Universidade Guarulhos, Centro de Pós Graduação e Pesquisa, Guarulhos, SP, Brasil.
Universidade Estadual de Ponta Grossa, Departamento de Odontologia, Ponta Grossa, PR, Brasil.
J Appl Oral Sci. 2017 Mar-Apr;25(2):140-146. doi: 10.1590/1678-77572016-0388.
Using Fourier transform infrared analysis (FTIR) in vitro, the effects of varying radiant exposure (RE) values generated by second and third generation LED LCUs on the degree of conversion (DC) and maximum rate of polymerization (Rpmax) of an experimental Lucirin TPO-based RC were evaluated.
1 mm or 2 mm thick silicon molds were positioned on a horizontal attenuated total reflectance (ATR) unit attached to an infrared spectroscope. The RC was inserted into the molds and exposed to varying REs (18, 36 and 56 J/cm2) using second (Radii Plus, SDI) and third generation LED LCUs (Bluephase G2/Ivoclar Vivadent) or a quartz tungsten based LCU (Optilux 501/SDS Kerr). FTIR spectra (n=7) were recorded for 10 min (1 spectrum/s, 16 scans/spectrum, resolution 4 cm-1) immediately after their application to the ATR. The DC was calculated using standard techniques for observing changes in aliphatic to aromatic peak ratios both prior to, and 10 min after curing, as well as during each 1 second interval. DC and Rpmax data were analyzed using 3-way ANOVA and Tukey's post-hoc test (p=0.05).
No significant difference in DC or Rpmax was observed between the 1 mm or 2 mm thick specimens when RE values were delivered by Optilux 501 or when the 1 mm thick composites were exposed to light emitted by Bluephase G2, which in turn promoted a lower DC when 18 J/cm2 (13 s) were delivered to the 2 mm thick specimens. Radii Plus promoted DC and Rpmax values close to zero under most conditions, while the delivery of 56 J/cm2 (40 s) resulted in low DC values.
The third generation LCU provided an optimal polymerization of Lucirin TPO-based RC under most tested conditions, whereas the second generation LED-curing unit was useless regardless of the RE.
通过傅里叶变换红外分析（FTIR）体外，评估第二代和第三代 LED LCU 产生的不同辐射暴露（RE）值对实验性 Lucirin TPO 基 RC 转化率（DC）和最大聚合速率（Rpmax）的影响。
将 1 毫米或 2 毫米厚的硅模具放置在水平衰减全反射（ATR）单元上，该单元连接到红外光谱仪。将 RC 插入模具中，并使用第二代（Radii Plus，SDI）和第三代 LED LCU（Bluephase G2/Ivoclar Vivadent）或石英钨基 LCU（Optilux 501/SDS Kerr）以不同的 RE（18、36 和 56 J/cm2）进行暴露。FTIR 光谱（n=7）在应用于 ATR 后立即记录 10 分钟（1 光谱/s，16 次扫描/光谱，分辨率 4 cm-1）。使用标准技术计算 DC，以观察固化前后脂肪族峰与芳香族峰比值的变化，以及每个 1 秒间隔的变化。使用 3 因素方差分析和 Tukey 事后检验（p=0.05）分析 DC 和 Rpmax 数据。
当使用 Optilux 501 输送 RE 值或当 1 毫米厚的复合材料暴露在 Bluephase G2 发射的光下时，1 毫米厚的标本之间的 DC 或 Rpmax 没有差异，这反过来又导致当将 18 J/cm2（13 s）输送到 2 毫米厚的标本时，DC 较低。Radii Plus 在大多数情况下促进了接近零的 DC 和 Rpmax 值，而输送 56 J/cm2（40 s）则导致 DC 值较低。
在大多数测试条件下，第三代 LCU 提供了 Lucirin TPO 基 RC 的最佳聚合，而第二代 LED 固化单元无论 RE 值如何都是无用的。
