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PubMedDate not supplied

Effect of surface treatments on the bond strength between composite resin and acrylic resin denture teeth.

PURPOSE: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. MATERIALS AND METHODS: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. RESULTS: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. CONCLUSION: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.

Acrylic Resins↗
PubMed1975

Femoral head replacement with the christiansen endoprosthesis. A follow-up study, and a report on 175 arthroplasties with the present model of the prosthesis with acrylic cement fixation.

A review of the experience gained after 300 consecutive femoral head replacements using the Christiansen Endoprosthesis is given. The arthroplasties were performed mainly for fresh, displaced femoral neck fractures in elderly patients and for complications of these fractures, such as pseudarthrosis and aseptic necrosis. The patient material is divided into 2 groups. Group 1: Patients who had the older prosthesis model with plastic capitulum pieces inserted, and Group 2: Patients who had the present prosthesis model with metal-capped capitulum pieces inserted together with acrylic cement fixation. While the results initially were promising in the first group, a longer follow-up was very disappointing. Wear of the plastic material resulted in a pronounced foreign body synovitis with pain and reduced mobility. Furthermore, there were osteolysis and fractures related to the prosthesis in a great number of patients observed for more than 2 years. This led to a change in the construction of the capitulum piece of the prosthesis which was now equipped with a metal cap and to the use of acrylic cement fixation of the shaft piece. The follow-up results in these patients (Group 2) have been most encouraging, with absence of the above-mentioned complications after up to 6 years' observation. The mortality and complications encountered are discussed. It is concluded that femoral head replacement on the indications outlined, using the present prosthesis model with acrylic cement fixation, represents a very good alternative in the treatment of displaced femoral neck fractures and their complications.

Acrylates↗
PubMed2001

[A clinical report on hydrophilic acrylic foldable lens implantation].

OBJECTIVE: To investigate the therapeutic effects of hydrophilic acrylic foldable lens implantation. METHODS: This prospective randomized placebo-controlled study comprised 214 eyes of 190 patients after phacoemulsification. The hydrophilic acrylic foldable lens was implanted in group 1 (114 eyes), and the PMMA intraocular lens (IOL) implanted in the control group 2 (100 eyes). Within the 3-6 month follow-up period, the changes of visual acuity, corneal astigmatism and endothelial cells, the location of IOL and the degree of posterior capsular opaqueness postoperatively between the two groups were compared. RESULTS: The visual acuity of group 1 was significantly better than that of group 2 within 3 days postoperatively (P < 0.05), but there was no statistically significant difference after 3 months. The surgically induced astigmatism, incidents of posterior capsular opaqueness and subluxation of IOL of group 1 were significantly lower than that of group 2 after 3 months postoperatively (P < 0.05). The comparison of the endothelial cell loss ratio between the two groups was not significantly different (P > 0.05). CONCLUSION: The hydrophilic acrylic foldable IOL is easy to handle during implantation, highly biocompatible in the eyes, with less postoperative inflammatory reactions and shorter recovery period, and may provide satisfactory therapeutic effects.

Acrylic Resins↗
PubMed2002

[Light scattering observed on the surface of acrylic intraocular lenses ten years after implantation].

PURPOSE: To report the long-term status of acrylic intra-ocular lenses. CASES: We describe two cases of increased light scattering on the surface of acrylic intraocular lenses ten years after implantation. The scattering was non-symptomatic and visual acuity was normal. Biomicroscopy and a Scheimpflug photography system showed that the scattering apparently derived from the anterior surface of the lens, but no deposit or membranous structure was observed on the lens surface. CONCLUSION: Surface scattering from acrylic intra-ocular lenses is a new finding in long-term observations. A possible etiology may be structural changes of the internal polymer.

Acrylic Resins↗
PubMed1998

[Synthesis and application of novel acrylic resin as enteric coating].

The pH sensitive two- and three-component acrylic resins were synthesized by radical solution copolymerization of methyl methacrylate (MMA), methacrylic acid (MAA) and/or butyl acrylate (BA) and their acid values were measured by acid-base titration. The dissolution of naproxen pellets coated with the synthesized resins in dissolution medium of different pH value was studied. The results show that the acrylic resin with different acid value can be prepared by adjusting the monomer ratios (MMA:MAA or MMA:MAA:BA). The smaller the acid value of the resin is, the higher pH sensitive value it has. The release of naproxen from pellets coated with these resins is greatly influenced by the pH value of the dissolution medium and the pH sensitive value of the coating resin. The three-component resins are plastic and can be used as coating material without adding plastisizers.

