title: Compressive strength of two newly developed glass-ionomer materials for use with the Atraumatic Restorative Treatment (ART) approach in class II cavities.
abstract: OBJECTIVE
  The null-hypotheses tested were that no difference in compressive strength of ART class II cavities exists between those restored with (1) glass-carbomer and a commonly used glass-ionomer; (2) KMEM and the commonly used glass-ionomer and; (3) glass-carbomer and KMEM.
  
  
  METHODS
  100 molar teeth, stratified by size, were randomly allocated to the four test groups. Large ART class II cavities were drilled and restored with Clearfil photoposterior (negative control), Fuji IX (positive control), Glass-carbomer and Ketac Molar Easymix (KMEM) (experimental groups). Half of the samples in each test group were 5000 times thermocycled between 5 degrees C and 55 degrees C, with a 30s dwell time in each bath and a transfer time of 10s. The restorations were statically tested at the marginal ridge until failure, using a rounded rectangular testing rod at crosshead speed of 1.0mm/min. ANOVA and Student's t-test were applied to test for differences between the dependent variable (compressive strength at the final breaking point) and the independent variables (thermocycling and restorative material).
  
  
  RESULTS
  Restorations of Clearfil photoposterior had a statistically significant higher mean compressive strength value at final breaking point than those of the three glass-ionomers tested (p=0.0001). No thermocycling effect was observed (p=0.19). ANOVA between the three glass-ionomer materials and mean compressive strength at final breaking point showed no statistically significant difference (p=0.09).
  
  
  CONCLUSIONS
  Class II ART cavities restored with the newly launched Glass-carbomer and Ketac Molar Easymix were not significantly more fracture resistant than comparable restorations using the conventional glass-ionomer Fuji IX.
authors.affiliation: Department of Preventive and Restorative Dentistry, Radboud University Nijmegen Medical Centre, College of Dental Sciences, Nijmegen, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Koenraads
authors.forename: G
authors.initials: G
authors.lastname: Van der Kroon
authors.forename: J E
authors.initials: JE
authors.lastname: Frencken
mesh_terms: D000180:Acrylic Resins; D019245:Compressive Strength; D003737:Dental Cavity Preparation / Q000379:methods*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements; D006801:Humans; D008963:Molar
chemical_list: D000180:Acrylic Resins; D005899:Glass Ionomer Cements; C515713:Ketac Molar Easymix; C479038:carbomer