Par M, Repusic I, Skenderovic H, Sever E Klaric, Marovic D, Tarle Z
Oper Dent. 2018 Jan/Feb;43(1):E19-E31. doi: 10.2341/17-041-L.
To monitor the real-time changes in light transmittance during composite curing and to use transmittance data to determine the curing times required for a complete polymerization.
Three conventional and three bulk fill composites were cured with two light-emitting diode curing units at layer thicknesses of 2 mm and 4 mm. The real-time light transmittance data were collected by a UV-Vis spectrometer in the wavelength range of 350-550 nm, plotted against time (t) and fitted to an exponential function f(t), whose first derivative ΔT(t) = df(t)/dt represented the rate of transmittance change. As the changing transmittance reflects structural changes that occur during polymerization, ΔT(t) > 0 was considered to indicate an ongoing polymerization, whereas ΔT(t) values approaching zero suggested a complete polymerization. This principle was used to determine times required for a complete polymerization (t) for each material/thickness/curing unit combination.
Light transmittance was significantly influenced by the material type, sample thickness, and curing unit, amounting to 2.9%-27.0% for the bulk fill and 0.7%-16.7% for the conventional composites. The values of t amounted to 15.3-23.3 seconds for the bulk fill composites at 2 mm, 20.2-33.3 seconds for the conventional composites at 2 mm, 26.9-42.1 seconds for the bulk fill composites at 4 mm, and 40.1-59.8 seconds for the conventional composites at 4 mm. Additionally, an exponential relationship was discovered between the light transmittance and t.
Some of the t values considerably exceeded the curing times recommended by the manufacturers.
监测复合树脂固化过程中透光率的实时变化，并利用透光率数据确定完全聚合所需的固化时间。
使用两个发光二极管固化装置，以2毫米和4毫米的层厚对三种传统复合树脂和三种大块充填复合树脂进行固化。通过紫外可见光谱仪在350 - 550纳米波长范围内收集实时透光率数据，绘制透光率随时间（t）的变化曲线，并拟合为指数函数f(t)，其一阶导数ΔT(t) = df(t)/dt表示透光率变化率。由于透光率的变化反映了聚合过程中发生的结构变化，ΔT(t) > 0被认为表明正在进行聚合，而ΔT(t)值接近零则表明聚合完成。该原理用于确定每种材料/厚度/固化装置组合完全聚合所需的时间（t）。
透光率受材料类型、样品厚度和固化装置的显著影响，大块充填复合树脂的透光率变化为2.9% - 27.0%，传统复合树脂为0.7% - 16.7%。2毫米厚的大块充填复合树脂的t值为15.3 - 23.3秒，2毫米厚的传统复合树脂为20.2 - 33.3秒，4毫米厚的大块充填复合树脂为26.9 - 42.1秒，4毫米厚的传统复合树脂为40.1 - 59.8秒。此外，还发现透光率与t之间存在指数关系。
一些t值大大超过了制造商推荐的固化时间。
