Ilie Nicoleta, Keßler Andreas, Durner Jürgen
Department of Operative/Restorative Dentistry, Periodontology and Pedodontics, Ludwig-Maximilians-University of Munich, Germany.
J Dent. 2013 Aug;41(8):695-702. doi: 10.1016/j.jdent.2013.05.008. Epub 2013 May 21.
To assess the effect of irradiation time and distance of the light tip on the micro-mechanical properties and polymerisation kinetics of two bulk-fill resin-based composites at simulated clinically relevant filling depth.
Micro-mechanical properties (Vickers hardness (HV), depth of cure (DOC) and indentation modulus (E)) and polymerisation kinetics (real-time increase of degree of cure (DC)) of two bulk-fill resin-based composites (Tetric EvoCeram(®) Bulk Fill, Ivoclar Vivadent and x-tra base, Voco) were assessed at varying depth (0.1-6mm in 100μm steps for E and HV and 0.1, 2, 4 and 6mm for DC), irradiation time (10, 20 or 40s, Elipar Freelight2) and distances from the light tip (0 and 7mm). Curing unit's irradiance was monitored in 1mm steps at distances up to 10mm away from the light tip on a laboratory-grade spectrometer.
Multivariate analysis (α=0.05), Student's t-test and Pearson correlation analysis were considered. The influence of material on the measured mechanical properties was significant (η(2)=0.080 for E and 0.256 for HV), while the parameters irradiation time, distance from the light tip and depth emphasise a stronger influence on Tetric EvoCeram(®) Bulk Fill. The polymerisation kinetics could be described by an exponential sum function, distinguishing between the gel and the glass phase. The above mentioned parameters strongly influenced the start of polymerisation (gel phase), and were of less importance for the glass phase.
Both materials enable at least 4mm thick increments to be cured in one step under clinically relevant curing conditions.
The susceptibility to variation in irradiance was material dependent, thus properties measured under clinically simulated curing conditions might vary to a different extent from those measured under ideal curing conditions.
在模拟临床相关充填深度的条件下，评估光固化头的照射时间和距离对两种大块充填树脂基复合材料的微观力学性能及聚合动力学的影响。
在不同深度（弹性模量和维氏硬度以100μm步长从0.1 - 6mm变化，固化度以0.1、2、4和6mm变化）、照射时间（10、20或40秒，Elipar Freelight2）以及距光固化头的距离（0和7mm）条件下，评估两种大块充填树脂基复合材料（Tetric EvoCeram(®) Bulk Fill，义获嘉伟瓦登特公司；x-tra base，VOCO公司）的微观力学性能（维氏硬度（HV）、固化深度（DOC）和压痕模量（E））及聚合动力学（固化度（DC）的实时增加）。在实验室级光谱仪上，在距光固化头最远10mm处，以1mm步长监测固化单元的辐照度。
采用多变量分析（α = 0.05）、学生t检验和皮尔逊相关分析。材料对所测力学性能的影响显著（弹性模量的η(2)=0.080，维氏硬度的η(2)=0.256），而照射时间、距光固化头的距离和深度参数对Tetric EvoCeram(®) Bulk Fill的影响更强。聚合动力学可用指数和函数描述，可区分凝胶相和玻璃相。上述参数对聚合起始（凝胶相）影响强烈，对玻璃相影响较小。
在临床相关固化条件下，两种材料均可一步固化至少4mm厚的增量。
辐照度变化的敏感性因材料而异,因此在临床模拟固化条件下测得的性能可能与在理想固化条件下测得的性能在不同程度上有所不同。
