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Indonesian Journal of Dentistry 2006; Edisi Khusus KPPIKG XIV: 288-293ln dental bleaching, carbamide peroxide is usually used at concentration of 10%, 15%, to 20%. The result of our previous study showed that the application of l0% and 15% carbamid peroxide bleaching agent has increased the surface hardness of glass ionomer cement. The purpose of this study was to observe the effect of 20% carbamide peroxide bleaching to glass ionomer surface hardness. Twenty specimens of glass ionomer cement type II after exposed to 20% carbamide peroxide were divided into two application time group: 4 and 8 hours per day. Glass ionomer cement surface hardness was measured by Vickers Microhardness Tester seri HMV-2 with a wieght 0,025 Hv for 20 second. The measurement was conducted at before/no application, a week after application, and 2 weeks after the application bleaching agent. The one way analysis of variance showed a significant difference of surface hardness of GIC type II between before/no application, after a week, and after 2 weeks application in both group. t can be concluded that the application of 20% carbamide peroxide bleaching agent could increase the surface hardness of glass ionomer cement after 1 week and 2 week application periode. |
