title: [Comparison of the failure mode of various types of glass ionomer cements].
abstract: OBJECTIVE
  To investigate the failure mode of various types of glass ionomer cements by Hertzian indentation test.
  
  
  METHODS
  Discs of 10 mm diameter and 2 mm thickness were prepared for six glass ionomer cement products (A-D: conventional type setting through an acid-base chemical reaction, A and B without reinforcement, C with silver reinforcement, D with ceramic reinforcement; E and F: resin-modified type), ten for each. These were tested on top of glass-reinforced polyamide-nylon 6, 6 substrates by a universal testing machine, loading centrally with a 20 mm diameter ball. Load at the first crack was recorded. Failure mode was observed under scanning electron microscope.
  
  
  RESULTS
  The former four products presented typical brittle fracture, while the latter two usually fractured incompletely. The failure loads at the first crack of the six glass ionomer cements were (258.86 +/- 10.49), (230.88 +/- 21.66), (281.90 +/- 25.39), (282.11 +/- 9.60), (756.67 +/- 83.50) and (1 148.00 +/- 147.78) N, respectively. Significant difference was found between the former four and the latter two products.
  
  
  CONCLUSIONS
  The type (setting mode) of glass ionomer cement controls its failure mode. Inclusion of metallic or ceramic filler has little effect on increasing the load bearing capacity of glass ionomer cement.
authors.affiliation: Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510055, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Xin-chun
authors.initials: XC
authors.lastname: Zhang
authors.forename: B W
authors.initials: BW
authors.lastname: Darvell
mesh_terms: D019245:Compressive Strength; D003776:Dental Porcelain / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D012117:Resins, Synthetic / Q000737:chemistry; D012834:Silver / Q000737:chemistry
chemical_list: D005899:Glass Ionomer Cements; D012117:Resins, Synthetic; D003776:Dental Porcelain; D012834:Silver