Investigations on retrograde root filling using a composite resin, Retroplast, bonded to the root surface with the dentinbonding agent Gluma have been described. Here, detailed information is given about the surgical procedures. The aim was to obtain a thin retrograde composite filling on the root apex, made slightly concave, sealing the main root canal, accessory canals as well as dentinal tubules. Hemostasis was obtained primarily by appying 1% adrenaline and by using a needle suction tip, and care was taken not to damage the surrounding tissues by the various chemicals. The healing results, after up to 1 year, of 388 cases of various tooth types, treated with either retrograde composite or with amalgam were compared. The healing classification included four categories: 1) complete healing; 2) fibrous healing; 3) uncertain; and 4) failures. In the composite group, the healing rates were as follows: 74% showed complete healing, 4% fibrous healing, 15% uncertain, and 7% were failures. In the amalgam group, 59% showed complete healing, 3% fibrous healing, 30% uncertain, and 8% were failures. Complete healing occurred significantly more often after filling with Retroplast than after filling with amalgam (p < 0.00005). Significantly fewer cases with complete healing occurred in lower front teeth in proportion to other tooth types. The number of immediate postoperative complications did not differ significantly between the composite and the amalgam groups.