Comparative Evaluation of Ultrasonic and Sonic Irrigant Activation Systems: Assessing Extrusion Risk, Debridement, and Biofilm Removal in Distinct Apical Preparation Sizes [PERSON] 1  
1 BonenLab--Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal 1  
[PERSON] 1,2  
[PERSON] 1,2  
[PERSON] 1 and [PERSON] 1,2,*  
1 BonenLab--Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal 12 Associated Laboratory for Green Chemistry-Network of Chemistry and Technology (LAQV-REQUIMTE), University of Porto, 4200-393 Porto, Portugal 2  
[PERSON] 1,2,*  
1 BonenLab--Laboratory for Bone Metabolism and Regeneration, Faculty of Dental Medicine, University of Porto, 4200-393 Porto, Portugal 12 Associated Laboratory for Green Chemistry-Network of Chemistry and Technology (LAQV-REQUIMTE), University of Porto, 4200-393 Porto, Portugal 2  
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Footnote 7: https://www. and employing flexible, non-cutting polymer tips. These strategically designed flexible tips are intended to prevent modifications of the root canal's morphology and avoid unintended dentin removal [10; 11]. Numerous studies have consistently demonstrated the increased efficacy of both ultrasonic and sonic activation devices when compared to conventional needle irrigation, regarding the removal of pulp tissue remnants [12], the eradication of microorganisms (both planktonic and biofilm) [13; 14; 15], and elimination of the smear layer and dentin debris [7; 16]. However, despite these valuable insights, it is worth noting that these studies have employed various experimental setups, making it challenging to perform a comprehensive and comparative analysis of their findings. An additional layer of complexity arises from the varied use of distinct apical preparation sizes, further hindering the comparison of data and its direct translation into the clinical setting. The issue of apical preparation size remains a relevant matter in this context, carrying significant clinical implications. However, it remains a topic of ongoing debate as, while several studies endorse the significant enlargement of root canals to ensure effective irrigation, others express caution about larger preparation sizes, citing the potential risk of apical transportation and zipping issues [17; 18]. Accordingly, and to the best of the authors' knowledge, no comprehensive study addressed simultaneously the different relevant clinical implications of different irrigant activating systems to different apical preparation sizes. Therefore, the present _ex vivo_ study aimed to compare the effectiveness of ultrasonic activation, sonic activation, and conventional manual needle irrigation methods, specifically in the context of two different apical sizes: 35/.06 and 50/.06. Within the confines of a single experimental setting, this study evaluates the performance of these systems across multiple crucial parameters.