Par Matej, Marovic Danijela, Attin Thomas, Tarle Zrinka, Tauböck Tobias T
Department of Conservative and Preventive Dentistry, Center for Dental Medicine, University of Zurich, Plattenstrasse 11, Zurich, Switzerland; Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia.
Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia.
J Dent. 2020 Oct;101:103448. doi: 10.1016/j.jdent.2020.103448. Epub 2020 Aug 7.
To compare the effect of high-intensity (3 s with 3440 mW/cm) and conventional (10 s with 1340 mW/cm) light-curing on shrinkage properties and degree of conversion of conventional and bulk-fill resin composites, including two composites specifically designed for high-intensity curing.
Real-time linear shrinkage and shrinkage force of 1.5 mm thick composite specimens were measured for 15 min after the start of light-curing using custom-made devices. From the shrinkage force data, maximum shrinkage force rate and time to achieve maximum shrinkage force rate were determined. Degree of conversion was measured using Fourier transform infrared spectrometry.
Flowable composites showed significantly higher linear shrinkage compared to sculptable composites (1.93-2.91 % vs. 1.15-1.54 %), as well as significantly higher shrinkage forces (18.7-24.4 N vs. 13.5-17.0 N). Degree of conversion amounted to 45.8-60.1 %. For high-intensity curing, degree of conversion was significantly lower in three out of seven composites, whereas shrinkage forces were either increased, decreased, or unchanged compared to conventional curing. For high-intensity curing, maximum shrinkage rates were 6-61 % higher, whereas times to achieve maximum shrinkage force rate were 15-53 % shorter compared to conventional curing. Composites specifically designed for high-intensity curing showed shrinkage parameters comparable to other investigated composites.
Shrinkage behavior under conditions of high-intensity light-curing was material-dependent. Shrinkage force kinetics were more strongly affected by high-intensity curing than absolute values of linear shrinkage and shrinkage force.
Despite being attractive for its convenience, high-intensity curing can lead to considerably faster development of shrinkage forces in the early stage of polymerization.
比较高强度（3秒，3440毫瓦/平方厘米）和传统（10秒，1340毫瓦/平方厘米）光固化对传统树脂复合材料和大块充填树脂复合材料收缩性能及转化率的影响，其中包括两种专门为高强度固化设计的复合材料。
使用定制设备在光固化开始后15分钟测量1.5毫米厚复合材料试样的实时线性收缩和收缩力。根据收缩力数据，确定最大收缩力速率和达到最大收缩力速率的时间。使用傅里叶变换红外光谱法测量转化率。
可流动复合材料的线性收缩明显高于可雕刻复合材料（1.93 - 2.91%对1.15 - 1.54%），收缩力也明显更高（18.7 - 24.4牛对13.5 - 17.0牛）。转化率为45.8 - 60.1%。对于高强度固化，七种复合材料中有三种的转化率明显较低，而与传统固化相比，收缩力要么增加、要么降低、要么不变。对于高强度固化，最大收缩速率比传统固化高6 - 61%，而达到最大收缩力速率的时间比传统固化短15 - 53%。专门为高强度固化设计的复合材料的收缩参数与其他研究的复合材料相当。
高强度光固化条件下的收缩行为取决于材料。与线性收缩和收缩力的绝对值相比，收缩力动力学受高强度固化的影响更大。
尽管高强度固化因其便利性具有吸引力，但在聚合早期可导致收缩力的发展明显加快。
