Sönmez Sinem, Koç Cemre
Dept. of Endodontics, Faculty of Dentistry, Aydın Adnan Menderes University, 09100, Aydın, Turkey.
Odontology. 2025 Apr;113(2):666-674. doi: 10.1007/s10266-024-01002-3. Epub 2024 Sep 6.
This study assessed the stress distribution under occlusal forces in mandibular molars after utilizing several nickel-titanium rotary systems and identified potential root fracture patterns through finite element analysis (FEA). Five three-dimensionally printed mandibular molars were used, with one tooth left unshaped and the remaining four shaped using ProTaper Gold (Dentsply, Tulsa Dental Specialties, Tulsa, OK), Reciproc Blue (VDW, Munich, Germany), XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland), and Hyflex EDM (Coltene/Whaledent, Altst€atten, Switzerland) rotary systems. Subsequently, micro-CT scans were performed on the teeth, and representative FEA models were generated. Two distinct loadings, vertical and oblique, were applied, and stress parameters including von Mises stress, maximum principal stress, and minimum principal stress were recorded and compared across groups. Although stress values in both loading conditions correlated with volume increases post-shaping, the stress distribution patterns indicative of potential fractures were comparable across groups. Stresses under oblique loads were observed to be higher than those under vertical loads. Several rotary systems, based on the volumetric changes they induce in dental hard tissues, may elevate stress values throughout the tooth, leading to root fractures in regions where stress concentration occurs. Conservative root canal shaping leads to a lower overall stress concentration. In mandibular molars, oblique forces have a more destructive effect compared to vertical forces.
本研究利用几种镍钛旋转系统评估了下颌磨牙在咬合力作用下的应力分布，并通过有限元分析（FEA）确定了潜在的牙根骨折模式。使用了五颗三维打印的下颌磨牙，一颗牙齿未进行塑形，其余四颗分别使用ProTaper Gold（登士柏，塔尔萨牙科专业公司，塔尔萨，俄克拉何马州）、Reciproc Blue（VDW，慕尼黑，德国）、XP-endo Shaper（FKG Dentaire，拉绍德封，瑞士）和Hyflex EDM（科尔tene/Whaledent，阿尔特施泰滕，瑞士）旋转系统进行塑形。随后，对牙齿进行了显微CT扫描，并生成了代表性的有限元分析模型。施加了两种不同的载荷，即垂直载荷和斜向载荷，并记录了包括冯·米塞斯应力、最大主应力和最小主应力在内的应力参数，并在各组之间进行了比较。尽管两种载荷条件下的应力值都与塑形后体积增加相关，但各组中指示潜在骨折的应力分布模式具有可比性。观察到斜向载荷下的应力高于垂直载荷下的应力。基于它们在牙齿硬组织中引起的体积变化，几种旋转系统可能会提高整个牙齿的应力值，从而导致应力集中区域的牙根骨折。保守的根管塑形会导致较低的整体应力集中。在下颌磨牙中，与垂直力相比，斜向力具有更大的破坏作用。