Acrylic Resins↗
PubMedDate not supplied

Late postoperative opacification of hydrophilic acrylic intraocular lenses.

BACKGROUND AND OBJECTIVE: To evaluate the incidence of postoperative opacification of hydrophilic acrylic intraocular lenses (IOLs) and discuss the surgical management. PATIENTS AND METHODS: Seventy-two eyes of 72 consecutive patients who received the same type of hydrophilic acrylic IOL (Intraocular Optical International, I.O.I., California, USA) after uneventful phacoemulsification were evaluated retrospectively. Systemic status, follow-up time, recognition time of IOL opacification, time lapse between implantation and explantation, and surgical technique during explantation were reported. RESULTS: IOL opacification was noted in 3 patients (4.1%). Time lapse between implantation and first recognition of opacification was 6.3+/-1.5 months (range: 5-8 months). Two of the patients had insulin-dependent diabetes mellitus and both were on renal dialysis for diabetic nephropathy, whereas one had no systemic disease. Opacified hydrophilic acrylic IOLs were exchanged with Acrysof IOL, and no further opacification occurred after lens exchange. CONCLUSION: Use caution on implantation of hydrophilic IOLs because late opacification is a serious complication requiring further surgery.

Acrylates↗
PubMed2002

Durability of acrylic tooth bond to polymeric denture base resins.

The effect of ageing in simulated mouth conditions on bond strength between acrylic teeth and denture base resins was evaluated. Bonding was tested in tension according to ADA specification No. 15. The data was analysed using two-way analysis of variance and Tukey test at P < 0.05. The ageing effect on bond strength became significant after six months of exposure when bonding of acrylic teeth to heat-cured and autopolymerised resins was significantly reduced, P = 0.001 and P = 0.03 respectively. The bond strength value of the autopolymerised resin to acrylic tooth after one year in test environment was half the acceptable value of 31.0 MPa suggested by the ADA specification No. 15, whereas tooth bond strength to heat-cured resin was acceptable even after one year of exposure.

Acrylic Resins↗
PubMedDate not supplied

The effect of different polishing techniques on the surface roughness of acrylic resin materials.

This study evaluated three methods of surface polishing on acrylic denture base materials. Specimens of three commercial heat-cured acrylic resin materials were finished using burs, sandpaper discs and rubber wheels, and polished with polishing soap, paste, or by application of a UV-light-activated resin sealant. The resulting surface roughness was examined by scanning electron microscopy as well as measured by means of a stylus profile Perthometer. Surface roughness was reduced by polishing. Polishing paste and UV-light-activated resin sealant were more, and equally, effective in reducing surface roughness compared to polishing soap. Polishing paste or UV-light-activated resin sealant may be used to create a smoother surface on acrylic dentures.

Acrylic Resins↗
PubMed2002

Reinforcement of acrylic resins for provisional fixed restorations. Part III: effects of addition of titania and zirconia mixtures on some mechanical and physical properties.

Acrylic resins have been used in many different applications in dentistry, especially in the fabrication of provisional fixed partial dentures. Ideally, a provisional crown and bridge material should be easy to handle and should protect teeth against physical, chemical, and thermal injuries. Some of the problems associated with this use are related to the material's poor mechanical properties. It has been demonstrated that acrylic resin can be strengthened through the addition of structural component of different size distributed in the acrylic matrix, thus forming a composite structure. The purpose of this study was to investigate the addition effects of mixtures of titania (titanium dioxide, TiO(2)) powder and zirconia (zirconium dioxide, ZrO(2)) powder being incorporated with pre-polymerized beads mixed in monomer liquid, on some mechanical and physical properties of PMMA resin. The pre-polymerized powder poly(methyl methacrylate) resin was admixed with titania and zirconia powder. A mixing ratio was controlled by volume % of 0, 1.0, 2.0, and 3.0 (samples with 0 v/o served as control groups). For using mixture of titania and zirconia, total amount of the mixture was controlled by volume % of 1.0, 2.0, and 3.0, in which titania and zirconia were mixed at the ratio 1 :1, 1 :2 and 2 :1. Prior to mechanical tests, all rectangular-shaped samples (25 mm x 2 mm x 5 mm) were stored in 37 degrees C distilled water for 7 days after polishing all six sides of samples. Samples were then subjected to the three-point bending flexion test to evaluate the bending strength as well as the modulus of elasticity. Weight gain and exothermic reaction survey were investigated as well. All data were collected and analyzed with one-way analysis of variance (ANOVA) and Sidak method (p=0.05). It was found that the addition of particles generally decreased the water absorbed by the composite system. Only 1 percent by volume concentration of 1 :1 ratio and 2 percent by volume concentration of 1 :2 and 2 :1 ratios had significantly higher strength than control group. There was significantly higher toughness (in terms of energy-to-break) for 1 percent by volume concentration of 1 :1 ratio and 2 percent by volume concentration of 2 :1 ratio than control group. There was no significant difference between control group and all percent by volume combinations in modulus of elasticity. In addition, there was no significant variations of exothermic reaction.

