PDF: A Histological Study of the Effect of Diameter Enlargement of the Apical Portion of the Root Canal

The influence of intentional enlargement of the apical foramen in periapical repair was studied in dogs.

After biopulpectomy, 134 root canals were overinstrumented 2 mm beyond the apical foramen and the apices enlarged using files #40, 60, or 80. The root canals were filled 1 to 3 mm short of the apex using radiographic measurements.

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The animals were killed 3, 7, 30, and 120 days after the endodontic treatment and the teeth were processed for microscopic studies. 

The results showed the proliferation of periodontal connective tissue into the root canals and morphological changes accompanying maturation of this connective tissue with increasing time.

The observations indicated that enlargement of the apical foramina permitted ingrowth of connective tissue into the root canals and the formation of a thick layer of cementum in the apical root canals.

Connective tissue ingrowth from the periodontal ligament region into the interior of the canal has been observed by several researchers.

Such tissue formation has been observed in partially filled canals where the remaining spaces were occupied with blood clots or from apical overinstrumentation.