An ultrastructural study of root canal walls in contact with endodontic biomaterials.

The aim of this in vitro study was to compare structural and ultrastructural changes to the unmineralized extracellular matrix after using two root canal restoration materials, one calcium hydroxide based and the other calcium oxide based. Pig teeth were restored with no preliminary root canal preparation. The filling materials were left in the root canals for 3, 8, 15, or 21 days. Observations were carried out by scanning electron microscopy. Results showed that when the calcium oxide-based material was used, it penetrated tubules and the unmineralized extracellular matrix material was reduced to a minimum. Teeth filled with the calcium hydroxide-based material were similar to control samples with an intact predentine. These observations suggest that the calcium oxide-based material induces changes in the unmineralized extracellular matrix of the endodontium.