Aim: This study evaluated the infl uence of 20% sodium ascorbate (SA) and 10% ascorbic acid (AA) hydrogels on the microleakage of class V composite restorations after an offi ce bleaching protocol (B). Methods: Sixty bovine incisors were sectioned at one point extending 8 mm from the amelodentinal junction toward the incisal edge, and at a second point extending 2 mm from the amelodentinal junction toward the root apex. Root canals were sealed with a composite and the teeth were divided into 5 groups. In Group C (control group), the teeth were prepared (P; 4 × 3 mm depth × diameter; diamond bur 3131, KG Sorensen), etched, rinsed (ER), submitted to an adhesive system protocol (Ambar, FGM), and restored (R) with a microhybrid composite (Opallis, FGM); In Group IR, the teeth were bleached (B; 2 sessions, 1 week interval, 35% hydrogen peroxide, Whitness HP Blue, FGM) + P + ER + R; In Group SA, teeth were B + P + SA (20%/15 minutes) + ER + R; In Group AA, teeth were B + P + AA (10%/15 minutes) + ER + R; and in Group MR, the teeth were B + stored in water (37°C/14 days) + P + ER + R. Specimens were submitted to an aging process by thermocycling (5 × 10 4 cycles of 5°C and 55°C with a dwelling time of 30 s), varnish-sealed, immersed in basic fuchsin (3 h), washed and sectioned with a diamond disc. Microleakage was measured with the aid of ImageTool  software. ANOVA and Tukey's post hoc test (p < 0.05) were applied. Results: Microleakage (mm) and standard deviations per group were as follows: C, 0.29 (0.06) A ; IR, 1.86 (0.15) C ; SA, 1.08 (0.09) B ; AA, 1.07 (0.10) B ; MR, 1.02 (0.12) B . Conclusions: Bleached teeth submitted to superfi cial treatment with 20% SA and 10% AA applied for 15 minutes prior to restoration presented reduced microleakage, as compared to immediately restored bleached teeth. Use of these antioxidants led to a microleakage comparable to that observed after a waiting period of 14 days prior to restoration. Dental Materials; Dental Leakage; Tooth Bleaching.Efeito de hidrogéis de ascorbato de sódio e ácido ascórbico na microinfi ltração de restaurações de resina composta realizadas após aplicação de um protocolo de clareamento em consultório • Objetivo: Este estudo avaliou a infl uência da utilização de hidrogéis de ascorbato de sódio (SA) e ácido ascórbico (AA) na microinfi ltração de restaurações classe V de resina composta realizadas após a aplicação de um protocolo de clareamento em consultório (B). Métodos: Sessenta incisivos bovinos foram seccionados a 8 mm da junção amelodentinária em direção incisal e a 2 mm em direção ao ápice radicular. Os canais radiculares foram selados com um compósito e os dentes foram divididos em 5 grupos: no grupo C (controle), os dentes foram preparados (P; 4 × 3 mm profundidade × diâmetro; ponta diamantada 3131, KG Sorensen), condicionados, lavados (ER), submetidos a um protocolo adesivo (Ambar, FGM) e restaurados (R) com uma resina composta microhíbrida (Opallis, FGM); no grupo IR, os dentes foram clareados (B; 2 sessões, 1 semana de intervalo, peróxido de hidr...