Available online at www.ijmrhs.com I n t e r n a t i o n a l J o u r n a l o f M e d i c a l R e s e a r c h & H e a l t h S c i e n c e s • I J M R H S • International Journal of Medical Research & Health Sciences, 2019, 8(3): 59-72 59 ISSN No: 2319-5886 ABSTRACT Mechanical properties (impact strength, compressive strength and fexural strength) have been studied for (Polymethyl-methacrylate (PMMA)) polymer reinforced with nano (TiO 2 +ZnO) (0 v%, 1 v%, 2 v%, 3 v%, 4 v% and 5 v%). Ultrasonic dispersion technique was used to prepare the nanocomposites samples, follow with cold casting technique using Tefon molds standard conditions. Charpy impact instrument was used to measure the impact strength, the compressive strength of each sample which was tested in newton units using digital compression tester (TinusOlsen: H50KT, England), while fexural strength can be found from mathematical formulas which depend on the impact strength, compressive strength and fexural strength. Results show that values increase in 1 v%, then decrease alternately by (2 v%, 3 v%, 4 v%, and 5 v%), while 0 v% is the less value of volume fraction of fllers. Young modules values increase alternately by the volume fraction of fllers until 2 v%, while if it is higher and lower than 2 v% it decreases the modulus of elasticity. Keywords: Polymethyl-methacrylate (PMMA), Polymer nano-composites, Impact strength, Compressive strength, Flexural strength, Young modules, Dentures Mechanical Characteristics of (TiO 2 -ZnO)/PMMA Nanocomposites for Dentures Warqaa A. Shakir 1 , Mithaq R. Mohammed 2 * and Israa H. Hilal 1 1 Solar Energy Research Center, Renewable Energy Directorate, Higher Education and Scientifc Research Ministry, Baghdad, Iraq 2 Al-Iraqia University, College of Dentistry, Baghdad, Iraq *Corresponding e-mail: mithaqalzuhairy@gmail.com INTRODUCTION Many modern technologies require materials with unusual combinations of properties that cannot be met by conventional metal, ceramics, alloys, and polymeric materials [1]. The most extensively used material for the fabrication of dentures is PMMA acrylic resin, as it possesses a combination of favorable characteristics such as light weight, fabrication is inexpensive, lack of toxicity, stability in the oral environment and appropriate aesthetic and color matching ability [2]. However although it does not ideal in every aspect; and has several drawbacks that need to be addressed including low impact resistance, low thermal conductivity which compromises the patient assessment of taste and palatability [3]. Many attempts have been made to overcome these defects and improve the performance of PMMA denture matrix material either by modifying the structure of PMMA or by copolymerization with rubber or reinforcement by incorporation of different forms and types of fllers like metallic wire, fbers and the use of metallic oxides [4- 7]. Great attention is directed towards the use of nano-sized fllers with the development of nanotechnology and nano-phased materials to reinforce the denture base resins thus producing a polymer nano-composite with improved physical and mechanical properties as compared to those flled with micro-scale particles [8]. Generally, the term composite is utilized to materials that are created mechanically by bonding two or more different materials together. The resulting materials have characteristics that are different from the characteristics of the component in isolation [9], the use of multiple nano-fllers rather than single additive develops a high performance composite which cannot be achieved by using single fller [10]. Polymer nano-composites have achieved great interest as high-performance structural materials this is due to their dimensional stability with high strength to stiffness ratio [11]. Liu, et al., found that TMSPM had remarkable effectiveness on the mechanical properties of the composites due to the improvement of interfacial adhesion between fller and matrix with better dispersion of the modifcated particles in the matrix.