Histological observations of periradicular healing following root canal treatment.

The purpose of this study was to observe histologically the sequence of events leading to resolution of periradicular tissues, with a view to advancing the perception of periapical healing. Our material consisted of periapical specimens obtained from 15 single-rooted, endodontically treated teeth of patients aged 25-40 years. All the teeth required extraction because of complicated crown-root fracture following trauma, iatrogenic aetiology (cervical root resorption following bleaching) or extensive carious lesions. The patients were informed that, based on their clinical condition, surgical procedures should be performed under flap reflection in order to extract the fractured root. Informed consent, which was necessary for the surgery, was obtained in all cases. A small block section containing the apical root tip and surrounding periapical tissues was removed prior to root extraction. The results of histological examination revealed osteoblastic activty and osteoid bone formation six days after the root canal instrumentation. Periapical tissue healing was observed despite the presence of overfilled material. The lining epithelium was infiltrated with chronic inflammatory cells and surrounded by collagen bundles and newly formed bone.