title: Surface roughness of polyvinyl siloxane impression materials following chemical disinfection, autoclave and microwave sterilization.
abstract: BACKGROUND
  Autoclave sterilization and microwave sterilization has been suggested as the effective methods for the disinfection of elastomeric impressions, but subjecting elastomeric impressions to extreme temperature may have adverse effects on critical properties of the elastomers.
  
  
  OBJECTIVE
  To evaluate the effect of chemical disinfection as well as autoclave and microwave sterilization on the surface roughness of elastomeric impression materials.
  
  
  METHODS
  The surface roughness of five commercially available polyvinyl siloxane impression materials (Coltene President, Affinis Perfect impression, Aquasil, 3M ESPE Express and GC Exafast) were evaluated after subjecting them to chemical disinfection, autoclaving and microwave sterilization using a Talysurf Intra 50 instrument. Twenty specimens from each material were fabricated and divided into four equal groups, three experimental and one control (n=25). The differences in the mean surface roughness between the treatment groups were recorded and statistically analyzed.
  
  
  RESULTS
  No statistically significant increase in the surface roughness was observed when the specimens were subjected to chemical disinfection and autoclave sterilization, increase in roughness and discoloration was observed in all the materials when specimens were subjected to microwave sterilization.
  
  
  CONCLUSIONS
  Chemical disinfection did not have a significant effect but, since it is less effective, autoclave sterilization can be considered effective and autoclaving did not show any specimen discoloration as in microwave sterilization. Microwave sterilization may be considered when impressions are used to make diagnostic casts. A significant increase in surface roughness may produce rougher casts, resulting in rougher tissue surfaces for denture and cast restorations.
  
  
  CONCLUSIONS
  Autoclave sterilization of vinyl polysiloxane elastomeric impressions for 5 minutes at 134°C at 20 psi may be considered an effective method over chemical disinfection and microwave sterilization, because chemical disinfection does not eliminate all disease-causing microorganisms and microwave sterilization leads to a rougher impression surface.
authors.affiliation: Associate Professor, Department of Dental Health, Dental Biomaterials Research Chair, College of Applied Medical Science, King Saud University, Riyadh, Saudi Arabia, Phone: (966) 554299995, Fax: (966) 014355883, e-mail: aalkhuraif@ksu.edu.sa.
authors.forename: Abdulaziz Abdullah
authors.initials: AA
authors.lastname: Al Kheraif
mesh_terms: D003116:Color; D003407:Creosote / Q000737:chemistry; D019551:Dental Disinfectants / Q000737:chemistry*; D003760:Dental Impression Materials / Q000737:chemistry*; D004203:Disinfection / Q000379:methods*; D004338:Drug Combinations; D020724:Elastomers / Q000737:chemistry; D005566:Formocresols / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D006847:Hydrocarbons, Iodinated / Q000737:chemistry; D008422:Materials Testing; D008872:Microwaves / Q000627:therapeutic use*; D011145:Polyvinyls / Q000737:chemistry*; D011312:Pressure; D012828:Silicones; D012833:Siloxanes / Q000737:chemistry*; D013242:Sterilization / Q000379:methods*; D013499:Surface Properties; D013943:Thymol / Q000737:chemistry; D013997:Time Factors
chemical_list: D019551:Dental Disinfectants; D003760:Dental Impression Materials; D004338:Drug Combinations; D020724:Elastomers; D005566:Formocresols; D006847:Hydrocarbons, Iodinated; D011145:Polyvinyls; D012828:Silicones; D012833:Siloxanes; C480691:aquasil; C118335:president, silicone impression material; C034183:vinyl polysiloxane; D013943:Thymol; D003407:Creosote; C034472:Septodont