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At least 397 records · Page 22Linked to original sources
PubMed2001

Syntheses, characterization and application of cross-linked polystyrene-ethyleneglycol acrylate resin (CLPSER) as a novel polymer support for polypeptide syntheses.

Cross-linked polystyrene-ethyleneglycol acrylate resin (CLPSER) was developed for the solid-phase synthesis of peptide by introducing a cross-linker, O,O'-bis(2-acrylamidopropyl)polyethylene glycol(1900) (Acr(2)PEG), into polystyrene. The cross-linker was prepared by treating acryloyl chloride with O,O'-bis(2-aminopropyl) polyethylene glycol(1900) [(NH(2))(2)PEG] in the presence of diisopropylethylamine. The copolymer was prepared either by bulk or inverse suspension copolymerization of Acr(2)PEG(1900) and styrene using sorbitan monolaurate as the suspension stabilizer, and a mixture of ammonium peroxodisulfate and benzoyl peroxide as the radical initiators. The resin was characterized using gel-phase (13)C NMR, infrared (KBr) spectroscopic techniques and the morphological features of the resin were investigated using scanning electron microscopy photographs. CLPSER showed excellent swelling in a broad range of solvents and was found to be chemically inert to various reagents and solvents used in solid-phase peptide synthesis. To demonstrate the usefulness of the new resin in polypeptide synthesis, the support was derivatized with an 'internal reference' amino acid (norleucine) and a handle 4-(4-hydroxymethyl-3-methoxy)butyric acid. The new resin was compared with commercial supports such as Merrifield and Sheppard resins by synthesizing an acyl carrier protein (65-74) fragment under the same experimental conditions. HPLC profiles revealed the high efficiency of the newly developed support. Resin capability in peptide synthesis was further demonstrated by the solid phase synthesis of a 25-residue peptide from the E2/NS1 region hepatitis C viral polyprotein.

Acrylates↗
PubMed2006

Effect of relining, water storage and cyclic loading on the flexural strength of a denture base acrylic resin.

OBJECTIVES: This study investigated the effect of relining, water storage and cyclic loading on the ultimate flexural strength (FS(U)) and on the flexural strength at the proportional limit (FS(Pl)) of a denture base acrylic resin (Lucitone 550-L). METHODS: Rectangular bars of L were made (64 mm x 10 mm x 2 mm) and relined (1.3mm) with four relining resins (Kooliner-K, Ufi Gel Hard-UGH, Tokuso Rebase Fast-TR and New Truliner-NT). In addition, specimens relined with L and intact L specimens were made (64 mm x 10 mm x 3.3 mm). A three-point flexural test was applied on the specimens (n=10) after (1) polymerization; (2) water storage (30 days); (3) cyclic loading (10,000 cycles at 5 Hz) and (4) water storage (30 days)+cyclic loading. Data (MPa) were analyzed with three-way ANOVA and Tukey's HSD tests (alpha=0.05). To test for a possible correlation between FS(U) and FS(Pl), a linear regression coefficient "r" was calculated. RESULTS: After water storage, L-UGH and L-TR demonstrated an increased FS(U) (41.49-50.64 MPa and 49.95-57.36 MPa, respectively) (P<0.05). Only L-TR demonstrated an increased FS(Pl) (20.58-24.21 MPa) after water storage (P<0.05). L-L had the highest FS(U) (between 78.57 and 85.09 MPa) and FS(Pl) (between 31.30 and 34.17 MPa) (P<0.05). The cyclic loading decreased the FS(U) and FS(Pl) of all materials (P<0.05). Regression analysis showed a strong linear correlation between the two variables (r=0.941). CONCLUSIONS: Water storage improved the FS(U) of L-UGH and L-TR and the FS(Pl) of L-TR. L-L produced the highest FS(U) and FS(Pl). The FS(U) and FS(Pl) of all materials were detrimentally influenced by cyclic loading.

Acrylic Resins↗
PubMed1994

An interocclusal record made of a combination of wax and acrylic resin.

The correct mounting of casts on articulators is a fundamental step in obtaining good clinical results and reducing the time spent in the adjustment of oral prostheses. This procedure for retruded contact mounting of casts, based on a tripod of contacts with a combination of wax and acrylic resin, permits great accuracy in a short period of time.

Acrylic Resins↗
PubMed1992

Dental acrylic resin radiopacity: literature review and survey of practitioners' attitudes.

This study was initiated to ascertain the existence and some specifics of medical problems caused by traumatic ingestion/aspiration of fragments of radiolucent dental prostheses, and to evaluate opinions of radiopacity inclusion. A survey of 50 United States departments of oral surgery and emergency medicine yielded a 60% response. Results indicated that such medical problems are seen and would be reduced by incorporation of radiopaque materials. However, current technology cannot produce clinically acceptable levels of radiopacity without degrading physical and esthetic properties of the acrylic resin.

Acrylic Resins↗
PubMed2006

Characterization of acrylic resins used for restoration of artworks by pyrolysis-silylation-gas chromatography/mass spectrometry with hexamethyldisilazane.

