Abstract
OBJECTIVES: 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). SIGNIFICANCE: 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.
