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Color change and fracture resistance of two preveneered stainless-steel crowns after sterilization.

PURPOSE
This study compared the fracture resistance and color stability of two commercially available, preveneered stainless-steel crowns before and after four sterilization techniques.


METHODS
Thirty-five crowns from each of two manufacturers were divided into five groups. Four groups were sterilized twice using one of the following techniques: steam autoclave at both 121 degrees C (15 PSI) for 20 min and 132 degrees C (30 PSI) for 8 min; Chemiclave with formaldehyde at 132 degrees C for 20 min; and 2% gluteraldehyde for 10 h. The fifth group from each manufacturer was the control. Color of facings was measured before and after each sterilization in triplicate using a colorimeter, and the variance of each color parameter was analyzed for significance. Fracture resistance was measured for each group and differences between the control and experimental groups analyzed for significance.


RESULTS
The results of this study show that high heat and chemical sterilizations have little effect on color and fracture resistance of the preveneered stainless-steel crowns. Student's t test analysis revealed a significantly decreased resistance to fracture with Kinder Krowns sterilized in 2% gluteraldehyde. Chemiclave sterilization caused the most negative color change in all three color parameters measured for both types of crowns.


CONCLUSIONS
As neither steam technique produced significant changes in fracture resistance or color changes that were clinically detectable, the results of this study indicate that the two steam techniques tested can be used by clinicians to sterilize either Kinder Krowns or Nu Smile preveneered stainless-steel crowns.