Mostafa Asmaa, Sadek Hoda M Abdel, Hamdy Amina, Emam Marwa
Fixed Prosthodontics Department, Faculty of Dentistry, Ain Shams University, Organization of african unity St., Abbasia, Cairo, 11566, Egypt.
Fixed Prosthodontics Department, Faculty of Dentistry, Ain Shams University, Organization of african unity St., Abbasia, Cairo, 11566, Egypt; Fixed Prosthodontics Department, Faculty of Dentistry, Galala University, Galala Plateau, Attaka, Suez, Egypt.
J Dent. 2025 May;156:105706. doi: 10.1016/j.jdent.2025.105706. Epub 2025 Mar 21.
This study aimed to compare the effects of two milling systems (4-axis and 5-axis) and two materials - polyetheretherketone (PEEK) and computer-aided-design/computer-assisted-manufacturing (CAD/CAM) Composite- on the marginal and internal fit of custom-made post and core restorations.
Eighteen single-rooted premolars were endodontically treated and prepared with a standardized post space of 10 mm. The teeth were scanned to receive post and core restorations, fabricated using the SHERAEco-mill 40 (4-axis) and SHERAEco-mill 50 (5-axis) milling machines (Shera Werkstoff-Technologie, Germany) and two materials-PEEK and Composite. Marginal and internal fit were measured using Geomagic Control X (3D Systems, Rock Hill, SC, USA), based on root mean square (RMS) values obtained from comparing the STL files of the design with the scanned, milled restorations. Data was analyzed with a two-way ANOVA and pairwise t-tests, with Bonferroni correction (p < 0.05).
Pairwise comparisons revealed significant differences in RMS values between milling machines, with 4-axis milled posts showing higher marginal (139.45±24.59 µm) and internal RMS values (135.04±8.68 µm) than 5-axis milled posts (104.14±10.51 µm and 116.22±9.89 µm, respectively). Higher significant RMS values in marginal surfaces were detected (118.60±16.7023.64 µm) for PEEK posts compared to (89.68±4.32 µm) for Composite posts milled with 5-axis. No significant differences were observed between materials for marginal or internal fit in 4-axis and internal fit in 5-axis.
This in vitro study findings demonstrated a superiority of 5-axis milling machines over 4-axis machines in achieving superior marginal and internal fit for post and core restorations, irrespective of the material utilized. While material selection did not significantly influence fit when employing 4-axis milling, a notable discrepancy emerged with 5-axis milling, where PEEK restorations exhibited poorer marginal fit compared to composite restorations.
5-axis milling machines demonstrated superior performance in producing custom-made post and core restorations with enhanced marginal and internal fit compared to 4-axis machines. This improved fit can potentially enhance seating accuracy, minimize cement thickness and micro-gaps, and ultimately contribute to improved long-term clinical outcomes. Furthermore, the lack of significant differences in fit observed between PEEK and CAD/CAM composite materials with 4-axis milling provides clinicians with greater flexibility in material selection based on other clinically relevant factors, such as esthetics, mechanical properties, adhesive properties, and patient preferences.
本研究旨在比较两种铣削系统（四轴和五轴）以及两种材料——聚醚醚酮（PEEK）和计算机辅助设计/计算机辅助制造（CAD/CAM）复合材料——对定制桩核修复体边缘适合性和内部适合性的影响。
18颗单根前磨牙经根管治疗，并制备成标准化的10mm桩道。对牙齿进行扫描以获得桩核修复体，使用SHERAEco-mill 40（四轴）和SHERAEco-mill 50（五轴）铣床（德国Shera Werkstoff-Technologie公司）以及两种材料——PEEK和复合材料进行制作。基于从设计的STL文件与扫描、铣削后的修复体进行比较所获得的均方根（RMS）值，使用Geomagic Control X（美国南卡罗来纳州罗克希尔的3D Systems公司）测量边缘适合性和内部适合性。数据采用双向方差分析和两两t检验，并进行Bonferroni校正（p<0.05）。
两两比较显示，铣床之间的RMS值存在显著差异，四轴铣削的桩显示出比五轴铣削的桩更高的边缘RMS值（139.45±24.59µm）和内部RMS值（135.04±8.68µm）（五轴铣削的桩分别为104.14±10.51µm和116.22±9.89µm）。与五轴铣削的复合材料桩（89.68±4.32µm）相比，PEEK桩在边缘表面检测到更高的显著RMS值（118.60±16.7023.64µm）。在四轴的边缘适合性或内部适合性以及五轴的内部适合性方面，材料之间未观察到显著差异。
这项体外研究结果表明，无论使用何种材料，五轴铣床在实现桩核修复体更好的边缘适合性和内部适合性方面优于四轴铣床。虽然在使用四轴铣削时材料选择对适合性没有显著影响，但在五轴铣削时出现了明显差异，其中PEEK修复体与复合材料修复体相比边缘适合性较差。
与四轴铣床相比，五轴铣床在生产具有更好边缘适合性和内部适合性的定制桩核修复体方面表现出卓越性能。这种改善的适合性可能会提高就位精度，最小化粘结剂厚度和微间隙，并最终有助于改善长期临床效果。此外，在四轴铣削中PEEK与CAD/CAM复合材料之间在适合性方面未观察到显著差异，这为临床医生根据其他临床相关因素（如美学、机械性能、粘结性能和患者偏好）进行材料选择提供了更大的灵活性。
