An in vitro comparative study on effect of chlorhexidine, grape seed extract, riboflavin/chitosan on shear bond strength of composite resin to dentin

Background: The biggest limitation in the restorative dentistry is the squalor property of the adhesive dentin layer interface which further includes non-organization between the collagen and resin from the inter-fibril space. An important challenge to the dentin bond durability is degradation of collagen from the matrix‑bound proteases, namely matrix metalloproteinases (MMPs) and cysteinecathepsins. Pretreatment of the bonding substrate with agents that inhibit the activity of MMPs might improve bond durability. Chlorhexidine (CHX) is reported to be a strong MMP inhibitor. Riboflavin helps in collagen cross‑linking by its ability to produce free radicals when photoactivated with spectral range from ultraviolet to visible light.(6) In addition to cross‑linking, reinforcement of the collagen can be achieved by incorporating biopolymers such as chitosan that can be cross‑linked with collagen fibrils. Recent studies have shown that a PA-based cross-linker agent (grape seed extract) increased the mechanical properties of demineralized dentin matrixand enhanced the resin–dentin bond strength after one hour treatment. Objective: The objective of this study was to evaluate the influence of chlorhexidine (CHX), riboflavin/chitosan, grape seed extract (GSE) modification on shear bond strengthof composite resin to dentin after thermocycling. Methods: Sixty extracted human mandibular secondpremolars were used and a flat surface was then prepared by removing the occlusal one‑third to expose the mid-colonal dentin. The teeth were randomly assigned into four groups ‑ Group A in which self‑etch adhesive was applied and Groups B, C, D were pretreated with 2% CHX, 1% riboflavin/chitosan and 6.5% GSE, respectively, before the application of self‑etch adhesive. Composite build‑ups were constructed and subjected to thermo cycling. The shear bond strength was evaluated using the universal testing machine. Data were analyzed using one‑way analysis of variance and Tukey’s test. Results: The mean shear bond strength values for Group A(control), Group B (CHX), Group C (riboflavin/chitosan) and Group D (GSE) modification) were 22.26, 28.76, 26.57, 24.87 MPa, respectively. A stastically significant difference was found between the shear bond strength of all the groups (P<0.05) of 2% CHX, 6.5% GSE, 1% Rivoflabin/chitosan when compared with the control group. Conclusions: Pretreatment with CHX, rivoflabin/chitosan and GSE leads to a significant increase in shear bond strength of composite resin to dentin.