Dental Pulp Stem Cell Response to Bleaching

Cells were implanted on the dentin side of the disc. After attachment, the enamel-dentin disc was overturned in the medium to expose the enamel surface above the liquid level with a 1 mm gap; the enamel surface was surrounded by a light cured resin barriers (Opalescence PF; Ultradent Products, South Jordan, Utah [UT], US) to prevent the bleach from spilling into the medium (Fig. S1). After that, approximately 0.5 mL of thickened bleaching gel was daubed on the enamel surface at 37 °C. We tested two concentrations of bleaching gel, 40% H₂O₂ and 15% carbamide peroxide (Opalescence Boost and Opalescence PF, respectively; Ultradent Products, South Jordan, Utah [UT], US)^{6 (link)}. Five groups were created: G1, untreated DPSCs; G2, 15% bleaching gel for 90 min; G3, 15% bleaching gel and 1 μM HC030031 (TRPA1 inhibitor, ApexBio; ApexBio, Houston, Texas [TX], US) for 90 min; G4, 40% bleaching gel for three 15-min periods in a row; and G5, 40% bleaching gel and 1 μM HC030031 for three 15-min periods in a row. As a small molecule drug that inhibits TRPA1, HC030031 can be used as a tool to study the role of TRPA1 channels in pain^{23 (link)}. In the inhibition group, HC030031 was dissolved in the culture medium to directly inhibit TRPA1.