Gen Dent. 2024 Sep-Oct;72(5):49-53.
This in vitro study evaluated the influence of radiant exposure and material shade on the degree of conversion (DC) and microhardness of a resin-based composite (RBC). Sixty-four RBC specimens in shades A1E (enamel) and A4D (dentin) were light cured at a calibrated exitance of 1000 mW/cm for 5, 10, 15, or 20 seconds, resulting in radiant exposure levels of 5, 10, 15, or 20 J/cm. The DC was determined using Fourier-transform infrared spectroscopy (n = 3 per shade per exposure level). The Knoop hardness number (KHN) was measured on the top and bottom surfaces of each specimen (n = 5 per shade per exposure level). Data were analyzed using 2- and 3-way analyses of variance and post hoc Tukey tests (α = 0.05). The RBC shade did not affect the DC (P = 0.860), and the lowest DC values were achieved with an exposure level of 5 J/cm (P < 0.001). The shade did not affect the KHN on the top surface, but the radiant exposure level did, with the application of 5 J/cm resulting in significantly lower values (P < 0.05). For the bottom surface, shade A1E showed significantly higher KHN values than A4D (P < 0.001). An increase in the radiant exposure led to increased DC and KHN for both shades of RBC until reaching a saturation point of 10 J/cm for A1E and the top surface of A4D. The darker and more opaque shade was not adequately polymerized at a 2-mm depth, even when the highest radiant exposure level was applied.
这项体外研究评估了辐射剂量和材料遮光度对一种树脂基复合材料（RBC）的聚合度（DC）和显微硬度的影响。将 64 个 RBC 样本分别置于 A1E（牙釉质）和 A4D（牙本质）色调中，以校准后的出射光强度 1000 mW/cm 进行光固化，时间分别为 5、10、15 或 20 秒，从而产生 5、10、15 或 20 J/cm 的辐射剂量。使用傅里叶变换红外光谱法（每个暴露水平下每种色调各 3 个样本）测定 DC。在每个样本的顶面和底面测量维氏硬度数（KHN）（每个暴露水平下每种色调各 5 个样本）。使用 2 因素和 3 因素方差分析以及事后 Tukey 检验（α=0.05）分析数据。RBC 色调不影响 DC（P=0.860），5 J/cm 的最低辐射剂量水平下获得的 DC 值最低（P<0.001）。该色调不影响顶面的 KHN，但辐射剂量水平有影响，5 J/cm 时显著降低（P<0.05）。对于底面，A1E 色调的 KHN 值明显高于 A4D（P<0.001）。两种 RBC 色调的辐射剂量增加均导致 DC 和 KHN 增加，直至 A1E 的 10 J/cm 和 A4D 顶面达到饱和点。即使使用最高辐射剂量水平，颜色更深、更不透明的色调在 2mm 深度也无法充分聚合。
