Background/Objectives: This study aimed to compare the effects of two bleaching techniques—light-activated (Zoom) and laser-activated—on the surface roughness of nanohybrid and microhybrid composites, using atomic force microscopy (AFM) for topographic evaluation. Methods: Sixty composite resin discs were fabricated, with 30 nanohybrid and 30 microhybrid samples. Each type was divided into three subgroups: control, Zoom bleaching, and laser bleaching (n = 10 per group). Zoom bleaching employed 40% hydrogen peroxide activated by Philips Zoom light, while laser bleaching used a diode laser (940 nm) with QuickLase gel. Surface roughness parameters (Sa, Sq, Sz) were measured using AFM, and statistical analysis was performed. Results: Both bleaching protocols increased surface roughness compared to controls. Microhybrid composites showed higher roughness after Zoom (103.12 ± 19.25 nm) and laser bleaching (106.16 ± 25.21 nm), while nanohybrid composites had lower values after Zoom (57.77 ± 13.88 nm) and laser (78.13 ± 23.29 nm). Significant differences were found between composite types post-bleaching (p 0.001 for Zoom; p = 0.019 for laser). However, differences between bleaching methods within the same composite were not significant. Conclusions: Both Zoom and laser bleaching negatively affect composite surfaces, with laser showing a greater impact. Nanohybrid composites demonstrated superior resistance to surface alteration, suggesting better clinical durability. These results highlight the importance of material selection when bleaching patients with existing composite restorations.
Fadhil et al. (Thu,) studied this question.
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