Dettogne Erica Feleti Lorençon, Toubes Kênia Maria Pereira Soares de, Morgan Luis Fernando Dos Santos Alves, Seraidarian Paulo Isaías, Maia Lucas Moreira, Silveira Frank Ferreira
Department of Dentistry, Pontifical Catholic University of Minas Gerais, Belo Horizonte, MG, Brazil.
UNIUBE - University of Uberaba, Uberaba, MG, Brazil.
Braz Dent J. 2024 Dec 16;35:e246083. doi: 10.1590/0103-644020246083. eCollection 2024.
The amount of residual dentin thickness and tooth position in the dental arch is crucial to determine whether an intraradicular post should be used. This study aimed to compare stress distribution on the root dentin of an endodontically treated tooth rehabilitated with CAD/CAM milled glass fiber posts (MP), cast metal posts (CMP), or prefabricated posts (PP) with or without ferrule support, using the finite element method.
A human upper central incisor was selected, scanned, and treated endodontically. The canal was then prepared for post-placement and scanned again for the fabrication of digital posts. The geometries of MP and CMP were based on the measurements made by digital scanning of the root canal. In contrast, the geometry of PP was determined by technical drawings provided by the manufacturer, taking into account the post-space preparation and the cement. Six digital models were established: MP1 with ferrule support, MP2 without ferrule support; CMP1 with ferrule support, CMP2 without ferrule support; PP1 with ferrule support, and PP2 without ferrule support. The simulation was performed using the finite element method.
Oblique forces were identified as more relevant to the metallic element compared to vertical forces. The presence of a ferrule was considered a protective factor for the remaining tooth structure. When the ferrule was absent, stresses were more evenly distributed in MP compared to CMP and PP. Posts with a higher modulus of elasticity were associated with higher and unequal stresses in the root dentin, which could predispose the tooth to fractures.
As for the restoration set as a whole, it can be concluded that stress distribution on the root dentin was more evenly distributed on the milled post than on the other posts when a ferrule was absent, and the oblique forces were more detrimental to the tooth structure than vertical forces and that ferrule support was a protective factor for the remaining tooth structure.
The results of the study provide valuable information on how different types of intraradicular posts and the presence of a ferrule affect the stress distribution in dentin. In the absence of a ferrule, milled and customized computer-aided design/computer-aided manufacturing (CAD/CAM) glass fiber posts can exhibit better fracture resistance and adhesion strength than prefabricated fiberglass posts and metal posts.
根管内牙本质剩余厚度和牙弓中牙齿位置对于确定是否应使用根管内桩至关重要。本研究旨在使用有限元方法比较用计算机辅助设计/计算机辅助制造（CAD/CAM）研磨玻璃纤维桩（MP）、铸造金属桩（CMP）或预成桩（PP）修复的根管治疗牙齿的牙根牙本质上的应力分布，这些桩有无箍环支持。
选取一颗人上颌中切牙，进行扫描并进行根管治疗。然后预备根管以放置桩，并再次扫描以制作数字桩。MP和CMP的几何形状基于根管的数字扫描测量。相比之下，PP的几何形状由制造商提供的技术图纸确定，同时考虑到桩道预备和粘结剂。建立了六个数字模型：有箍环支持的MP1、无箍环支持的MP2；有箍环支持的CMP1、无箍环支持的CMP2；有箍环支持的PP1和无箍环支持的PP2。使用有限元方法进行模拟。
与垂直力相比，斜向力被确定与金属元件更相关。箍环的存在被认为是剩余牙齿结构的保护因素。当没有箍环时，与CMP和PP相比，MP中的应力分布更均匀。弹性模量较高的桩与牙根牙本质中较高且不均匀的应力相关，这可能使牙齿易于骨折。
就整个修复体而言，可以得出结论，当没有箍环时，牙根牙本质上的应力分布在研磨桩上比在其他桩上更均匀分布，并且斜向力比垂直力对牙齿结构更具损害性，并且箍环支持是剩余牙齿结构的保护因素。
该研究结果提供了关于不同类型的根管内桩以及箍环的存在如何影响牙本质应力分布的有价值信息。在没有箍环的情况下，研磨和定制的计算机辅助设计/计算机辅助制造（CAD/CAM）玻璃纤维桩比预成玻璃纤维桩和金属桩可表现出更好的抗折性和粘结强度。
