Benetti Ana R, Asmussen Erik, Munksgaard E Christian, Dewaele Magali, Peutzfeldt Anne, Leloup Gaëtane, Devaux Jacques
School of Dentistry, Universidade Norte do Paraná (UNOPAR), PR, Brazil.
Dent Mater. 2009 Aug;25(8):1007-13. doi: 10.1016/j.dental.2009.01.104. Epub 2009 Apr 16.
The purpose of this study was to investigate the effect of light-curing protocol on softening and elution of monomers in ethanol as measured on a model polymer. It was a further aim to correlate the measured values with previously reported data on degree of conversion and glass transition temperature for the same polymer and curing protocols.
Different light-curing protocols were used in order to investigate the influence of energy density, power density, and mode of cure on the properties of a model polymer. The modes of cure were continuous, pulse-delay, and stepped irradiation of the specimens. Wallace hardness was used to determine the softening of the polymer after storage in ethanol for 24h. Elution of monomers from the polymer was assessed after 7 days in ethanol by means of high-pressure liquid chromatography (HPLC). Data were submitted to two- and three-way analysis of variance (ANOVA), Newman-Keuls' multiple comparison test, and linear regression analysis.
Energy density, power density, and mode of cure of the polymer influenced the softening and elution of monomers in ethanol. As energy density increased, softening and elution in ethanol decreased. At same energy density, the influence of power density varied with the mode of cure. When compared to the continuous mode of cure, and at same energy density, pulse-delay irradiation resulted in polymers that in general were more susceptible to softening, but eluted monomers to a lower extent. Less elution was also found with step-cured polymers. Significant, negative correlations were detected between softening and elution in ethanol, respectively, and degree of conversion and between softening and elution in ethanol, respectively, and glass transition temperature.
A complex relationship exists between curing protocol and the properties selected for investigation. The effect of different combinations of exposure periods and power densities are important to understanding how the curing protocol affects the properties of polymer-based materials.
本研究旨在通过对一种模型聚合物的测试，探究光固化方案对乙醇中单体软化和洗脱的影响。另一个目的是将测量值与先前报道的相同聚合物及固化方案的转化率和玻璃化转变温度数据相关联。
采用不同的光固化方案，以研究能量密度、功率密度和固化模式对模型聚合物性能的影响。固化模式包括对样品进行连续、脉冲延迟和分步照射。通过华莱士硬度来测定聚合物在乙醇中储存24小时后的软化情况。在乙醇中放置7天后，通过高压液相色谱法（HPLC）评估聚合物中单体的洗脱情况。数据进行双因素和三因素方差分析（ANOVA）、纽曼-基尔斯多重比较检验以及线性回归分析。
聚合物的能量密度、功率密度和固化模式影响乙醇中单体的软化和洗脱。随着能量密度增加，乙醇中的软化和洗脱减少。在相同能量密度下，功率密度的影响因固化模式而异。与连续固化模式相比，在相同能量密度下，脉冲延迟照射导致的聚合物通常更易软化，但单体洗脱程度较低。分步固化的聚合物洗脱量也较少。分别在乙醇中的软化与洗脱和转化率之间，以及乙醇中的软化与洗脱和玻璃化转变温度之间检测到显著的负相关。
固化方案与所选择的研究性能之间存在复杂关系。曝光时间和功率密度的不同组合的影响对于理解固化方案如何影响聚合物基材料的性能很重要。
