en ترمیمی Cosmetic and Restorative Dentistry پژوهشي Research <p> <strong>Background:</strong> The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfi l AP-X, Gradia Direct) and fi ve nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. </p><p> <strong>Materials and Methods</strong>: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L*a*b* system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab*) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). </p><p> <strong>Results:</strong> All specimens showed a signifi cant increase in staining with a similar trend and no signifi cant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both signifi cant and unsignifi cant differences of the h index. </p><p> <strong>Conclusions:</strong> Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested. </p><hr><p></p><p> <strong>Source: </strong>Dental Research Journal</p><p><a href="http://drj.mui.ac.ir/index.php/drj/article/view/885" target="_blank"><font color="#0000ff"> Full Text</font></a></p> Bleaching, composite resin, surface discoloration 0 0 http://idai.ir/browse.php?a_code=A-10-32-1070&slc_lang=en&sid=1 Claudio Poggio claudio.poggio@unipv.it 10031947532846004653 10031947532846004653 Yes Departments of Operative Dentistry, 2Orthodontics, University of Pavia, Italy Riccardo Beltrami 10031947532846004654 10031947532846004654 No Departments of Operative Dentistry, 2Orthodontics, University of Pavia, Italy Andrea Scribante 10031947532846004655 10031947532846004655 No Orthodontics, University of Pavia, Italy Marco Colombo 10031947532846004656 10031947532846004656 No Departments of Operative Dentistry, 2Orthodontics, University of Pavia, Italy Marco Chiesa 10031947532846004657 10031947532846004657 No Departments of Operative Dentistry, 2Orthodontics, University of Pavia, Italy