Glass-ionomer cement as retrograde filling material. An experimental investigation in monkeys

The tissue reaction following the use of glass-ionomer and amalgam, as retrograde filling materials was investigated in an experimental study using 8 monkeys. After apicectomy of the upper central incisors, amalgam and glass-ionomer cement was used at random as retrograde filling material. 2 animals at a time were sacrificed after 2 weeks, 1, 3 and 6 months. Irrespective of the length of time, the tissue reactions were similar for the 2 materials. 2 weeks after surgery, a vascular granulation tissue containing lymphocytes, plasma cells and polymorpho-nucleated leukocytes was observed close to the retrograde fillings. 1 month after surgery, good healing was found, the granulation tissue being replaced by new osteoid or bone formation. After 3 and 6 months, there was complete healing with no inflammatory reaction and a mature alveolar bone surrounding the apicectomized roots.