title: Diametral tensile strength of two dental composites when immersed in ethanol, distilled water and artificial saliva.
abstract: OBJECTIVE
  To examine the effect of distilled water, artificial saliva and ethanol on the tensile strength of direct tooth-coloured restorative material.
  
  
  METHODS
  The study was conducted at Dr. Ishrat ul Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences (DUHS), Karachi, from April 2011 to September 2012. The testing was performed at the Pakistan Council of Scientific and Industrial Research (PCSIR) laboratories. Two composite resins Filtek Z250 and Spectrum TPH were tested. Specimens (13 mm x 3 mm x 2 mm) of each material were prepared in the stainless steel mould according to the manufacturers' instructions and distributed into 3 equal groups: one immersed in distilled water, the other in artificial saliva, and the last one in ethanol for 24 hours. Tensile strength was determined after 24 hours in universal Instron Testing Machine.
  
  
  RESULTS
  There were 72 specimens in all; 36 (50%) each for Filtek Z250 and Spectrum TPH. The three sub-groups in each case had 12 (33.3%) specimens. For the Filtek Z250, there was no statistically significant difference between immersion in distilled water and artificial saliva, but the ethanol group presented lower tensile strength (p<0.05). For the Spectrum TPH, samples immersed in ethanol and artificial saliva presented lower tensile strength compared to distilled water (p<0.05).
  
  
  CONCLUSIONS
  The tested composite resins were affected by the immersion media and adversely affected the mechanical properties of composite resins.
authors.forename: Abdur
authors.initials: A
authors.lastname: Rehman
authors.forename: Faiza
authors.initials: F
authors.lastname: Amin
authors.forename: Muhammad
authors.initials: M
authors.lastname: Abbas
mesh_terms: D003188:Composite Resins; D000431:Ethanol; D007101:Immersion; D008422:Materials Testing; D010154:Pakistan; D012464:Saliva, Artificial; D013718:Tensile Strength; D014867:Water
chemical_list: D003188:Composite Resins; C444701:Filtek Z250; D012464:Saliva, Artificial; C467914:TPH spectrum; D014867:Water; D000431:Ethanol