Radiographic evaluation of periradicular repair after endodontic treatmentof dog's teeth with induced periradicular periodontitis

Eighty-four root canals of premolars from six dogs were left open for 7 day s, and then sealed and followed for 45 days until periradicular periodontit is developed. The root canals were then treated endodontically using 5.25% sodium hypochlorite as the irrigating solution. After instrumentation, all root canals were filled with a calcium hydroxide-based antibacterial dressi ng (Calen PMCC or Calasept) that was left in place for 30 days. After this period the root canals were filled with gutta-percha cones and a root canal sealer (Sealapex or AH Plus) - group I: Calen PMCC + Sealapex; group II: C alasept + Sealapex; group III: Calen PMCC + AH Plus; and group IV: Calasept + AH Plus. Periapical radiographs of the teeth were made after root canal filling and after 90, 180, 270, and 360 days. Radiographic images were digi talized by scanning, and the Mocha program was used to measure the periapic al lesions. Analysis showed that the lesions of groups I to III were statis tically similar reduction in size, whereas group IV had a smaller reduction in lesion size (p < 0.05).