Objective

This study evaluates critical material properties resulting from ultra-fast (3 s) photo-polymerization at high radiant emittance of a pre-production, novel bulk-fill resin-based composite (RBC) modified for reversible addition-fragmentation chain transfer (RAFT) polymerization.

Methods

The output characteristics of the associated light curing unit (LCU) were measured on a laboratory-grade spectrometer. Real-time Fourier Transform Infrared Spectroscopy (FTIR) and mechanical investigations (depth-sensing indentation with a linear and spatial distribution of the measured properties, and three-point bend tests) were performed using, as reference material, an established bulk-fill RBC of comparable chemical composition. Micro-mechanical properties were mapped to quantify material tolerance to sub-optimal curing conditions (exposure distance of 5 mm and an angulation of the LCU of 20° and 30°) vs. ideal curing conditions (exposure distance of 0 mm and no angulation), with 3 s polymerization. Weibull statistics, one- and multiple-way analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) post hoc-test (α = 0.05) were used for data comparison.

Results

The change in cure mechanism to RAFT polymerisation gave slightly faster initial polymerisation kinetics, but DC measured 300 s post irradiation was similar, irrespective of material, curing depth or polymerisation condition. Slightly better polymerisation, in layers thicker than 4-mm, was identified in the RAFT polymerised RBC. However, slightly lower flexural modulus and hardness, up to 1.5-mm subsurface, were related to the ca. one wt.% lower inorganic filler content.

Significance

RAFT polymerisation induced comparable properties to a RBC cured via free radical polymerisation of comparable chemical composition. The RAFT polymerised RBC with high irradiance for 3 s was equivalent to 10 s of moderate irradiance. However, the clinical tolerance for 3 s irradiance should be limited to an exposure distance of 5-mm and angulation of the LCU should be avoided. If this is not possible, an additional 3 s polymerisation is recommended.

中文翻译：

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RAFT改性树脂复合材料中超快（3 s）光固化的结果。

目的

这项研究评估了用于可逆加成-断裂链转移（RAFT）的新型预生产，新型填充树脂基复合材料（RBC）在高辐射发射下的超快（3 s）光聚合产生的关键材料性能聚合。

方法

相关的光固化单元（LCU）的输出特性是在实验室级光谱仪上测量的。实时傅立叶变换红外光谱（FTIR）和机械研究（具有测量特性的线性和空间分布的深度感应压痕，以及三点弯曲测试）使用已建立的填充体RBC作为参考材料进行具有可比较的化学组成。微机械性能映射到量化的材料耐受亚最佳固化条件（5毫米曝光距离和的20°和30°的LCU的角度）VS。理想的固化条件（曝光距离为0 mm，无角度），聚合3 s。事后检验（α = 0.05）使用Weibull统计，方差单向和多方分析（ANOVA）和Tukey诚实诚实差异（HSD）进行数据比较。

结果

RAFT聚合固化机理的变化使初始聚合动力学稍快一些，但辐照后300 s测得的DC相似，无论材料，固化深度或聚合条件如何。在RAFT聚合的RBC中，发现厚度大于4毫米的聚合略好。但是，弯曲模量和硬度略低一些，直至地下1.5毫米，都与约2,000毫米有关。无机填料含量降低1 wt。％。

意义

RAFT聚合引发的化学性质与通过类似化学组成的自由基聚合固化的RBC相当。具有3秒钟高辐照度的RAFT聚合RBC相当于10秒钟中等辐照度。但是，对3 s辐照的临床耐受性应限于5 mm的暴露距离，并应避免LCU成角度。如果不可能，建议再聚合3 s。