A procedure based on the technique of the pyrolysis-GC/MS has been applied, in this work, in order to determine the composition of synthetic acrylic resins employed in artworks. The method is based on the on line derivatization of these resins using hexamethyldisilazane (HMDS). Results obtained have been compared with those others from direct pyrolysis and in situ thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH). Sensitivity using HMDS as derivatising reagent is found similar to that from direct pyrolysis and methylation with TMAH. Better resolution of the most representative peaks has been also obtained. Additionally, this method reduces the formation of free acrylic acid molecules during the pyrolysis process and, in consequence, more simplified and well-resolved chromatograms are obtained. Finally, the reported procedure has been successfully used for characterizing several acrylic-based varnishes and binding media currently used in Fine Arts and real pictorial samples from graffiti performed on a Middle Ages bridge.

Acrylic Resins↗
PubMed1980

[Studies on the thinning of the upper acrylic resin complete denture with the reinforced palate. (Part 2) Influence of the different palate forms on the thin plate dentures (author's transl)].

In this paper, succeeding the study of the part 1 on the thinning of the upper acrylic resin complete denture with the reinforced palate, it was investigated to keep the same stiffness and strength as the normal resin dentures, and to make the patient comfortable. Besides, many different palate forms exist in the patient's mouth in clinical cases, and so, influence of these forms on the thin plate dentures comes into question. Therefore, 3 types of the palate forms (the standard shape, the extremely large torus and the generally shallow shape) were established, and then the flexural stiffness and strength, and the deformation of the denture bases were scrutinized in this paper. The results obtained in this investigation are as follows: 1) The maxillary torus with sheer bulk had little influence on the flexural stiffness and strength. But, about the generally shallow-shaped denture bases, the mechanical properties dropped a little as compared the normal resin denture bases. The reinforced thin denture bases of which thickness was 60% of the normal one, showed the excellent mechanical properties in spite of the difference of the palate forms. 2) In the upper complete denture base, in spite of the palate forms, anteriority and posteriority of the one were deformed against the load direction around the frontal section through the bilateral canines, and the bilateral ridges of the one were deformed to the load direction around the midline of the denture base. The deformation was extremely decreased by not only the palate but also the whole of the denture base as the reinforced one.

Acrylic Resins↗
PubMed1992

The effect of disinfection procedures on flexural properties of denture base acrylic resins.

This study evaluates the effects of long-term disinfection immersion on the flexural properties of denture base resins; it was conducted against a background of increasing awareness of the importance of cross-infection control in dental clinics and laboratories. The transverse bend testing procedure used followed that specified in the International Standard for denture base polymers. The results demonstrate that alcohol-based disinfectants are not suitable for use with denture base materials of non-cross-linked acrylic resin.

Acrylic Resins↗
PubMed2000

In vitro colonisation of acrylic resin denture base materials by Streptococcus oralis and Actinomyces viscosus.

AIM: The aim of the study was to compare the attachment of two typical strains of oral bacteria to four denture base materials. DESIGN: In vitro study. METHOD: Discs of acrylic resin denture base materials (Paladon 65, polished and unpolished; Palapress; Microbase, polished and unpolished, and Triad VLC) were placed into Petri dishes with Schaedler's medium, inoculated with Streptococcus oralis 34 or Actinomyces viscosus T14V. MAIN OUTCOME MEASURES: After 24 h or 48 h the numbers of adhering bacteria were measured. RESULTS: The bacteria adhered to all discs in similar numbers: 3-9 x 10(6)/ml (viable cell count) and 9-22 x 10(8)/ml (total cell count) for T14V, and 2-6 x 10(6)/ml (viable cell count) and 1.5-3 x 10(8)/ml (total cell count) for 34. CONCLUSIONS: Polishing had little effect on adherence. Denture base materials are not resistant against adherence and possible surface damage by oral bacteria. Therefore, thorough oral hygiene is important for denture wearers.

Acrylic Resins↗
PubMed1992

Fabrication of a fixed provisional restoration utilizing a light-curing acrylic resin.

The properly fabricated provisional restoration must take into account the following interrelated factors: pulpal protection, periodontal health, occlusion, esthetics, and phonetics. The techniques advocated for construction of a provisional restoration include direct, indirect, and a combination of direct and indirect techniques. Two simple techniques that use light-curing acrylic resin for the fabrication of fixed provisional restorations are presented, and advantages and disadvantages of these techniques are discussed.

Acrylic Resins↗
PubMed1990

Comparison of the dimensional stability of two waxes and two acrylic resin processing techniques in the production of complete dentures.

Two base plate waxes and two denture processing techniques were independently compared for dimensional stability. Occlusion rims were constructed from extra hard and medium soft base plate waxes and teeth were set. Acrylic resin bases were processed by a trial packing technique, and a continuous injection system. Tooth movement was measured in the horizontal and vertical planes to assess wax and denture base dimensional changes at various steps in the process, and after 1, 3, and 8 weeks of denture base immersion in water at room temperature. Posterior palatal border adaptation, incisal pin opening and loss of centric occlusion contacts, were also measured. Results showed there were no significant differences between the two waxes as determined by tooth movement in the horizontal and vertical planes. In comparison to the trial packing technique, the continuous injection system showed significantly smaller changes for incisal pin opening and loss of centric occlusion, and better adaptation of the posterior palatal border to the cast. Measurement of tooth movement in the horizontal and vertical planes showed no significant differences between the two processing techniques for times prior to immersion in water, whereas after 8 weeks immersion the continuous injection technique showed smaller dimensional changes, relative to the original dimensions at the time of investing.

Acrylic Resins↗