Effect of Bond Strength of Chitosan Containing Cavity Disinfectant on Deep or Superficial Dentin

Chlorhexidine (CHX) has been widely reported as an inhibitor of matrix metalloproteinases (MMPs), contributing to the preservation of dentin bond integrity, while chitosan (CS) has been proposed as a natural biomodifier with potential collagen-stabilizing and cross-linking effects on the dentin matrix. These properties make both agents relevant candidates for improving the durability of adhesive interfaces. This in vitro study evaluated the effect of CS- and CHX-containing cavity disinfectants on the microtensile bond strength (µTBS) of a two-step self-etch adhesive applied to superficial and deep dentin. Forty-eight sound human molars were randomly assigned to superficial and deep dentin groups, which were further subdivided according to surface treatment: control (no treatment), 2% CHX, and 2.5% CS. A two-step self-etch adhesive system (Clearfil SE Bond) and resin composite were applied according to the manufacturers' instructions. After storage and thermocycling, beam-shaped specimens were prepared and subjected to µTBS testing. Data were analyzed using appropriate statistical methods, and significance was set at p < 0.05. CS pretreatment resulted in higher µTBS values compared with the control group in both superficial and deep dentin, with statistically significant differences observed (p < 0.05), while CHX-treated groups showed intermediate values, with no consistent statistically significant difference compared with CS. In general, superficial dentin exhibited higher bond strength values than deep dentin (p < 0.05). Within the limitations of this in vitro study, chitosan-containing cavity disinfectant was associated with significantly higher µTBS values compared with the untreated control in both superficial and deep dentin when used with a two-step self-etch adhesive. However, these findings should be interpreted with caution and should not be generalized beyond the specific materials and experimental conditions evaluated.