Lateef Ammar Aziz, Hameed Mohammed Rasheed, Fadhil Noor Hayder, Ali Ahmed Hamid
Aesthetic and Restorative Dentistry Department, College of Dentistry, University of Baghdad, Baghdad, Iraq.
PLoS One. 2025 Jan 24;20(1):e0318095. doi: 10.1371/journal.pone.0318095. eCollection 2025.
This study evaluated the extent to which obturation materials bypass fractured endodontic instruments positioned in the middle and apical thirds of severely curved simulated root canals using different obturation techniques. Sixty resin blocks with simulated root canals were used, each with a 50° curvature, a 6.5 mm radius of curvature, and a length of 16.5 mm, prepared to an ISO #15 diameter and taper. Canals were shaped using ProTaper Universal files (Dentsply Maillefer) attached to an X-smart Plus endo motor (Dentsply), set at 3.5 Ncm torque and 250 rpm, up to size S2 at working length. To simulate fractures, F2 and F3 files were weakened 3 mm from the tip, then twisted to break in the apical and middle sections of the canal, respectively. All samples were sealed with GuttaFlow 2 and divided into three groups (n = 20/group) according to obturation technique: A) single cone, B) lateral condensation with a rotary spreader, and C) softcore obturators. Each group was then divided into two subgroups (n = 10) based on the instrument fracture location (1 = apical, 2 = middle). The linear intrusion of obturation materials through the fractured instruments was measured using ImageJ software and analyzed statistically with ANOVA, Tukey tests, and independent t-tests, with significance set at p<0.05. Material bypass in group B1 (3.27 ± 0.63 mm) was significantly greater than in group A1 (2.39 ± 0.44 mm) and group C1 (2.91 ± 0.77 mm). In group C2, bypass (5.76 ± 0.64 mm) was significantly higher than in group A2 (3.82 ± 0.2 mm) and group B2 (2.27 ± 0.96 mm). Additionally, bypass in group A2 was greater than in group B2, and group B1 had more bypass than B2, while group C2 exceeded C1. The lateral condensation technique with a rotary spreader and softcore obturators increased the bypass of obturation materials through fractured instruments in simulated curved canals. These techniques may thus enhance material flow in endodontic procedures involving instrument fractures.
本研究评估了使用不同的充填技术时，充填材料绕过位于严重弯曲的模拟根管中三分之一和根尖三分之一处折断的牙髓器械的程度。使用了60个带有模拟根管的树脂块，每个根管具有50°的弯曲度、6.5毫米的弯曲半径和16.5毫米的长度，制备成ISO #15的直径和锥度。使用连接到X-smart Plus牙髓动力仪（登士柏）的ProTaper Universal锉（登士柏马伊莱费尔）对根管进行预备，设置扭矩为3.5 Ncm，转速为250 rpm，直至工作长度达到S2号锉。为模拟折断，将F2和F3号锉从尖端起3毫米处削弱，然后分别在根管的根尖段和中段扭转使其折断。所有样本均用GuttaFlow 2密封，并根据充填技术分为三组（每组n = 20）：A）单锥法，B）使用旋转扩孔钻进行侧向加压充填，C）软核充填材料。然后根据器械折断位置将每组再分为两个亚组（n = 10）（1 =根尖，2 =中段）。使用ImageJ软件测量充填材料通过折断器械的线性侵入情况，并采用方差分析、Tukey检验和独立t检验进行统计学分析，显著性设定为p<0.05。B1组（3.27±0.63毫米）的材料绕过情况显著大于A1组（2.39±0.44毫米）和C1组（2.91±0.77毫米）。在C2组中，绕过情况（5.76±0.64毫米）显著高于A2组（3.82±0.2毫米）和B2组（2.27±0.96毫米）。此外，A2组的绕过情况大于B2组，B1组的绕过情况多于B2组，而C2组超过C1组。使用旋转扩孔钻进行侧向加压充填技术和软核充填材料增加了充填材料在模拟弯曲根管中通过折断器械的绕过情况。因此，这些技术可能会在涉及器械折断的牙髓治疗过程中增强材料的流动性。
