Opalescence pf 10

In this in vitro study, twenty-two unused Invisalign aligners (Santa Clara, CA, USA) were used to prepare 144 specimens to test four physical properties: tensile strength, hardness, surface roughness, and translucency. To test each physical property, the specimens were allocated into four groups (Figure 1): a testing group at baseline (TG1, n= 12), a testing group after 2 weeks of dental bleaching (TG2, n = 12), a control group at baseline (CG1, n = 12), and a control group after 2 weeks of immersion in distilled water (CG2, n = 12). Specimens in CG1 and TG1 were immediately tested, while specimens in CG2 were stored in an incubator in distilled water at 37 °C for 2 weeks to simulate oral conditions. Next, specimens in TG2 were bleached using 10% carbamide peroxide (Opalescence PF 10%, Ultradent Products, New York City, NY, USA), which was applied on the internal surfaces of the specimens for 8 h a day at 37 °C, then wiped off; the specimens were kept in distilled water at mouth temperature in the incubator for 16 h. This process was repeated every day for 2 weeks before the specimens in TG2 were tested. This means that the 10% carbamide peroxide bleaching material was applied on the Invisalign specimens for a total of 112 h (8 h/day × 14 days) in TG2. The sample size was calculated according to other studies [19 (link),20 (link),21 (link)].