EFFECT OF CARBAMIDE PEROXIDE AND HYDROGEN-PEROXIDE ON THE SURFACE-MORPHOLOGY AND ZINC-OXIDE LEVELS OF IRM(R) FILLINGS

The effect of 10% carbamide peroxide or 10% hydrogen peroxide on the s urface morphology and zinc oxide levels of IRM fillings was tested. Ni nety IRM samples were treated with either 10% carbamide peroxide, 10% hydrogen peroxide or phosphate buffer which served as control. Treatme nt consisted of placing the samples in a dry incubator at 37 degrees C for 1, 3 or 7 days. At each time point, the samples were removed from the test solutions, dried and prepared for surface scanning electron microscopy and energy dispersive spectrometric analysis. After 3 days, 10% carbamide peroxide significantly reduced the zinc oxide levels as compared to the 10% hydrogen peroxide group (p<0.01) and the controls (p<0.01). 10% hydrogen peroxide reduced the zinc oxide levels similar ily to the control. No significant changes in the zinc oxide levels we re found between 3 and 7 days in any of the groups tested. Microscopic examination of the carbamide peroxide group revealed granular surface with well defined crystalline areas. In the hydrogen peroxide group, numerous cracks with multiple sun burstlike areas were found. At the m acroscopic level, the samples of this group appeared cracked and more swollen, as compared to controls and samples treated with carbamide pe roxide. In conclusion, both 10% carbamide peroxide and 10% hydrogen pe roxide altered the surface morphology and the zinc oxide levels of IRM fillings, but their modes of action differed.