Objective

The aim of this in vitro study was to test the effect of different composite modulation protocols (pre-heating, light-curing time and oligomer addition) for bulk filling techniques on resin polymerization stress, intra-pulpal temperature change and degree of conversion.

Methods

Class I cavities (4 mm depth × 5 mm diameter) were prepared in 48 extracted third molars and divided in 6 groups. Restorations were completed with a single increment, according to the following groups: (1) Filtek Z250XT (room temperature – activated for 20 s); (2) Filtek Z250XT (at room temperature – activated for 40 s); (3) Filtek Z250XT (pre-heated at 68 °C – activated for 20 s); (4) Filtek Z250XT (pre-heated at 68 °C – activated for 40 s); (5) Filtek BulkFill (at room temperature – activated for 20 s); (6) Filtek Z250XT (modified by the addition of a thio-urethane oligomer at room temperature – activated for 40 s). Acoustic emission test was used as a real-time polymerization stress (PS) assessment. The intra-pulpal temperature change was recorded with a thermocouple and bottom/top degree of conversion (DC) measured by Raman spectroscopy. Data were analyzed with one-way ANOVA/Tukey's test (α = 5%).

Results

Pre-heating the resin composite did not influence the intra-pulpal temperature (p = 0.077). The thio-urethane-containing composite exhibited significantly less PS, due to a lower number of acoustic events. Groups with pre-heated composites did not result in significantly different PS. Filtek BulkFill and the thio-urethane experimental composite presented significantly higher DC.

Significance

Resin composite pre-heating was not able to reduce polymerization stress in direct restorations. However, thio-urethane addition to a resin composite could reduce the polymerization stress while improving the DC.

中文翻译：

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不同复合调制方案对整体填充树脂修复体的转化和聚合应力分布的影响。

 客观的

这项体外研究的目的是测试散装填充技术的不同复合调制方案（预热、光固化时间和低聚物添加）对树脂聚合应力、牙髓内温度变化和转化程度的影响。

 方法

在 48 颗拔除的第三磨牙中制备 I 类蛀牙（深度 4 mm × 直径 5 mm），并分为 6 组。根据以下组，以单次增量完成修复： (1) Filtek Z250XT（室温 - 激活 20 秒）； (2) Filtek Z250XT（室温下 – 激活 40 秒）； (3) Filtek Z250XT（68℃预热——激活20秒）； (4) Filtek Z250XT（68℃预热——激活40秒）； (5) Filtek BulkFill（室温下 – 激活 20 秒）； (6) Filtek Z250XT（通过在室温下添加硫代氨基甲酸酯低聚物进行改性 - 激活 40 秒）。声发射测试用作实时聚合应力（PS）评估。用热电偶记录牙髓内温度变化，并通过拉曼光谱测量底部/顶部转化度（DC）。数据采用单向方差分析/Tukey 检验（ α = 5%）进行分析。

 结果

预热树脂复合材料不会影响牙髓内温度（ p = 0.077）。由于声学事件数量较少，含硫代氨基甲酸酯的复合材料表现出明显较低的 PS。具有预热复合材料的组并未产生显着不同的 PS。 Filtek BulkFill 和硫代聚氨酯实验复合材料呈现出明显更高的 DC。

 意义

树脂复合材料预热无法降低直接修复体中的聚合应力。然而，在树脂复合材料中添加硫代氨基甲酸酯可以降低聚合应力，同时提高 DC。