title: The effect of repeated microwave irradiation on the dimensional stability of a specific acrylic denture resin.
abstract: OBJECTIVE
  To determine the dimensional stability of a poly(methyl methacrylate) (PMMA) acrylic resin when subjected to multiple sessions of repeated microwave irradiation at power settings of 700 and 420 W.
  
  
  METHODS
  Twenty standardized denture bases were fabricated using a PMMA resin. Points of measurement were marked on each denture base with a standardized template, and the distances between points were recorded using a digital microscope. The denture bases were randomly placed into two experimental groups of 10 bases each. Individual denture bases were placed into a glass beaker containing 200 ml of room temperature deionized water and then exposed to either 700 or 420 W of microwave radiation for 3 minutes. The denture bases were allowed to cool to room temperature, and measurements between points were recorded. This process was carried out for two microwave periods with measurements being completed after each period. The data were then analyzed for any significant changes in distances between points using a Student's t-test.
  
  
  RESULTS
  All denture bases experienced 1.0 to 2.0 mm or approximately 3% linear dimensional change after each period of microwaving. Results were significant with all t-tests having values of p < 0.05.
  
  
  CONCLUSIONS
  This report showed that the denture bases deformed significantly under experimental conditions at either 700 W for 3 minutes in 200 ml of water or 420 W for 3 minutes in 200 ml of water.
authors.affiliation: Former Prosthodontic Resident, University of Pittsburgh, School of Dental Medicine, Pittsburgh, PA.
authors.forename: David A
authors.initials: DA
authors.lastname: Wagner
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Pipko
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects* / Q000627:therapeutic use; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects* / Q000627:therapeutic use; D003819:Denture Bases; D003778:Dentures; D006801:Humans; D008872:Microwaves; D019904:Polymethyl Methacrylate / Q000737:chemistry / Q000528:radiation effects / Q000627:therapeutic use
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D019904:Polymethyl Methacrylate
keywords: Heating; complete; dental; prosthesis; warpage