Influence of the enlargement of the apical foramen in periapical repair of contaminated teeth of dog.

Root canals of dogs' premolar teeth were exposed to contamination and to the development of periapical inflammation over a period of 45 days. Root canals were overinstrumented 2 mm beyond the apical foramen with file No. 60 and were underfilled by 2 to 3 mm short of the roentgenographic apex. Ninety days after endodontic treatment, healing and ingrowth of connective tissue into the root canal occurred in 67.8% of the cases. These results suggest that the diameter of the apical foramen and the intensity of the canal contamination are determining factors for periapical tissue repair in cases of pulpal necrosis.