The Effect of Magnesium Oxide (MgO) Nano-Fillers on the Antibacterial Activity and Some Properties of Heat Cured Acrylic Resin

The effect of magnesium oxide (MgO) Nano-Fillers on the antibacterial activity and some properties of heat cured acrylic resin Thoalnorain A. Shakir, B. D. S.1, Shorouq M. Abass, B. D. S. , M. Sc.2 1 Master Student. Department of Prosthodontics, College of Dentistry, University of Baghdad.2 Assistant Professor, Department of Prosthodontics, College of Dentistry, University of Baghdad. Background Polymethyl methacrylate (PMMA) resins were mostly used in fabrication of removable dentures. They supports microbial colonization and biofilm formation on its surface, which is a crucial step for various oral infections. The aim of the current study was to investigate the effect of MgO nanoparticles by using incorporation and immersion technique at different duration and percentages on the Staphylococcus aureus colony forming unites (CFU) and some properties of heat cured acrylic denture base material. Materials and methods two techniques (immersion and incorporation) were used to introduce nanosized MgO powder to heat cured acrylic resin. MgO nanoparticles solution was prepared from the addition of 7 % of unmodified nanoparticles by weight to 50 ml of normal saline.1.5 % of MgO nano fillers were incorporated into heat cured acrylic to obtain PMMA/ MgO nanocomposite. The antibacterial activity of 7 % MgO nanoparticles aqueous solution was evaluated at two different periods (10 and 30 minutes) by using colony forming unites (CFU) of Staphylococcus aureus. The impact strength of study specimens was measured by Charpy impact testing machine. Three point bending approach was performed to evaluate the transverse strength of test specimens. Surface roughness was conducted by profilometer device (portable roughness tester). Results the results of this study showed that the immersion of acrylic specimens in 7 % MgO nanoparticles solution for different periods led to a highly significant reduction in colony forming unites (CFU) of Staphylococcus aureus in comparison with the control group. In addition, a non-significant difference in impact strength, transverse strength and surface roughness was obtained by 30 minutes immersion in that solution, while a highly significant difference was resulted from the incorporation of 1.5 % of unmodified MgO nano particles when compared with control group. Conclusion immersion in 7 % MgO nanoparticles solution was significantly effective in reducing the growth of Staphylococcus aureus on heat cured acrylic resin, with insignificant effect on the impact strength, transverse strength and surface roughness. MgO Nano particles, heat cured acrylic, Staphylococcus aureus.1. Introduction Polymethyl methacrylate (PMMA) resins were mostly used in fabrication of removable dentures. The popularity and universal use of PMMA based resin as a denture base material comes from its ease of processing and reparability, low coast, lightweight, biocompatibility, low water solubility and sorption, excellent aesthetic appearance [1] and accuracy of fit [2]. However, it still far from fulfilling all the criteria of ideal denture base material and have several drawbacks such as the susceptibility to microbial colonization and biofilm formation on its surface making the denture a harbor of microorganisms and source of various infections [3]. Moreover, effective biofilm removal requires a degree of manual dexterity that is often lacking among older individuals [4]. Over the years, many researches have focused on ways to improve the antimicrobial activity of PMMA based rein via surface and chemical modification. These studies led to development of new denture polymers with suitable mechanical and physical properties that include anionic PMMA polymers [5]. While, a number of studies have been conducted to establish an intra-oral drug delivery system through the incorporation of certain antifungal or antimicrobial agents into acrylic resin [6]. Metal oxide nanoparticles have been extensively used in different industrial and biomedical applications due to their unique properties [7]. Among the most known nanometals, much attention have been focused on magnesium oxide nanoparticles because of their antibacterial activity against various pathogens [8, 9]. The present study was conducted to investigate the effect of incorporation and immersion MgO nanoparticles at different percentage and durations on the colony forming unites (CFU) of Staphylococcus aureus and also on the impact strength, transverse strength and surface roughness of heat cured acrylic denture base material.2. MATERIALS AND METHODS One hundred thirty (130) specimens were fabricated to be used in this study.40 specimens were prepared from heat cured acrylic to evaluate the antibacterial activity of 7 % MgO nanoparticles aqueous solution in two different periods (10 and 30 minutes) and divided into 4 groups, 2 groups for each selected period. Impact strength, transverse strength and surface roughness were then evaluated by the constr