New Ultrasonic Tip for Root Canal Filling of the Mesial Canals of Mandibular Molars with Isthmus: A Laboratory Evaluation Using Computed Microtomography. - Barreto CDCG; Calefi PHS; Vivacqua-Gomes N; Alcalde MP; Vivan RR; Duarte MAH; Vasconcelos BC (Journal of endodontics, 2023)