co·pal res·in(kōpăl rĕzin)
Brittle natural resin with a melting range that exceeds 149 degrees C. When deposited as a film from an organic solvent, it is used in dentistry as a liner for a cavity preparation before the restoration is placed.
Copal resin (kōpəl),
n.pr brand name for a mixed resin of diverse plant origin used in cavity varnishes. Its effectiveness in protecting the pulp from the phosphoric acid in dental cements is questioned.