Crack Formation During Apicectomy: Operating Microscope Observations and SEM Images

Methods: In Part 1, the root canals of 48 extracted teeth were prepared and root filled with gutta percha and sealer.  Half were resected 3 mm from the apex using a low-speed TC surgical bur (H33L, Komet, Brasseler, Germany) and the rest with a high-speed bur (H162, Komet). Twelve roots from each group were polished with a bur (H135UF, Komet). In Part 2, root-end cavities were prepared using ultrasonic tips (ProUltra® surgical tip SURG 2, Dentsply). In Part 3, cavities were randomly assigned to either receive mineral trioxide aggregate (MTA) or super EBA (sEBA) root-end fillings.  At each stage the root ends were examined by three endodontists using a DOM (x21.25) and impressions taken to make epoxy replicas for SEM (x25). Regression and Kappa analyses were performed. 

Results: With regards to number of cracks, 13, 44 and 22 cracks in Parts 1, 2, and 3 respectively, were found with SEM. The correlation between DOM and SEM was only moderate (Kappa score 0.4568, P = 0.0008). False positive identifications of cracks were made with the DOM at all stages.

Conclusions:

The DOM may lead to an over-diagnosis of cracks. Restorations with either MTA or sEBA reduced the number of cracks visible after ultrasonic preparation.