title: Nanoindentation and surface roughness profilometry of poly methyl methacrylate denture base materials.
abstract: OBJECTIVE
  Polymers have a wide range of applications in dentistry. Poly methyl methacrylate (PMMA) is the most popular for making orthodontic retainers, dentures as well as synthetic teeth. Prior to clinical applications, the appliances are polished in the dental laboratory to achieve smooth, polished and comfortable surfaces. The objective of this study was to analyze the surface roughness profiles of PMMA dentures polished using two different approaches. In addition, the effects of ultrasonication and sandblasting were also evaluated on the fitting surface of PMMA dentures.
  
  
  METHODS
  This was an in vitro study using non-contact mode surface roughness profilometer and nano-indenter. Samples were polished using two different techniques (Standard and modified). Both cold cure and heat cure PMMA denture surfaces were evaluated for roughness, nanohardness and elastic modulus.
  
  
  RESULTS
  The absolute hardness was recorded 297.72±19.04 MPa and 229.93±18.53 MPa for heat cured PMMA and cold cured PMMA. Manufactured acrylic teeth were harder (319.20±12.58 MPa) with an elastic modulus of (4.34±1.86 GPa). Modified polishing techniques (group 3) produced smoother surface.
  
  
  CONCLUSIONS
  It was concluded that elastic moduli of acrylic tooth and heat cure PMMA is not very different. Surface treatments such as ultrasonication or sandblasting do not affect the roughness profiles of denture fitting surfaces.
authors.affiliation: College of Dentistry, Taibah University, Madinah Al Munawwarah, Saudi Arabia.
authors.forename: Muhammad Sohail
authors.initials: MS
authors.lastname: Zafar
authors.affiliation: Department of Mechanical Engineering, College of Engineering, Taibah University, Madinah Al Munawwarah, Saudi Arabia.
authors.forename: Naseer
authors.initials: N
authors.lastname: Ahmed
mesh_terms: D003764:Dental Materials; D003775:Dental Polishing / Q000379:methods; D003819:Denture Bases; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing / Q000379:methods*; D019904:Polymethyl Methacrylate
chemical_list: D003764:Dental Materials; D019904:Polymethyl Methacrylate
keywords: Elastic modulus; fitting surface; polishing; sand blasting