Effect of trichloroacetic acid hydrogel on self-etch adhesive bond strength to dental tissues

Trichloroacetic acid (TCA) is a soft tissue cauterizing agent applied to gingival margins prior to cervical tooth-colored restorations. The present in vitro study evaluated the effects of two different concentrations of TCA hydrogel as a hemostatic/preconditioning agent on the shear bond strength (SBS) of a self-etch adhesive to tooth structures.

Thirty-six flat enamel and 36 flat dentin surfaces were prepared using human molars; each group was subdivided into three subgroups (n = 12). The groups were made ready as follows: In groups 1 (E1 and D1), the enamel (E) and dentin (D) surfaces were designated as control groups and remained intact. In groups 2 (E2 and D2), 35% TCA gel was applied to enamel and dentin surfaces for 30 seconds. In groups 3 (E3 and D3), 50% TCA gel was applied to enamel and dentin surfaces for 30 seconds. Clearfil SE Bond and Z100 composite resin were applied to the surfaces according to manufacturers' instructions. After 24 hours of incubation and thermocycling, the composite cylinders underwent an SBS test in a DARTEC test machine. Data were analyzed using the ANOVA and Scheffe's test (α=0.05).

The mean SBS±SD in the study groups were 34.73±5.66, 35.32±7.3, 23.75±9.67, 20.94±9.84, 19.32±6.20, 23.50±6.63 MPa in the E1, E2, E3, D1, D2 and D3 groups, respectively. ANOVA revealed significant differences between the SBS values of enamel groups (p=0.001). There were no significant differences between the dentin groups (p=0.425).

Application of 35 and 50% concentrations of TCA to dentin had no detrimental effect on the bond produced by two-step self-etch adhesive under study; however, application of only 35% TCA to enamel did not result in a detrimental effect on the same adhesive.