An in vitro evaluation of plaster of Paris barriers used under amalgam and glass ionomer to repair furcation perforations.

Furcation perforations were created in the pulpal floor of 60 teeth and were repaired with amalgam alone, plaster of Paris under amalgam, light-cured glass ionomer alone, and plaster of Paris under light-cured glass ionomer. After the access openings were filled with composite resin, the teeth were immersed in 2% erythrocin B dye solution for 2 wk, sectioned longitudinally, and dye penetration was measured. The light-cured glass ionomer group provided the least amount of leakage, followed by the group of plaster of Paris under glass ionomer. The groups using amalgam alone and plaster of Paris under amalgam showed the most leakage. The plaster of Paris barrier prevented the overextension of the repair materials when used under amalgam and glass ionomer.