The authors surveyed 64 dental schools in North America about their instruction on the use of bases and liners. Respondents cited the materials being taught at the time of the survey, two years before the survey and four years before the survey. There was no consensus as to the materials being used. Copal varnishes and dentin bonding agents, or DBAs, were used most often in Class II preparations more than 2 millimeters from the pulp, and glass ionomers and DBAs were equally popular for Class II preparations within 1 mm of the pulp. Most schools were pleased with the materials they are currently teaching but continue to review material selection annually.