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At least 415 records · Page 23Linked to original sources
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↗
PubMed2005

Hardness of heat-polymerized acrylic resins after disinfection and long-term water immersion.

STATEMENT OF THE PROBLEM: In selecting a disinfectant for dental prostheses, compatibility between the disinfectant and the type of denture base material must be considered to avoid adverse effects on the hardness of the acrylic resin. PURPOSE: This study investigated the hardness of 2 denture base resins after disinfection and long-term water immersion. MATERIAL AND METHODS: Thirty-two disk-shaped specimens (13 mm in diameter and 8 mm thick) were fabricated from each resin (Lucitone 550 and QC-20), polished, stored in water at 37 degrees C for 48 hours, and submitted to hardness tests (Vickers hardness number [VHN]) before disinfection. Disinfection methods included scrubbing with 4% chlorhexidine gluconate for 1 minute, immersion for 10 minutes in 1 of the tested disinfectant solutions (n=8) (3.78% sodium perborate, 4% chlorhexidine gluconate, or 1% sodium hypochorite), and immersion in water for 3 minutes. The disinfection procedures were repeated 4 times, and 12 hardness measurements were made on each specimen. Control specimens (not disinfected) were stored in water for 56 minutes. Hardness tests (VHN) were also performed after 15, 30, 60, 90, and 120 days of storage in water. Statistical analyses of data were conducted with a repeated measures 3-way analysis of variance (ANOVA) and Tukey post-hoc test (alpha=.05). RESULTS: Mean values +/- SD for Lucitone 550 (16.52 +/- 0.94 VHN) and QC-20 (9.61 +/- 0.62 VHN) demonstrated a significant (P <.05) decrease in hardness after disinfection, regardless of material and disinfectant solutions used (Lucitone 550: 15.25 +/- 0.74; QC-20: 8.09 +/- 0.39). However, this effect was reversed after 15 days of storage in water. Both materials exhibited a continuous increase (P <.05) in hardness values for up to 60 days of water storage, after which no significant change was observed. CONCLUSION: Within the limitations of this in vitro study, QC-20 and Lucitone 550 specimens exhibited significantly lower hardness values after disinfection regardless of the disinfectant solution used.

Acrylic Resins↗
PubMed1995

Surgical treatment of complications 45 years after extraperiosteal pneumonolysis and plombage using acrylic resin balls for cavitary pulmonary tuberculosis.

An infected axillary sinus tract discharged balls made of an acrylic resin consisting essentially of polymerized methyl methacrylate (Lucite) 45 years following performance of an extraperiosteal pneumonolysis and Lucite ball plombage for collapse therapy of right upper lobe cavitary tuberculosis. Surgical extraction of the balls was performed, followed by a partial decortication of the lung and intrathoracic transposition of a pectoralis major muscle flap to fill the residual pleural space. Primary healing was attained, and the patient is well 1 1/2 years after surgery.

Axilla↗
PubMed1992

The bond strength of elastomer tray adhesives to thermoplastic and acrylic resin tray materials.

This study evaluated the bond strength of selected impression materials (Permlastic, Express, and Hydrosil) to a thermoplastic custom tray material as a function of drying time of the adhesive after application to a tray material. In addition, bond strengths of a polysulfide impression material to an acrylic resin tray material and to a thermoplastic tray material made directly against wax were evaluated. Bond strengths were obtained directly from values of applied load at failure and important conclusions were drawn.

Acrylic Resins↗
PubMedDate not supplied

[Loss of interproximal periodontal tissue. A clinical solution with construction of a removable acrylic resin appliance].

One of the problems of difficult solution in clinic are the tissue lost from periodontic surgery procedures. The purpose of this survey is to help find the solution of this problem, and we show a case where the patient has great interdental tissue lost after surgery and was solucionated with an acrylic resin appliance. The clinic results prove the efficiency of the appliance, diminishing or having the hole esthetic and phonetic problem solucionated, besides the low-cost of its confection and also allows the patient to have a good plaque control.

Acrylic Resins↗
PubMed1998

Retention of oral microorganisms on cobalt-chromium alloy and dental acrylic resin with different surface finishes.

STATEMENT OF PROBLEM: The effect of surface finish of dental materials on the subsequent contamination by microorganisms. PURPOSE: This study compared the retention of Streptococcus oralis, Actinomyces viscosus, and Candida albicans on polished, sandblasted (fine and coarse) and electrobrightened cobalt-chromium alloy and dental acrylic resin to assess in vitro the effect of such techniques on prosthesis contamination. MATERIAL AND METHODS: Standardized cell suspensions were incubated with test materials for 1 hour at 37 degrees C, after which retained cells were counted by using image analysis (percentage area of a microscopic field covered by cells). RESULTS: Retention of bacterial cells was substantial (S oralis 12% to 20% and A viscosus 9% to 16%) irrespective of surface finish. Maximal retention was observed on cobalt-chromium alloy that had undergone fine sandblasting and electrobrightening (P < .01). For C albicans, an increase in surface roughness (0.15 to 3.53 microns) resulted in an increase in retention (3% to 9%). CONCLUSION: Cell size and the type of roughening significantly affected the retention of microorganisms on surfaces. Electrobrightening of cobalt-chromium alloy did not reduce the surface roughness or subsequent cell attachment.

Acrylic Resins↗
PubMedDate not supplied

[Passivity of certain disinfectant substances in the presence of acrylic resins].

On the basis of data published in the specialized literature the authors have experimented the effects of five substances currently used for the disinfection of prostheses. These included: Denclen (a British product), Super Quick's (made in the FRG), and Leodent also a West German product), as well as two general disinfectants of the buccal cavity: perogen and bromocet, on the acrylic resins used for the dental prostheses: Superpont (made in Czechoslovakia) and Romacryl (a Romanian product). The study showed that these substances, both the special ones and the general disinfectants are not completely passive when in contact with the acrylic prostheses. They should be used with care, and in accordance with the indications concerning concentration and duration of application.

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↗
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↗
PubMed1992

Dimensional accuracy and stability of acrylic resin denture bases.

Proponents of injection molding systems have claimed a number of benefits over conventional press-pack dough molding systems. The aim of this study was to evaluate a recently developed injection (dry heat) procedure of processing compared with press-pack dough molding utilizing three curing cycles. The dimensional accuracy and stability of acrylic resin bases produced by the two molding procedures were compared. Dimensional changes were assessed over a period of 4 months using an optical comparator. The results demonstrate that baseplates produced by the injection molding procedure exhibit less shrinkage than those produced by the conventional press-pack procedures.

Acrylic Resins↗