Cytotoxicity of denture base acrylic /fixed orthodontic courses by IDA

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Information about Cytotoxicity of denture base acrylic /fixed orthodontic courses by IDA

Published on May 9, 2014

Author: indiandentalacademy


PowerPoint Presentation: INDIAN DENTAL ACADEMY Leader in continuing dental education Cytotoxicity of denture base acrylic resins PowerPoint Presentation: INTRODUCTION EFFECT OF POLYMER TO MONOMER RATIO EFFECT OF STORAGE TIME AND WATER IMMERSION EFFECT OF POLYMERIZATION CYCLE EFFECT OF POLYMERIZATION METHOD SUMMARY AND CONCLUSION REFERENCES Cytotoxicity of denture base acrylic resins:A literature review.: Cytotoxicity of denture base acrylic resins:A literature review. Janaina Habi Jorge, Eunice Teresinha Giampaolo,DDS, PhD, Ana Lucia Machado, DDS, PhD, and Carlos Eduardo Vergani, DDS, PhD. Araraquara Dental School, Sao Paulo State University, Araraquara, Sao Paulo, Brazil. (J Prosthet Dent 2003;90: 2,190-193.) PowerPoint Presentation:  Acrylic resins are widely used in the fabrication of denture bases and have been shown to be cytotoxic as a result of substances that leach from the resin. The primary eluate is residual monomer. It has the potential to cause irritation, inflammation, and an allergic response to the oral mucosa. Clinical signs include crythema, erosion of oral mucosa, and a burning sensation on the mucosa and tongue. PowerPoint Presentation:  Resins used for the manufacture of denture bases have displayed various degrees of in vitro cytotoxicity and in vivo allergic responses. Residual monomer concentration varies with the methods and the conditions of polymerization. The variations in chemical composition and purity of the commercially available resin systems, the degree of conversion of their constituent monomers, and manipulative variables may all affect the biologic and physical properties of the acrylic resins. This article reviews the literature published from 1973 to 2000, selected by use of a Medline search (U.S. National Library of Medicine). EFFECT OF POLYMER TO MONOMER RATIO: EFFECT OF POLYMER TO MONOMER RATIO According to Kedjarune et al, the more monomer added to the mixture, the greater the amount of residual monomer and, therefore, the more potential for cytotoxicity. Lamb et al observed that resins prepared with a high proportion of polymer (5:3) resulted in significantly lower levels of residual monomer, as compared to those prepared with a lower ratio(4:3). EFFECT OF STORAGE TIME AND WATER IMMERSION: EFFECT OF STORAGE TIME AND WATER IMMERSION Sheridan et al reported that the cytotoxic effect of acrylic resins was greater in the first 24 hours after polymerization and decreased with time. The authors concluded the longer prosthesis is soaked, the less cytotoxic effect it is likely to have. Lefebvre et al observed that the effect of substances released from 4 light – polymerizing denture base resins on epithelial cells is greater in initial 24 hours period. PowerPoint Presentation: Different substances can be released in different concentrations changing the physical and chemical properties of the materials. The cytotoxic effect may occur for several days but it can be minimized if prostheses are stored in water for 24 hours. Weaver and Goebel reported that the immersion of prosthesis in heated water decreased the hypersensitivity reaction in the examined patients. EFFECT OF POLYMERIZATION CYCLE: EFFECT OF POLYMERIZATION CYCLE Kedjarune et al observed a reduced amount of residual monomer when the polymerization time was extended, thus resulting in less cytotoxic effects. Harrison and Huggett conducted a study wherein 23 heat – polymerized denture base polymers were subjected to various polymerization cycles. The results of this investigation showed that a 7 – hour incubation in water at 70 0 C followed by 1 hour at 100 0 C was ideal. PowerPoint Presentation: Vallitty et al performed a study with 2 autopolymerized resins in which the reaction was initiated by barbituric acid and 2 heat-polymerized resins activated by benzoyl peroxide. The results showed that the autopolymerized resins exhibited higher contents of residual monomers than the heat polymerized resins. Lamb et al observed that levels of residual monomers in autopolymerized resins were higher for specimens polymerized at 22 0 C, as compared with those polymerized at 55 0 C. EFFECT OF POLYMERIZATION METHOD: EFFECT OF POLYMERIZATION METHOD The cytotoxic effects of heat – activated, chemically – activated, and microwave – activated acrylic resins on gingival fibroblasts were also reported by Sheridan et al, who observed that, among the tested materials, the greatest cytotoxic effect was produced by chemically activated acrylic resins. PowerPoint Presentation: According to Hensten – Pettersen and Wictorin, the cytotoxic effect is greater in autopolymerized resins than in heat polymerized resins. Similar findings were observed by other researchers as Yunus et al, Blagojevic & Murphy, De Clerk, Truong and Thomasz and others. Visible light – polymerized denture base resins have been claimed to be nontoxic after polymerization. However, several studies have shown that these materials have varying levels of cytotoxicity. The extent of their toxic effect appears to be related to the specific formulation of the material and polymerization time. PowerPoint Presentation: To summarize, the reviewed studies indicated that autopolymerized resins are more cytotoxic than the heat – polymerized denture base resins, which in turn are more cytotoxic than the microwave – polymerized resins. SUMMARY & CONCLUSION: SUMMARY & CONCLUSION REFERENCES: REFERENCES Weaver RE, Goebel WM, Reactions to acrylic resin dental prostheses. J Prosthet Dent 1980;48:138-42. Tucker TN. Allergy to acrylic resin denture base. J Prosthet Dent 1981;16:602. Kallus T. Evaluation of the toxicity of denture base polymers after subcutaneous implantation in guinea pigs. J Prosthet Dent 1984;52:126-34. Nakamura M, Kawahara H. Long-term biocompatibility test of denture base resins in vitro. J Prosthet Dent 1984;52:694-9. Lefebvre CA, Schuster GS Caughman GB, Caughman WF. Effects of denture base resins on oral epithelial cells. Int J Prosthodont 1991;4:371-6. Okita N, Hensten-Pettersen A. In vitro cytotoxicity of tissue conditioners. J Prosthet Dent 1991;66:656-9. PowerPoint Presentation: Thank You Leader in continuing dental education

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