School of Dentistry, University of Anápolis, Anápolis, GO, Brazil.
Department of Prosthodontics, School of Dentistry, University of Anápolis, Anápolis, GO, Brazil.
Comput Methods Programs Biomed. 2021 Aug;207:106195. doi: 10.1016/j.cmpb.2021.106195. Epub 2021 May 24.
Differences in dental maturation may affect the prognosis and clinical management of traumatized teeth. However, evaluation of the outcomes of dental trauma to the tooth and support structures in an in vivo model involves major methodological and ethical implications. Thus, the aim of the present study was to perform a three-dimensional finite element analysis of permanent maxillary central incisors in different stages of root development under different trauma settings.
The study factors included two trauma conditions (B, buccal; I, incisal) on upper permanent central incisors showing three different stages of root development (CR, complete rhizogenesis; IRA; incomplete rhizogenesis in the apical third of the root; and IRM, incomplete rhizogenesis in the middle third of the root) to yield six models. The complete rhizogenesis model was obtained with a cone-beam computed tomography examination of an extracted tooth. The two incomplete rhizogenesis models were modeled on the basis of similar examinations of patients. Trauma was simulated by applying a 300 N static surface to surface load on the incisal edge or perpendicular to the buccal surface of the tooth. The displacement and equivalent von Mises (σvM) stress values were obtained for alveolar bone, periodontal ligament, apical papilla, and dentin for the quantitative analysis. A σvM color-coded scale was used for qualitative analysis.
The force direction had a greater influence on the stress than the root-formation stage. Buccal forces resulted in higher stress concentration in the bone and periodontal ligament, especially in B-CR. Lower stress was found on the periodontal ligament as the root formation progressed (decrease of 8% from B-IRA to B-CR and 11% from B-IRM to B-CR). The incomplete rhizogenesis models showed higher σvM stress peak values in dentin in comparison with complete rhizogenesis (increase of 52% from B-CR to B-IRA and 56% from B-CR to B-IRM).
Buccal forces yielded greater stress values regardless of the stage of rhizogenesis. Teeth with fully formed roots showed a higher stress concentration in the alveolar bone and periodontal ligament in comparison with immature teeth, with the latter presenting high stresses in the tooth crown.
牙齿萌出的不同阶段可能会影响外伤性牙齿的预后和临床处理。然而，在体内模型中评估牙齿和支持结构外伤性损伤的结果涉及到重大的方法学和伦理学问题。因此，本研究的目的是对不同萌出阶段的上颌恒中切牙进行三维有限元分析，研究因素包括两种创伤条件（B，颊侧；I，切侧）对上颌恒中切牙的影响，这些牙齿分别处于根发育的三个不同阶段（CR，完全根形成；IRA，根尖三分之一处的不完全根形成；IRM，根中部三分之一处的不完全根形成），共产生 6 种模型。完全根形成模型通过对提取牙齿的锥形束计算机断层扫描检查获得。两个不完全根形成模型是基于对患者的类似检查建模的。通过在牙切缘或垂直于牙颊面施加 300 N 的静态面-面负荷模拟创伤。对牙槽骨、牙周膜、根尖乳头和牙本质进行了位移和等效 von Mises（σvM）应力值的定量分析。使用σvM 彩色编码比例尺进行定性分析。
力的方向对牙本质的影响大于根形成阶段。颊侧力导致骨和牙周膜的应力集中更高，尤其是在 B-CR。随着根形成的进展，牙周膜的应力降低（从 B-IRA 到 B-CR 降低 8%，从 B-IRM 到 B-CR 降低 11%）。与完全根形成相比，不完全根形成模型的牙本质中的σvM 应力峰值更高（从 B-CR 到 B-IRA 增加 52%，从 B-CR 到 B-IRM 增加 56%）。
无论根形成阶段如何，颊侧力都会产生更大的应力值。与不成熟的牙齿相比，完全形成根的牙齿在牙槽骨和牙周膜中的应力集中更高，而后者在牙冠中表现出较高的应力。
