title: A comparison of the mechanical properties of a gallium-based alloy with a spherical high-copper amalgam.
abstract: OBJECTIVE
  The aim of the present study was to investigate how the mechanical properties of a palladium free gallium-based alloy (Galloy) compare with a leading spherical high-copper amalgam (Tytin).
  
  
  METHODS
  Cylindrical specimens were mechanically condensed, according to the ISO 1559:1986 standard, to measure compressive strength, Vickers hardness, static creep and dimensional change on setting. Disc and beam shaped specimens were manually prepared to assess the diametral tensile and flexural strengths of the investigated alloys.
  
  
  RESULTS
  The mean hardness, 1h compressive fracture strength, 24 h diametral tensile and 24h flexural strengths of Galloy were significantly lower (P<0.001) than Tytin. No significant differences in modulus of elasticity, creep, dimensional change on setting, 24 and 168 h compressive fracture strength for the two alloys were identified.
  
  
  CONCLUSIONS
  The significant reduction in the 1 h mean compressive fracture strength and hardness identified for Galloy compared with Tytin possibly indicate a slower setting reaction in the gallium-based alloy. Manual condensation of the gallium-based alloy produced specimens with inferior mechanical properties possibly due to the increased likelihood of introducing voids within the test specimens. Previous reports indicating poor corrosion resistance and moisture sensitivity of gallium-based alloys highlight the need for further research to investigate the effect of the oral environment on the gallium-based alloy.
authors.affiliation: School of Dentistry, St. Chad's Queensway, B4 6NN, Birmingham, UK. den5fjs6@hotmail.com
authors.forename: F J
authors.initials: FJ
authors.lastname: Shaini
authors.forename: G J
authors.initials: GJ
authors.lastname: Fleming
authors.forename: A C
authors.initials: AC
authors.lastname: Shortall
authors.forename: P M
authors.initials: PM
authors.lastname: Marquis
mesh_terms: D019245:Compressive Strength; D003300:Copper / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry*; D004548:Elasticity; D005708:Gallium / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D016062:Porosity; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D003722:Dental Alloys; C100747:Galloy; D014867:Water; C036886:tytin; D003300:Copper; D003723:Dental Amalgam; D005708:Gallium