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Apical Dentin Microcrack Formation After Ultrasonic Instrumentation in Flattened Root Canals: A Comparative Analysis
Mariana Pereira Pereira de Souza da Silva1, Adriana da Costa Ribeiro2, Jeynifer Rafaella Bezerra de Oliveira1
1Department of Clinical and Preventive Dentistry, Federal University of Pernambuco, Recife, Pernambuco, Brazil.
Introduction:
Although ultrasonic inserts are frequently used for the instrumentation of flat root canals, there is a lack of studies investigating whether instrument contact with the canal walls induces the formation of dentinal microcracks. This study aimed to evaluate the formation of apical microcracks, caused by ultrasonic instrumentation, using micro-computed tomography (microCT) and optical coherence tomography (OCT).
Method:
Twenty maxillary second premolars were randomly divided into 2 groups (n = 10): ultrasonic group and brushing group. All specimens were initially prepared using Reciproc Blue files 25/.05 and 40/.06. The brushing group received additional brushing movements with Reciproc Blue 40/.06 and the ultrasonic group underwent instrumentation with a Clearsonic Black ultrasonic insert. Pre- and post-instrumentation images were obtained using both microCT and OCT and were analyzed with specialized software.
Results:
Statistically significant difference was observed for the treatment variable regarding apical microcrack presence (P < .05). In the brushing group, all apical microcracks identified post-instrumentation were also present preoperatively. In contrast, new incidences were identified in the ultrasonic group via microCT. No significant differences were found for the evaluator (P > .05) or the imaging technique used (P > .05). Intra- and interexaminer agreement was nearly perfect, with kappa values ranging from 0.858 to 0.975.
Conclusion:
The inclusion of an ultrasonic insert during biomechanical preparation did not significantly increase the incidence of apical microcracks when compared with a nonultrasonic protocol. OCT demonstrated high reliability for detecting apical microcracks in extracted teeth.
