Objective

To measure the degrees of conversion (DC), conversion kinetics, and the effect of post-irradiation time on rapid photo-polymerized bulk-fill resin composites under conditions equivalent to clinical depths of 1 and 4 mm.

Methods

36 specimens (n = 3), based on two resin composites incorporating PowerCure rapid-polymerization technology in two consistencies (PFill; PFlow) and two comparators with matching consistencies (Eceram; EFlow), were investigated from the same manufacturer (Ivoclar AG, Liechtenstein). Specimens were prepared within 4 mm diameter cylindrical molds, of either 1 mm or 4 mm depths respectively, to simulate near-surface and deep locations in a bulk-fill restoration. The independent variables in this study were: materials, thickness and time. Two high irradiance polymerization protocols were utilized for PowerCure materials: 2000 and 3050 mW/cm² for 5 and 3 s, respectively. A standard (1200 mW/cm²) polymerization protocol was used with control materials. FTIR was utilized to measure DC in real-time for 24 h post-irradiation. The data were analyzed using Welch’s-ANOVA, Games-Howell post-hoc test, kinetic dual-exponential sum function and independent sample t-tests (p = 0.05).

Results

The DC of the materials ranged between 44.7–59.0 % after 5 min, which increased after 24 h reaching 55.7–71.0 % (p < 0.05). Specimen thickness did not influence the overall DC. At 5 min, the highest DC was shown in EFlow. But PFlow, irradiated for 3 s and 5 s exhibited comparable results (p > 0.05). PFill composite irradiated with the 3 s and 5 s protocols did not differ from ECeram (p > 0.05). Specimen thickness and material viscosity affected polymerization kinetics and rate of polymerization (RP_max). Faster polymerization occurred in 1 mm specimens (except PFill-5 s and ECeram). PFill and PFlow exhibited faster conversion than the controls. RP_max varied across the specimen groups between 4.3–8.8 %/s with corresponding DC _RPmax between 22.2–45.3 %.

Significance

Polymerization kinetics and RP_max were influenced by specimen thickness and material viscosity. PFill and PFlow materials produced an overall comparable conversion at 5 min and 24 h post-irradiation, despite the ultra-short irradiation times, throughout the 4 mm specimen thickness.

中文翻译：

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快速光聚合树脂复合材料的转化动力学。

目的

为了测量转化度（DC），转化动力学以及辐照后时间在相当于临床深度为1和4 mm的条件下对快速光聚合本体填充树脂复合材料的影响。

方法

对来自同一制造商（Ivoclar AG，列支敦士登）的36个样品（n = 3）进行了研究，该样品基于两种采用PowerCure快速聚合技术的树脂复合材料，具有两个浓度（PFill; PFlow）和两个具有匹配浓度的比较器（Eceram; EFlow） ）。在直径分别为1mm或4mm的4mm直径的圆柱形模具中制备样品，以模拟大块填充物修复体中的近表面和深处。这项研究中的独立变量是：材料，厚度和时间。PowerCure材料采用了两种高辐照度聚合方案：分别为2000和3050 mW / cm ²进行5 s和3 s。标准（1200 mW / cm ²）聚合规程与对照材料一起使用。FTIR用于在辐照后24小时内实时测量DC。使用Welch的-ANOVA，Games-Howell事后检验，动力学双指数和函数和独立样本t检验对数据进行了分析（p = 0.05）。

结果

材料的DC在5分钟后介于44.7-59.0％之间，在24小时后增加，达到55.7-71.0％（p <0.05）。样品厚度不影响总DC。在5分钟时，EFlow中显示了最高DC。但是，PFlow照射3 s和5 s表现出可比的结果（p> 0.05）。用3 s和5 s方案辐照的PFill复合材料与ECeram无差异（p> 0.05）。试样厚度和材料粘度影响聚合动力学和聚合速率（RP _max）。1 mm样品中发生了更快的聚合反应（PFill-5 s和ECeram除外）。PFill和PFlow的转化速度快于对照。整个样本组的RP _max在4.3–8.8％/ s之间变化，相应的DC _RPmax在22.2〜45.3％之间。

意义

聚合动力学和RP _max受样品厚度和材料粘度的影响。尽管辐照时间超短，但在整个4 mm样品厚度中，PFill和PFlow材料在辐照后5分钟和24 h产生了总体可比的转化率。