Effect of nonthermal atmospheric plasma, grape seed extract, and bromelain on immediate bonding of composite to bleached and microabraded surfaces

Background: Tooth whitening procedures such as bleaching and microabrasion alters the enamel surface and thus reduce the composites’ bond strength. Hence, various surface treatments were introduced to overcome this problem. Aim: To assess the effect of nonthermal atmospheric plasma (NTAP), grape seed extract (GSE) and bromelain on the shear bond strength (SBS) of the composite after bleaching and microabrasion. Materials and Methods: Eighty extracted maxillary anterior teeth were distributed into two groups. Group 1: bleaching and Group 2: Microabrasion and further subdivided into four subgroups (n = 10) based on the form of surface treatment employed. Group A: no surface treatment, Group B: bromelain, Group C: GSE, Group D: NTAP. Composite resin was bonded to the labial surface and placed in artificial saliva for 24 h. SBS testing was done for all the samples. Statistical Analysis: Analysis was performed using two-way analysis of variance and post hoc Tukey's test with P < 0.05 considered statistically significant. Results: Group 1D revealed the highest bond strength (35.4 Mpa) and Group 1A showed the least bond strength values (15.7 Mpa). Among the bleaching groups, significant difference was observed between all the subgroups except Group 1A and 1B (P = 0.972). In microabrasion group, significant difference was observed between Group 2A and 2D (P = 0.0001), Group 2B and 2D (P = 0.0010), and Group 2C and 2D (P = 0.0001). Conclusions: Following bleaching, NTAP application and GSE significantly improved the SBS of composite resin. Application of NTAP to microabraded surfaces increased the bond strength of composite resin.