Effects of different bleaching application durations on enamel in terms of tooth color, microhardness, and surface roughness

Abstract The aim of this research was to assess the color differences (∆ E 00 ), Vickers microhardness, whiteness index, and surface roughness values of different durations of bleaching the enamel. One hundred and eight teeth were utilized for color evaluation, roughness, and microhardness (n = 36). Teeth were assigned to three groups (n = 12) based on the durations of the bleaching application. Bleaching agent was applied for 20 minutes in group 1, 40 minutes in group 2, and 60 minutes in group 3. The color was measured with a Vita Easyshade Advance 4.0 spectrophotometer before applying the bleach, and 24 hours, 7, and 14 days after bleaching application. The CIEDE2000 and whiteness index for dentistry values were calculated. The microhardness and surface roughness values were obtained before application and 7 and 14 days after application. Data were analyzed using two‐way ANOVA and post‐hoc LSD tests Group 3 had the largest color and whiteness changes. The whiteness index for dentistry values were statistically significantly increased, considering baseline measurements within all groups ( P < .05). For the Vickers micohardness values, in group 3, a statistically significant difference was observed among baseline, and 7 days after application ( P < .05). However, the surface roughness values showed no significant difference in any measurement ( P > .05). According to this research in all groups, effective whitening was accomplished. Based on the results evaluated for whiteness, color alteration, microhardness, and roughness, the optimal bleaching duration of application was in 40 minutes.