Department of Biomaterials Institute of Clinical Dentistry, University of Oslo, Norway.
Department of Biomaterials Institute of Clinical Dentistry, University of Oslo, Norway.
Dent Mater. 2024 Nov;40(11):1881-1894. doi: 10.1016/j.dental.2024.09.001. Epub 2024 Sep 14.
Dental resin composites' performance is intricately linked to their polymerisation shrinkage characteristics. This study compares polymerisation shrinkage using advanced 3D micro-computed tomography (micro-CT) and traditional 2D linear assessments. It delves into the crucial role of filler content on shrinkage and the degree of conversion in dental resin composites, providing valuable insights for the field.
Five experimental dental composite materials were prepared with increasing filler contents (55-75 wt%) and analysed using either 3D micro-CT for volumetric shrinkage or a custom-designed linometer for 2D linear shrinkage. The degree of conversion was assessed using Optical Photothermal Infrared (O-PTIR) and Fourier-Transform Infrared (FTIR) spectroscopy. Light transmittance through a 2-mm layer was evaluated using a NIST-calibrated spectrometer. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDX) examined surface morphology and elemental distribution. Correlation between the investigated parameters was determined using Spearman correlation analyses.
The study found significant differences in polymerisation-related properties among different filler content categories, with volumetric shrinkage consistently demonstrating higher mean values than linear shrinkage across most groups. Volumetric shrinkage decreased with increasing curing depth, showing no direct correlation between filler content and shrinkage levels at different curing depths. The results highlighted a strong negative correlation between filler content and degree of conversion, volumetric and linear shrinkage, as well as maximum shrinkage rate. Light transmittance showed a moderate correlation with the filler content and a weak correlation with other tested parameters.
This study underscores the importance of considering both volumetric and linear shrinkage in the design and analysis of dental composite materials. The findings advocate optimising filler content to minimise shrinkage and enhance material performance. Integrating micro-CT and O-PTIR techniques offers novel insights into dental composites' polymerisation behaviour, providing a foundation for future research to develop materials with improved clinical outcomes.
牙科树脂复合材料的性能与其聚合收缩特性密切相关。本研究通过先进的 3D 微计算机断层扫描（micro-CT）和传统的 2D 线性评估比较聚合收缩。深入探讨了填料含量对收缩和牙科树脂复合材料转化率的关键作用，为该领域提供了有价值的见解。
制备了五种实验性牙科复合树脂材料，其填料含量逐渐增加（55-75wt%），并使用 3D micro-CT 进行体积收缩分析或定制设计的测微计进行 2D 线性收缩分析。采用光学光热红外（O-PTIR）和傅里叶变换红外（FTIR）光谱法评估转化率。通过 NIST 校准的分光光度计评估通过 2mm 层的光透射率。扫描电子显微镜（SEM）和能量色散 X 射线光谱（EDX）检查表面形貌和元素分布。使用 Spearman 相关分析确定研究参数之间的相关性。
该研究发现不同填料含量类别之间聚合相关性能存在显著差异，大多数组的体积收缩平均值始终高于线性收缩。随着固化深度的增加，体积收缩减小，在不同固化深度下，填料含量与收缩水平之间没有直接相关性。结果突出表明，填料含量与转化率、体积和线性收缩以及最大收缩率之间呈强烈负相关。光透射率与填料含量呈中度相关，与其他测试参数呈弱相关。
本研究强调在设计和分析牙科复合材料时应同时考虑体积收缩和线性收缩。研究结果主张优化填料含量以最小化收缩并提高材料性能。整合 micro-CT 和 O-PTIR 技术为牙科复合材料的聚合行为提供了新的见解，为未来开发具有改善临床效果的材料的研究奠定了基础。
