Answer: A cavity varnish provides a barrier against fluid penetration into the underlying dentin. When applied to dentin, a varnish may reduce postoperative sensitivity and limit migration of corrosion products into dentin, thereby reducing tooth discoloration. RMGI liner/base products seal the tooth and strongly bond to the restoration to reduce the incidence of microleakage between the tooth and the restoration. ... Reduces postoperative sensitivity — RMGI liner/bases offer a strong bond to the tooth, sealing the tooth structure to protect against microleakage.
Hope this helps...... Stay safe and have a Merry Christmas!!!!!!! :D