Industry Leading Esthetics AND Durability
Purpose: The purpose of this study was (1) to compare the load to failure of primary esthetic crowns that have been cycled under fatigue to an uncycled control group (2) to compare the differences in load to failure of zirconia crowns to an esthetic stainless steel crown (ESSC) and (3) to compare these loads with previously reported posterior occlusal forces.
Methods: Zirconia crowns and ESSC’s for the first primary mandibular molars were cemented to idealized epoxy dies with glass ionomer cement. The test groups underwent 50,000 load-cycles at 100-N in the Electropuls machine. All crowns were then fractured using a universal testing machine with a stainless steel ball fixture, set in a uniaxial lever. The 3 types of crowns were compared to the control group, in terms of load to failure, by means of 2-way ANOVA. Pairwise comparisons were performed with Fisher’s protected least significant differences.
Conclusions: Based on this study’s results, the following conclusions can be made:
1. All four groups of crowns (fatigued and control) tested were found to withstand forces greater than the posterior occlusal load range
documented by Braun and colleagues.
2. Crowns in the control group had a significantly higher load to failure than cycled crowns (p< 0.05).
3. EZ Pedo had a significantly lower load to failure than Kinder Krown (p< 0.05) and NuSmile (p< 0.05), and NuSmile had significantly lower load to failure than Kinder Krown (p= 0.03).
4. Further research is needed involving multiaxial forces, variations in temperature, variations in tooth preparation, and variations in chemical and moisture conditions in order to expand on current research to produce more clinically relevant results.
*Jamie L. Orrick, DDS, Resident – Indiana University/Riley Hospital for Children
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