fa Effect of a Combined Bleaching Regimen on the Microhardness of a Sealed Methacrylate-based and a Silorane-based Composite ترمیمی Cosmetic and Restorative Dentistry پژوهشي Research <p> <strong>Statement of Problem:</strong> The use of tooth bleaching agents has been very popular treatment in dentistry. The bleaching agents have an inherent potential to impair surface properties of existing composite resin restorations. </p><p> <strong>Purpose:</strong> This study evaluated the effect of a combined bleaching regimen on the surface microhardness of a Silorane-based and a sealed methacrylate-based composite. </p><p> <strong>Materials and Method</strong>: Forty-five specimens of methacrylate-based composite (Ice) and 18 specimens of Silorane composite (Filtek Silorane, 3M ESPE USA) were prepared and randomly divided into 5 (1-5) and 2 (6-7) groups (n=9), respectively. After 8-week aging, groups 1 and 6 were remained with no treatment. In groups 2, 4 and 5, the specimens were covered by a surface sealant and light cured. In groups 3, 4, 5 and 7, the specimens were bleached with hydrogen peroxide 40% and then carbamide peroxide 20% for seven days. In group 5, after bleaching, the sealant was removed by polishing. Surface microhardness was measured and the data were analyzed using one-way ANOVA and Tukey tests (α=0.05). </p><p> <strong>Results:</strong> The microhardness values of groups 2 to 4 were significantly lower than that of group1 (p <0.05). There was no significant difference among groups 1, 5, 6 and 7 (p> 0.05). </p><p> <strong>Conclusion:</strong> The combined bleaching regimen used in this study had a substantial negative effect on methacrylate and sealed methacrylate composites but not on Silorane composite. Polishing following the bleaching on the sealed composite yielded a hardness value similar to that of unsealed methacrylate composite (control). </p><hr><p></p><p> <strong>Source: </strong>Journal of Dentistry Shiraz University of Medical Sciences</p><p> <a href="http://dentjods.sums.ac.ir/index.php/JDSUMS/article/view/5" target="_blank"><font color="#0000ff">Full Text</font></a></p> 0 0 http://idai.ir/browse.php?a_code=A-10-32-2415&slc_lang=fa&sid=1 F. Shafiei 100319475328460011443 100319475328460011443 No Dept. of Operative Dentistry, Biomaterial Research Center, School of Dentistry, Shiraz University of Medical Science, Shiraz, Iran S. Doustfatemeh sam_dft@yahoo.com 100319475328460011444 100319475328460011444 Yes Undergraduate Student, School of Dentistry, Shiraz University of Medical Science, Shiraz, Iran