Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Croatia.
Department of Biomaterials, Institute of Clinical Dentistry, University of Oslo, Norway.
Dent Mater. 2024 Nov;40(11):1895-1908. doi: 10.1016/j.dental.2024.09.002. Epub 2024 Sep 14.
This study presents a novel multi-technique approach that integrates micro-CT and optical photothermal infrared spectroscopy (O-PTIR) to evaluate polymerisation differences, so-called spatio-temporal polymerisation properties, between flowable and sculptable dental resin-based composites.
Ten commercially available dental composites were investigated, including flowable and sculptable counterparts from the same manufacturer. Eight parameters were evaluated: short-term polymerisation characteristics (degree of conversion after 5 min, maximum polymerisation rate, time to reach maximum polymerisation rate) was measured using ATR-FTIR with real-time monitoring; changes in the degree of conversion with depth were evaluated with O-PTIR, 3D visualisation of shrinkage patterns, overall volumetric shrinkage, depth-specific shrinkage, and porosity were measured using micro-CT; surface morphology with detailed measurements of elemental composition was characterised using SEM/EDX; light transmittance was analysed with a NIST-referenced spectrometer.
The study found that the increase in filler weight and volume ratio reduced the degree of conversion and polymerisation shrinkage, while moderately influencing the maximum polymerisation rates. The time to reach maximum polymerisation rates and light transmittance were not dependent on the filler amount. O-PTIR assessed a depth-dependent decrease in the degree of conversion for both composite types, with flowable composites generally showing a greater decrease in the degree of conversion than sculptable composites, except for bulk-fill composites. Micro-CT scans showed significantly higher flowable shrinkage values than their sculptable counterparts, highlighting the performance differences between the two types of composites.
The findings of this study have practical implications for the selection and use of dental composites. Flowable composites, despite their higher degrees of conversion and polymerisation rates, also exhibit higher volumetric shrinkage, which can be detrimental for clinical applications. The new measurement methods used in this study provide a comprehensive overview of the polymerisation behaviour of commercially available dental composites, offering valuable insights for material optimisation.
本研究提出了一种新的多技术方法，将微 CT 和光学光热红外光谱（O-PTIR）相结合，评估流动性和可雕刻牙科树脂基复合材料之间的聚合差异，即所谓的时空聚合特性。
研究了十种市售牙科复合材料，包括同一制造商的流动性和可雕刻性复合材料。评估了八个参数：使用 ATR-FTIR 进行实时监测，测量短期聚合特性（5 分钟后转化率、最大聚合速率、达到最大聚合速率的时间）；使用 O-PTIR 评估转化率随深度的变化，使用微 CT 测量收缩模式的 3D 可视化、整体体积收缩、深度特定收缩和孔隙率；使用 SEM/EDX 对表面形貌进行详细的元素组成测量；使用 NIST 参考分光光度计分析透光率。
研究发现，填料重量和体积比的增加降低了转化率和聚合收缩率，而对最大聚合速率的影响适中。达到最大聚合速率的时间和透光率与填料量无关。O-PTIR 评估了两种复合材料类型的深度依赖性转化率降低，流动性复合材料的转化率降低通常大于可雕刻复合材料，除了块状填充复合材料。微 CT 扫描显示，流动性复合材料的收缩值明显高于其可雕刻复合材料，突出了两种复合材料之间的性能差异。
本研究的结果对牙科复合材料的选择和使用具有实际意义。尽管流动性复合材料的转化率和聚合速率较高，但它们的体积收缩率也较高，这可能对临床应用不利。本研究中使用的新测量方法提供了对市售牙科复合材料聚合行为的全面概述，为材料优化提供了有价值的见解。
