Seidel Kathrin, Johannes Kirsten, Herrmann Eva, Aini Tuba, Zahn Tugba, Güth Jan-Frederik
Department of Prosthetic Dentistry, Center for Dentistry and Oral Medicine, Goethe University Frankfurt, Frankfurt, Germany.
Institute for Biostatistics and Mathematical Modeling, Goethe University Frankfurt, Frankfurt, Germany.
Clin Oral Investig. 2025 May 14;29(6):298. doi: 10.1007/s00784-025-06370-w.
This study aimed to determine which factors most strongly affect volumetric tooth substance removal during preparation for full ceramic restorations and how these parameters interact. A novel digital method was used to design preparation geometries using three-dimensional (3D) graphic software.
A digital workflow involving Boolean operations was applied to an STL dataset of a maxillary first molar to generate 720 preparation designs. Each design varied by preparation angle, chamfer depth, finish line distance from the cementoenamel junction (CEJ), and occlusal reduction. Volumetric tooth removal was evaluated for each parameter, as well as for their combined effects.
All preparation parameters influenced tooth substance removal. The finish line distance from the CEJ showed the greatest effect, followed by chamfer depth. Preparation angle and occlusal reduction had less pronounced effects.
Increasing the vertical finish line distance and minimizing chamfer depth substantially reduce tooth substance removal. While adequate occlusal clearance is essential, its effect on total volume loss is relatively minor. The influence of the preparation angle was more relevant for full crowns than for partial restorations.
Clinicians are encouraged to favor partial restorations whenever possible, as they result in less invasive preparations, even when compared to full crowns made from high-strength materials with reduced thickness requirements such as monolithic zirconia. To preserve tooth structure, both the material's minimum thickness and the vertical position of the finish line should be carefully considered. These findings support a conservative preparation approach tailored to material properties and clinical requirements.
本研究旨在确定在全瓷修复体预备过程中，哪些因素对牙体组织体积去除的影响最为显著，以及这些参数之间是如何相互作用的。采用一种新颖的数字方法，使用三维（3D）图形软件设计预备体几何形状。
将涉及布尔运算的数字工作流程应用于上颌第一磨牙的STL数据集，以生成720种预备体设计。每种设计在预备角度、肩台深度、肩台与牙釉质牙骨质界（CEJ）的距离以及咬合面降低量方面有所不同。对每个参数以及它们的综合影响进行了牙体组织体积去除的评估。
所有预备参数均影响牙体组织的去除。肩台与CEJ的距离显示出最大的影响，其次是肩台深度。预备角度和咬合面降低量的影响则不太明显。
增加垂直肩台距离并最小化肩台深度可大幅减少牙体组织的去除。虽然足够的咬合间隙至关重要，但其对总体积损失的影响相对较小。预备角度的影响对于全冠修复比对部分修复更为相关。
鼓励临床医生尽可能选择部分修复体，因为即使与由诸如整体式氧化锆等厚度要求降低的高强度材料制成的全冠相比，部分修复体的预备侵入性也较小。为了保留牙体结构，应仔细考虑材料的最小厚度和肩台的垂直位置。这些发现支持了一种根据材料特性和临床需求量身定制的保守预备方法。
