Objective      To determine the effect of sodium ascorbate hydrogel on the shear bond strength of enamel to composite resin after Beyond cold-light bleaching.       Methods      According to random number table

80 specimens were divided into 8 groups (A: no bleaching; B: bleaching

no sodium ascorbate hydrogel; C1-3/D1-3: bleaching and application of 10%/20% sodium ascorbate hydrogel for 30

60

and 180 min

respectively

n=10). Specimens were bonded with a total etch bonding system and composite resin. They were tested for shear bond strength (SBS). Adhesive remnant index (ARI) were analyzed for optimal concentration of sodium ascorbate hydrogel and reaction time.       Results      SBS of group B were significantly lower than the unbleached group (group A

P0.05). Sodium ascorbate hydrogel application following bleaching increased the resin-enamel bond strength. There were obvious differences between C2

3/D2

3 and B/C1/D1（P0.05）

while there was no statistic  significance between C2 and C3

D2 and D3

C2 and D2

and C3 and D3（P0.05）. While in ARI test

there were obvious difference between group A and the other groups（P0.05）.        Conclusion      Shear bond strength of enamel to composite resin after Beyond cold-light bleaching could be enhanced obviously with the application of 10% sodium ascorbate hydrogel for 60 min.