Nedeljka Ivković, et al., The residual monomer in dental acrylic resin and its adverse effects Contemporary Materials, IV1 (2013) Page 84 of 91 Review UDK 616.31476+678 doi: 10.7251/COMEN1301084I THE RESIDUAL MONOMER IN DENTAL ACRYLIC RESIN AND ITS ADVERSE EFFECTS Nedeljka Ivković 1,* , Djordje Božović 1 , Siniša Ristić 1 , Vladan Mirjanić 2 , Olivera Janković 2 1 Faculty of Medicine, Department of stomatology, University of East Sarajevo, Republic of Srpska 2 Faculty of Medicine, department of stomatology, University of Banja Luka, Republic of Srpska Abstract: Acrylic based resins are frequently used in daily dental practice. The most common use of the materials includes denture bases and denture liners, temporary crowns and orthodontic appliances. In the mouth, properties and functional efficiency of applied acrylic resins depend on internal factors related to the methods and conditions of polymerization and on external factors that are related to the environment in which the material is placed. Residual monomer, which is released as a result of interaction of both sets of factors is often associated with irritation, inflammatory and allergic reactions of oral mucosa. The aim of this paper is to review literature dealing with the conditions of polymerization and biodegradation of acrylic resins under certain conditions in the oral cavity and their impact on oral health (reviewed literature available on Medline database during the past two decades.) Conclusion: Methods and conditions of acrylate polymerization, on the one hand, and properties of saliva, chewing and the presence of microorganisms in the oral cavity, on the other hand, can be considered responsible for the release of residual monomers. Clinically significant events followed by redness and erosion of the oral mucosa, burning sensation and burning mucosa and tongue, may be due to the effects of released, potentially cytotoxic, residual monomers. Keywords: acrylic resin, dentures, residual monomer, cytotoxicity, biodegradation, oral manifestations. INTRODUCTION Acrylic-based resins are frequently used in daily dental practice, as they are able to provide the essential properties and have necessary characteri- stics for their use in diverse functions. Polymethyl methacrylate (PMMA)–based acrylic resins are used for fabrication of various dental prostheses and den- ture liners, temporary crowns and orthodontic appli- ances. Acrylic resin bases of removable partial or complete dentures and tooth-supported or implant- retained overdentures are used to replace the lost tissues and transfer masticatory forces from the den- ture to the residual ridges. Denture liners are used to improve the fit of denture bases, thus re-establishing the retention, support and stability of removable prostheses. Temporary crowns are used during the interval between tooth preparation and placement of the definitive crown, while orthodontic appliances are used for space maintenance, tipping teeth, over- bite reduction, block movements and retention [1−5]. In the oral cavity, properties and functional values of acrylic resin based products depend on its endogenous factors caused by polymerization (degree of conversion of their constituent monomers, methods and the conditions of polymerization) [1-9] as well as exogenous factors caused by conditions present in oral cavity (saliva, bacteria, mastication) [5]. All these factors make a complex and intricate interplay of interactions, resulting in significant bio- logical effect on oral cavity tissues. Biological, as the most common toxic effect on oral cells and tis- sues, achieves a residual monomer that occurs as a result of the polymerization process and/or biode- gradation of dental materials in the oral cavity. This article reviews the literature published during the past two decades, selected by use of a Medline search (US National Library of Medicine), which investigated residual monomer cytotoxic * Corresponding author: neda.ivkovic @ yahoo.com