Absorption↗
PubMed2003

The effect of the addition of different fibres on the transverse and impact strength of acrylic resin denture base material.

The aim of the present study was to investigate the effect of the addition of different types of fibres on the transverse and impact strength of acrylic resin denture base material. The addition of glass fibres (strand) and polyethylene fibres produced a non significant increase in the modulus of elasticity, compared with the control of conventional heat-cured acrylic resin. The addition of glass fibres (woven and strand), polyethylene and carbon fibres to acrylic resin produced a non significant increase in the modulus of rupture. The addition of carbon, glass (strand) and polyethylene fibres produced a significant increase in the impact strength. Within the limitations of this study the addition of silk fibres did not produce an improvement in the mechanical properties.

Acrylic Resins↗
PubMed1976

A new skin protecting ointment against acrylic resins.

In order to protect the hands of dentists, dental technicians and dental nurses from direct contacts with acrylic monomer, a new type of protective monoglyceride containing ointment has been introduced. The monoglyceride-based ointment was found to prevent penetration of the monomeric part of an autopolymerising acrylic resin and was also shown to have significantly smaller decreasing influence on the ability to manipulate instruments and materials than a compared silicone-based ointment. Furthermore, even with addition of 1% by volume of the monoglyceride-based ointment there was no marked influence on the mechanical properties (elastic modulous and ultimate tensile strength) of an investigated acrylic tray material.

Acrylic Resins↗
PubMed2004

[Catalytic application of synthesizing n-butyl acrylate by a new type nanometer complex heteropoly acid catalyst H3PW12O40/SiO2].

A new nanometer complex heteropoly acid with Keggin structure, H3PW12O40/SiO2, were prepared by sol-gel method, and were characterized with IR, UV, XRD and TEM techniques. By means of this nanometer catalytic materials, the optimum conditions of the n-butyl acrylate synthesis have been studied. The results show that the complex heteropoly acid H3PW12O40/SiO2 nanoparticles have the mean grain size of 40 nm and they are typical amorphous. A strong chemical interaction exists between H3PW12O40 and silica surface. The nanoparticles have high catalytic activity for synthesizing n-butyl acrylate. The optimum catalytic conditions are as follows: the mole ratio of acrylic acid and n-butyl alcohol is 1:1.2, the reaction temperature is approximately 90-96 degrees C, and the catalyst quantity in the reaction is 10% of the acid mass. The conversion proportion is 94.37% and product yield 91.2% in 5 h. Apparently, the unique structure of the Keggin anions and surface acid center and the high specific surface area and the pseudoliquid phase of H3PW12O40/SiO2 play an important role in the esterification reactions with the acid catalyst.

Acrylates↗
PubMed1991

[The effect of clover silage treated with acrylic acid on selected indicators of metabolism in cows around the time of parturition and the status of their calves].

A trial was conducted with 16 cows divided into control and test group (eight cows in either); since day 57.6 +/- 21.1 before parturition, test cows were given feed rations for 107 days which contained 16.0 kg clover-grass silage a day, treated with 3 l acrylic acid per t ensiled matter. Control group of cows was administered feed rations containing silage treated with 4 l formic acid per 1 t ensiled matter from day 55.5 +/- 21.9. In the blood (plasma) of test cows the alkaline phosphatase activity was increasing gradually, in the time after parturition a tendency of lower glucose (P 0.05 to 0.01), thyroxine and triiodothyronine concentrations was observed, and the phagocytal activity of leucocytes and its index decreased. The levels of ketone bodies and aspartate aminotransferase activity were found to be higher. In this period in urine the pH value and net acid-base output were lower, while the inorganic phosphorus concentration was higher. No difference were observed in colostrum density, liveweight of born calves and in the target metabolic parameters in the blood (plasma) of calves. In the 30-day period of investigation the cows of test group gave an average daily milk yield lower by 1.5 l (in comparison with control cows). The residues of acrylic acid (method sensitivity of 1.0 mg acrylic acid in 1 l sample) were not detected in their colostrum and milk.

