International Journal of Enhanced Research in Science, Technology & Engineering ISSN: 2319-7463, Vol. 5 Issue 4, April-2016 Page | 130 Fourier Transform Infrared (FT-IR) Spectroscopy of Modified Heat Cured Acrylic Resin Denture Base Material Inas A.M. Jawad 1 , Ammar A. Al-Hamdani 2 , Rizgar M. A. Hasan 3 1 BDS, MSc, Department of Prosthetic Dentistry. College of Dentistry, University of Mosul, Iraq 2 BSc, MSc, PhD, Department of Basic Sciences. College of Dentistry, University of Mosul 3 BDS, MSc, PhD, Department of Prosthetic Dentistry. College of Dentistry, Hawler Medical University, Iraq ABSTRACT Aims: Modifying heat cured denture base acrylic resin with new additives and the use of FT-IR spectroscopy to investigate and characterize the produced materials. Methods: Thermally activated Zinc Oxide (ZnO) and Zinc Diacrylate (ZDA) powders were synthesized. Heat cured acrylic resin denture base material had modified by adding inactivated ZnO powder with and without acrylic acid (AA), thermally activated ZnO powder, AA liquid, or ZDA powder in 5%by weight. FT-IR Spectrophotometer was used to assess the chemical conversion of the cured samples. Results: Both ordinary and thermally activated ZnO filler appear to have no chemical bonding with the cured resin structure. FT-IR analysis proved the successful synthesis of ZDA and its polymerization with MMA to form copolymer poly (methyl methacrylate-co-zinc acrylate) copolymer. The addition of AA resulted in a copolymer poly (methymathacrylate-co-acrylic acid) but failed to conjugate the ZnO to the resin matrix. Conclusion: The addition of an inactivated ZnO or a thermally activated ZnO powders appear to be just incorporation of a filler without changing the PMMA structure, while the addition of AA or ZDA result in copolymers with PMMA. The method in which the ZDA was added to the heat cured acrylic resin could be considered as a new way of chemical bonding or engagement of Zn ions to acrylic structure to produce a new enhanced denture bases. Keywords: Acrylic acid, Acrylic resin, Denture base, FT-IR spectroscopy, ZnO, Zinc diacrylate. INTRODUCTION The selection of materials for the construction of dentures is crucial because this directly relates to the performance and life span of the appliance during service in the oral cavity [1] . However, it was in 1937, “Dr. Walter Wright” introduced PMMA material as denture base material and it was found to be the most superior material over all other denture base materials [2,3] . It is a combination of advantages rather than one excellent aspect that accounts for its wide usage [4] , including its popularity in satisfying aesthetic demands, its ease of processing, low cost, light weight, low water sorption and solubility; and ability to be repaired easily [1,5-7] . However, it has certain drawbacks like residual monomer allergy, inferior mechanical strength, brittleness, relatively low modulus of elasticity, low thermal conductivity, high coefficient of thermal expansion, thermal shrinkage, porosity, crazing, war page, poor adhesion to metal and porcelain and requirement of mechanical retention makes it more prone to failure during the clinical service [1,4,5,8] . Generally, there are three ways which have been investigated to improve the mechanical properties of denture bases; development of an alternative material to PMMA, reinforcement of PMMA with stronger materials and chemical modification of PMMA [9] . The reinforcement of polymers used in dentistry with metal-composite systems has been a prime interest [10] . The essential requirement for obtaining reinforced acrylic resin material with desiring mechanical properties is good adhesion between reinforcements and acrylic matrix [11] . In addition, the size of metal oxide particles should be small for better dispersion and proper processing [12] .