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Clay or wax is used extensively as a modeling material for trial facial prostheses. This article describes a technique that uses a resilient acrylic resin as a matrix to lodge the ocular component and wax as the sculpturing medium for orbital prostheses. The technique can be adapted and used for all facial prostheses.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A denture tooth position index transfers the position of the denture teeth to the master cast during metal framework and bar-substructure fabrication stage. This article describes the use of light-polymerizing acrylic resin to fabricate a tooth position index.
A pilot study was conducted to evaluate the strengthening effect of a Ni-Cr metal plate on an acrylic resin test specimen. Test specimens were retained using a mechanical method and adhesion with 4-META resin. Three positions of the metal plate were evaluated: on the compression surface, on the tension surface, and in the middle layer. A three-point bend test was used to compare physical properties of the specimens with metal-plate reinforcement to a resin specimen without reinforcement. No advantage was derived from placing the metal plate in the center of the resin. Both methods of retention produced improved physical properties when placed on either the compressive or tensile side, but the greatest advantages were gained when an adhesive-retained plate was placed on the side in tension.
This investigation studies the relationship of hardness, elastic modulus and scratch width as dependent variables to the abrasion resistance of twenty-three dental acrylic resins. The multiple correlation R, when all three variables are used as predictors, is 0.727. Because of the significant intercorrelations between the variables themselves a stepwise multiple regression analysis showed hardness as a redundant variable. Abrasive wear can be estimated from the following equation Abrasive wear = 806.1 - 0.1498 modulus + 0.681 scratch width (R = 0.725; standard deviation of estimate +/- 50.8) The deletion of scratch width does not appreciably reduce the standard deviation of the estimate: Abrasive wear = 1063.4 - 0.2055 modulus (r = 0.683; standard deviation of estimate +/- 50.3) The method of curing the specimens conformed to the respective manufacturers' instructions. Abrasion and scratch tests were performed using methods developed by the authors and previously described in the literature, whereas the hardness and elastic modulus results were devised from standard test procedures. Further research is currently in progress to improve the predictive power of abrasion resistance with additional new variables.
This study evaluated the abrasiveness of four denture cleaners on the surface of denture base material and assessed their ability to remove Candida albicans. Acrylic resin discs 20 mm diameter and 2 mm thick were identically produced and polished. Four cleaners were evaluated: conventional toothpaste; toothpaste with stain remover; denture cleaning paste and an immersion type cleaner, and water were used as control. These were used at dilutions of 1:1, 1:2 and 1:3 with water. An electric toothbrush was used, and the discs cleaned to simulate 1 years' cleaning. The surface roughness of the discs were then measured, before and after cleaning, using a stylus profilometer, then inoculated with 1.2 x 10(6)C. albicans cells. The effectiveness of the denture cleaners to remove C. albicans cells was assessed following a single cleaning event. The immersion cleaner was significantly less abrasive than paste cleaners (P < 0.05). There were no significant differences between any dilutions for any cleaner used (P > 0.05). Immersion and paste cleaners removed almost all recoverable C. albicans from the discs, as cleaning with water alone was less effective (P < 0.05). An immersion type cleaner was found to be the most suitable cleaner because of its low abrasivity and effective removal of organic debris.
The use of powders, composed of a mixture of a chlorine-releasing agent with highly absorbent acrylic resin, for disinfecting body fluid spills was evaluated by laboratory tests. 'Encap' and 'Red Z' were found to absorb rapidly up to 200 ml of water to form a semi-solid gel. When experimental formulations containing 1%, 5% and 10% available chlorine were evaluated by a standardized surface test, those containing 10% gave the best results. The ease and rate of absorption of fluids by these formulations decreased as the fluid consistency increased and they seem more suitable for watery spills than for blood. The use of a powder based on peroxygen compounds ('Virkon') for disinfecting contaminated spills was evaluated by laboratory tests and hospital trials. Laboratory tests showed that 'Virkon' is strongly and rapidly bactericidal. In hospital ward trials by nurses using 'Virkon' on both natural and artificial spills, 60 of 62 contact plates pressed on to decontaminated surfaces proved negative, and no unpleasant fumes were generated when 'Virkon' was applied to urine. In another trial, 1% 'Virkon' solution proved very effective in decontaminating mortuary tables. Antiviral activity was not tested.
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A clinical model was introduced to study the ability of chlorhexidine, tannic acid, and iron to discolor dental plaque formed on acrylic resin surfaces. None of the agents caused discoloration when applied individually five times daily during a 5-day period. However, exposure of the dental plaque to either chlorhexidine or tannic acid before the iron applications produced marked staining. Possible mechanisms, among which denaturation appears to be significant, are discussed. The use of a strong oxidizing agent, peroxymonosulfate, completely bleached the established discolorations.
The first part of this study involved the development of a method for evaluating the effect of small surface defects (3.0 microns-80.0 microns) on the impact strength of acrylic denture base materials. The method was used to compare the properties of 12 denture base materials, some of which are described as "high-impact strength" products. The defects were introduced by drawing the specimens over abrasive papers of varying grit sizes or by notching with a craft knife. Flexural toughness tests were also carried out in order to evaluate the materials under both rapid (impact) and slow (flexural) rate test conditions. The impact resistance of acrylic resins was significantly reduced by the presence of very small surface defects (e.g., < 16 microns), and this was particularly noticeable for so-called high-impact resins. The latter have values of impact strength only slightly higher than standard acrylic products when defects are present. Testing "notched" specimens with small surface defects was a simple method of obtaining reproducible results. This test was sensitive enough to differentiate among several types of currently available denture base resins.
A technique is described for fabrication of a remount cast for a removable partial denture. This procedure consists of filling the occlusal/incisal third with acrylic resin and injecting polyvinylsiloxane impression material into the irreversible hydrocolloid impression. This technique provides a simple method for making a remount cast and enables the clinician to remove and easily place the partial denture on the cast during occlusal refinement procedures without damage to the removable partial denture or the remount cast.
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In vitro data demonstrated that the permeation of a UV-curable urethane acrylate resin system through glove materials was greatest for latex and neoprene gloves and less for two nitrile gloves. Permeation in vitro for the resin system took longer than 480 min. Individual components of the resin permeated faster when tested separately than when in the formulated system. In vivo 48-h patch test data suggested that neither nitrile glove would be adequate for worker protection, but the in vivo test exaggerated the duration of contact between resin, glove, and skin. Both nitrile gloves provide adequate protection under use conditions, provided the gloves were not re-used within 8 h.
Commercially produced provisional cylinders are commonly used during fabrication of fixed, provisional implant restorations. A procedure is presented for the fabrication of fixed, provisional implant restorations using laboratory-fabricated, autopolymerizing acrylic resin cylinders. These cylinders offer a number of advantages over commercially produced cylinders and may reduce the treatment cost of implant prosthodontics.