin restorations.

A new technique that improves interproximal access in direct provisional acrylic resin restorations is presented. In this technique a clear Mylar strip is placed interproximally and lifted off with an overimpression prior to the beginning of the tooth preparation procedures. Preparation of the tooth and fabrication of the provisional restorations then continues in the usual direct manner. The Mylar strip, now embedded in the overimpression, becomes incorporated as a separator between the adjacent provisional restorations. The acrylic resin provisional restorations are easily snapped apart and finished individually. The advantages of the technique and the need for marginal perfection around the full perimeter of the tooth are also discussed.

Acrylic Resins↗
PubMedDate not supplied

The in vitro color stability of acrylic resins for provisional restorations.

This study made an in vitro comparative evaluation of the color variation of four types of acrylic resin for provisional fixed prostheses, as determined using computerized spectrophotometry, before and after a 20- and 30-day cycle of immersion in four staining solutions. The four acrylic resins used for provisional fixed restorations were: Cold Pac, Trim, Protemp, and Mixacryl II. Thirty-two specimens for each resin were divided into four subgroups of eight elements, immersed in the four staining solutions (synthetic saliva, synthetic saliva and tea, synthetic saliva and coffee, and synthetic saliva and chlorhexidine in 0.12% water solution), and then placed into four thermostatic baths at 37 degrees C +/- 1 degree C. All specimens were measured for each resin before immersion (baseline). After 20 and 30 days, the specimens were analyzed by computerized spectrophotometry and compared. All data were analyzed with analysis of variance for repeated measures (P < .05). Only the Cold Pac resin was color stable in all staining solutions, while the others showed color changes from the different staining solutions.

Acrylic Resins↗
PubMed1997

Reinforcement of acrylic resins for provisional fixed restorations. Part II: Changes in mechanical properties as a function of time and physical properties.

In Part I, it was found that (i) 2 vol.% admixture of reinforcing elements in PMMA (Jet) resin matrix had a significant beneficial effects on the mechanical properties, and (ii) among these, zirconia exhibited the greatest improvements in modulus of elasticity, transverse strength, toughness, and hardness number. Using the best combination (i.e., PMMA resin matrix and 2 vol.% ZrO2), exothermic temperature raise and polymerization shrinkage were further investigated. Deterioration in mechanical properties due to prolonged water sorption were also studied for 5 weeks. The following can be concluded: (1) By increasing liquid/powder ratio for PMMA control samples, the peak temperature occurrence was retarded by 3 min and raised by 8 degrees C. (2) The effect of admixed oxide particles to PMMA resin matrix or the heat generated during polymerization was not significant. (3) The polymerization volumetric shrinkage was influenced by the a mixture of particles, with increases as large as 0.9% (or 0.3% in linear shrinkage). (4) PMMA resin admixed with 2 vol.% of zirconia particles showed a continuous weight gain due to water sorption, mechanical properties appears to be increasing up to 1-week sorption, followed by rapid drop of all properties. (5) Autopolymerizing acrylic resins are a resin-resin composite material of pre-polymerized beads embedded in a newly formed acrylic matrix. The main fracture modality appears to occur through the matrix and at the interface, although some trans-beads fractures were identified. (6) It was suggested that incorporating certain type of oxide particles into the pre-polymerized beads would provide stronger resin matrix.

Acrylic Resins↗
PubMedDate not supplied

Wetting properties of saliva substitutes on acrylic resin.

The good wetting of the acrylic resin by saliva substitutes is of clinical importance in xerostomic patients. This study evaluated the wetting properties of different artificial saliva formulations that were mucin-based, carboxymethylcellulose-based, and concentrated ion-based on poly(methyl methacrylate) denture base resin, and compared these properties with natural saliva. The wetting properties of the test materials were examined by contact angle measurements. Ninety-six samples that measured 30 x 30 x 3 mm were examined. The wetting properties of mucin-containing and carboxymethylcellulose-containing substitutes on poly(methyl methacrylate) were significantly better than those of human saliva. Mucin-containing artificial salivas had the best wetting properties on the acrylic resin for the materials tested.

Acrylic Resins↗
PubMed1997

Keratinization of palatal mucosa beneath metal-based removable partial and acrylic-based complete dentures compared with normal palatal mucosa: a clinical, cytological and histological study.

Normal human palatal epithelium is an orthokeratinizing tissue with a well-developed stratum corneum. Several cytological and histological studies showed that when the palate covered by a denture fully or partially, keratinization of the mucosa changes. The results of some studies suggested that keratinization changes from orthokeratosis to parakeratosis, and there is a reduction in the thickness of stratum corneum. Whereas the results of some other studies showed increased orthokeratinization. This study was planned to determine changes in keratinization of palatal mucosa in denture wearers compared with normal palatal mucosa. Keratinization of palatal mucosa was examined by mainly exfoliative cytology in three groups. Group-1 consisted of 51 patients wearing metal-based removable partial denture; group-2 consisted of 50 patients wearing acrylic-based complete denture and group-3 including 57 healthy volunteers who have not been wearing denture served as the controls. In each group, the results of exfoliative cytology were supported by histological examinations. Statistical results showed that either acrylic-based complete or cobalt-chromium-based removable partial dentures seem to reduce the quantity and/or quality of the keratin layer. The mean values of keratinization and the thickness of stratum corneum were significantly lower in the complete denture group than in the partial denture group. Furthermore the reliability of exfoliative cytology was confirmed by the guidance of histological examination.

Acrylic Resins↗