Peng Weiqi, Zhou Xuedong, Gao Yuan, Xu Xin
State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
J Endod. 2022 May;48(5):659-668. doi: 10.1016/j.joen.2021.12.012. Epub 2022 Feb 26.
The purpose of this study was to evaluate the influence of a contracted endodontic cavity (CEC) on dentin preservation, biomechanical property, and instrumentation efficacy of first permanent molars in comparison with a traditional endodontic cavity (TEC).
Forty-eight extracted intact maxillary and mandibular first molars were selected and scanned by micro-computed tomographic (micro-CT) imaging. Each tooth type was anatomically matched and assigned to the CEC group or the TEC group (n = 12). After root canal instrumentation with the ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer), the specimens were scanned by micro-CT again. Pre- and postpreparation micro-CT imaging was used to evaluate the dentin preservation and instrumentation efficacy. The results on volume and thickness reduction in the coronal dentin and pericervical dentin (PCD), root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness in the "danger zone" were measured and analyzed with the Shapiro-Wilk and independent sample t tests. Based on micro-CT imaging of maxillary and mandibular first molars, CEC and TEC models were constructed on the intact tooth, and 2 different static loads were applied to the occlusal load points. The stress distribution patterns and von Mises stress on the occlusal surface and cervical region were assessed by 3-dimensional finite element analysis.
The CEC had a significantly lower volume and thickness reduction of coronal dentin and PCD above the alveolar crest compared with the TEC group (P < .05), whereas no difference was observed in PCD below the alveolar crest between the 2 groups (P > .05). There was no difference regarding all instrumentation efficacy outcomes (root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness) in the danger zone between the 2 groups (P > .05). The CEC effectively reduced the maximum von Mises stress and stress concentration area on the occlusal surface and cervical region compared with the TEC.
The CEC preserved more coronal dentin and PCD above the alveolar crest and thus reduced stress concentration on the occlusal surface and cervical region. The CEC had no significant adverse effects on the instrumentation efficacy compared with the TEC given that the instrumentation procedures were performed with ProGlider and WaveOne Gold files.
本研究的目的是评估与传统牙髓腔（TEC）相比，收缩牙髓腔（CEC）对第一恒磨牙牙本质保存、生物力学性能及根管预备效果的影响。
选取48颗完整拔除的上颌和下颌第一磨牙，采用显微计算机断层扫描（micro-CT）成像进行扫描。每种牙型在解剖结构上进行匹配，并分为CEC组或TEC组（n = 12）。使用ProGlider（登士柏迈尔牙科，瑞士巴拉格）和WaveOne Gold（登士柏迈尔牙科）进行根管预备后，再次对标本进行micro-CT扫描。术前和术后的micro-CT成像用于评估牙本质保存和根管预备效果。采用Shapiro-Wilk检验和独立样本t检验对冠部牙本质和颈周牙本质（PCD）的体积和厚度减少量、根管体积和表面积、未预备表面积百分比、根管偏移和定心率以及“危险区”的根管壁厚度进行测量和分析。基于上颌和下颌第一磨牙的micro-CT成像，在完整牙齿上构建CEC和TEC模型，并在咬合加载点施加2种不同的静态载荷。通过三维有限元分析评估咬合面和颈部区域的应力分布模式和冯·米塞斯应力。
与TEC组相比，CEC组在牙槽嵴上方的冠部牙本质和PCD的体积和厚度减少量显著更低（P <.05），而两组在牙槽嵴下方的PCD方面未观察到差异（P >.05）。两组在“危险区”的所有根管预备效果指标（根管体积和表面积、未预备表面积百分比、根管偏移和定心率以及根管壁厚度）上均无差异（P >.05）。与TEC相比，CEC有效降低了咬合面和颈部区域的最大冯·米塞斯应力和应力集中区域。
CEC保留了更多牙槽嵴上方的冠部牙本质和PCD，从而降低了咬合面和颈部区域的应力集中。鉴于使用ProGlider和WaveOne Gold锉进行根管预备操作，与TEC相比，CEC对根管预备效果无显著不良影响。