Acrylates↗
PubMed1991

Denture materials and acrylic base materials.

Modifications in denture plastics, including acrylics containing butadiene-styrenes, block copolymers to increase toughness, and those with added soluble heavy-element salts to increase radiopacity are described. Developments in processing of denture bases by microwave, laser, and injection methods are described. Also reviewed are acrylics and their dimensional stability, including the effect of artificial salivas on properties. In addition, the rheological, glass transition, dynamic, impact, and fatigue properties of denture acrylics are presented. Adhesion of polymers to plastics and metals is reviewed, as well as the biocompatibility and adhesion of organisms to denture plastics. Soft denture materials are reviewed with respect to research on new materials and to clinical evaluations of existing products. Finally, studies on the wear of denture teeth are summarized.

Acrylic Resins↗
PubMed1991

Porcelain laminate veneer provisionalization using visible light-curing acrylic resin.

Placement of porcelain laminate veneers has become a relatively common procedure. Occasionally it is necessary to fabricate provisional restorations. For these situations, the use of self-curing acrylic resin and composite resin has been described in the literature. Extensive trimming and finishing procedures are often necessary, and, because of the inherent fragility of the materials, the provisional restorations are prone to breakage. To improve the technique, visible light-curing acrylic resin can be used to fabricate direct provisional restorations. The material is available in several shades, has excellent manipulative properties, and does not necessarily require a custom matrix, offering significant advantages over a composite resin or self-curing acrylic resin.

Acrylic Resins↗
PubMed1990

Tensile and shear strength of orthodontic bracket bonding with glass ionomer cement and acrylic resin. An in vitro comparison.

The tensile and shear strength for a polyalkeonate luting cement (AquaCEM) and a no-mix acrylic resin (Unite) in orthodontic bracket bonding were compared in an in vitro test. Brackets bonded/cemented to extracted premolar teeth were subjected to loads in a universal testing apparatus and the dislodging forces were recorded. The possible influences of setting time and of bracket base design were also studied. No significant differences between the cement and the resin were found after allowing 24 hours of setting time. This in contrast to the significantly stronger tensile strength but inferior shear strength for the polyalkeonate cement when stress was applied after 15 minutes. A significantly higher tensile strength value was recorded for a foil-meshed bracket base type compared to an integral base type with cut grooves after 15 minutes, but not after 24 hours. While the polyalkeonate cement adhesion mostly fractured within the cement layer, the acrylic bond more often failed in the enamel-adhesive interface. The results support the use of the fluoride-containing cement as an alternative to acrylic adhesives in orthodontic bracket bonding, especially in high-risk caries patients.

Acrylic Resins↗
PubMed1989

[Effects of various prosthodontic strengtheners on fatigue behaviour of acrylic resins].

The fatigue behaviour of acrylic sheet specimens containing reinforcers were investigated. Three different kinds of reinforcers namely, stainless steel, aluminum reinforcer and three flex wire were used as strengtheners in acrylic resin sheets. The tests were carried out on alternating bending fatigue testing machine specially designed to test sheet specimens. By applying static and dynamic bending moments of any desired magnitude within the permissible capacity likits of the machine the fatigue lives of the specimens were determined. Experimental results showed that stainless steel strengtheners had a significant positive effect on the fatigue behaviour of acrylic resin.

Acrylic Resins↗
PubMed1989

[Dimensional behavior of six light-cured veneer acrylics].

During irradiation light-cured veneer acrylics underwent shrinking by 2.2 to 4.8%. In operation, the temperature in the irradiation chambers of the light units increased up to a maximum of 87 degrees C. The coefficients of thermal expansion a20/100 of the acrylics ranged between 49.2 and 72.2 x 10(-6)/K. Dimensional changes of the acrylics due to high polymerization contraction and/or due to a different thermal behavior than that of the metal framework may produce stresses in the bond system and possibly promote a deterioration of metal retention.

Acrylic Resins↗